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| Sun Java System Message Queue 3.5 SP1 C Client Developer's Guide | |
Chapter 4
ReferenceThis chapter provides reference documentation for the Message Queue C-API. It includes information about the following:
- Data Types describes the C declarations for data types used by Message Queue messaging
- Function Reference describes the C functions that implement Message Queue messaging
- Header Files describes the contents of the C-API header files
For information on building C-Message Queue programs, see Chapter 2, "Building and Running Message Queue C Clients".
For information on how you use the C-API to complete specific programming tasks, see Chapter 3, "Using the C API".
Data TypesTable 4-1 summarizes the data types defined by the Message Queue C-API. The table lists data types in alphabetical order and provides cross references for types that require broader discussion.
Note that Message Queue data types designated as handles map to opaque structures (objects). Please do not attempt to dereference these handles to get to the underlying objects. Instead, use the functions provided to access the referenced objects.
Table 4-1 Message Queue C-API Data Type Summary
MQType
Description
ConstMQString
A constant MQString.
MQAckMode
An enum used to specify the acknowledgement mode of a session. Possible values include the following:
MQ_AUTO_ACKNOWLEDGE
MQ_CLIENT_ACKNOWLEDGE
MQ_DUPS_OK_ACKNOWLEDGE
MQ_SESSION_TRANSACTED.See Acknowledge Modes for more information.
MQBool
A boolean that can assume one of two values:
MQ_TRUE(=1)
MQ_FALSE(=0).MQChar
char type.
MQConnectionHandle
A handle used to reference a Message Queue connection. You get this handle when you call the MQCreateConnection function.
MQConsumerHandle
A handle used to reference a Message Queue consumer. A consumer can be durable, nondurable and synchronous, or asynchronous. You get this handle when you call one of the functions used to create consumers. See Receiving Messages for more information.
MQDeliveryMode
An enum used to specify whether a message is sent persistently:
MQ_NON_PERSISTENT_DELIVERY
MQ_PERSISTENT_DELIVERY.You specify this value with the MQSendMessageExt function or the MQSendMessageToDestinationExt function.
MQDestinationHandle
A handle used to reference a Message Queue destination. You get this handle when you call the MQCreateDestination function or the MQCreateTemporaryDestination function.
MQDestinationType
An enum used to specify the type of a destination:
MQ_QUEUE_DESTINATION
MQ_TOPIC_DESTINATION.You set the destination type using the MQCreateDestination function or the MQCreateTemporaryDestination function.
MQError
A 32-bit unsigned integer.
MQConnectionExceptionListenerFunc
The type of a callback function used for connection exception handling. For more information, see Callback Type for Connection Exception Handling.
MQFloat32
A 32-bit floating-point number.
MQFloat64
A 64-bit floating-point number.
MQInt16
A 16-bit signed integer.
MQInt32
A 32-bit signed integer.
MQInt64
A 64-bit signed integer.
MQInt8
An 8-bit signed integer.
MQMessageHandle
A handle used to reference a Message Queue message. You get this handle when you call the MQCreateBytesMessage function, or the MQCreateTextMessage function, or on receipt of a message.
MQMessageListenerFunc
The type of a callback function used for asynchronous message receipt. For more information, see Callback Type for Asynchronous Messaging.
MQMessageType
An enum passed back by the MQGetMessageType and used to specify the type of a message; possible values include the following:
MQ_TEXT_MESSAGE
MQ_BYTES_MESSAGE
MQ_UNSUPPORTED_MESSAGE.MQProducerHandle
A handle used to reference a Message Queue producer. You get this handle when you call MQCreateMessageProducer or MQCreateMessageProducerForDestination.
MQPropertiesHandle
A handle used to reference Message Queue properties. You use this handle to define or read connection properties and message headers or message properties. See Working With Properties for more information.
MQReceiveMode
An enum used to specify whether consumers are synchronous or asynchronous. It can be one of the following:
MQ_SESSION_SYNC_RECEIVE
MQ_SESSION_ASYNC_RECEIVE.See MQCreateSession for more information.
MQSessionHandle
A handle used to reference a Message Queue session. You get this handle when you call the MQCreateSession function.
MQStatus
A data type returned by nearly all functions defined in mqcrt.h. See Error Handling for more information on how you handle errors returned by Message Queue functions.
MQString
A null terminated UTF-8 encoded character string
MQType
An enum used to return the type of a single property; possible values include the following:
MQ_BOOL_TYPE
MQ_INT8_TYPE
MQ_INT16_TYPE
MQ_INT32_TYPE
MQ_INT64_TYPE
MQ_FLOAT32_TYPE
MQ_FLOAT64_TYPE
MQ_STRING_TYPE
MQ_INVALID_TYPE
Connection Properties
When you create a connection using the MQCreateConnection function, you must pass a handle to an object of type MQPropertiesHandle. To set the properties referenced by this handle, you do the following:
- Call the MQCreateProperties function to get a handle to a newly created properties object
- Call a function to set one of the connection properties listed in Table 4-2.
Which function you call depends on the type of the property you want to set; for example, to set an MQString property, you call the MQSetStringProperty function; to set a MQBool property, you call the MQSetBoolProperty function; and so on. Each function that sets a property requires that you pass a key name (constant) and value; these are listed and described in Table 4-2.
- When you have set all the properties you want to define for the connection, you can then create the connection, by calling the MQCreateConnection function.
The runtime library sets the connection properties that specify the name and version of the Message Queue product; you can retrieve these using the MQGetMetaData function. These properties are described at the end of Table 4-2, starting with MQ_NAME_PROPERTY.
Table 4-2 Connection Properties
Key Name
Description
MQ_CONNECTION_TYPE_PROPERTY
An MQString specifying the transport protocol of the connection service used by the client. Supported types are TCP or SSL.
Default: TCP
MQ_ACK_TIMEOUT_PROPERTY
A 32-bit integer specifying the maximum time in milliseconds that the client runtime will wait for any broker acknowledgement before returning an MQ_TIMEOUT_EXPIRED error. A value of 0 means there is no time-out.
Default: 0
MQ_BROKER_HOST_PROPERTY
An MQString specifying the broker host name to which to connect.
No default.
MQ_BROKER_PORT_PROPERTY
A 32-bit integer specifying the broker’s primary port number.
No default.
MQ_ACK_ON_PRODUCE_PROPERTY
An MQBool specifying whether the producing client waits for broker acknowledgement of receipt of message from the producing client.
If set to MQ_TRUE, the broker acknowledges receipt of all messages (persistent and non-persistent) from the producing client, and the producing client thread will block waiting for those acknowledgements.
If set to MQ_FALSE, broker does not acknowledge receipt of any message (persistent or non-persistent) from the producing client, and the producing client thread will not block waiting for broker acknowledgements.
Default: the broker acknowledges receipt of persistent messages only from the producing client, and the producing client thread will block waiting for those acknowledgements.
MQ_ACK_ON_ACKNOWLEDGE_PROPERTY
An MQBool specifying whether the broker confirms (acknowledges) consumer acknowledgements. A consumer acknowledgement can be initiated either by the client’s session or by the consuming client, depending on the session acknowledgement mode (see Table 4-3). If the session’s acknowledgement mode is MQ_DUPS_OK_ACKNOWLEDGE, this flag has no effect.
If set to MQ_TRUE, the broker acknowledges all consuming acknowledgements, and the consuming client thread blocks waiting for these broker acknowledgements.
If set to MQ_FALSE, the broker does not acknowledge any consuming client acknowledgements, and the consuming client thread will not block waiting for such broker acknowledgements.
Default: MQ_TRUE
For more information, see the discussion for the MQAcknowledgeMessages function and Message Acknowledgement.
MQ_CONNECTION_FLOW_COUNT_PROPERTY
A 32-bit integer, greater than 0, specifying the number of Message Queue messages in a metered batch. When this number of messages is delivered from the broker to the client runtime, delivery is temporarily suspended, allowing any control messages that had been held up to be delivered. Payload message delivery is resumed upon notification by the client runtime, and continues until the count is again reached.
Default: 100
MQ_CONNECTION_FLOW_LIMIT_ENBABLED
_PROPERTYAn MQBool specifying whether the value MQ_CONNECTION_FLOW_LIMIT_PROPERTY is used to control message flow. Specify MQ_TRUE to use the value and MQ_FALSE otherwise.
Default: MQ_FALSE
MQ_CONNECTION_FLOW_LIMIT_PROPERTY
A 32-bit integer, greater than 0, specifying the maximum number of unconsumed messages the client runtime can hold for each connection. Note however, that unless MQ_CONNECTION_FLOW_LIMIT_ENBABLED_PROPERTY is MQ_TRUE, this limit is not checked.
When the number of unconsumed messages held by the client runtime for the connection exceeds the limit, message delivery stops. It is resumed (in accordance with the flow metering governed by MQ_CONNECTION_FLOW_COUNT_PROPERTY) only when the number of unconsumed messages drops below the value set with this property.
This limit prevents a consuming client that is taking a long time to process messages from being overwhelmed with pending messages that might cause it to run out of memory.
Default: 1000
MQ_SSL_BROKER_IS_TRUSTED
An MQ_Bool specifying whether the broker is trusted.
Default: MQ_TRUE
MQ_SSL_CHECK_BROKER_FINGERPRINT
An MQ_Bool. If it is set to MQ_TRUE and if MQ_SSL_BROKER_IS_TRUSTED is MQ_FALSE, the broker’s certificate fingerprint is compared with the MQ_SSL_BROKER_CERT_FINGERPRINT property value in case of certificate authorization failure. If they match, the broker’s certificate is authorized for use in the SSL connection.
Default: MQ_FALSE
MQ_SSL_BROKER_CERT_FINGERPRINT
An MQString specifying the MD5 hash, in hex format, of the broker's certificate.
Default: NULL
MQ_NAME_PROPERTY
An MQString that specifies the name of the Message Queue product.This property is set by the runtime library. See the MQGetMetaData function for more information.
MQ_VERSION_PROPERTY
An MQInt32 that specifies the version of the Message Queue product. This property is set by the runtime library. See the MQGetMetaData function for more information.
MQ_MAJOR_VERSION_PROPERTY
An MQInt32 that specifies the major version of the Message Queue product. For example, if the version is 3.5.0.1, the major version would be 3.
This property is set by the runtime library. See the MQGetMetaData function for more information.
MQ_MINOR_VERSION_PROPERTY
An MQInt32 that specifies the minor version of the Message Queue product. For example, if the version is 3.5.0.1, the minor version would be 5.
This property is set by the runtime library. See the MQGetMetaData function for more information.
MQ_MICRO_VERSION_PROPERTY
An MQInt32 that specifies the micro version of the Message Queue product. For example, if the version is 3.5.0.1, the micro version would be 0.
This property is set by the runtime library. See the MQGetMetaData function for more information.
MQ_SERVICE_PACK_PROPERTY
An MQInt32 that specifies the service pack version of the Message Queue product. For example, if the version is 3.5.0.1, the service pack version would be 1.
This property is set by the runtime library. See the MQGetMetaData function for more information.
Acknowledge Modes
The Message Queue runtime supports reliable delivery by using transacted sessions or through acknowledgement options set at the session level. When you use the MQCreateSession function to create a session, you must specify an acknowledgement option for that session using the acknowledgeMode parameter. The value of this parameter is ignored for transacted sessions.
Table 4-3 describes the effect of the options you can set using the acknowledgeMode parameter.
Table 4-3 acknowledgeMode Values
Enum
Description
MQ_AUTO_ACKNOWLEDGE
The session automatically acknowledges each message consumed by the client. This happens when one of the receive functions returns successfully, or when the message listener processing the message returns successfully.
MQ_CLIENT_ACKNOWLEDGE
The client explicitly acknowledges all messages for the session that have been consumed up to the point when the MQAcknowledgeMessages function has been called. See the discussion of the function MQAcknowledgeMessages for additional information.
MQ_DUPS_OK_ACKNOWLEDGE
The session acknowledges after ten messages have been consumed and does not guarantee that messages are delivered and consumed only once.
MQ_SESSION_TRANSACTED
This value is read only. It is set by the library if you have passed MQ_TRUE for the isTransacted parameter to the MQCreateSession function. It is returned to you by the MQGetAcknowledgeMode function if the session is transacted.
Callback Type for Asynchronous Messaging
When you call the MQCreateAsyncMessageConsumer function or the MQCreateAsyncDurableMessageConsumer function, you must pass the name of an MQMessageListenerFunc type callback function that is to be called when the consumer receives a message to the specified destination.
The MQMessageListenerFunc type has the following definition:
MQError (* MQMessageListenerFunc)(
const MQSessionHandle sessionHandle,
const MQConsumerHandle consumerHandle,
MQMessageHandle messageHandlevoid * callbackData);
Parameters
sessionHandle
The handle to the session to which this consumer belongs. The client runtime specifies this handle when it calls your message listener.
consumerHandle
A handle to the consumer receiving the message. The client runtime specifies this handle when it calls your message listener.
messageHandle
A handle to the incoming message. The client runtime specifies this handle when it calls your message listener.
callbackData
The void pointer that you passed to the function MQCreateAsyncMessageConsumer or the function MQCreateAsyncDurableMessageConsumer.
The body of a message listener function is written by the receiving client. Mainly, the function needs to process the incoming message by examining its header, body, and properties. The client is also responsible for freeing the message handle (either from within the handler or from outside the handler) by calling MQFreeMessage.
In addition, you should observe the following guidelines when writing the message listener function:
- If you specify MQ_CLIENT_ACKNOWLEDGE as the acknowledge mode for the session, you must explicitly call the MQAcknowledgeMessages function to acknowledge messages that you have received. For more information, see the description of the function MQAcknowledgeMessages.
- Do not try to close the session (or the connection to which it belongs) and consumer handle in the message listener.
- It is possible for a message listener to return an error; however, this is considered a client programming error. If the listener discovers that the message is badly formatted or if it cannot process it for some other reason, it must handle the problem itself by re-directing it to an application-specific bad-message destination and process it later.
Callback Type for Connection Exception Handling
The client runtime will call this function when a connection exception occurs.
The MQConnectionExceptionListenerFunc type has the following definition:
Void (* MQConnectionExceptionListenerFunc)(
const MQConnectionHandle connectionHandle,
MQStatus exception,
void * callbackData);
Parameters
connectionHandle
The handle to the connection on which the connection exception occurred. The client runtime sets this handle when it calls the connection exception handler.
exception
An MQStatus for the connection exception that occurred. The client runtime specifies this value when it calls the exception handler.
You can pass this status result to any functions used to handle errors to get an error code or error string. For more information, see Error Handling.
callbackData
Whatever void pointer was passed as the listenerCallbackData parameter to the MQCreateConnection for more information.
The body of a connection exception listener function is written by the client. This function will only be called synchronously with respect to a single connection. If you install it as the connection exception listener for multiple connections, then it must be reentrant.
Do not try to close the session (or the connection to which it belongs) in the exception listener.
Function ReferenceThis section describes the C-API functions in alphabetical order. Table 4-4 lists the C-API functions.
MQAcknowledgeMessagesThe MQAcknowledgeMessages function acknowledges the specified message and all messages received before it on the same session. This function is valid only if the session is created with acknowledge mode set to MQ_CLIENT_ACKNOWLEDGE.
Return Value
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
Whether you receive messages synchronously or asynchronously, you can call the MQAcknowledgeMessages function to acknowledge receipt of the specified message and of all messages that preceded it.
When you create a session you specify one of several acknowledge modes for that session; these are described in Table 4-3. If you specify MQ_CLIENT_ACKNOWLEDGE as the acknowledge mode for the session, you must explicitly call the MQAcknowledgeMessages function to acknowledge receipt of messages consumed in that session.
By default, the calling thread to the MQAcknowledgeMessages function will be blocked until the broker acknowledges receipt of the acknowledgment for the broker consumed. If, when you created the session’s connection, you specified the property MQ_ACK_ON_ACKNOWLEDGE_PROPERTY to be MQ_FALSE, the calling thread will not wait for the broker to acknowledge the acknowledgement.
Common Errors
MQ_SESSION_NOT_CLIENT_ACK_MODE
MQ_MESSAGE_NOT_IN_SESSION
MQ_CONCURRENT_ACCESS
MQ_SESSION_CLOSED
MQ_BROKER_CLOSED
MQCloseConnectionThe MQCloseConnection function closes the connection to the broker.
MQCloseConnection (MQConnectionHandle connectionHandle);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
connectionHandle
The handle to the connection that you want to close. This handle is created and passed back to you by the MQCreateConnection function.
Closing the connection closes all sessions, producers, and consumers created from this connection. This also forces all threads associated with this connection that are blocking in the library to return.
Closing the connection does not actually release all the memory associated with the connection. After all the application threads associated with this connection (and its dependent sessions, producers, and consumers) have returned, you should call the MQFreeConnection function to release these resources.
Common Errors
MQ_CONCURRENT_DEADLOCK
(If the function is called from an exception listener or a consumer’s message listener.)
MQCloseMessageConsumerThe MQCloseMessageConsumer function closes the specified message consumer.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
A session’s consumers are automatically closed when you close the session or connection to which they belong. To close a consumer without closing the session or connection to which it belongs, use the MQCloseMessageConsumer function.
If the consumer you want to close is a durable consumer and you want to close this consumer permanently, you should call the function MQUnsubscribeDurableMessageConsumer after closing the consumer in order to delete any state information maintained by the broker for this consumer.
Common Errors
MQ_CONSUMER_NOT_IN_SESSION
MQ_BROKER_CONNECTION_CLOSED
MQCloseMessageProducerThe MQCloseMessageProducer function closes a message producer.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
producerHandle
A handle for this producer that was passed to you by the MQCreateMessageProducer function or by the MQCreateMessageProducerForDestination function.
This handle is invalid after the function returns.
Use the MQCloseMessageProducer function to close a producer without closing its associated session or connection.
Common Errors
MQ_PRODUCER_NOT_IN_SESSION
MQCloseSessionThe MQCloseSession function closes the specified session.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
sessionHandle
The handle to the session that you want to close. This handle is created and passed back to you by the MQCreateSession function.
This handle is invalid after the function returns.
Closing a session closes the resources (producers and consumers) associated with that session and frees up the memory allocated for that session.
There is no need to close the producers or consumers of a closed session.
Common Errors
MQ_CONCURRENT_DEADLOCK
(If called from a consumer’s message listener in the session.)
MQCommitSessionThe MQCommitSession function commits a transaction associated with the specified session.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
A transacted session supports a series of transactions. Transactions organize a session’s input message stream and output message stream into a series of atomic units. A transaction’s input and output units consist of those messages that have been produced and consumed within the session’s current transaction. (Note that the receipt of a message cannot be part of the same transaction that produces the message.) When you call the MQCommitSession function, its atomic unit of input is acknowledged and its associated atomic unit of output is sent.
The completion of a session’s current transaction automatically begins the next transaction. The result is that a transacted session always has a current transaction within which its work is done. Use the MQRollBackSession function to roll back a transaction.
Common Errors
MQ_NOT_TRANSACTED_SESSION
MQ_CONCURRENT_ACCESS
MQ_SESSION_CLOSED
MQ_BROKER_CONNECTION_CLOSED
MQCreateAsyncDurableMessageConsumerThe MQCreateAsyncDurableMessageConsumer function creates an asynchronous durable message consumer for the specified destination.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
sessionHandle
The handle to the session to which this consumer belongs. This handle is passed back by the MQCreateSession function. For this asynchronous durable consumer, the session must have been created with the MQ_SESSION_ASYNC_RECEIVE receive mode.
destinationHandle
A handle to a topic destination on which the consumer receives messages. This handle remains valid after the call.
durableName
An MQString specifying a name for the durable subscriber. The library makes a copy of the durableName string.
messageSelector
An expression (based on SQL92 conditional syntax) that specifies the criteria upon which incoming messages should be selected for this consumer.
Specify a NULL or empty string to indicate that there is no message selector for this consumer. In this case, all messages are delivered.
The library makes a copy of the messageSelector string.
For more information about SQL, see X/Open CAE Specification Data Management: Structured Query Language (SQL), Version 2, ISBN 1-85912-151-9, March 1966.
noLocal
Specify MQ_TRUE to inhibit delivery of messages published by this consumer’s own connection.
messageListener
The name of an MQMessageListenerFunc type callback function that is to be called when this consumer receives a message on the specified destination.
listenerCallbackData
A pointer to data that you want passed to your message listener function when it is called by the library.
consumerHandle
Output parameter for the handle that references the consumer for the specified destination.
In the case of an asynchronous consumer, you should not start a connection before calling the MQCreateAsyncDurableMessageConsumer function. (You should create a connection, create a session, set up your asynchronous consumer, create the consumer, and then start the connection.) Attempting to create a consumer when the connection is not stopped, will result in an MQ_CONCURRENT_ACCESS error.
The MQCreateAsyncDurableMessageConsumer function creates an asynchronous durable message consumer for the specified destination. You can define parameters to filter messages and to inhibit the delivery of messages you published to your own connection. Note that the session’s receive mode (sync/async) must be appropriate for the kind of consumer you are creating (sync/async). To create a synchronous durable message consumer for a destination, call the function MQCreateDurableMessageConsumer.
Durable consumers can only be used for topic destinations. If you are creating an asynchronous consumer for a queue destination or if you are not interested in messages that arrive to a topic while you are inactive, you might prefer to use the function MQCreateAsyncMessageConsumer.
The broker retains a record of this durable subscription and makes sure that all messages from the publishers to this topic are retained until they are either acknowledged by this durable subscriber or until they have expired. Sessions with durable subscribers must always provide the same client identifier. (See MQCreateConnection, clientID parameter.) In addition, each durable consumer must specify a durable name using the durableName parameter, which uniquely identifies (for each client identifier) the durable subscription when it is created.
A session’s consumers are automatically closed when you close the session or connection to which they belong. However, messages will be routed to the durable subscriber while it is inactive and delivered when the durable consumer is recreated. To close a consumer without closing the session or connection to which it belongs, use the MQCloseMessageConsumer function. If you want to close a durable consumer permanently, you should call the MQUnsubscribeDurableMessageConsumer after closing it to delete state information maintained by the Broker on behalf of the durable consumer.
Common Errors
MQ_NOT_ASYNC_RECEIVE_MODE
MQ_INVALID_MESSAGE_SELECTOR
MQ_DESTINATION_CONSUMER_LIMIT_EXCEEDEED
MQ_TEMPORARY_DESTINATION_NOT_IN_CONNECTION
MQ_CONSUMER_NO_DURABLE_NAME
MQ_QUEUE_CONSUMER_CANNOT_BE_DURABLE
MQ_CONCURRENT_ACCESS
MQ_SESSION_CLOSED
MQ_BROKER_CONNECTION_CLOSED
MQCreateAsyncMessageConsumerThe MQCreateAsyncMessageConsumer function creates an asynchronous message consumer for the specified destination.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
sessionHandle
The handle to the session to which this consumer belongs. This handle is created and passed back to you by the MQCreateSession function. For this asynchronous consumer, the session must have been created with the MQ_SESSION_ASYNC_RECEIVE receive mode.
destinationHandle
A handle to the destination on which the consumer receives messages. This handle remains valid after the call returns.
messageSelector
An expression (based on SQL92 conditional syntax) that specifies the criteria upon which incoming messages should be selected for this consumer.
Specify a NULL or empty string to indicate that there is no message selector for this consumer. In this case, all messages will be delivered.
The library makes a copy of the messageSelector string.
For more information about SQL, see X/Open CAE Specification Data Management: Structured Query Language (SQL), Version 2, ISBN 1-85912-151-9, March 1966.
noLocal
Specify MQ_TRUE to inhibit delivery of messages published by this consumer’s own connection.
The setting of this parameter applies only to topic destinations. It is ignored for queues.
messageListener
The name of an MQMessageListenerFunc type callback function that is to be called when this consumer receives a message for the specified destination.
listenerCallbackData
A pointer to data that you want passed to your message listener function when it is called by the library.
consumerHandle
Output parameter for the handle that references the consumer for the specified destination.
In the case of an asynchronous consumer, you should not start a connection before calling the MQCreateAsyncDurableMessageConsumer function. (You should create a connection, create a session, set up your asynchronous consumers, create the consumer, and then start the connection.) Attempting to create a consumer when the connection is not stopped will result in an MQ_CONCURRENT_ACCESS error.
The MQCreateAsyncMessageConsumer function creates an asynchronous message consumer for the specified destination. You can define parameters to filter messages and to inhibit the delivery of messages you published to your own connection. Note that the session’s receive mode (sync/async) must be appropriate for the kind of consumer you are creating (sync/async). To create a synchronous message consumer for a destination, use the MQCreateMessageConsumer function.
If this consumer is on a topic destination, it will only receive messages produced while the consumer is active. If you are interested in receiving messages published while this consumer is not active, you should create a consumer using the MQCreateAsyncDurableMessageConsumer function instead.
A session’s consumers are automatically closed when you close the session or connection to which they belong. To close a consumer without closing the session or connection to which it belongs, use the MQCloseMessageConsumer function.
Common Errors
MQ_NOT_ASYNC_RECEIVE_MODE
MQ_INVALID_MESSAGE_SELECTOR
MQ_DESTINATION_CONSUMER_LIMIT_EXCEEDEED
MQ_TEMPORARY_DESTINATION_NOT_IN_CONNECTION
MQ_CONCURRENT_ACCESS
MQ_SESSION_CLOSED
MQ_BROKER_CONNECTION_CLOSED
MQCreateBytesMessageThe MQCreatesBytesMessage function creates a bytes message and passes a handle to it back to you.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
After you obtain the handle to a bytes message, you can use this handle to define its content with the MQSetBytesMessageBytes function, to set its headers with the MQSetMessageHeaders function, and to set its properties with the MQSetMessageProperties function.
MQCreateConnectionThe MQCreateConnection function creates a connection to the broker.
If you want to connect to the broker over SSL, you must call the MQInitializeSSL function to initialize the SSL library before you create the connection.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A handle that specifies the properties that determine the behavior of this connection. You must create this handle using the MQCreateProperties function before you try to create a connection. This handle will be invalid after the function returns.
See Table 4-2 for information about connection properties.
username
An MQString specifying the user name to use when connecting to the broker.
The library makes a copy of the username string.
password
An MQString specifying the password to use when connecting to the broker.
The library makes a copy of the password string.
clientID
An MQString used to identify the connection. If you use the connection for a durable consumer, you must specify a non-NULL client identifier.
The library makes a copy of the clientID string.
exceptionListener
A connection-exception callback function used to notify the user that a connection exception has occurred.
listenerCallBackData
A data pointer that can be passed to the connection exceptionListener callback function whenever it is called. The user can set this pointer to any data that may be useful to pass along to the connection exception listener for this connection. Set this to NULL if you do not need to pass data back to the connection exception listener.
connectionHandle
Output parameter for the handle to the connection that is created by this function.
The MQCreateConnection function creates a connection to the broker. The behavior of the connection is specified by key values defined in the properties referenced by the propertiesHandle parameter. You must use the MQCreateProperties function to define these properties.
You cannot change the properties of a connection you have already created. If you need different connection properties, you must close and free the old connection and then create a new connection with the desired properties.
Use the exceptionListener parameter to pass the name of a user-defined callback function that can be called synchronously when a connection exception occurs for this connection. Use the exceptionCallBackData parameter to specify any user data that you want to pass to the callback function.
- Use the MQStartConnection function to start or restart the connection. Use the MQStopConnection function to stop a connection.
- Use the MQGetMetaData function to get information about the name of the Message Queue product and its version.
- Use the MQCloseConnection function to close a connection, and then use the MQFreeConnection function to free the memory allocated for that connection.
Common Errors
MQ_INCOMPATIBLE_LIBRARY
MQ_CONNECTION_UNSUPPORTED_TRANSPORT
MQ_COULD_NOT_CREATE_THREAD
MQ_INVALID_CLIENT_ID
MQ_CLIENT_ID_IN_USE
MQ_COULD_NOT_CONNECT_TO_BROKER
MQ_SSL_NOT_INITIALIZED
MQCreateDestinationThe MQCreateDestination function creates a a logical destination and passes a handle to it back to you.
MQCreateDestination
(const MQSessionHandle sessionHandle
ConstMQString destinationName,
MQDestinationType destinationType,
MQDestinationHandle * destinationHandle);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
The MQCreateDestination function creates a logical destination and passes a handle to it back to you. Note that the Message Queue administrator has to also create a physical destination on the broker, whose name and type is the same as the destination created here, in order for messaging to happen. For example, if you use this function to create a queue destination called myMailQDest, the administrator has to create a physical destination on the broker named myMailQDest.
If you are doing development, you can simplify this process by turning on the imq.autocreate.topic or imq.autocreate.queue properties for the broker. If you do this, the broker automatically creates a physical destination whenever a message consumer or message producer attempts to access a non-existent destination. The auto-created destination will have the same name as the logical destination name you specified using the MQCreateDestination function. By default, the broker has the properties imq.autocreate.topic and imq.autocreate.queue turned on.
Common Errors
MQ_INVALID_DESTINATION_TYPE
MQ_SESSION_CLOSED
MQCreateDurableMessageConsumerThe MQCreateDurableMessageConsumer function creates a synchronous durable message consumer for the specified topic destination.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
sessionHandle
The handle to the session to which this consumer belongs. This handle is passed back to you by the MQCreateSession function. For this (synchronous) durable consumer, the session must have been created with the MQ_SESSION_SYNC_RECEIVE receive mode.
destinationHandle
A handle to a topic destination on which the consumer receives messages. This handle remains valid after the call returns.
durableName
An MQString specifying the name of the durable subscriber to the topic destination. The library makes a copy of the durableName string.
messageSelector
An expression (based on SQL92 conditional syntax) that specifies the criteria upon which incoming messages should be selected for this consumer.
Specify a NULL or empty string to indicate that there is no message selector for this consumer. In this case, the consumer receives all messages. The library makes a copy of the messageSelector string.
For more information about SQL, see X/Open CAE Specification Data Management: Structured Query Language (SQL), Version 2, ISBN 1-85912-151-9, March 1966.
noLocal
Specify MQ_TRUE to inhibit delivery of messages published by this consumer’s own connection.
consumerHandle
Output parameter for the handle that references the consumer for the specified destination.
The MQCreateDurableMessageConsumer function creates a synchronous message consumer for the specified destination. A durable consumer receives all the messages published to a topic, including the ones published while the subscriber is inactive.
You can define parameters to filter messages and to inhibit the delivery of messages you published to your own connection. Note that the session’s receive mode (sync/async) must be appropriate for the kind of consumer you are creating (sync/async). To create an asynchronous durable message consumer for a destination, call the function MQCreateAsyncDurableMessageConsumer.
Durable consumers are for topic destinations. If you are creating a consumer for a queue destination or if you are not interested in messages that arrive to a topic while you are inactive, you should use the function MQCreateMessageConsumer.
The broker retains a record of this durable subscription and makes sure that all messages from the publishers to this topic are retained until they are either acknowledged by this durable subscriber or until they have expired. Sessions with durable subscribers must always provide the same client identifier (see MQCreateConnection, clientID parameter). In addition, each durable consumer must specify a durable name using the durableName parameter, which uniquely identifies (for each client identifier) the durable subscription when it is created.
A session’s consumers are automatically closed when you close the session or connection to which they belong. However, messages will be routed to the durable subscriber while it is inactive and delivered when the durable consumer is recreated. To close a consumer without closing the session or connection to which it belongs, use the MQCloseMessageConsumer function. If you want to close a durable consumer permanently, you should call the MQUnsubscribeDurableMessageConsumer function after closing it to delete state information maintained by the broker on behalf of the durable consumer.
Common Errors
MQ_NOT_SYNC_RECEIVE_MODE
MQ_INVALID_MESSAGE_SELECTOR
MQ_DESTINATION_CONSUMER_LIMITE_EXCEEDEED
MQ_TEMPORARY_DESTINATION_NOT_IN_CONNECTION
MQ_CONSUMER_NO_DURABLE_NAME
MQ_QUEUE_CONSUMER_CANNOT_BE_DURABLE
MQ_CONCURRENT_ACCESS
MQ_SESSION_CLOSED
MQ_BROKER_CONNECTION_CLOSED
MQCreateMessageConsumerThe MQCreateMessageConsumer function creates a synchronous message consumer for the specified destination.
MQCreateMessageConsumer
(const MQSessionHandle sessionHandle,
const MQDestinationHandle destinationHandle,
ConstMQString messageSelector,
MQBool noLocal
MQConsumerHandle * consumerHandle);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
sessionHandle
The handle to the session to which this consumer belongs. This handle is passed back to you by the MQCreateSession function. For this (synchronous) consumer, the session must have been created with the MQ_SESSION_SYNC_RECEIVE receive mode.
destinationHandle
A handle to the destination on which the consumer receives messages. This handle remains valid after the call returns.
messageSelector
An expression (based on SQL92 conditional syntax) that specifies the criteria upon which incoming messages should be selected for this consumer. Specify a NULL or empty string to indicate that there is no message selector for this consumer and that all messages should be returned.
The library makes a copy of the messageSelector string.
For more information about SQL, see X/Open CAE Specification Data Management: Structured Query Language (SQL), Version 2, ISBN 1-85912-151-9, March 1966.
noLocal
Specify MQ_TRUE to inhibit delivery of messages published by this consumer’s own connection. This applies only to topic destinations; it is ignored for queues.
consumerHandle
Output parameter for the handle that references the consumer for the specified destination.
The MQCreateMessageConsumer function creates a synchronous message consumer for the specified destination. You can define parameters to filter messages and to inhibit the delivery of messages you published to your own connection. Note that the session’s receive mode (sync/async) must be appropriate for the kind of consumer you are creating (sync/async). To create an asynchronous message consumer for a destination, use the MQCreateAsyncMessageConsumer function.
If the consumer is a topic destination, it can only receive messages that are published while it is active. To receive messages published while this consumer is not active, you should create a consumer using either the MQCreateDurableMessageConsumer function or the MQCreateAsyncDurableMessageConsumer function, depending on the receive mode you defined for the session.
A session’s consumers are automatically closed when you close the session or connection to which they belong. To close a consumer without closing the session or connection to which it belongs, use the MQCloseMessageConsumer function.
Common Errors
MQ_NOT_SYNC_RECEIVE_MODE
MQ_INVALID_MESSAGE_SELECTOR
MQ_DESTINATION_CONSUMER_LIMIT_EXCEEDEED
MQ_TEMPORARY_DESTINATION_NOT_IN_CONNECTION
MQ_CONCURRENT_ACCESS
MQ_SESSION_CLOSED
MQ_BROKER_CONNECTION_CLOSED
MQCreateMessageProducerThe MQCreateMessageProducer function creates a message producer that does not have a specified destination.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
sessionHandle
The handle to the session to which this producer should belong.
producerHandle
Output parameter for the handle that references the producer.
The MQCreateMessageProducer function creates a message producer that does not have a specified destination. In this case, you will specify the destination when sending the message itself by using either the MQSendMessageToDestination function or the MQSendMessageToDestinationExt function.
Using the MQCreateMessageProducer function is appropriate when you want to use the same producer to send messages to a variety of destinations. If, on the other hand, you want to use one producer to send many messages to the same destination, you should use the MQCreateMessageProducerForDestination function instead.
A session’s producers are automatically closed when you close the session or connection to which they belong. To close a producer without closing the session or connection to which it belongs, use the MQCloseMessageProducer function.
Common Errors
MQ_SESSION_CLOSED
MQCreateMessageProducerForDestinationThe MQCreateMessageProducerForDestination function creates a message producer with a specified destination.
MQCreateMessageProducerForDestination
(const MQSessionHandle sessionHandle,
const MQDestinationHandle destinationHandle,
MQProducerHandle * producerHandle);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
The MQCreateMessageProducerForDestination function creates a message producer with a specified destination. All messages sent out by this producer will go to that destination. Use the MQSendMessage function or the MQSendMessageExt function to send messages for a producer with a specified destination.
Use the MQCreateMessageProducer function when you want to use one producer to send messages to a variety of destinations.
A session’s producers are automatically closed when you close the session or connection to which they belong. To close a producer without closing the session or connection to which it belongs, use the MQCloseMessageProducer function.
Common Errors
MQ_SESSION_CLOSED
MQ_BROKER_CONNECTION_CLOSED
MQCreatePropertiesThe MQCreateProperties function creates a properties handle and passes it back to the caller.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
Output parameter for the handle that references the newly created properties object.
Use the MQCreateProperties function to get a properties handle. You can then use the appropriate MQSet...Property function to set the desired properties.
MQCreateSessionThe MQCreateSession function creates a session, defines its behavior, and passes back a handle to the session.
MQCreateSession
(const MQConnectionHandle connectionHandle,
MQBool isTransacted,
MQAckMode acknowledgeMode,
MQReceiveMode receiveMode
MQSessionHandle * sessionHandle);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
connectionHandle
The handle to the connection to which this session belongs. This handle is passed back to you by the MQCreateConnection function. You can create multiple sessions on a single connection.
isTransacted
An MQBool specifying whether this session is transacted. Specify MQ_TRUE if the session is transacted. In this case, the acknowledgeMode parameter is ignored.
acknowledgeMode
An enumeration of the possible kinds of acknowledgement modes for the session. See Table 4-3 for information on these values.
After you have created a session, you can determine its acknowledgement mode by calling the MQGetAcknowledgeMode function.
receiveMode
An enumeration specifying whether this session will do synchronous or asynchronous message receives. Specify MQ_SESSION_SYNC_RECEIVE or MQ_SESSION_ASYNC_RECEIVE.
If the session is only for producing messages, the receiveMode has no significance. In that case, specify MQ_SESSION_SYNC_RECEIVE to optimize the session’s resource use.
sessionHandle
A handle to this session. You will need to pass this handle to the functions you use to manage the session and to create destinations, consumers, and producers associated with this session.
The MQCreateSession function creates a new session and passes back a handle to it in the sessionHandle parameter. The number of sessions you can create for a single connection is limited only by system resources. A session is a single-thread context for producing and consuming messages. You can create multiple producers and consumers for a session, but you are restricted to use them serially. In effect, only a single logical thread of control can use them.
A session with a registered message listener is dedicated to the thread of control that delivers messages to the listener. This means that if you want to send messages, for example, you must create another session with which to do this. The only operations you can perform on a session with a registered listener, is to close the session or the connection.
After you create a session, you can create the producers, consumers, and destinations that use the session context to do their work.
- For a session that is not transacted, use the MQRecoverSession function to restart message delivery with the last unacknowledged message.
- For a session that is transacted, use the MQRollBackSession function to roll back any messages that were delivered within this transaction. Use the MQCommitSession function to commit all messages associated with this transaction.
- For a session that has acknowledgeMode set to MQ_CLIENT_ACKNOWLEDGE, use MQAcknowledgeMessages to acknowledge consumed messages.
- Use the MQCloseSession function to close a session and all its associated producers and consumers. This function also frees memory allocated for the session.
MQCreateTemporaryDestinationThe MQCreateTemporaryDestination function creates a temporary destination and passes its handle back to you.
MQCreateTemporaryDestination
(const MQSessionHandle sessionHandle
MQDestinationType destinationType,
MQDestinationHandle * destinationHandle);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
You can use a temporary destination to implement a simple request/reply mechanism. When you pass the handle of a temporary destination to the MQSetMessageReplyTo function, the consumer of the message can use that handle as the destination to which it sends a reply.
Temporary destinations are explicitly created by client applications; they are deleted when the connection is closed. They are maintained (and named) by the broker only for the duration of the connection for which they are created. Temporary destinations are system-generated uniquely for their connection and only their own connection is allowed to create message consumers for them.
For more information, see the Message Queue Administration Guide.
Common Errors
MQ_INVALID_DESTINATION_TYPE
MQ_SESSION_CLOSED
MQCreateTextMessageThe MQCreatesTextMessage function creates a text message and passes a handle to it back to you.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
After you obtain the handle to a text message, you can use this handle to define its content with the MQSetStringProperty function, to set its headers with the MQSetMessageHeaders function, and to set its properties with the MQSetMessageProperties function.
MQFreeConnectionThe MQFreeConnection function deallocates memory assigned to the specified connection and to all resources associated with that connection.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
You must call this function after you have closed the connection with the MQCloseConnection function and after all of the application threads associated with this connection and its dependent sessions, producers, and consumers have returned.
You must not call this function while an application thread is active in a library function associated with this connection or one of its dependent sessions, producers, consumers, and destinations.
Calling this function does not release resources held by a message or a destination associated with this connection. You must free memory allocated for a message or a destination by explicitly calling the MQFreeMessage or the MQFreeDestination function.
Common Errors
MQ_STATUS_CONNECTION_NOT_CLOSED
MQFreeDestinationThe MQFreeDestination function frees memory allocated for the destination referenced by the specified handle.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
Calling the MQFreeConnection or the MQCloseSession function does not automatically free destinations created for the connection or for the session.
MQFreeMessageThe MQFreeMessage function frees memory allocated for the message referenced by the specified handle.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
Calling the MQFreeConnection function does not automatically free messages associated with that connection.
MQFreePropertiesThe MQFreeProperties function frees the memory allocated to the referenced properties object.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
You should not free a properties handle if the properties handle passed to a function becomes invalid on its return. If you do, you will get an error.
MQFreeStringThe MQFreeString function frees the memory allocated for the specified MQString.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
statusString
An MQString returned by the MQGetStatusString function or by the MQGetErrorTrace function.
MQGetAcknowledgeModeThe MQGetAcknowledgeMode function passes back the acknowledgement mode of the specified session.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
sessionHandle
The handle to the session whose acknowledgement mode you want to determine.
ackMode
Output parameter for the ackMode. The ackMode returned can be one of four enumeration values. See Table 4-3 for information about these values.
If you want to change the acknowledge mode, you need to create another session with the desired mode.
MQGetBoolPropertyThe MQGetBoolProperty function passes back the value of the MQBool property for the specified key.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A properties handle whose property value for the specified key you want to get.
key
The name of a property key.
value
Output parameter for the property value.
Common Errors
MQ_NOT_FOUND
MQ_INVALID_TYPE_CONVERSION
MQGetBytesMessageBytesThe MQGetBytesMessageBytes function passes back the address and size of a bytes message body.
MQGetBytesMessageBytes
(const MQMessageHandle messageHandle,
const MQInt8 * messageBytes
MQInt32 * messageBytesSize);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
After you obtain the handle to a message, you can use the MQGetMessageType to determine its type and, if the type is MQ_BYTES_MESSAGE, you can use the MQGetBytesMessageBytes function to retrieve the message bytes (message body).
The bytes message passed to you by this function is not a copy. You should not modify the bytes or attempt to free it.
MQGetDestinationTypeThe MQGetDestinationType passes back the type of the specified destination.
MQGetDestinationType
(const MQDestinationHandle destinationHandle,
MQDestinationType * destinationType);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
destinationHandle
A handle to the destination whose type you want to know.
destinationType
Output parameter for the destination type; either MQ_QUEUE_DESTINATION or MQ_TOPIC_DESTINATION.
Use the MQGetDestinationType function to determine the type of a destination: queue or topic. There may be times when you do not know the type of the destination to which you are replying: for example, when you get a handle from the MQGetMessageReplyTo function. Because the semantics of queue and topic destinations differ, you need to determine the type of a destination in order to reply appropriately.
Once you have created a destination with a specified type, you cannot change the type dynamically. If you want to change the type of a destination, you need to free the destination using the MQFreeDestination function and then to create a new destination, with the desired type, using the MQCreateDestination or the MQCreateTemporaryDestination function.
MQGetErrorTraceThe MQGetErrorTrace function returns an MQString describing the error trace at the time when a function call failed for the calling thread.
MQString MQGetErrorTrace ()
Having found that a Message Queue function has not returned successfully, you can get an error trace when the error occurred by calling the MQGetErrorTrace function in the same thread that called the unsuccessful Message Queue function.
The MQGetErrorTrace function returns an MQString describing the error trace if it can determine this information. The function will return a NULL string if there is no error trace available.
The following is an example of an error trace output.
You must call the MQFreeString function to free the MQString returned by the MQGetErrorTrace function when you are done.
MQGetFloat32PropertyThe MQGetFloat32Property function passes back the value of the MQFloat32 property for the specified key.
MQGetFloat32Property
(const MQPropertiesHandle propertiesHandle,
ConstMQString key,
MQFloat32 * value);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A properties handle whose property value for the specified key you want to get.
key
The name of a property key.
value
Output parameter for the property value.
Common Errors
MQ_NOT_FOUND
MQ_INVALID_TYPE_CONVERSION
MQGetFloat64PropertyThe MQGetFloat64Property function passes back the value of the MQFloat64 property for the specified key.
MQGetFloat64Property
(const MQPropertiesHandle propertiesHandle,
ConstMQString key,
MQFloat64 * value);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A properties handle whose property value for the specified key you want to get.
key
The name of a property key.
value
Output parameter for the property value.
Common Errors
MQ_NOT_FOUND
MQ_INVALID_TYPE_CONVERSION
MQGetInt16PropertyThe MQGetInt16Property function passes back the value of the MQInt16 property for the specified key.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A properties handle whose property value for the specified key you want to get.
key
The name of a property key.
value
Output parameter for the property value.
Common Errors
MQ_NOT_FOUND
MQ_INVALID_TYPE_CONVERSION
MQGetInt32PropertyThe MQGetInt32Property function passes back the value of the MQInt32 property for the specified key.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A properties handle whose property value for the specified key you want to get.
key
The name of a property key.
value
Output parameter for the property value.
Common Errors
MQ_NOT_FOUND
MQ_INVALID_TYPE_CONVERSION
MQGetInt64PropertyThe MQGetInt64Property function passes back the value of the MQInt64 property for the specified key.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A properties handle whose property value for the specified key you want to get.
key
The name of a property key.
value
Output parameter for the property value.
Common Errors
MQ_NOT_FOUND
MQ_INVALID_TYPE_CONVERSION
MQGetInt8PropertyThe MQGetInt8Property function passes back the value of the MQInt8 property for the specified key.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A properties handle whose property value for the specified key you want to get.
key
The name of a property key.
value
Output parameter for the property value.
Common Errors
MQ_NOT_FOUND
MQ_INVALID_TYPE_CONVERSION
MQGetMessageHeadersThe MQGetMessageHeaders function passes back a handle to the message headers.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
messageHandle
The message handle.
headersHandle
Output parameter for the handle to the message header properties.
The MQGetMessageHeaders function passes back a handle to the message headers. The message header includes the fields described in Table 4-5. Note that most of the fields are set by the send function; the client can optionally set only two of these fields for sending messages.
Table 4-5 Message Header Properties
Key
Type
Set By
MQ_CORRELATION_ID_HEADER_PROPERTY
MQString
Client (optional)
MQ_MESSAGE_TYPE_HEADER_PROPERTY
MQString
Client (optional)
MQ_PERSISTENT_HEADER_PROPERTY
MQBool
Send function
MQ_EXPIRATION_HEADER_PROPERTY
MQInt64
Send function
MQ_PRIORITY_HEADER_PROPERTY
MQInt8
Send function
MQ_TIMESTAMP_HEADER_PROPERTY
MQInt64
Send function
MQ_MESSAGE_ID_HEADER_PROPERTY
MQString
Send function
MQ_REDELIVERED_HEADER_PROPERTY
MQBool
Message Broker
You are responsible for freeing the headersHandle after you are done with it. Use the MQFreeProperties function to free the handle.
Use the MQGetMessageProperties function to determine whether any application-defined properties were set for this message and to find out their value.
MQGetMessagePropertiesThe MQGetMessageProperties function passes back the user-defined properties for a message.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
messageHandle
A handle to a message whose properties you want to get.
propertiesHandle
Output parameter for the handle to the message properties.
The MQGetMessageProperties function allows you to get application-defined properties for a message. Properties allow an application, via message selectors, to select or filter messages on its behalf using application-specific criteria. Having obtained the handle, you can either use one of the MQGet...Property functions to get a value (if you know the key name) or you can iterate through the properties using the MQPropertiesKeyIterationStart function.
You will need to call the function MQFreeProperties to free the resources associated with this handle after you are done using it.
Common Errors
MQ_NO_MESSAGE_PROPERTIES
MQGetMessageReplyToThe MQGetMessageReplyTo function passes back the destination where replies to this message should be sent.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
messageHandle
A handle to a message expecting a reply. This is the handle that is passed back to you when you receive the message.
destinationHandle
Output parameter for the handle to the reply destination.
The sender uses the MQSetMessageReplyTo function to specify a destination where replies to the message can be sent. This can be a normal destination or a temporary destination. The receiving client can pass the message handle to the MQGetMessageReplyTo function and determine whether a destination for replies has been set up for the message by the sender and what that destination is. The consumer of the message can then use that handle as the destination to which it sends a reply.
You might need to call the MQGetDestinationType function to determine the type of the destination whose handle is returned to you: queue or topic so that you can set up your reply appropriately.
The advantage of setting up a temporary destination for replies is that Message Queue automatically creates a physical destination for you, rather than your having to have the administrator create one, when the broker’s auto.create.destination property is turned off.
You are responsible for freeing the destination handle by calling the function MQFreeDestination.
Common Errors
MQ_NO_REPLY_TO_DESTINATION
MQGetMessageTypeThe MQGetMessageType function passes back information about the type of a message: MQ_TEXT_MESSAGE or MQ_BYTES_MESSAGE.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
messageHandle
A handle to a message whose type you want to determine.
messageType
Output parameter that contains the message type: MQ_TEXT_MESSAGE or MQ_BYTES_MESSAGE.
After you obtain the handle to a message, you can determine the type of the message using the MQGetMessageType function. Having determined its type, you can use the MQGetTextMessageText function or the MQGetBytesMessageBytes function to obtain the message content.
Note that other message types might be added in the future. You should not design your code so that it only expects two possible message types.
MQGetMetaDataThe MQGetMetaData function returns name and version information for the current Message Queue product.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
connectionHandle
The handle to the connection that you want the meta information about.
propertiesHandle
Output parameter that contains the properties handle.
The Message Queue product you are using is identified by a name and a version number. For example: “Sun Java(tm) System Message Queue 3.5.0.1.” The version number consists of a major, minor, micro, and service pack component. For example, the major part of version 3.5.0.1 is 3; the minor is 5; the micro is 0; the service pack is 1.
The name and version information of the Message Queue product are set by the library when you call the MQCreateConnection function to create the connection. You can retrieve this information by calling the MQGetMetaData function and passing a properties handle. Once the function returns and passes the handle back, you can use one of the MQGet...Properties functions to determine the value of a property (key). These properties are described at the end of Table 4-2.
MQGetPropertyTypeThe MQGetPropertyType function returns the type of the property value for a property key in the specified properties handle.
MQGetPropertyType
(const MQPropertiesHandle propertiesHandle,
ConstMQString key,
MQType * propertyType);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A properties handle that you want to access.
key
The property key for which you want to get the type of the property value.
propertyType
Output parameter for the type of the property value.
Use the appropriate MQGet...Property function to find the value of the specified property key.
Common Errors
MQ_NOT_FOUND
MQGetStatusCodeThe MQGetStatusCode function returns the error code associated with specified status.
Parameters
Having found that a Message Queue function has not returned successfully, you can determine the reason by passing the return status. This function will return the error code associated with the specified status. These codes are listed and described in Appendix A.
Some functions might return an MQStatus that contains an NSPR or NSS library error code instead of a Message Queue error code when they fail. For NSPR and NSS library error codes, the MQGetStatusString function will return the symbolic name of the NSPR or NSS library error code. See NSPR and NSS public documentation for NSPR and NSS error code symbols and their interpretation at the following locations:
- For NSPR error codes, see the “NSPR Error Handling” chapter:
http://www.mozilla.org/projects/nspr/reference/html/index.html- For SSL and SEC error codes, see the “NSS and SSL Error Codes” chapter:
http://www.mozilla.org/projects/security/pki/nss/ref/ssl/To obtain an MQString that describes the error, use the MQGetStatusString function. To get an error trace associated with the error, use the MQGetErrorTrace function.
MQGetStatusStringThe MQGetStatusString function returns an MQString describing the specified status.
Parameters
Having found that a Message Queue function has not returned successfully, you can determine the reason why by passing the return status. This function will return an MQString describing the error associated with the specified status.
To obtain the error code for the specified status, use the MQGetStatusCode function. To get an error trace associated with the error, use the MQGetErrorTrace function.
You must call the MQFreeString function to free the MQString returned by the MQGetStatusString function when you are done.
MQGetStringPropertyThe MQGetStringProperty function passes back the value of the specified key for the specified MQString property.
MQGetStringProperty
(const MQPropertiesHandle propertiesHandle,
ConstMQString key,
ConstMQString * value);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A properties handle whose property value for the specified key you want to get.
key
The name of a property key.
value
Output parameter that points to the value of the specified key
You should not modify or attempt to free the value returned.
MQGetTextMessageTextThe MQGetTextMessageText function passes back the contents of a text message.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
messageHandle
A handle to an MQ_TEXT_MESSAGE message that is passed to you when you receive a message.
messageText
The output parameter that points to the message text.
After you obtain the handle to a message, you can use the MQGetMessageType to determine its type and, if the type is text, you can use the MQGetTextMessageText function to retrieve the message text.
The MQString passed to you by this function is not a copy. You should not modify the bytes or attempt to free it.
MQInitializeSSLThe MQInitializeSSL function initializes the SSL library. You must call this function once and only once before you create any connection that uses SSL.
MQInitializeSSL (ConstMQString certificateDatabasePath);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
The Message Queue C-API library uses NSS to support the SSL transport protocol between the Message Queue C client and the Message Queue broker.
Before you connect to a broker over SSL, you must initialize the SSL library by calling the MQInitializeSSL function. The certificateDatabasePath parameter specifies the path to the NSS certificate database where cert7.db or cert8.db, key3.db, and secmod.db are located.
Common Errors
MQ_INCOMPATIBLE_LIBRARY
MQ_SSL_ALREADY_INITIALIZED
MQPropertiesKeyIterationGetNextThe MQPropertiesKeyIterationGetNext function passes back the address of the next property key in the referenced properties handle.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A properties handle whose contents you want to access.
key
The output parameter for the next properties key in the iteration. You should not attempt to modify or free it.
To get message properties:
- Start the process by calling the MQPropertiesKeyIterationStart function.
- Loop using the MQPropertiesKeyIterationHasNext function.
- Extract the name of each property key by calling the MQPropertiesKeyIterationGetNext function.
- Determine the type of the property value for a given key by calling the MQGetPropertyType function.
- Use the appropriate MQGet...Property function to find the property value for the specified property key.
If you know the property key, you can just use the appropriate MQGet...Property function to access its value.
You should not modify or free the property key that is passed back to you by this function. Note that this function is not multi-thread-safe.
MQPropertiesKeyIterationHasNextThe MQPropertiesKeyIterationHasNext function returns MQ_TRUE if there are additional property keys left in the iteration.
Return Value
MQBool
Parameters
To get message properties:
- Start the process by calling the MQPropertiesKeyIterationStart function.
- Loop using the MQPropertiesKeyIterationHasNext function.
- Extract the name of each property key by calling the MQPropertiesKeyIterationGetNext function.
- Determine the type of the property value for a given key by calling the MQGetPropertyType function.
- Use the appropriate MQGet...Property function to find the value for the specified property key.
If you know the property key, you can just use the appropriate MQGet...Property function to get its value. Note that this function is not multi-thread-safe.
MQPropertiesKeyIterationStartThe MQPropertiesKeyIterationStart function starts or resets the iteration process or the specified properties handle.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
To get message properties:
- Start the process by calling the MQPropertiesKeyIterationStart function.
- Loop using the MQPropertiesKeyIterationHasNext function.
- Extract the name of each property key by calling the MQPropertiesKeyIterationGetNext function.
- Determine the type of the property value for a given key by calling the MQGetPropertyType function.
- Use the appropriate MQGet...Property function to find the property value for the specified property key.
If you know the property key, you can just use the appropriate MQGet...Property function to get its value. Note that this function is not multi-thread-safe.
MQReceiveMessageNoWaitThe MQReceiveMessageNoWait function passes a handle back to a message delivered to the specified consumer if a message is available.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
consumerHandle
The handle to the message consumer. This handle is passed back to you when you create a synchronous message consumer.
messageHandle
Output parameter for the handle to the message to be received. You are responsible for freeing the message handle when you are done by calling the MQFreeMessage function.
This function can only be called if the session is created with receive mode MQ_SESSION_SYNC_RECEIVE. The MQReceiveMessageNoWait function passes a handle back to you in the messageHandle parameter if there is a message arrived for the consumer specified by the consumerHandle parameter. If there is no message for the consumer, the function returns immediately with an error.
When you create a session, you specify one of several acknowledge modes for that session; these are described in Table 4-3. If you specify MQ_CLIENT_ACKNOWLEDGE as the acknowledge mode for the session, you must explicitly call the MQAcknowledgeMessages function to acknowledge messages that you have received. For more information, see the description of the function MQAcknowledgeMessages.
You can use the MQReceiveMessageWait function if you want the receive function to block while waiting for a message to arrive. You can use the MQReceiveMessageWithTimeout function to wait for a specified time for a message to arrive.
Common Errors
MQ_NOT_SYNC_RECEIVE_MODE
MQ_CONCURRENT_ACCESS
MQ_NO_MESSAGE
MQ_CONSUMER_CLOSED
MQ_SESSION_CLOSED
MQ_BROKER_CONNECTION_CLOSED
MQReceiveMessageWaitThe MQReceiveMessageWait function passes a handle back to a message delivered to the specified consumer when the message becomes available.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
consumerHandle
The handle to the message consumer. This handle is passed back to you when you create a synchronous message consumer.
messageHandle
Output parameter for the handle to the message to be received. You are responsible for freeing the message handle when you are done by calling the MQFreeMessage function.
This function can only be called if the session is created with receive mode MQ_SESSION_SYNC_RECEIVE. The MQReceiveMessageWait function passes a handle back to you in the messageHandle parameter if there is a message arrived for the consumer specified by the consumerHandle parameter. If there is no message for the consumer, the function blocks until a message is delivered.
When you create a session, you specify one of several acknowledge modes for that session; these are described in Table 4-3. If you specify MQ_CLIENT_ACKNOWLEDGE as the acknowledge mode for the session, you must explicitly call the MQAcknowledgeMessages function to acknowledge messages that you have received. For more information, see the description of the function MQAcknowledgeMessages.
You can use the MQReceiveMessageNoWait function instead if you do not want to block while waiting for a message to arrive. You can use the function MQReceiveMessageWithTimeout to wait for a specified time for a message to arrive.
Common Errors
MQ_NOT_SYNC_RECEIVE_MODE
MQ_CONCURRENT_ACCESS
MQ_CONSUMER_CLOSED
MQ_SESSION_CLOSED
MQ_BROKER_CONNECTION_CLOSED
MQReceiveMessageWithTimeoutThe MQReceiveMessageWithTimeout function passes a handle back to a message delivered to the specified consumer if a message is available within the specified amount of time.
MQReceiveMessageWithTimeout
(const MQConsumerHandle consumerHandle,
MQInt32 timeoutMilliseconds,
MQMessageHandle * messageHandle);
Return Value
MQStatus. See the MQStatusIsError function for more information.
consumerHandle
The handle to the message consumer. This handle is passed back to you when you create a synchronous message consumer.
timeoutMilliseconds
The number of milliseconds to wait for a message to arrive.
messageHandle
Output parameter for the handle to the message to be received. You are responsible for freeing the message handle when you are done by calling the MQFreeMessage function.
This function can only be called if the session is created with receive mode MQ_SESSION_SYNC_RECEIVE. The MQReceiveMessageWithTimeout function passes a handle back to you in the messageHandle parameter if a message arrives for the consumer specified by the consumerHandle parameter in the amount of time specified by the timoutMilliseconds parameter. If no message arrives within the specified amount of time, the function returns an error.
When you create a session, you specify one of several acknowledge modes for that session; these are described in Table 4-3. If you specify MQ_CLIENT_ACKNOWLEDGE as the acknowledge mode for the session, you must explicitly call the MQAcknowledgeMessages function to acknowledge messages that you have received. For more information, see the description of the function MQAcknowledgeMessages.
You can use the MQReceiveMessageWait function to block while waiting for a message to arrive. You can use the MQReceiveMessageNoWait function if you do not want to wait for the message to arrive.
Common Errors
MQ_NOT_SYNC_RECEIVE_MODE
MQ_CONCURRENT_ACCESS
MQ_TIMEOUT_EXPIRED
MQ_CONSUMER_CLOSED
MQ_SESSION_CLOSED
MQ_BROKER_CONNECTION_CLOSED
MQRecoverSessionThe MQCRecoverSession function stops message delivery and restarts message delivery with the oldest unacknowledged message.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
You can only call this function for sessions that are not transacted. To rollback message delivery for a transacted session, use the MQRollBackSession function. This function may be most useful if you use the MQ_CLIENT_ACKNOWELDGE mode.
All consumers deliver messages in a serial order. Acknowledging a received message automatically acknowledges all messages that have been delivered to the client.
Restarting a session causes it to take the following actions:
- Stop message delivery in this session
- Mark all messages that might have been delivered but not acknowledged as “redelivered”
- Restart the delivery sequence including all unacknowledged messages that had been previously delivered. (Redelivered messages might not be delivered in their original delivery order.)
Common Errors
MQ_TRANSACTED_SESSION
MQ_CONCURRENT_ACCESS
MQ_SESSION_CLOSED
MQ_BROKER_CONNECTION_CLOSED
MQRollBackSessionThe MQRollBackSession function rolls back a transaction associated with the specified session.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
A transacted session groups messages into an atomic unit known as a transaction. As messages are produced or consumed within a transaction, the broker tracks the various sends and receives, completing these operations only when you call the MQCommitSession function.
If a send or receive operation fails, you must use the MQRollBackSession function to roll back the entire transaction. This means that those messages that have been sent are destroyed and those messages that have been consumed are automatically recovered.
Common Errors
MQ_NOT_TRANSACTED_SESSION
MQ_CONCURRENT_ACCESS
MQ_SESSION_CLOSED
MQ_BROKER_CONNECTION_CLOSED
MQSendMessageThe MQSendMessage function sends a message using the specified producer.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
producerHandle
The handle to the producer sending this message. This handle is passed back to you by the MQCreateMessageProducerForDestination function.
messageHandle
A handle to the message you want to send.
The MQSendMessage function sends the specified message on behalf of the specified producer to the destination associated with the message producer. If you use this function to send a message, the following message header fields are set to default values when the send completes.
If you set those message properties, they will be ignored when a message is sent. To send a message with these properties set to different values, you can use the MQSendMessageExt function to specify different values for these properties.
You cannot use this function with a producer that is created without a specified destination.
Common Errors
MQ_PRODUCER_NO_DESTINATION
MQ_PRODUCER_CLOSED
MQ_SESSION_CLOSED
MQ_BROKER_CONNECTION_CLOSED
MQSendMessageExtThe MQSendMessageExt function sends a message using the specified producer and allows you to specify selected message header properties.
MQSendMessageExt
(const MQProducerHandle producerHandle,
const MQMessageHandle messageHandle
MQDeliveryMode msgDeliveryMode,
MQInt8 msgPriority,
MQInt64 msgTimeToLive);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
producerHandle
The handle to the producer sending this message. This handle is passed back to you by the MQCreateMessageProducerForDestination function.
messageHandle
A handle to the message you want to send.
msgDeliveryMode
An enum
MQ_PERSISTENT_DELIVERY
MQ_NONPERSISTENT_DELIVERY.msgPriority
A integer value of 0 through 9; 0 being the lowest priority and 9 the highest.
msgTimeToLive
An integer value specifying in milliseconds how long the message will live before it expires. When a message is sent, its expiration time is calculated as the sum of its time-to-live value and current GMT. A value of 0 indicates that he message will never expire.
The MQSendMessageExt function sends the specified message on behalf of the specified producer to the destination associated with the message producer. Use this function if you want to change the default values for the message header properties as shown in the next table.
Property
Default value
msgDeliveryMode
MQ_PERSISTENT_DELIVERY
msgPriority
4
msgTimeToLive
0, meaning no expiration limit
If you set these message headers using the MQSetMessageHeaders function before the send, they will be ignored when the message is sent. When the send completes, these message headers hold the values that are set by the send.
You cannot use this function with a producer that is created without a specified destination.
You can set the broker property MQ_ACK_ON_PRODUCE_PROPERTY to make sure that the message has reached its destination on the broker:
- By default, the broker acknowledges receiving persistent messages only.
- If you set the property to MQ_TRUE, the broker acknowledges receipt of all messages (persistent and non-persistent) from the producing client.
- If you set the property to MQ_FALSE, the broker does not acknowledge receipt of any message (persistent or non-persistent) from the producing client.
Note that “acknowledgement” in this case is not programmatic but internally implemented. That is, the client thread is blocked and does not return until the broker acknowledges messages it receives from the producing client.
Common Errors
MQ_PRODUCER_NO_DESTINATION
MQ_INVALID_PRIORITY
MQ_INVALID_DELIVERY_MODE
MQ_PRODUCER_CLOSED
MQ_SESSION_CLOSED
MQ_BROKER_CONNECTION_CLOSED
MQSendMessageToDestinationThe MQSendMessageToDestination function sends a message using the specified producer to the specified destination.
MQSendMessageToDestination
(const MQProducerHandle producerHandle,
const MQMessageHandle messageHandle,
const MQDestinationHandle destinationHandle);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
producerHandle
The handle to the producer sending this message. This handle is passed back to you by the MQCreateMessageProducer function.
messageHandle
A handle to the message you want to send.
destinationHandle
A handle to the destination where you want to send the message.
The MQSendMessageToDestination function sends the specified message on behalf of the specified producer to the specified destination. If you use this function to send a message, the following message header fields are set as follows when the send completes.
To send a message with these properties set to different values, you must use the MQSendMessageToDestinationExt function, which allows you to set these three header properties.
If you set these message headers using the MQSetMessageHeaders function before the send, they will be ignored when the message is sent. When the send completes, these message headers hold the values that are set by the send.
You cannot use this function with a producer that is created without a specified destination.
Common Errors
MQ_PRODUCER_HAS_DEFAULT_DESTINATION
MQ_PRODUCER_CLOSED
MQ_SESSION_CLOSED
MQ_BROKER_CONNECTION_CLOSED
MQSendMessageToDestinationExtThe MQSendMessageToDestinationExt function sends a message to the specified destination for the specified producer and allows you to set selected message header properties.
MQSendMessageToDestinationExt
(const MQProducerHandle producerHandle,
const MQMessageHandle messageHandle,
const MQDestinationHandle destinationHandle,
MQDeliveryMode msgDeliveryMode,
MQInt8 msgPriority,
MQInt64 msgTimeToLive);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
producerHandle
The handle to the producer sending this message. This handle is passed back to you when you call the MQCreateMessageProducer function.
messageHandle
A handle to the message you want to send.
destinationHandle
A handle to the destination where you want to send the message.
msgDeliveryMode
An enum of either MQ_PERSISTENT_DELIVERY or MQ_NONPERSISTENT_DELIVERY.
msgPriority
A integer value of 0 through 9; 0 being the lowest priority and 9 the highest.
msgTimeToLive
An integer value specifying in milliseconds how long the message will live before it expires. When a message is sent, its expiration time is calculated as the sum of its time-to-live value and current GMT. A value of 0 indicates that the message will never expire.
The MQSendMessageToDestinationExt function sends the specified message on behalf of the specified producer to the specified destination. Use this function if you want to change the default values for the message header properties as shown below:
Property
Default value
msgDeliveryMode
MQ_PERSISTENT_DELIVERY
msgPriority
4
msgTimeToLive
0, meaning no expiration limit
If these default values suit you, you can use the MQSendMessageToDestination function to send the message.
You cannot use this function with a producer that is created with a specified destination.
You can set the broker property MQ_ACK_ON_PRODUCE_PROPERTY to make sure that the message has reached its destination on the broker:
- By default, the broker acknowledges receiving persistent messages only from the producing client.
- If you set the property to MQ_TRUE, the broker acknowledges receipt of all messages (persistent and non-persistent) from the producing client.
- If you set the property to MQ_FALSE, the broker does not acknowledge receipt of any message (persistent or non-persistent) from the producing client.
Note that “acknowledgement” in this case is not programmatic but internally implemented. That is, the client thread is blocked and does not return until the broker acknowledges messages it receives.
Common Errors
MQ_PRODUCER_HAS_DEFAULT_DESTINATION
MQ_INVALID_PRIORITY
MQ_INVALID_DELIVERY_MODE
MQ_PRODUCER_CLOSED
MQ_SESSION_CLOSED
MQ_BROKER_CONNECTION_CLOSED
MQSetBoolPropertyThe MQSetBoolProperty function sets an MQBool property with the specified key to the specified value.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A handle to the properties object whose property value for the specified key you want to set.
key
The name of the property key. The library makes a copy of the property key.
value
The MQBool property value.
Common Errors
MQ_HASH_VALUE_ALREADY_EXISTS
MQSetBytesMessageBytesThe MQSetBytesMessageBytes function defines the body for a bytes message.
MQSetBytesMessageBytes
(const MQMessageHandle messageHandle,
const MQInt8 * messageBytes,
MQInt32 messageSize);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
messageHandle
A handle to an MQ_BYTES_MESSAGE message whose body you want to set.
messageBytes
A pointer to the bytes you want to set. The library makes a copy of the message bytes.
messageSize
An integer specifying the number of bytes in messageBytes.
After you obtain the handle to a bytes message from MQCreateBytesMessage, you can use this handle to define its body with the MQSetBytesMessageBytes function, to set its application-defined properties with the MQSetMessageProperties function, and to set certain message headers with the MQSetMessageHeaders function.
MQSetFloat32PropertyThe MQSetFloat32Property function sets an MQFloat32 property with the specified key to the specified value.
MQSetFloat32Property
(const MQPropertiesHandle propertiesHandle,
ConstMQString key,
MQFloat32 value);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A handle to the properties object whose property value for the specified key you want to set.
key
The name of a property key. The library makes a copy of the property key.
value
The MQFloat32 property value.
Common Errors
MQ_HASH_VALUE_ALREADY_EXISTS
MQSetFloat64PropertyThe MQSetFloat64Property function sets an MQFloat64 property with the specified key to the specified value.
MQSetFloat64Property
(const MQPropertiesHandle propertiesHandle,
ConstMQString key,
MQFloat64 value);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A handle to the properties object whose property value for the specified key you want to set.
key
The name of a property key. The library makes a copy of the property key.
value
The MQFloat64 property value.
Common Errors
MQ_HASH_VALUE_ALREADY_EXISTS
MQSetInt16PropertyThe MQSetInt16Property function sets an MQInt16 property with the specified key to the specified value.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A handle to the properties object whose property value for the specified key you want to set.
key
The name of a property key. The library makes a copy of the property key.
value
The MQInt16 property value.
Common Errors
MQ_HASH_VALUE_ALREADY_EXISTS
MQSetInt32PropertyThe MQSetInt32Property function sets an MQInt32 property with the specified key to the specified value.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A handle to the properties object whose property value for the specified key you want to set.
key
The name of a property key. The library makes a copy of the property key.
value
The MQInt32 property value.
Common Errors
MQ_HASH_VALUE_ALREADY_EXISTS
MQSetInt64PropertyThe MQSetInt64Property function sets an MQInt64 property with the specified key to the specified value.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A handle to the properties object whose property value for the specified key you want to set.
key
The name of a property key. The library makes a copy of the property key.
value
The MQInt64 property value.
Common Errors
MQ_HASH_VALUE_ALREADY_EXISTS
MQSetInt8PropertyThe MQSetInt8Property function sets an MQInt8 property with the specified key to the specified value.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A handle to the properties object whose property value for the specified key you want to set
key
The name of a property key. The library makes a copy of the property key.
value
The MQInt8 property value.
Common Errors
MQ_HASH_VALUE_ALREADY_EXISTS
MQSetMessageHeadersThe MQSetMessageHeaders function creates the header part of the message.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
messageHandle
A handle to a message.
headersHandle
A handle to the header properties object. This handle will be invalid after the function returns.
After you have created a properties handle and defined values for message header properties using one of the MQSet...Property functions, you can pass the handle to the MQSetMessageHeaders function to define the message header properties.
The message header properties are described in Table 4-6. For sending messages, the client can only set two of these: the correlation ID property and the message type property. The client is not required to set these; they are provided for the client’s convenience. For example, the client can use the key MQ_MESSAGE_TYPE_HEADER_PROPERTY to sort incoming messages according to application-defined message types.
Table 4-6 Message Header Properties
Key
Type
Set By
MQ_CORRELATION_ID_HEADER_PROPERTY
MQString
Client (optional)
MQ_MESSAGE_TYPE_HEADER_PROPERTY
MQString
Client (optional)
MQ_PERSISTENT_HEADER_PROPERTY
MQBool
Send function
MQ_EXPIRATION_HEADER_PROPERTY
MQInt64
Send function
MQ_PRIORITY_HEADER_PROPERTY
MQInt8
Send function
MQ_TIMESTAMP_HEADER_PROPERTY
MQInt64
Send function
MQ_MESSAGE_ID_HEADER_PROPERTY
MQString
Send function
MQ_REDELIVERED_HEADER_PROPERTY
MQBool
Message Broker
Header properties that are not specified in the headersHandle are not affected. You cannot use this function to override header properties that are set by the broker or the send function. The header properties for persistence, expiration, and priority (Table 4-6) are set to default values if the user called the MQSendMessage or MQSendMessageToDestination function, or they are set to values the user specifies (in parameters) if the user called the MQSendMessageExt or the MQSendMessageToDestinationExt function.
Use the MQSetBytesMessageBytes function or the MQSetStringProperty to set the body of a message. Use the MQSetMessageProperties function to set the application-defined properties of a message that are not part of the header.
Common Errors
MQ_PROPERTY_WRONG_VALUE_TYPE
MQSetMessagePropertiesThe MQSetMessageProperties function sets the specified properties for a message.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
messageHandle
A handle to a message whose application-defined properties you want to set.
propertiesHandle
A handle to a properties object that you have created and set using one of the set property functions. This handle is invalid after the function returns.
After you obtain the handle to a message, you can use this handle to define its body with the MQSetStringProperty function or the MQSetBytesMessageBytes function, to set its header properties with the MQSetMessageHeaders function, and to set its application-defined properties with the MQSetMessageProperties function.
Property values are set prior to sending a message. The MQSetMessageProperties function allows you to set application-defined properties for a message. Properties allow an application, via message selectors, to select or filter, messages on its behalf using application-specific criteria.
You define the message properties and their values using the MQCreateProperties function to create a properties object, then you use one of the set property functions to define each key and value in it. See Working With Properties for more information.
To change the properties of a message, call the MQSetMessageProperties function, passing a different properties handle.
MQSetMessageReplyToThe MQSetMessageReplyTo function specifies the destination where replies to this message should be sent.
MQSetMessageReplyTo
(const MQMessageHandle messageHandle,
const MQDestinationHandle destinationHandle);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
messageHandle
A handle to a message expecting a reply.
destinationHandle
The destination to which the reply is sent. Usually this is a handle to a destination that you created using the MQCreateDestination function or the function MQCreateTemporaryDestination. The handle is still valid when this function returns.
The sender uses the MQSetMessageReply function to specify a destination where replies to the message can be sent. This can be a normal destination or a temporary destination. The receiver of a message can use the MQGetMessageReplyTo function to determine whether a sender has set up a destination where replies are to be sent. The advantage of setting up a temporary destination for replies is that Message Queue automatically creates a physical destination for you, rather than your having to have the administrator create one if the broker’s auto_create_destination property is turned off.
MQSetStringPropertyThe MQSetStringProperty function sets an MQString property with the specified key t to the specified value.
MQSetStringProperty
(const MQPropertiesHandle propertiesHandle,
ConstMQString key,
ConstMQString value);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
propertiesHandle
A handle to the properties object whose property value for the specified key you want to set. You get this handle from the MQCreateProperties function.
key
The name of a property key. The library makes a copy of the property key
value
The property value to set. The library makes a copy of the value.
The library makes a copy of the property key and also makes a copy of the value.
MQSetTextMessageTextThe MQSetTextMessageText function defines the body for a text message.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
messageHandle
A handle to a message whose text body you want to set.
messageText
An MQString specifying the message text. The library makes a copy of the message text.
After you obtain the handle to a text message, you can use this handle to define its body with the MQSetStringProperty function. You can set its application-defined properties with the MQSetMessageProperties function, and you can set certain message headers with the MQSetMessageHeaders function.
MQStartConnectionThe MQStartConnection function starts the specified connection to the broker and starts or resumes message delivery.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
connectionHandle
The handle to the connection that you want to start. This handle is the handle that is created and passed back to you by the MQCreateConnection function.
When a connection is created it is in stopped mode. Until you call this function, messages are not delivered to any consumers. Call this function to start a connection or to restart a connection that has been stopped with the MQStopConnection function. To create an asynchronous consumer, you could have the connection in stopped mode, and start or restart the connection after you have set up the asynchronous message consumer.
Use the MQCloseConnection function to close a connection, and then use the MQFreeConnection function to free the memory allocated to the connection.
Common Errors
MQ_BROKER_CONNECTION_CLOSED
MQStatusIsErrorThe MQStatusIsError function returns MQ_TRUE if the status parameter passed to it represents an error.
Parameters
Nearly all Message Queue C library functions return an MQStatus. You can pass this status result to the MQStatusIsError function to determine whether your call succeeded or failed. If the MQStatusIsError function returns MQ_TRUE(=1), the function failed; if it returns MQ_FALSE(=0), the function returned successfully.
If the MQStatusIsError returns MQ_TRUE, you can get more information about the error that occurred by passing the status returned to the MQGetStatusCode function. This function will return the error code associated with the specified status.
To obtain an MQString that describes the error, use the MQGetStatusString function. To get an error trace associated with the error, use the MQGetErrorTrace function.
MQStopConnectionThe MQStopConnection function stops the specified connection to the broker. This stops the broker from delivering messages.
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
connectionHandle
The handle to the connection that you want to stop. This handle is passed back to you by the MQCreateConnection function.
You can restart message delivery by calling the MQStartConnection function. When the connection has stopped, delivery to all the connection’s message consumers is inhibited: synchronous receives block, and messages are not delivered to message listeners. This call blocks until receives and/or message listeners in progress have completed.
You should not call MQStopConnection in a message listener callback function.
Use the MQCloseConnection function to close a connection, and then use the MQFreeConnection function to free the memory allocated to the connection.
Common Errors
MQ_BROKER_CONNECTION_CLOSED
MQ_CONCURRENT_DEADLOCK
MQUnsubscribeDurableMessageConsumerThe MQUnsubscribeDurableMessageConsumer function unsubscribes the specified durable message consumer.
MQUnsubscribeDurableMessageConsumer
(const MQSessionHandle sessionHandle,
ConstMQString durableName);
Return Value
MQStatus. See the MQStatusIsError function for more information.
Parameters
sessionHandle
The handle to the session to which this consumer belongs. This handle is created and passed back to you by the MQCreateSession function.
durableName
An MQString specifying the name of the durable subscriber.
When you call the MQUnsubscribeDurableMessageConsumer function, the client runtime instructs the broker to delete the state information that the broker maintains for this consumer. If you try to delete a durable consumer while it has an active topic subscriber or while a received message has not been acknowledged in the session, you will get an error. You should only unsubscribe a durable message consumer after closing it.
Common Errors
MQ_CANNOT_UNSUBSCRIBE_ACTIVE_CONSUMER
MQ_CONSUMER_NOT_FOUND
Header FilesThe Message Queue C-API is defined in the header files listed in Table 4-7. The files are listed in alphabetical order. The file mqcrt.h includes all the Message Queue C-API header files.
Table 4-7 Message Queue C-API Header Files
File Name
Contents
mqbasictypes.h
Defines the types MQBool, MQInt8, MQInt16, MQInt32, MQInt64, MQFloat32, MQFloat64.
mqbytes-message.h
Function prototypes for creating, getting, setting bytes message.
mqcallback-types.h
Asynchronous receive and connection exception handling callback types.
mqconnection.h
Function prototypes for creating, managing, and closing connections. Function prototype for creating session.
mqconnection-props.h
Connection property constants
mqconsumer.h
Function prototypes for synchronous receives and closing the consumer.
mqcrt.h
All Message Queue C-API public header files.
mqdestination.h
Function prototypes to free destinations and get information about destinations.
mqerrors.h
Error codes
mqheader-props.h
Message header property constants
mqmessage.h
Function prototypes for getting and setting parts of message, freeing message, and acknowledging message.
mqproducer.h
Function prototypes for sending messages and closing the message producer.
mqproperties.h
Function prototypes for creating, setting, and getting properties
mqsession.h
Function prototypes for managing and closing sessions; for creating destinations, message producers and message consumers.
mqssl.h
Function declaration for initializing the SSL library.
mqstatus.h
Function prototypes for getting error information.
mqtext-message.h
Function prototypes for creating, getting, setting text message.
mqtypes.h
Enumeration of types that can be stored in a properties object, of types of message that can be received, of acknowledgement modes, of delivery modes, of destination types, of session receiving modes, and of handle types.
mqversion.h
Version information constant definitions.