User’s Guide

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Modeling Message Flow in ALSB

In ALSB, a message flow defines the implementation of a proxy service. You can create and configure ALSB proxy services in the ALSB Console or the ALSB Plug-in for WorkSpace Studio. This section describes message flows and presents guidelines for designing them.

The following sections describe message flows in ALSB:

For instructions on creating and configuring message flows in the ALSB Console, see:

For instructions on creating and configuring message flows in the ALSB Plug-in for WorkSpace Studio, see:

 


Message Flow Components

A message flow is composed of components that define the logic for routing and manipulating messages as they flow through a proxy service. Nodes are configured to route messages through the message flow, and stages and actions contain rules for processing and transforming messages.

Most of the processing logic in a message flow is handled in pipelines. A pipeline is a named sequence of stages representing a non-branching one-way processing path. Pipelines belong to one of the following categories:

To implement the processing logic of a proxy service, request and response pipelines are paired together in pipeline pair nodes. These pipeline pair nodes can be combined with other nodes into a single-rooted tree structure to control overall flow.

Table 3-1 describes the components available for defining message flows.

Table 3-1 Message Flow Components
Component Type
Summary
Start node
Every message flow begins with a start node. All messages enter the message flow through the start node, and all response messages are returned to the client through the start node. There is nothing to configure in a start node.
Pipeline pair node
A pipeline pair node combines a single request pipeline and a single response pipeline in one top-level element. A pipeline pair node can have only one direct descendant in the message flow. During request processing, only the request pipeline is executed when ALSB processes a pipeline pair node. The execution path is reversed when ALSB processes the response pipeline.
Stage
Request pipelines, response pipelines, and error handlers can contain stages, where you configure actions to manipulate messages passing through the pipeline.
Error handler
An error handler can be attached to any node or stage, to handle potential errors at that location.
Branch node
A branch node allows processing to proceed along exactly one of several possible paths. Operational branching is supported for WSDL-based services, where the branching is based on operations defined in the WSDL. Conditional branching is supported for conditions defined in an XPath-based switch table.
Route node
A route node performs request/response communication with another service. It represents the boundary between request and response processing for the proxy service. When the route node dispatches a request message, the request processing is considered complete. When the route node receives a response message, the response processing begins. The route node supports conditional routing as well as request and response transformations.
Because a route node represents the boundary between request and response processing, it cannot have any descendants in the message flow.

Figure 3-1 shows a high level view of components in a message flow definition.

Figure 3-1 Components of Message Flow

Components of Message Flow

Building a Message Flow

The only components required in a message flow are a start node and a route node. No restrictions exist on what other components can be chained together in the message flow. You could create a single route node that contained all the logic for the flow. Or, you could link two pipeline pair nodes without a branch node in between. If you use branch nodes, each branch node could start with a different element. One branch could terminate with a route node, another could be followed by a pipeline pair, and yet another could have no descendant. (When a branch with no descendants is executed at run time, response processing begins immediately.)

However, in general, a message flow is likely to be designed in one of the following ways:

Message Execution

Table 3-2 briefly describes how messages are processed in a typical message flow.

Table 3-2 Path of a Message During a Message Flow
Message Flow Node
What Happens During Message Processing?
Request Processing
 
Start node
Request processing begins at the start node.
Pipeline pair node
Executes the request pipeline only.
Branch node
Evaluates the branch table and proceeds down the relevant branch.
Route node
Performs the route along with any request transformations.
In the message flow, regardless of whether routing takes place or not, the route node represents the transition from processing a request to processing a response. At the route node, the direction of the message flow is reversed. If a request path does not have a route node, the response processing is initiated in the reverse direction without waiting for any response.
Response Processing
Skips any branch nodes and continues with the node that preceded the branch.
Route node
Executes any response transformations.
Branch node
Skips any branch nodes and continues with the node that preceded the branch.
Pipeline pair node
Executes the response pipeline.
Start node
Sends the response back to the client.

 


Branching in Message Flows

Two kinds of branching are supported in message flows: operational branching, configured in an operational branch node, and conditional branching, configured in a conditional branch node.

Operational Branching

When message flows define WSDL-based proxy services, operation-specific processing is required. When you create an operational branch node in a message flow, you can build branching logic based on the operations defined in the WSDL.

You must use operational branching when a proxy service is based on a WSDL with multiple operations. You can consider using an operational branch node to handle messages separately for each operation.

Conditional Branching

Use conditional branching to branch based on a specified condition, for example the document type of a message.

Conditional branching is driven by a lookup table with each branch tagged with simple, unique string values, for example, QuantityEqualToOrLessThan150 and QuantityMoreThan150.

You can configure a conditional branch to branch based on the value of a variable in the message context (declared, for example, in a stage earlier in the message flow), or you can configure the condition to branch based on the results of an XPath expression defined in the branch itself.

At run time, the variable or the expression is evaluated, and the resulting value is used to determine which branch to follow. If no branch matches the value, the default branch is followed. A branch node may have several descendants in the message flow: one for each branch, including the default branch. You should always define a default branch. You should design the proxy service in such a way that the value of a lookup variable is set before reaching the branch node.

For example, consider the following case using a lookup variable. A proxy service is of type any SOAP or any XML, and you need to determine the type of the message so you can perform conditional branching. You can design a stage action to identify the message type and then design a conditional branching node later in the flow to separate processing based on the message type.

Now consider the following case using an XPath expression in the conditional branch node. You want to branch based on the quantity in an order. That quantity is passed via a variable that can be retrieved from a known location in $body. You could define the following XPath expression to retrieve the quantity:

declare namespace openuri="http://www.openuri.org/";
declare namespace com="bea.com/demo/orders/cmnCust";
./openuri:processCust/com:cmnCust/com:Order_Items/com:Item/com:Quantity

The condition (for example, <500) is then evaluated in order down the message flow against the expression. Whichever condition is satisfied first determines which branch is followed. If no branch condition is satisfied, then the default branch is followed.

You can use conditional branching to expose the routing alternatives for the message flow at the top level flow view. For example, consider a situation where you want to invoke service A or service B based on a condition known early in the message flow (for example, the message type). You could configure the conditional branching in a routing table in the route node. However, that makes the branching somewhat more difficult to follow if you are just looking at the top level of the flow. Instead, you could use a conditional branch node to expose this branching in the message flow itself and use simple route nodes as the subflows for each of the branches.

Consider your business scenario before deciding whether you configure branching in the message flow or in a stage or route node. When making your decision, remember that configuring branches in the message flow can be awkward in the design interface if a large number of branches extend from the branch node.

 


Configuring Actions in Stages and Route Nodes

Actions provide instructions for handling messages in pipeline stages, error handler stages, and route nodes. The context determines which actions are available in the ALSB Console or in the ALSB Plug-in for WorkSpace Studio, as described in the following sections:

See Also

Communication Actions

Communication actions control message flow. Table 3-3 describes the communication actions.

Table 3-3 Communication Actions
Action
Use to...
Available in
Dynamic publish
Publish a message to a service specified by an XQuery expression.
  • Pipeline stage
  • Error handler stage
  • Route node
Publish
Identify a statically specified target service for a message and to configure how the message is packaged and sent to that service.
  • Pipeline stage
  • Error handler stage
Publish table
Publish a message to zero or more statically specified services. Switch-style condition logic is used to determine at run time which services will be used for the publish.
  • Pipeline stage
  • Error handler stage
Routing options
Modify any or all of the following properties in the outbound request: URI, Quality of Service, Mode, Retry parameters, Message Priority.
  • Pipeline stage
Service callout
Configure a synchronous (blocking) callout to an ALSB-registered proxy or business service. See Constructing Service Callout Messages.
  • Pipeline stage
  • Error handler stage
Transport headers
Set the header values in messages. See Configuring Transport Headers in Message Flows.
  • Pipeline stage
  • Error handler stage

Flow Control Actions

Flow controls actions implement conditional routing, conditional looping, and error handling. You can also use them to notify the invoker of success or to skip the rest of the actions in the stage. Table 3-4 describes the flow control actions.

Table 3-4 Flow Control Actions
Action
Use to...
Available in
For each
Iterate over a sequence of values and execute a block of actions
  • Pipeline stage
  • Error handler stage
If... then...
Perform an action or set of actions conditionally, based on the Boolean result of an XQuery expression.
  • Pipeline stage
  • Route node
  • Error handler stage
Raise error
Raise an exception with a specified error code (a string) and description.
  • Pipeline stage
  • Error handler stage
Reply
Specify that an immediate reply be sent to the invoker.
The reply action can be used in the request, response or error pipeline. You can configure it to result in a reply with success or failure. In the case of reply with failure where the inbound transport is HTTP, the reply action specifies that an immediate reply is sent to the invoker.
  • Pipeline stage
  • Error handler stage
Resume
Resume message flow after an error is handled by an error handler. This action has no parameters and can only be used in error handlers.
  • Error handler stage
Skip
Specify that at run time, the execution of this stage is skipped and the processing proceeds to the next stage in the message flow. This action has no parameters and can be used in the request, response or error pipelines.
  • Pipeline stage
  • Error handler stage

Message Processing Actions

The actions in this category process the message flow. Table 3-5 describes the message processing actions.

Table 3-5 Message Processing Actions
Action
Use to...
Available in
Assign
Assign the result of an XQuery expression to a context variable.
  • Pipeline stage
  • Error handler stage
Delete
Delete a context variable or a set of nodes specified by an XPath expression.
  • Pipeline stage
  • Error handler stage
Insert
Insert the result of an XQuery expression at an identified place relative to nodes selected by an XPath expression.
  • Pipeline stage
  • Error handler stage
Java callout
Invoke a Java method, or EJB business service, from within the message flow.
  • Pipeline stage
  • Error handler stage
MFL transform
Convert message content from XML to non-XML, or vice versa, in the message pipeline. An MFL is a specialized XML document used to describe the layout of binary data. It is a BEA proprietary language used to define rules to transform formatted binary data into XML data, or vice versa.
  • Pipeline stage
  • Error handler stage
Rename
Rename elements selected by an XPath expression without modifying the contents of the element.
  • Pipeline stage
  • Error handler stage
Replace
Replace a node or the contents of a node specified by an XPath expression. The node or its contents are replaced with the value returned by an XQuery expression.
A replace action can be used to replace simple values, elements and even attributes. An XQuery expression that returns nothing is equivalent to deleting the identified nodes or making them empty, depending upon whether the action is replacing entire nodes or just node contents.
The replace action is one of a set of Update actions.
  • Pipeline stage
  • Error handler stage
Validate
Validate elements selected by an XPath expression against an XML schema element or a WSDL resource. You can validate global elements only; ALSB does not support validation against local elements.
  • Pipeline stage
  • Error handler stage

Reporting Actions

You use the actions in this category to log or report errors and generate alerts if required in a message flow within a stage. Table 3-4 describes the reporting actions.

Table 3-6 Reporting Actions
Action
Use to...
Available in
Alert
Generate alerts based on message context in a pipeline, to send to an alert destination. Unlike SLA alerts, notifications generated by the alert action are primarily intended for business purposes, or to report errors, and not for monitoring system health. Alert destination should be configured and chosen with this in mind.
If pipeline alerting is not enabled for the service or enabled at the domain level, the configured alert action is bypassed during message processing.
  • Pipeline stage
  • Error handler stage
Log
Construct a message to be logged and to define a set of attributes with which the message is logged.
  • Pipeline stage
  • Error handler stage
Report
Enable message reporting for a proxy service.
  • Pipeline stage
  • Error handler stage

Configuring Transport Headers in Message Flows

The transport header action is a communication type action, and it is available in pipeline stages and error handler stages.

Configuring Global Pass Through and Header-Specific Copy Options for Transport Headers

The following options are available when you configure a transport headers action:

Use the options in a way that best suits your scenario. Both options result in the headers in the source header set being copied to the target header set, overwriting any existing value in the target set. Note that the Pass all Headers through Pipeline option is executed before the header-specific Copy Header options. In other words, for a given transport headers action configuration, if you select Pass all Headers through Pipeline, there is no need to select the Copy Header option for given headers.

However, you can select Pass all Headers through Pipeline to copy all headers, and subsequently configure the action such that individual headers are deleted by selecting Delete Header for specific headers.

WARNING: Because transport headers are specific to the transport types, it is recommended that the pass-through (or copy) options only be used to copy headers between services of the same transport type. Passing (or copying) headers between services of different transport types can result in an error if the header being passed is not accepted by the target transport. For the same reasons, be careful when you specify a header name using the Set Header option.

Understanding How the Run Time Uses the Transport Headers Settings

As described above, you can use transport header actions to configure the values of the transport headers for outbound requests (the messages sent out by a proxy service in route, publish, or service callout actions) and inbound responses (the response messages a proxy service sends back to clients). In general, the header values can be:

The transport headers action allows you to set, delete, or pass-through the headers in $inbound or $outbound. If you set or delete these headers and then log $inbound or $outbound, you can see the effects of your changes. However, when the message is sent out, the ALSB binding layer may modify or remove some headers in $inbound or $outbound and the underlying transport may in turn, ignore some of these headers and use its own values. An important distinction is that any modifications done by the binding layer on a header are done directly to $inbound and $outbound, whereas modifications done by the transport affects only the message's wire format. For example, although you can specify a value for the outbound Content-Length header, the binding layer deletes it from $outbound when sending the message. Consequently, the modification is visible in the response path (for example, you can see the modified value if you log $outbound). If you set the User-Agent header in $outbound, the HTTP transport ignores it and use its own value—however, the value in $outbound is not changed.

Table 3-7 describes the transport headers that are ignored or overwritten at run time and other limitations that exist for specific transport headers.

Table 3-7 Limitations to Transport Header Values You Specify in Transport Header Actions
Transport
Description of Limitation...
Transport Headers Affected By Limitation...
Outbound Request
Inbound Response
HTTP
ALSB run time may overwrite these headers in the binding layer when preparing the message for dispatch. If these headers are modified, $inbound and $outbound are updated accordingly.
  • Content-Type
  • Content-Type
 
The underlying transport may ignore these headers and use different values when sending the message. Any changes done by the transport will not be reflected in $inbound or $outbound.
  • Accept
  • Content-Length
  • Connection
  • Host
  • User-Agent
  • Content-Length
  • Date
  • Transfer-Encoding
JMS
Can only be set when the request is with respect to a one-way service or a request/response service based on JMSMessageID correlation.
If sending to a request/response service based on JMSCorrelationID correlation, these headers are overwritten at run time.
  • JMSCorrelationID
  • JMSCorrelationID
 
Should be set to the message time-to-live in milliseconds. The resulting value in the message received is the sum of the time-to-live value specified by the client and the GMT at the time of the send or publish1.
  • JMSExpiration
  • JMSExpiration
 
The ALSB run time sets these headers. In other words, any specifications you make for these headers at design time are overwritten at run time.
  • JMSMessageID
  • JMSRedelivered
  • JMSTimestamp
  • JMSXDeliveryCount
  • JMSXUserID
  • JMS_IBM_PutDate2
  • JMS_IBM_PutTime 2
  • JMS_IBM_PutApplType 2
  • JMS_IBM_Encoding 2
  • JMS_IBM_Character_Set 2
  • JMSMessageID
  • JMSRedelivered
  • JMSTimestamp
  • JMSXDeliveryCount
  • JMSXUserID
  • JMS_IBM_PutDate 2
  • JMS_IBM_PutTime 2
  • JMS_IBM_PutApplType 2
  • JMS_IBM_Encoding 2
  • JMS_IBM_Character_Set 2
 
Because IBM MQ does not allow certain properties to be set by a client application, if you set these headers with respect to an IBM MQ destination, a run-time exception is raised.
  • JMSXDeliveryCount
  • JMSXUserID
  • JMSXAppID
  • JMSXDeliveryCount
  • JMSXUserID
  • JMSXAppID
 
These headers cannot be deleted when the Pass all Headers through Pipeline option is also specified.
  • JMSDeliveryMode
  • JMSExpiration
  • JMSMessageID
  • JMSRedelivered
  • JMSTimestamp
  • JMSXDeliveryCount
  • JMSDeliveryMode
  • JMSExpiration
  • JMSMessageID
  • JMSRedelivered
  • JMSTimestamp
  • JMSXDeliveryCount
  • JMSCorelationID—if the inbound message has the correlation ID set. For example, if the inbound response comes from a registered JMS business service
FTP
No limitations. In other words you can set or delete the header(s)3 for File and FTP transports and your specifications are honored by the ALSB run time.
   
File
   
E-mail
The ALSB run time sets these headers. In other words, any specifications you make for these headers at design time are overwritten at run time.
  • Content-Type
  • Content-Type
 
These headers have no meaning for outbound requests. If they are set dynamically (that is, if they are set in the $outbound headers section), they are ignored.4
These headers are received in $inbound. Date is the time the mail was sent by the sender. From is retrieved from incoming mail headers.
  • From
  • Date
 

1For example, if you set the JMSExpiration header to 1000, and at the time of the send, GMT is 1,000,000 (as a result of System.currentTimeMillis()), the resulting value of the JMSExpiration property in the JMS message is 1,000,1000

2Header names with the JMS_IBM prefix are to be used with respect to destinations hosted by an IBM MQ server

3For FTP and file proxies, there is an transport request header 'fileName'. The value of this request header is the name of the file being polled.

4From and Date headers are also not applicable for $outbound request headers for e-mail business services. So there is no point in setting these headers for e-mail business services.

Note: The same limitations around setting certain transport headers and metadata are true when you set the inbound and outbound context variables, and when you use the ALSB Test Console to test your proxy or business services.

 


Performing Transformations in Message Flows

Transformation maps describe the mapping between two data types. ALSB supports data mapping that uses the XQuery and the eXtensible Stylesheet Language Transformation (XSLT) standards. XSLT maps describe XML-to-XML mappings. XQuery maps can describe XML-to-XML, XML to non-XML, and non-XML to XML mappings.

The point in a message flow at which you specify a transformation depends on whether:

Transformations and Publish Actions

When transformations are designed in publish actions, the transformations have a local copy of the $outbound variable and message-related variables ($header, $body, and $attachments). Any changes you make to an outbound message in a publish action affect only the published message. In other words, the changes you make in the publish action are rolled back before the message flow proceeds to any actions that follow the publish action in your message flow.

For example, consider a message flow that deals with a large purchase order, and you have to send the summary of the purchase order, through e-mail, to the manager. The summary of the of the purchase order is created in the SOAP body of the incoming message when you include a publish action in the request pipeline. In the publish action, the purchase order data is transformed into a summary of the purchase order—for example, all the attachments in $attachments can be deleted because they are not required in the summary of the purchase order.

Transformations and Route Nodes

You may need to route messages to one of two destinations, based on a WS-addressing header. In that case, content-based routing and the second destination require the newer version of the document in the SOAP body. In this situation, you can configure the route node to conditionally route to one of the two destinations. You can configure a transformation in the route node to transform the document for the second destination.

You can also set the control elements in the outbound context variable ($outbound) to influence the behavior of the system for the outbound message (for example, you can set the Quality of Service).

See Inbound and Outbound Variables and Constructing Messages to Dispatch for information about the sub-elements of the inbound and outbound variables and how the content of messages is constructed using the values of the variables in the message context.

See also:

 


Constructing Service Callout Messages

When ALSB makes a call to a service via a service callout action, the content of the message is constructed using the values of variables in the message context. The message content for outbound messages is handled differently depending upon the type of the target service. How the message content is created depends on the type of the target service and whether you choose to configure the SOAP body or the payload (parameters or document), as described in the following topics:

SOAP Document Style Services

Messages for SOAP Document Style services (including EJB document and document-wrapped services), can be constructed as follows:

To illustrate how messages are constructed during callouts to SOAP Document Style services, consider a service callout action configured as follows:

Assume also that at run time, the request document variable, myreq, is bound to the following XML.

Listing 3-1 Content of Request Variable (myreq)
<sayHello xmlns="http://www.openuri.org/">
    <intVal>100</intVal>
    <string>Hello AquaLogic</string>
</sayHello>

At run time, the SOAP request header variable, reqheader, is bound to the following SOAP header.

Listing 3-2 Content of SOAP Request Header Variable (reqheader)
<soap:Header xmlns:soap=http://schemas.xmlsoap.org/soap/envelope/
xmlns:wsa="http://schemas.xmlsoap.org/ws/2003/03/addressing">
    <wsa:Action>...</wsa:Action>
    <wsa:To>...</wsa:To>
    <wsa:From>...</wsa:From>
    <wsa:ReplyTo>...</wsa:ReplyTo>
    <wsa:FaultTo>...</wsa:FaultTo>
  </soap:Header>

In this example scenario, the full body of the message sent to the external service is shown in Listing 3-3 (the contents of the myreq and reqheader variables are shown in bold).

Listing 3-3 Message Sent to the Service as a Result of Service Callout Action
<?xml version="1.0" encoding="UTF-8"?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
    <soap:Header xmlns:soap=http://schemas.xmlsoap.org/soap/envelope/
    xmlns:wsa="http://schemas.xmlsoap.org/ws/2003/03/addressing">
        <wsa:Action>...</wsa:Action>
        <wsa:To>...</wsa:To>
        <wsa:From>...</wsa:From>
        <wsa:ReplyTo>...</wsa:ReplyTo>
        <wsa:FaultTo>...</wsa:FaultTo>
    </soap:Header>
    <soapenv:Body>
        <sayHello xmlns="http://www.openuri.org/">
            <intVal>100</intVal>
            <string>Hello AquaLogic</string>
        </sayHello>
    </soapenv:Body>
</soapenv:Envelope>

Based on the configuration of the service callout action described above, the response from the service is assigned to the myresp variable. The full response from the external service is shown in Listing 3-4.

Listing 3-4 Response Message From the Service as a Result of Service Callout Action
<?xml version="1.0" encoding="UTF-8"?>
<env:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:soapenc="http://schemas.xmlsoap.
org/soap/encoding/" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <env:Header/>
    <env:Body env:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
        <m:sayHelloResponse xmlns:m="http://www.openuri.org/">
            <result xsi:type="xsd:string">This message brought to you by Hello AquaLogic and the number 100
            </result>
        </m:sayHelloResponse>
    </env:Body>
</env:Envelope>

In this scenario, the myresp variable is assigned the value shown in Listing 3-5.

Listing 3-5 Content of Response Variable (myresp) as a Result of Service Callout Action
<m:sayHelloResponse xmlns:m="http://www.openuri.org/">
    <result ns0:type="xsd:string" xmlns:ns0="http://www.w3.org/2001/XMLSchema-instance">
This message brought to you by Hello AquaLogic and the number 100
    </result>
</m:sayHelloResponse>

SOAP RPC Style Services

Messages for SOAP RPC Style services (including EJB RPC services) can be constructed as follows:

To illustrate how messages are constructed during callouts to SOAP RPC Style services, look at this example with the following configuration:

In this scenario, the body of the outbound message to the service is shown in Listing 3-6.

Listing 3-6 Content of Outbound Message
<?xml version="1.0" encoding="UTF-8"?>
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
    <soapenv:Body>
        <sayHello2 xmlns="http://www.openuri.org/">
            <intVal>100</intVal>
            <string >Hello AquaLogic</string>
        </sayHello2>
    </soapenv:Body>
</soapenv:Envelope>

The response returned by the service to which the call was made is shown in Listing 3-7.

Listing 3-7 Content of Response Message From the helloWorld Service
<?xml version="1.0" encoding="UTF-8"?>
<env:Envelope xmlns:env="http://schemas.xmlsoap.org/soap/envelope/"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:soapenc="http://schemas.xmlsoap.org/soap/encoding/"
xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <env:Header/>
    <env:Body env:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
        <m:sayHello2Response xmlns:m="http://www.openuri.org/">
            <result xsi:type="n1:HelloWorldResult" xmlns:n1="java:">
                <message xsi:type="xsd:string">
                This message brought to you by Hello AquaLogic and the number 100
                </message>
            </result>
        </m:sayHello2Response>
    </env:Body>
</env:Envelope>

The message context variable output1 is assigned the value shown in Listing 3-8.

Listing 3-8 Content of Output Variable (output1)
<message ns0:type="xsd:string" xmlns:ns0="http://www.w3.org/2001/XMLSchema-intance">
This message brought to you by Hello AquaLogic and the number 100</message>

XML Services

Messages for XML services can be constructed as follows:

To illustrate how messages are constructed during callouts to XML services, take for example a service callout action configured as follows:

Assume also that at run time, the request document variable, myreq, is bound to the following XML.

Listing 3-9 Content of myreq Variable
<sayHello xmlns="http://www.openuri.org/">
    <intVal>100</intVal>
    <string>Hello AquaLogic</string>
</sayHello>

In this scenario:

Messaging Services

In the case of Messaging services:

For example, if the request message context variable myreq is bound to an XML document of the following format: <hello>there</hello>, the outbound message contains exactly this payload. The response message context variable (myresp) is bound to a reference element similar to the following:

<binary-content ref=" cid:1850733759955566502-2ca29e5c.1079b180f61.-7fd8"/>

 


Handling Errors as the Result of a Service Callout

You can configure error handling at the message flow, pipeline, route node, and stage level. The types of errors that are received from an external service as the result of a service callout include transport errors, SOAP faults, responses that do not conform to an expected response, and so on.

The fault context variable is set differently for each type of error returned. You can build your business and error handling logic based on the content of the fault variable. To learn more about $fault, see Fault Variable.

Transport Errors

When a transport error is received from an external service and there is no error response payload returned to ALSB by the transport provider (for example, in the case that an HTTP 403 error code is returned), the service callout action throws an exception, which in turn causes the pipeline to raise an error. The fault variable in a user-configured error handler is bound to a message formatted similarly to that shown in Listing 3-11.

Listing 3-11 Contents of the ALSB fault Variable—Transport Error, no Error Response Payload
<con:fault xmlns:con="http://www.bea.com/wli/sb/context">
  <con:errorCode>BEA-380000</con:errorCode>
  <con:reason>Not Found</con:reason>
   <con:details>
   .......
   </con:details>
    <con:location>
       <con:node>PipelinePairNode1</con:node>
       <con:Pipeline>PipelinePairNode1_request</con:Pipeline>
    <con:Stage>Stage1</con:Stage>
    </con:location>
</con:fault>

In the case that there is a payload associated with the transport error—for example, when an HTTP 500 error code is received from the business service and there is XML payload in the response—a message context fault is generated with the custom error code: BEA-382502.

The following conditions must be met for a BEA-382502 error response code to be triggered as the result of a response from a service—when that service uses an HTTP or JMS transport:

If the transport is HTTP, the ErrorResponseDetail element will also contain the HTTP error code returned with the response. The ErrorResponseDetail element in the fault contains error response payload received from the service. Listing 3-12 shows an example of the ErrorResponseDetail element.

Listing 3-12 Contents of the ALSB fault Variable—Transport Error, with Error Response Payload
<ctx:Fault xmlns:ctx="http://www.bea.com/wli/sb/context">
    <ctx:errorCode>BEA-382502<ctx:errorCode>
    <ctx:reason> Service callout has received an error response from the server</ctx:reason>
    <ctx:details>
        <alsb:ErrorResponseDetail xmlns:alsb="http://www.bea.com/...">
            <alsb:detail> <![CDATA[
. . .                 
]]>
            </alsb:detail>           <alsb:http-response-code>500</alsb:http-response-code>
        </alsb:ErrorResponseDetail>
    </ctx:details>
    <ctx:location>. . .</ctx:location>
</ctx:Fault>
Note: The XML schema for the service callout-generated fault is shown in XML Schema for the Service Callout-Generated Fault Details.

SOAP Faults

In case an external service returns a SOAP fault, the ALSB run time sets up the context variable $fault with a custom error code and description with the details of the fault. To do so, the contents of the 3 elements under the <SOAP-ENV:Fault> element in the SOAP fault are extracted and used to construct an ALSB fault element.

Take for example a scenario in which a service returns the following error.

Listing 3-13 SOAP Fault Returned From Service Callout
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"> 
  <SOAP-ENV:Body>
    <SOAP-ENV:Fault>
      <faultcode>SOAP-ENV:Client</faultcode>
      <faultstring>Application Error</faultstring>
      <detail>
        <message>That’s an Error!</message>
        <errorcode>1006</errorcode>
      </detail>
    </SOAP-ENV:Fault>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

The <faultcode>, <faultstring>, and <detail> elements are extracted and wrapped in an <alsb:ReceivedFault> element. Note that the faultcode element in Listing 3-15 contains a QName—any related namespace declarations are preserved. If the transport is HTTP, the ReceivedFault element will also contain the HTTP error code returned with the fault response.

The generated <alsb:ReceivedFault> element, along with the custom error code and the error string are used to construct the contents of the fault context variable, which in this example takes a format similar to that shown in Listing 3-14.

Listing 3-14 Contents of the ALSB Fault Variable—SOAP Fault

<ctx:Fault xmlns:ctx="http://www.bea.com/wli/sb/context">
    <ctx:errorCode>BEA-382500<ctx:errorCode>
    <ctx:reason> service callout received a soap Fault response</ctx:reason>
    <ctx:details>
        <alsb:ReceivedFault xmlns:alsb="http://www.bea.com/...">
            <alsb:faultcode
xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">SOAP-ENV:Clien
            </alsb:faultcode>
            <alsb:faultstring>Application Error</alsb:faultstring>
            <alsb:detail>
                <message>T
hat’s an Error!</message>
                <errorcode>1006</errorcode>
            </alsb:detail>

          <alsb:http-response-code>500</alsb:http-response-code>
        </alsb:ReceivedFault>
    </ctx:details>
    <ctx:location> </ctx:location>
</ctx:Fault>

Note: The unique error code BEA-382500 is reserved for the case when service callout actions receive SOAP fault responses.

Unexpected Responses

When a service returns a response message that is not what the proxy service run time expects, a message context fault will be generated and initialized with the custom error code BEA-382501. The details of the fault include the contents of the SOAP-Body element of the response. If the transport is HTTP, the ReceivedFault element will also contain the HTTP error code returned with the fault response.

The XML schema definition of the service callout-generated fault details is shown in Listing 3-15.

Listing 3-15 XML Schema for the Service Callout-Generated Fault Details
<xs:complexType name="ReceivedFaultDetail">
        <xs:sequence>
            <xs:element name="faultcode" type="xs:QName"/>
            <xs:element name="faultstring" type="xs:string"/>
            <xs:element name="detail" minOccurs="0" >
               <xs:complexType>
                 <xs:sequence>
                        <xs:any namespace="##any" minOccurs="0" maxOccurs="unbounded" processContents="lax" />
                 </xs:sequence>
        <xs:anyAttribute namespace="##any" processContents="lax" />
               </xs:complexType>
            </xs:element>
            <xs:element name="http-response-code" type="xs:int" minOccurs="0"/>\
type="xs:int" minOccurs="0"/>
        </xs:sequence>
</xs:complexType>

<xs:complexType name="UnrecognizedResponseDetail">
        <xs:sequence>
            <xs:element name="detail" minOccurs="0" type="xs:string" />
        </xs:sequence>
</xs:complexType>

<xs:complexType name="ErrorResponseDetail">
        <xs:sequence>
            <xs:element name="detail" minOccurs="0" type="xs:string" />
        </xs:sequence>
</xs:complexType>

 


Handling Errors in Message Flows

The process described in the next paragraph constitutes an error handling pipeline for the stage of an error handler. In addition, an error pipeline can be defined for a pipeline (request or response) or for an entire proxy service.

The error handler at the stage level is invoked for handling an error; If the stage-level error handler is not able to handle a given type of error, the pipeline error handler is invoked. If the pipeline-level error handler also fails to handle the error, the service-level error handler is invoked. If the service-level error handler also fails, the error is handled by the system.The following table summarizes the scope of the error handlers at various levels in the message flow.

Table 3-8 Scope of Error Handlers
Level
Scope
Stage
Handles all the errors within a stage.
Pipeline
Handles all the errors in a pipeline, along with any unhandled errors from any stage in a pipeline.
Service
Handles all the errors in a proxy service, along with any unhandled errors in any pipeline in a service.

Note: All WS-Security errors are handled at this level.

System
Handles all the errors that are not handled any where else in a pipeline.

Note: There are exceptions to the scope of error handlers. For example, an exception thrown by a non-XML transformation at the stage level is only caught by the service-level error handler. Suppose a transformation occurs that transforms XML to MFL for an outgoing proxy service response message, it always occurs in the binding layer. Therefore, for example, if a non-XML output is missing a mandatory field at the stage level, only a service-level error handler can catch this error.

For more information on error messages and error handling, see “Error Messages and Handling” in Proxy Services: Error Handlers in Using the AquaLogic Service Bus Console.

You can handle errors by configuring a test that checks if an assertion is true and use the reply action configured false. You can repeat this test at various levels. Also you can have an error without an error handler at a lower level and handle it through an error handler at an higher level in message flow. In general, it is easier to handle specific errors at a stage level of the message flow and use error handlers at the higher level for more general default processing of errors that are not handled at the lower levels. It is good practice to explicitly handle anticipated errors in the pipelines and allow the service-level handler to handle unanticipated errors.

Note: You can only handle WS-Security related errors at the service level.

Generating the Error Message, Reporting, and Replying

A predefined context variable (the fault variable) is used to hold information about any error that occurs during message processing. When an error occurs, this variable is populated with information before the appropriate error handler is invoked. The fault variable is defined only in error handler pipelines and is not set in request and response pipelines, or in route or branch nodes. For additional information about $fault, see Predefined Context Variables .

In the event of errors for request/response type inbound messages, it is often necessary to send a message back to the originator outlining the reason why an error occurred. You can accomplish this by using a Reply with Failure action after configuring the message context variables with the response you want to send. For example, when an HTTP message fails, Reply with Failure generates the HTTP 500 status. When a JMS message fails, Reply with Failure sets the JMS_BEA_Error property to true. The ALSB error actions are discussed in “Error Messages and Handling” in Proxy Services: Error Handlers in Using the AquaLogic Service Bus Console.

An error handling pipeline is invoked if a service invoked by a proxy service returns a SOAP fault or transport error. Any received SOAP fault is stored in $body, so if a Reply with Failure is executed without modifying $body, the original SOAP fault is returned to the client that invoked the service. If a reply action is not configured, the system error handler generates a new SOAP fault message. The proxy service recognizes that a SOAP fault is returned because a HTTP error status is set, or the JMS property SERVER_Error is set to true.

Some use cases require error reporting. You can use the report action in these situations. For example, consider a scenario in which the request pipeline reports a message for tracking purposes, but the service invoked by the route node fails after the reporting action. In this case, the reporting system logged the message, but there is no guarantee that the message was processed successfully, only that the message was successfully received.

You can use the ALSB Console to track the message to obtain an accurate picture of the message flow. This allows you to view the original reported message indicating the message was submitted for processing, and also the subsequent reported error indicating that the message was not processed correctly. To learn how to configure a report action and use the data reported at run time, see Proxy Services: Actions in Using the AquaLogic Service Bus Console.

Example of Action Configuration in Error Handlers

This example shows how you can configure the report and reply actions in error handlers. The message flow shown in Figure 3-2 includes an error handler on the validate loan application stage. The error handler in this case is a simple message flow with a single stage configured—it is represented in the ALSB Console as shown in Figure 3-2.

Figure 3-2 Error Handler Message Flow

Error Handler Message Flow

The stage is, in turn, configured with actions (replace, report, and reply) as shown in Figure 3-3.

Figure 3-3 Actions in Stage Error Handler

Actions in Stage Error Handler

The actions control the behavior of the stage in the pipeline error handler as follows:

For configuration information, see “Error Messages and Handling” in Proxy Services: Error Handlers in Using the AquaLogic Service Bus Console.

 


Using Dynamic Routing

When you do not know the service you need to invoke from the proxy service you are creating, you can use dynamic routing.

For any given proxy service, you can use one of the following techniques to dynamically route messages:

Implementing Dynamic Routing

You can use dynamic routing to determine the destination during the runtime of a proxy service. To achieve this you can use a routing table in an XML file to create an XQuery resource.

Note: Instead of using the XQuery resource, you can also directly use the XML file from which the resource is created.

An XML file or the Xquery resource can be maintained easily. At runtime you provide the entry in the routing table that will determine the routing or publishing destination of the proxy service.The XML file or the XQuery resource contains a routing table, which maps a logical identifier to (such as the name of a company) to the physical identifier (the fully qualified name of the service in ALSB). The logical identifier, which is extracted from the message, maps on to the physical identifier, which is the name of the service you want to invoke.

Note: To use the dynamic route action, you need the fully qualified name of the service in ALSB.

In a pipeline the logical identifier is obtained with an XPath into the message.You assign the XML table in the XQuery resource to a variable. You implement a query against the variable in the routing table to extract the physical identifier based on the corresponding logical identifier. Using this variable you will be able to invoke the required service. The following sections describe how to implement dynamic routing.

Sample XML File

You can create an XQuery resource from the following XML file. Save this as sampleXquery.xml.

Listing 3-16 Sample XML File
<routing>
   <row>
      <logical>BEA Systems</logical>
      <physical>default/goldservice</physical>
   </row>
   <row>
      <logical>ABC Corp</logical>
      <physical>default/silverservice</physical>
   </row>
</routing>

Creating an XQuery Resource From the Sample XML

  1. In an active session, select Project Explorer from the left navigation panel. The Project View page is displayed.
  2. Select the project to which you want to add the XQuery resource.
  3. In the Project View page, select the XQuery resource from the Select Resource Type drop-down list. The Create XQuery page is displayed.
  4. In the Resource Name field, enter the name of the resource. This is a mandatory.
  5. In the Resource Description field, provide the a description for the resource. This is optional.
  6. In the XQuery field, provide the path to the XML you are using as an XQuery resource. Click on Browse to locate the file. Optionally, you can copy and paste the XML in the XQuery field. This is mandatory.
  7. Save the XQuery resource.
  8. Activate the session.

Creating and Configuring the Proxy Service to Implement Dynamic Routing

  1. In an active session, select Project Explorer from the left navigation panel. The Project View page is displayed.
  2. Select the project to which you want to add the proxy service.
  3. In the Project View page, select the Proxy Service resource from the Select Resource Type drop-down list. The General Configuration page is displayed.
  4. In the Service Name field of the General Configuration page, enter the name of the proxy service. This is mandatory.
  5. Select the type of service by clicking on the button adjacent to various types of services available under Service Type. For more information on selecting the service type, see Proxy Services: Actions.
  6. Click Finish. On the Summary page, click Save to save the proxy service.
  7. On the Project View page, click the Edit Message Flow icon against the newly created proxy service in the Resource table. The Edit Message Flow page is displayed.
  8. Click on the message flow to add a pipeline pair to the message flow.
  9. Click on Request Pipeline icon select Add Stage from the menu.
  10. Click on the Stage1 icon to and select Edit Stage from the menu. The Edit Stage Configuration page appears.
  11. Click Add Action icon. Choose Add an Action item from the menu.
  12. Choose the Assign action from Message Processing.
  13. Click on Expression. The XQuery Expression Editor is displayed.
  14. Click on XQuery Resources. The browser displays the page where you can import the XQuery resource. Click on the Browse to locate the XQuery resource.
  15. Click on Validate to validate the imported XQuery resource.
  16. Save the imported XQuery resource on successful validation.
  17. On the Edit Stage Configuration page, enter the name of the variable in the field.
  18. This assigns the XQuery resource to this variable. The variable now contains the externalized routing table.

  19. Click on the Assign action icon to add another assign action.
  20. Note: To do this repeat step 11 to step 13 .
  21. Enter the following Xquery:
  22. <ctx: route>
    <ctx: service isProxy=’false’> {$routingtable/row[logical/text()=$logicalidentifier]/physical/text()}
    </ctx: service>
    </ctx: route>

    In the above code, replace $logicalidentifier by the actual XPath to extract the logical identifier from the message (example from $body).

  23. Click on Validate to validate the Xquery.
  24. Save the Xquery on successful validation.
  25. On the Edit Stage Configuration page, enter the name of the variable (for example, routeresult) in the field.
  26. This extracts the XML used by the dynamic route action into this variable.

  27. Click on the message flow to add a route node to the end of the message flow.
  28. Click on the Route Node icon and select Edit from the menu.
  29. Click the Add Action icon. Choose Add an Action item from the menu.
  30. Choose the Dynamic Route action.
  31. Click on Expression. The XQuery Expression Editor is displayed.
  32. Enter the variable from step 22 (for example, $routeresult)

 


Accessing Databases Using XQuery

ALSB provides read-access to databases from proxy services without requiring you to write a custom EJB or custom Java code and without the need for a separate database product like AquaLogic Data Services Platform. You can use the execute-sql() function to make a simple JDBC call to a database to perform simple database reads. Any SQL query is legal, from a query that gets a single tax rate for the supplied location to a query that does a complex join to obtain an order's current status from several underlying database tables.

A database query can be used to get data for message enrichment, for routing decisions, or for customizing the behavior of a proxy service. Take for example a scenario in which an ALSB proxy service receives “request for quote” messages. The proxy service can route the requests based on the customer's priority to one of a number of quotation business services (say, standard, gold, or platinum level services). The proxy service can then perform a SQL-based augmentation of the results that those services return—for example, based on the selected ship method and the weight of the order, the shipping cost can be looked up and that cost added to the request for quote message.

fn-bea:execute-sql() describes the syntax for the function and provides examples of its use. The execute-sql() function returns typed data and automatically translates values between SQL/JDBC and XQuery data models.

You can store the returned element in a user-defined variable in an ALSB message flow.

The following databases and JDBC drivers are supported using the execute-sql() function:

Use non-XA drivers for datasources you use with the fn-bea:execute-sql() function—the function supports read-only access to the datasources.

WARNING: In addition to specifying a non-XA JDBC driver class to use to connect to the database, you must ensure that you disable global transactions and two-phase commit. (Global transactions are enabled by default in the WebLogic Server console for JDBC data sources.) These specifications can be made for your data source via the WebLogic Server Administration Console. See Create JDBC Data Sources in the WebLogic Server Administration Console Online Help.

For complete information about database and JDBC drivers support in ALSB, see Supported Database Configurations in Supported Configurations for AquaLogic Service Bus.

Databases other than the core set described in the preceding listing are also supported. However, for the core databases listed above, the XQuery engine does a better recognition and mapping of data types to XQuery types than it does for the non-core databases—in some cases, a core database’s proprietary JDBC extensions are used when fetching data. For the non-core databases, the XQuery engine relies totally on the standard type codes provided by the JDBC driver and standard JDBC resultset access methods.

When designing your proxy service, you can enter XQueries inline as part of an action definition instead of entering them as resources. You can also use inline XQueries for conditions in If...Then... actions in message flows. For information about using the inline XQuery editor, see Creating Variable Structure Mappings.

 


Understanding Message Context

The message context is a set of variables that hold message context and information about messages as they are routed through the ALSB. Together, the header, body, and attachments variables, (referenced as $header, $body and $attachments in XQuery statements) represent the message as it flows through ALSB. The canonical form of the message is SOAP. Even if the service type is not SOAP, the message appears as SOAP in the ALSB message context.

Message Context Components

In a Message Context, $header contains a SOAP header element and $body contains a SOAP Body element. The Header and Body elements are qualified by the SOAP 1.1 or SOAP 1.2 namespace depending on the service type of the proxy service. Also in a Message Context, $attachments contains a wrapper element called attachments with one child attachment element per attachment. The attachment element has a body element with the actual attachment.

When a message is received by a proxy service, the message contents are used to initialize the header, body, and attachments variables. For SOAP services, the Header and Body elements are taken directly from the envelope of the received SOAP message and assigned to $header and $body respectively. For non-SOAP services, the entire content of the message is typically wrapped in a Body element (qualified by the SOAP 1.1 namespace) and assigned to $body, and an empty Header element (qualified by the SOAP 1.1 namespace) is assigned to $header.

Binary and MFL messages are initialized differently. For MFL messages, the equivalent XML document is inserted into the Body element that is assigned to $body. For binary messages, the message data is stored internally and a piece of reference XML is inserted into the Body element that is assigned to $body. The reference XML looks like <binary-content ref="..."/>, where "..." contains a unique identifier assigned by the proxy service.

The message context is defined by an XML schema. You must use XQuery expressions to manipulate the context variables in the message flow that defines a proxy service.

The predefined context variables provided by ALSB can be grouped into the following types:

For information about the predefined context variables, see Predefined Context Variables.

The $body contains message payload variable. When a message is dispatched from ALSB you can decide the variables, whose you want to include in the outgoing message. That determination is dependent upon whether the target endpoint is expecting a SOAP or a non-SOAP message:

For non-SOAP services, if the Body element of $body contains a binary-content element, then the referenced content stored internally is sent ‘as is’, regardless of the target service type.

For more information, see Message Context.

The types for the message context variables are defined by the message context schema (MessageContext.xsd). When working with the message context variables in the BEA XQuery Mapper, you need to reference MessageContext.xsd, which is available in a JAR file, BEA_HOME/alsb_3.0/lib/sb-kernel-api.jar, and the transport-specific schemas, which are available at

BEA_HOME/alsb_3.0/lib/transports/

where BEA_HOME represents the directory in which you installed ALSB.

To learn about the message context schema and the transport specific schemas, see Message Context Schema.

Guidelines for Viewing and Altering Message Context

Consider the following guidelines when you want to inspect or alter the message context:

Copying JMS Properties From Inbound to Outbound

It is assumed that the interfaces of the proxy services and of the invoked business service may be different. Therefore, ALSB does not propagate any information (such as the transport headers and JMS properties) from the inbound variable to the outbound variable.

The transport headers for the proxy service’s request and response messages are in $inbound and the transport headers for the invoked business service’s request and response are in $outbound.

For example, the following XQuery expression can be used in a case where the user-defined JMS properties for a one-way message (an invocation with no response) need to be copied from inbound message to outbound message:

Use the transport headers action to set

$inbound/ctx:transport/ctx:request/tp:headers/tp:user-header 

as the first child of:

./ctx:transport/ctx:request/tp:headers 

in the outbound variable.

To learn how to configure the transport header action, see:

 


Working with Variable Structures

The following sections describe

Using the Inline XQuery Expression Editor

ALSB allows you to import XQueries that have been created with an external tool such as the BEA XQuery Mapper. You can use these XQueries anywhere in the proxy service message flow by binding the XQuery resource input to an Inline XQuery, and binding the XQuery resource output to an action that uses the result as the input; for example, the assign, replace, or insert actions.

However, you can enter the XQuery inline as part of the action definition instead of entering the XQuery as a resource. You can also use Inline XQueries for the condition in an If...Then... action.

Use the Inline XQuery Expression Editor to enter simple XQueries that consist of the following:

Note: For more complex XQueries, it is recommended that you use the XQuery Mapper, especially if you are not familiar with XQuery.

Inline XQueries can be used effectively to:

Note: You can also use the Inline XQuery Expression Editor to create variable structures. For more information, see Using Variable Structures.

Inline XQueries

ALSB allows you to import XQueries that have been created with an external tool such as the BEA XQuery Mapper. You can use these XQueries anywhere in the proxy service message flow by binding the XQuery resource input to an inline XQuery, and binding the XQuery resource output to an action that uses the result as the action input; for example, the assign, replace, or insert actions. However, you can enter the XQuery inline as part of the action definition instead of entering the XQuery as a resource. You can also use inline XQueries for the condition in an If...Then... action.

The inline XQuery and XPath editors allow you to declare a variable’s structure by mapping it to a type or element and then creating path expressions with a drag and drop action from the graphical representation of the structure. You can also enter the path expressions manually.

You can use this feature directly for all user-defined variables, as well as $inbound, $outbound, and $fault. However, you cannot use it directly to access XML attachments in $attachments, headers in $header, or documents and RPC parameters in $body, with one exception— you can use it directly to access documents and parameters in $body for request messages received by a WSDL proxy service.

To learn more about creating variable structures, see Creating Variable Structure Mappings.

To learn more about XQuery engine support and the relationship with the DSP functions and operators, see XQuery Implementation.

Uses of the Inline XQuery Expression Editor

You typically use the Inline XQuery Expression Editor to enter simple XQueries that consist of the following:

Note: For more complex XQueries, we recommend that you use the BEA XQuery Mapper, an editor with drag-and-drop functionality. See Transforming Data Using the XQuery Mapper in Transforming Data Using the XQuery Mapper.

Examples of good uses of inline XQueries are:

You can also use the Inline XQuery Expression Editor to create variable structures. For more information, see Using Variable Structures.

Using Variable Structures

You can use the Inline XQuery Expression Editor to create variable structures, with which you define the structure of a given variable for design purposes. For example, it is easier to browse the XPath variable in the console rather than viewing the XML schema of the XPath variable.

Note: It is not necessary to create variable structures for your runtime to work. Variable structures define the structure of the variable or the variable path but do not create the variable. Variables are created at runtime as the target of the assign action in the stage.

In a typical programming language, the scope of variables is static. Their names and types are explicitly declared. The variable can be accessed anywhere within the static scope.

In ALSB, there are some predefined variables, but you can also dynamically create variables and assign value to them using the assign action or using the loop variable in the for-loop. When a value is assigned to a variable, the variable can be accessed anywhere in the proxy service message flow. The variable type is not declared but the type is essentially the underlying type of the value it contains at any point in time.

Note: The scope of the for-loop variable is limited and cannot be accessed outside the stage.

When you use the Inline XQuery Expression Editor, the XQuery has zero or more inputs and one output. Because you can display the structure of the inputs and the structure of the output visually in the Expression Editor itself, you do not need to open the XML schema or WSDL resources to see their structure when you create the Inline XQuery. The graphical structure display also enables you to drag and drop simple variable paths along the child axis without predicates, into the composed XQuery.

Each variable structure mapping entry has a label and maps a variable or variable path to one or more structures. The scope of these mappings is the stage or route node. Because variables are not statically typed, a variable can have different structures at different points (or at the same point) in the stage or route node. Therefore, you can map a variable or a variable path to multiple structures, each with a different label. To view the structure, select the corresponding label with a drop-down list.

Note: You can also create variable structure mappings in the Inline XPath Expression Editor. However, although the variable or a variable path is mapped to a structure, the XPaths generated when you select from the structure are XPaths relative to the variable. An example of a relative XPath is ./ctx:attachment/ctx:body.

Creating Variable Structure Mappings

The following sections describe how to create several types of variable structure mappings:

Sample WSDL

This sample WSDL is used in most of the examples in this section. You need to save this WSDL as a resource in your configuration. For more information, see Creating the Resources You Need for the Examples.

Listing 3-17 Sample WSDL
<definitions 
    name="samplewsdl"
    targetNamespace="http://example.org"
    xmlns="http://schemas.xmlsoap.org/wsdl/"
    xmlns:s0="http://www.bea.com"
    xmlns:s1="http://example.org"
    xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/">
<types>
  <xs:schema
    attributeFormDefault="unqualified"
    elementFormDefault="qualified"
    targetNamespace="http://www.bea.com"
    xmlns:xs="http://www.w3.org/2001/XMLSchema">
    <xs:element name="PO" type="s0:POType"/>
    <xs:complexType name="POType">
      <xs:all>
        <xs:element name="id" type="xs:string"/>
        <xs:element name="name" type="xs:string"/>
      </xs:all>
    </xs:complexType>
    <xs:element name="Invoice" type="s0:InvoiceType"/>
    <xs:complexType name="InvoiceType">
      <xs:all>
        <xs:element name="id" type="xs:string"/>
        <xs:element name="name" type="xs:string"/>
      </xs:all>
    </xs:complexType>
</xs:schema>
</types>
<message name="POTypeMsg">
    <part name="PO" type="s0:POType"/>
</message>
<message name="InvoiceTypeMsg">
    <part name="InvReturn" type="s0:InvoiceType"/>
</message>

<portType name="POPortType">
    <operation name="GetInvoiceType">
      <input message="s1:POTypeMsg"/>
      <output message="s1:InvoiceTypeMsg"/>
    </operation>
</portType>
<binding name="POBinding" type="s1:POPortType">
<soap:binding style="rpc" transport="http://schemas.xmlsoap.org/soap/http"/>
    <operation name="GetInvoiceType">
      <soap:operation soapAction="http://example.com/GetInvoiceType"/>
      <input>
        <soap:body use="literal"/>
      </input>
      <output>
        <soap:body use="literal"/>
    </output>
  </operation>
</binding>
</definitions>

Creating the Resources You Need for the Examples

To make use of the examples that follow, you save the sample WSDL as a resource in your configuration and create the sample business service and proxy service that use the sample WSDL.

The instructions that follow tell how to accomplish the tasks in the ALSB Console:

Save the WSDL as a Resource
  1. In the left navigation pane in the ALSB Console, under Change Center, click Create to create a new session for making changes to the current configuration.
  2. In the left navigation pane, click Project Explorer.
  3. In the Project View page, click the project to which you want to add the WSDL.
  4. In the Project View page, in the Create Resource field, select WSDL under Interface.
  5. In the Create a New WSDL Resource page in the Resource Name field, enter SampleWSDL. This is a required field.
  6. In the WSDL field, copy and paste the text from the sample WSDL into this field.
  7. Note: This is a required field.
  8. Click Save. The new WSDL SampleWSDL is included in the list of resources and saved in the current session. You must now create a proxy service that uses this WSDL, see Create a Proxy Service That Uses the Sample WSDL.
Create a Proxy Service That Uses the Sample WSDL
  1. In the left navigation pane, click Project Explorer.
  2. In the Project View page, select the project to which you want to add the proxy service.
  3. In the Project View page, in the Create Resource field, select Proxy Service under Service.
  4. In the Edit a Proxy Service - General Configuration page, in the Service Name field, enter ProxywithSampleWSDL. This is a required field.
  5. In the Service Type field, which defines the types and packaging of the messages exchanged by the service:
    1. Select WSDL Web Service from under Create a New Service.
    2. Click Browse. The WSDL Browser is displayed.
    3. Select SampleWSDL, then select POBinding in the Select WSDL Definitions pane.
    4. Click Submit.
  6. Keep the default values for all other fields on the General Configuration page, then click Next.
  7. Keep the default values for all fields on the Transport Configuration pages, then click Next.
  8. In the Operation Selection Configuration page, make sure SOAP Body Type is selected in the Selection Algorithm field, then click Next.
  9. Review the configuration data that you have entered for this proxy service, then click Save. The new proxy service ProxywithSampleWSDL is included in the list of resources and saved in the current session.To build message flow for this proxy service, see Build a Message Flow for the Sample Proxy Service.
Build a Message Flow for the Sample Proxy Service
  1. In the Project View page, in the Actions column, click the Edit Message Flow icon for the ProxywithSampleWSDL proxy service.
  2. In the Edit Message Flow page, click the ProxywithSampleWSDL icon, then click Add Pipeline Pair. PipelinePairNode1 is displayed, which includes request and response pipelines.
  3. Click the Request Pipeline icon, then click Add Stage. The Stage Stage1 is displayed.
  4. Click Save. The basic message flow is created for the ProxywithSampleWSDL proxy service.
Create a Business Service That Uses the Sample WSDL
  1. In the left navigation pane, click Project Explorer. The Project View page is displayed.
  2. Select the project to which you want to add the business service.
  3. From the Project View page, in the Create Resource field, select Business Service from under Service. The Edit a Business Service - General Configuration page is displayed.
  4. In the Service Name field, enter BusinesswithSampleWSDL. This is a required field.
  5. In the Service Type field, which defines the types and packaging of the messages exchanged by the service, do the following:
    1. Select WSDL Web Service from under Create a New Service.
    2. Click Browse. The WSDL Browser is displayed.
    3. Select SampleWSDL, then select POBinding in the Select WSDL Definitions pane.
    4. Click Submit.
  6. Keep the default values for all other fields on the General Configuration page, then click Next.
  7. Enter an endpoint URI in the Endpoint URI field on the Transport Configuration page.
    Click Add, and then click Next.
  8. Use the default values for all fields on the SOAP Binding Configuration page.
    Click Next.
  9. Review the configuration data that you have entered for this business service, and then click Save. The new business service BusinesswithSampleWSDL is included in the list of resources and is saved in the current session.
  10. From the left navigation pane, click Activate under Change Center. The session ends and the configuration is deployed to run time. You are now ready to use the examples—continue in Example 1: Selecting a Predefined Variable Structure.

Example 1: Selecting a Predefined Variable Structure

In this example, you select a predefined variable structure using the proxy service ProxyWithSampleWSDL, which has a service type WSDL Web Service that uses the binding POBinding from SampleWSDL.

The proxy service message flow needs to know the structure of the message in order to manipulate it. To achieve this, ALSB automatically provides a predefined structure that maps the body variable to the SOAP body structure as defined by the WSDL of the proxy service for all the messages in the interface. This predefined structure mapping is labeled body.

Note: This predefined structure is also supported for messaging services with a typed interface.

To select a predefined variable structure:

In the Variable Structures panel on the XQuery Expression Editor page, select body from the drop-down list of built-in structures.

The variable structure body is displayed in Figure 3-4.

Figure 3-4 Variable Structures—body

Variable Structures—body

Example 2: Creating a Variable Structure That Maps a Variable to a Type

Suppose the proxy service ProxyWithSampleWSDL invokes a service callout to the business service BusinessWithSampleWSDL, which also has a service type WSDL Web Service that uses the binding POBinding from SampleWSDL. The operation GetInvoiceType is invoked.

In this example, the message flow needs to know the structure of the response parameter in order to manipulate it. To achieve this, you can create a new variable structure that maps the response parameter variable to the type InvoiceType.

To map a variable to a type:

  1. In the Variable Structures panel, click Add New Structure. Additional fields are displayed in Figure 3-5.
  2. Figure 3-5 Variable Structures—Add a New Structure


    Variable Structures—Add a New Structure

  3. Select the XML Type.
  4. In the Structure Label field, enter InvoiceType as the display name for the variable structure you want to create. This display name enables you to give a meaningful name to the structure so you can recognize it at design time but it has no impact at run time.
  5. In the Structure Path field, enter $InvoiceType as the path of the variable at run time.
  6. To select the type InvoiceType, do the following:
    1. Under the Type field, select the appropriate radio button, then select WSDL Type from the drop-down list.
    2. Click Browse. The WSDL Browser is displayed.
    3. In the WSDL Browser, select SampleWSDL, then select InvoiceType under Types in the Select WSDL Definitions pane.
    4. Click Submit. InvoiceType is displayed under your selection WSDL Type.
  7. Click Add. The new variable structure InvoiceType is included under XML Type in the drop-down list of variable structures.
  8. The variable structure InvoiceType is displayed in Figure 3-6.

    Figure 3-6 Variable Structures—InvoiceType


    Variable Structures—InvoiceType

Example 3: Creating a Variable Structure that Maps a Variable to an Element

Suppose a temporary variable has the element Invoice described in the SampleWSDL WSDL. In this example, the ProxyWithSampleWSDL message flow needs to access this variable. To achieve this, you can create a new variable structure that maps the variable to the element Invoice.

To map a variable to an element:

  1. In the Variable Structures panel, click Add New Structure.
  2. Make sure you select the XML Type.
  3. In the Structure Label field, enter Invoice as the meaningful display name for the variable structure you want to create.
  4. In the Structure Path field, enter $Invoice as the path of the variable structure at run time.
  5. To select the element Invoice, do the following:
    1. For the Type field, make sure you select the appropriate radio button.Then select WSDL Element from the drop-down list.
    2. Click Browse.
    3. In the WSDL Browser, select SampleWSDL, then select Invoice under Elements in the Select WSDL Definitions pane.
    4. Click Submit. Invoice is displayed under your selection WSDL Element.
  6. Click Add. The new variable structure Invoice is included under XML Type in the drop-down list of variable structures.
  7. The variable structure Invoice is displayed in Figure 3-7.

    Figure 3-7 Variable Structures—Invoice


    Variable Structures—Invoice

Example 4: Creating a Variable Structure That Maps a Variable to a Child Element

The ProxyWithSampleWSDL proxy service routes to the document style Any SOAP business service that returns the Purchase Order in the SOAP body. In this example, the ProxyWithSampleWSDL proxy service message flow must then manipulate the response. To achieve this, you can create a new structure that maps the body variable to the PO element, and specify the PO element as a child element of the variable. You need to specify it as a child element because the body variable contains the SOAP Body element and the PO element is a child of the Body element.

To map a variable to a child element:

  1. In the Variable Structures panel, click Add New Structure.
  2. Make sure you select the XML Type.
  3. In the Structure Label field, enter body to PO as the meaningful display name for the variable structure you want to create.
  4. In the Structure Path field, enter $body as the path of the variable structure at run time.
  5. To select the PO element:
    1. Under the Type field, make sure you select the appropriate radio button, and then select WSDL Element from the drop-down list.
    2. Click Browse.
    3. In the WSDL Browser, select SampleWSDL, then select PO under Elements in the Select WSDL Definitions pane.
    4. Click Submit.
  6. Select the Set as child checkbox to set the PO element as a child of the body to PO variable structure.
  7. Click Add. The new variable structure body to PO is included under XML Type in the drop-down list of variable structures.
  8. The variable structure body to PO is displayed in Figure 3-8.

    Figure 3-8 Variable Structures—body to PO


    Variable Structures—body to PO

Example 5: Creating a Variable Structure that Maps a Variable to a Business Service

The ProxyWithSampleWSDL proxy service routes the message to the BusinessWithSampleWSDL business service, which also has a service type WSDL Web Service that uses the binding POBinding from SampleWSDL. In this example, the message flow must then manipulate the response. To achieve this, you can define a new structure that maps the body variable to the BusinessWithSampleWSDL business service. This results in a map of the body variable to the SOAP body for all the messages in the WSDL interface of the service.

Note: This mapping is also supported for messaging services with a typed interface.

To map a variable to a business service:

  1. In the Variable Structures panel, click Add New Structure.
  2. Select Service Interface.
  3. In the Structure Label field, enter BusinessService as the meaningful display name for the variable structure.
  4. In the Structure Path field, $body is already set as the default. This is the path of the variable structure at run time.
  5. To select the business service, do the following:
    1. Under the Service field, click Browse. The Service Browser is displayed.
    2. In the Service Browser, select the BusinessWithSampleWSDL business service, then click Submit. The business service is displayed under the Service field.
    3. In the Operation field, select All.
  6. Click Add. The new variable structure BusinessService is included under Service Interface in the drop-down list of variable structures.
  7. The variable structure BusinessService is displayed in Figure 3-9.

    Figure 3-9 Variable Structures—Business Service


    Variable Structures—Business Service

Example 6: Creating a Variable Structure That Maps a Child Element to Another Child Element

Modify the SampleWSDL so that the ProxyWithSampleWSDL proxy service receives a single attachment. The attachment is a Purchase Order. In this example, the proxy service message flow must then manipulate the Purchase Order. To achieve this, you can define a new structure that maps the body element in $attachments to the PO element, which is specified as a child element. The body element is specified as a variable path of the form:

$attachments/ctx:attachment/ctx:body 

You can select and copy the body element from the predefined attachments structure, paste this element as the variable path to be mapped in the new mapping definition.

To map a child element to another child element:

  1. In the Variable Structures panel, select attachments from the drop-down list of built-in structures.
  2. The variable structure attachments is displayed in Figure 3-10.

    Figure 3-10 Variable Structures—attachments


    Variable Structures—attachments

  3. Select the body child element in the attachments structure. The variable path of the body element is displayed in the Property Inspector on the right side of the page:
  4. $attachments/ctx:attachment/ctx:body
  5. Copy the variable path of the body element.
  6. In the Variable Structures panel, click Add New Structure.
  7. Select the XML Type.
  8. In the Structure Label field, enter PO attachment as the meaningful display name for this variable structure.
  9. In the Structure Path field, paste the variable path of the body element:
  10. $attachments/ctx:attachment/ctx:body

    This is the path of the variable structure at run time.

  11. To select the PO element:
    1. Under the Type field, make sure the appropriate radio button is selected, then select WSDL Element.
    2. Click Browse.
    3. In the WSDL Browser, select SampleWSDL, then select PO under Elements in the Select WSDL Definitions pane.
    4. Click Submit.
  12. Select the Set as child checkbox to set the PO element as a child of the body element.
  13. Click Add. The new variable structure PO attachment is included under XML Type in the drop-down list of variable structures.
  14. If there are multiple attachments, add an index to the reference when you use fields from this structured variable in your XQueries. For example, if you drag the PO field to the XQuery field, but as PO will be the second attachment, change the inserted value from
  15. $attachments/ctx:attachment/ctx:body/bea:PO/bea:id

    to

    $attachments/ctx:attachment[2]/ctx:body/bea:PO/bea:id

 


Quality of Service

The following sections discuss quality of service features in ALSB messaging:

Delivery Guarantees

ALSB supports reliable messaging. When messages are routed to another service from a route node, the default quality of service (QoS) is exactly once if the proxy service transport is defined as JMS/XA; otherwise best effort QoS is supported.

Quality of service is set in the qualityOfService element in the $outbound context variable.

The following delivery guarantee types are provided in ALSB, shown in Table 3-9.

Table 3-9 Delivery Guarantee Types
Delivery Reliability
Description
Exactly once
Exactly once reliability means that messages are delivered from inbound to outbound exactly once, assuming a terminating error does not occur before the outbound message send is initiated. Exactly once means reliability is optimized.
Exactly once delivery reliability is a hint, not a directive. When exactly once is specified, exactly once reliability is provided if possible. If exactly once is not possible, then at least once delivery semantics are attempted; if that is not possible, best effort delivery is performed.
The default value of the qualityOfService element is exactly-once for a route node action for the following inbound transports:
  • e-mail
  • FTP
  • File
  • JMS/XA
  • SFTP
  • Transactional Tuxedo

Note: Do not retry the outbound transport when the QoS is exactly once

At least once
At least once semantics means the message is delivered to the outbound from the inbound at least once, assuming a terminating error does not occur before the outbound message send is initiated. Delivery is considered satisfied even if the target service responds with a transport-level error. However it is not satisfied in the case of a time-out, a failure to connect, or a broken communication link. If failover URLs are specified, at least once semantics is provided with respect to at least one of the URLs.
At least once delivery semantics is attempted if exactly once is not possible but the qualityOfService element is exactly-once.
Best effort
Best effort means that there is no reliable messaging and there is no elimination of duplicate messages—however, performance is optimized. It is performed if the qualityOfService element is best-effort. Best effort delivery is also performed if exactly once and at least once delivery semantics are not possible but the qualityOfService element is exactly-once.
The default value of the qualityOfService element for a route node is best-effort for the following inbound transports:
  • HTTP
  • JMS/nonXA
  • Non-Transactional Tuxedo
The default value of the qualityOfService element is always best-effort for the following:
  • Service callout action — always best-effort, but can be changed if required.
  • Publish action — defaults to best-effort, modifiable

Note: When the value of the qualityOfService element is best-effort for a publish action, all errors are ignored. However, when the value of the qualityOfService element is best-effort for a route node action or a Service callout action, any error will raise an exception.

For more detailed information about quality of service for other transports, see the documentation for the transport, at AquaLogic Service Bus Transports.

Overriding the Default Element Attribute

To override the default exactly once quality of service attribute, you must set the qualityOfService in the outbound message context variable ($outbound). For more information, see Message Context Schema.

You can override the default qualityOfService element attribute for the following:

To override the qualityOfService element attribute, you must use the route options action to route or publish, and also select the checkbox for a service callout action. See Message Context Schema.

Delivery Guarantee Rules

The delivery guarantee supported when a proxy service publishes a message or routes a request to a business service depends on the following conditions:

However, if the inbound proxy service is a Local Transport and is invoked by another proxy service, the inbound transport of the invoking proxy service is responsible for the delivery guarantee. That is because a proxy service that invokes another proxy service is optimized into a direct invocation if the transport of the invoked proxy service is a Local Transport. For more information on transport protocols, see Proxy Services and Business Services in Using the AquaLogic Service Bus Console.

Note: No delivery guarantee is provided for responses from a proxy service.

The following rules govern delivery guarantees, shown in Table 3-10.

Table 3-10 Delivery Guarantee Rules
Delivery Guarantee Provided
Rule
Exactly once
The proxy service inbound transport is transactional and the value of the qualityOfService element is exactly-once to an outbound JMS/XA transport.
At least once
The proxy service inbound transport is file, FTP, or e-mail and the value of the qualityOfService element is exactly-once.
At least once
The proxy service inbound transport is transactional and the value of the qualityOfService element, where applicable, is exactly-once to an outbound transport that is not transactional.
No delivery guarantee
All other cases, including all response processing cases.

Note: To support at least once and exactly-once delivery guarantees with JMS, you must exploit JMS transactions and configure a retry count and retry interval on the JMS queue to ensure that the message is redelivered in the event of a server crash or a failure that is not handled in an error handler with a Reply or Resume action. File, FTP, and e-mail transports also internally use a JMS/XA queue. The default retry count for a proxy service with a JMS/XA transport is 1. For a list of the default JMS queues created by ALSB, see AquaLogic Service Bus Deployment Guide.

The following are additional delivery guarantee rules:

Threading Model

The ALSB threading model works as follows:

Note: In a request or response flow publish action, responses are always discarded because publish actions are inherently a one-way message send.

Splitting Proxy Services

You may want to split a proxy service in the following situations:

Outbound Message Retries

In addition to configuring inbound retries for messages using JMS, you can configure outbound retries and load balancing. Load balancing, failover, and retries work in conjunction to provide performance and high availability. For each message, the list of URLs you provide as failover URLs is automatically ordered based on the load balancing algorithm into a failover sequence. If the retry count is N, the entire sequence is retried N times before stopping. The system waits for the specified retry interval before commencing subsequent loops through the sequence. After completing the retry attempts, if there is still an error, the error handler pipeline for the route node is invoked. For more information on the error handler pipeline, see “Adding Pipeline Error Handling” in Proxy Services in Using the AquaLogic Service Bus Console.

Note: For HTTP transports, any HTTP status other than 200 or 202 is considered an error by ALSB and must be retried. Because of this algorithm, it is possible that ALSB retries errors like authentication failure that may never be rectified for that URL within the time period of interest. On the other hand, if ALSB also fails over to a different URL for subsequent attempts to send a given message, the new URL may not give the error.
Note: For quality of service=exactly once failover or retries will not be executed.

 


Content Types, JMS Type, and Encoding

To support interoperability with heterogeneous endpoints, ALSB allows you to control the content type, the JMS type, and the encoding used.

ALSB does not make assumptions about what the external client or service needs, but uses the information configured for this purpose in the service definition. ALSB derives the content type for outbound messages from the service type and interface. Content type is a part of the e-mail and HTTP protocols.

If the service type is:

Additionally, there is a JMS type, which can be byte or text. You configure the JMS type to use when you define the service in ALSB Console or in the ALSB Plug-in for WorkSpace Studio.

You can override the content type in the outbound context variable ($outbound) for proxy services invoking a service, and in the inbound context variable ($inbound) for a proxy service response. For more information on $outbound and $inbound context variables, see Inbound and Outbound Variables.

Encoding is also explicitly configured in the service definition for all outbound messages. For more information on service definitions, see Proxy Services in and Business Service in Using the AquaLogic Service Bus Console.

 


Throttling Pattern

In ALSB, you can restrict the message flow to a business service. This technique of restricting a message flow to a business service is known as throttling. For information, see Throttling in ALSB in the AquaLogic Service Bus Operations Guide.

 


WS-I Compliance

ALSB provides Web Service Interoperability (WS-I) compliance for SOAP 1.1 services in the run-time environment. The WS-I basic profile has the following goals:

The WS-I basic profile is available at the following URL:

http://www.ws-i.org/Profiles/BasicProfile-1.1.html.

When you configure a proxy service or business service based on a WSDL, you can use the ALSB Console or the ALSB Plug-in for WorkSpace Studio to specify whether you want ALSB to enforce WS-I compliance for the service. For information on how to do this, see

When you configure WS-I compliance for a proxy service, checks are performed on inbound request messages received by that proxy service. When you configure WS-I compliance for an invoked service, checks are performed when any proxy receives a response message from that invoked service. BEA recommends that you create an error handler for these errors, since by default, the proxy service SOAP client receives a system error handler-defined fault. For more information on creating fault handlers, see:

For messages sent from a proxy service, whether as outbound request or inbound response, WS-I compliance checks are not explicitly performed. That is because the pipeline designer is responsible for generating most of the message content. However, the parts of the message generated by ALSB should satisfy all of the supported WS-I compliance checks. This includes the following content:

The Enforce WS-I Compliance checkbox is displayed as shown in Figure 3-11.

Figure 3-11 Enforce WS-I Compliance Checkbox

Enforce WS-I Compliance Checkbox

WS-I Compliance Checks

Note: WS-I compliance checks require that the system knows what operation is being invoked on a service. For request messages received by a proxy service, that means that the context variable $operation should not be null. That depends upon the operation selection algorithm being configured properly. For response messages received from invoked services, the operation should be specified in the action configurations for route, publish, and service callout.

When you configure WS-I compliance checking for a proxy service or a business service, ALSB carries out the following checks, shown in Table 3-11.

Table 3-11 ALSB WS-I Compliance Checks
Check
WS-I Basic Profile Details
ALSB Description
3.1.1 SOAP Envelope Structure
R9980 An Envelope must conform to the structure specified in SOAP 1.1, Section 4, “SOAP Envelope” (subject to amendment).
This check applies to request and response messages. If a response message is checked and the message does not possess an outer Envelope tag, a soap:client error is generated. If the message is an Envelope tag but possesses a different namespace, it is handled by the 3.1.2 SOAP Envelope Namespace.
3.1.2 SOAP Envelope Namespace
R1015 A Receiver must generate an error if they encounter an envelope whose document element is not soap:Envelope.
This check applies to request and response messages and is related to the 3.1.1 SOAP Envelope Structure. If a request message has a local name of Envelope, but the namespace is not SOAP 1.1, a soap:VersionMismatch error is generated.
3.1.3 SOAP Body Namespace Qualification
R1014 The child elements of the soap:body element in an Envelope must be namespace qualified.
This check applies to request and response messages. All request error messages generate a soap:Client error.
3.1.4 Disallowed Constructs
R1008 An Envelope must not contain a Document Type Declaration.
This check applies to request and response messages. All request error messages generate a soap:Client error.
3.1.5 SOAP Trailers
R1011 An Envelope must not have any child elements of soap:Envelope following the soap:body element.
This check applies to request and response messages. All request error messages generate a soap:Client error.
3.1.9 SOAP attributes on SOAP 1.1 elements
R1032 The soap:Envelope, soap:header, and soap:body elements in an Envelope must not have attributes in the namespace http://schemas.xmlsoap.org/soap/envelope/
This check applies to request and response messages. Any request error messages generate a soap:client error.
3.3.2 SOAP Fault Structure
R1000 When an Envelope is a fault, the soap:Fault element must not have element children other than faultcode, faultstring, faultactor, and detail.
This check only applies to response messages.
3.3.3 SOAP Fault Namespace Qualification
R1001 When an Envelope is a Fault, the element children of the soap:Fault element must be unqualified.
This check only applies to response messages.
3.4.6 HTTP Client Error Status Codes
R1113 An instance should use a “400 Bad Request” HTTP status code if a HTTP request message is malformed.
R1114 An instance should use a “405 Method not Allowed” HTTP status code if a HTTP request message is malformed.
R1125 An instance must use a 4xx HTTP status code for a response that indicates a problem with the format of a request.
Only applies to responses for a proxy service where you cannot influence the status code returned due to errors in the request.
3.4.7 HTTP Server Error Status Codes
R1126 An instance must return a “500 Internal Server Error” HTTP status code if the response envelope is a fault.
This check applies differently to request and response messages. For request messages, any faults generated have a 500 Internal Server Error HTTP status code. For response messages, an error is generated if fault responses are received that do not have a 500 Internal Server Error HTTP status code.
4.7.19 Response Wrappers
R2729 An envelope described with an rpc-literal binding that is a response must have a wrapper element whose name is the corresponding wsdl:operation name suffixed with the string Response.
This check only applies to response messages. ALSB never generates a non-fault response from a proxy service.
4.7.20 Part Accessors
R2735 An envelope described with an rpc-literal binding must place the part accessor elements for parameters and return value in no namespace.
R2755 The part accessor elements in a message described with an rpc-literal binding must have a local name of the same value as the name attribute of the corresponding wsdl:part element.
This check applies to request and response messages. Any request error messages generate a soap:client error.
4.7.22 Required Headers
R2738 An envelope must include all soapbind:headers specified on a wsdl:input or wsdl:output of a wsdl:operation of a wsdl:binding that describes it.
This check applies to request and response messages. Any request error messages generate a soap:client error.
4.7.25 Describing SOAPAction
R2744 A HTTP request message must contain a SOAPAction a HTTP header field with a quoted value equal to the value of the soapAction attribute of soap:operation, if present in the corresponding WSDL description.
R2745 A HTTP request message must contain a SOAP action a HTTP header field with a quoted empty string value, if in the corresponding WSDL description, the SOAPAction of soapbind:operation is either not present, or present with an empty string as its value.
This check applies to request messages and a soap:client error is returned.

 


Converting Between SOAP 1.1 and SOAP 1.2

ALSB supports SOAP 1.1 and SOAP 1.2. A SOAP 1.1 proxy service can invoke a SOAP 1.2 business service or vice versa. The SOAP namespace is automatically changed by ALSB before invoking the business service. If a fault comes back from the business service it is automatically changed to the SOAP version of the proxy service. It is, however, up to the pipeline actions to map the SOAP header-related XML attributes (like MustUnderstand) between the two versions. It is also up to the pipeline actions to change the SOAP encoded name space for encoded envelopes.


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