Oracle® Fusion Middleware
Part 4. Messaging

The Send to JMS filter enables you to configure a JMS messaging system to which the API Gateway sends messages. You can configure various settings for the message request and response (for example, destination and message type, how the message system should respond, and so on).

API Gateway provides all the required third-party JAR files for IBM WebSphere MQ and Apache ActiveMQ (both embedded and external).

The Request tab specifies the following properties of the request sent to the messaging system:

JMS Service:

Click the browse button on the right, and select an existing JMS service in the tree. To add a JMS Service, right-click the JMS Services tree node, and select Add a JMS Service. Alternatively, you can configure JMS services under the External Connections node in the Policy Studio tree. For more details, see the Configure messaging services topic.

Destination type:

Select one of the following from the list:

Defaults to Queue.

Destination:

Enter the name of the JMS queue, JMS topic, or JNDI lookup to specify where you want to drop the messages.

Delivery Mode:

Select one of the following delivery modes:

Priority Level:

You can use message priority levels to instruct the JMS provider to deliver urgent messages first. The ten levels of priority range from 0 (lowest) to 9 (highest). If you do not specify a priority level, the default level is 4. A JMS provider tries to deliver higher priority messages before lower priority ones but does not have to deliver messages in exact order of priority.

Time to Live:

By default, a message never expires. However, if a message becomes obsolete after a certain period, you may want to set an expiry time (in milliseconds). The default value is 0, which means the message never expires.

Message ID:

Enter an identifier to be used as the unique identifier for the message. By default, the unique identifier is the ID assigned to the message by API Gateway (${id}). However, you can use a proprietary correlation system, perhaps using MIME message IDs instead of API Gateway message IDs.

Correlation ID:

Enter an identifier for the message that API Gateway uses to correlate response messages with the corresponding request messages. Usually, if ${id} is specified in the Message ID field above, it is also used here to correlate request messages with their correct response messages.

Message Type:

This drop-down list enables you to specify the type of data to be serialized and sent in the JMS message to the JMS provider. The option selected depends on what part of the message you want to send to the consumer. For example, to send the message body, select the option to format the body according to the rules defined in the SOAP over JMS recommendation. Alternatively, to serialize a list of name-value pairs to the JMS message, choose the option to create a MapMessage.

Select one of thd following serialization options:

Attribute Name:

Enter the name of the API Gateway message attribute that holds the data that is to be serialized to a JMS message and sent over the wire to the JMS provider. The type of the attribute named here must correspond to that selected in the Message Type drop-down field above.

Custom Message Properties:

You can set custom properties for messages in addition to those provided by the header fields. Custom properties may be required to provide compatibility with other messaging systems. You can use message attribute selectors as property values. For example, you can create a property called AuthNUser, and set its value to ${authenticated.subject.id}. Other applications can then filter on this property (for example, only consume messages where AuthNUser equals admin). To add a new property, click Add, and enter a name and value in the fields provided on the Properties dialog.

Use the following policy to change JMS request message:

This setting enables you to customize the JMS message before it is published to a JMS queue or topic. Click the browse button on the right, and select a configured policy in the dialog. The selected policy is then invoked before the JMS request is sent to the queuing system.

When the selected policy is invoked, the JMS request message is available on the white board in the jms.outbound.message message attribute. You can therefore call JMS API methods to manipulate the JMS request further. For example, you could configure a policy containing a Scripting Language filter that runs a script such as the following against the JMS message:

function invoke(msg) {
 var jmsMsg = msg.get("jms.outbound.message");
 jmsMsg.setIntProperty("My_JMS_Report", 123);
 return true;
}

The Response tab specifies whether API Gateway uses asynchronous or synchronous communication when talking to the messaging system. For example, to use asynchronous communication, you can select the Do not set response option. If synchronous communication is required, you can select to read the response from a temporary queue or from a named queue or topic.

You can also specify whether API Gateway waits on a response message from a queue or topic from the messaging system. API Gateway sets the JMSReplyTo property on each message that it sends. The value of the JMSReplyTo property is the temporary queue, queue, or topic selected in this dialog. It is the responsibility of the application that consumes the message from the queue (JMS consumer) to send the message back to the destination specified in JMSReplyTo.

API Gateway sets the JMSCorrelationID property to the value of the Correlation ID field on the Request tab to correlate requests messages to their corresponding response messages. If you select to use a temporary queue or temporary topic, this is created when API Gateway starts up.

Configure how messaging system should respond:

Select where the response message is to be placed using one of the following options:

Wait for response:

If Do not set response is not selected, you can select whether API Gateway waits to receive a response: