9 Using Correlation Sets and Message Aggregation

This chapter describes how to use correlation sets to ensure that asynchronous callbacks locate the appropriate client. It also describes how to use aggregation patterns to route messages to the same instance.

This chapter includes the following sections:

• Introduction to Correlation Sets in an Asynchronous Service

• Creating Correlation Sets in Oracle JDeveloper

• Routing Messages to the Same Instance

9.1 Introduction to Correlation Sets in an Asynchronous Service

Correlation sets provide a method for directing web service responses to the correct BPEL process service component instance. You can use correlation sets to identify asynchronous messages to ensure that asynchronous callbacks locate the appropriate client. You define correlation sets when interactions are not simple invoke-receive activities.

Correlation sets are a BPEL mechanism that provides for the correlation of asynchronous messages based on message body contents. To use this method, define the correlation sets in your BPEL process. This method is designed for services that do not support WS-Addressing or for certain sophisticated conversation patterns, for example, when the conversation is in the form A > B > C > A instead of A > B > A.

9.1.1 Scenarios for Using Correlation Sets

Correlations enable you to associate asynchronous messages based on message body contents. Note that not all business scenarios require correlations:

• Synchronous calls do not require correlations because the conversation context is maintained in the stack or across a TCP connection.

• Consenting BPEL processes typically correlate messages using WS-Addressing headers to pass tokens that act like session cookies in a web application. For more information, see Using WS-Addressing in an Asynchronous Service.

Correlation is required in the following scenarios. In these cases, a BPEL process must be configured to view some content of the message to select the correct process instance to receive the message.

• When using an asynchronous service that does not support WS-Addressing.

• When receiving unsolicited messages from another system.

• When the message travels through several services and the response is solicited by the initial service from the last service directly.

• When communicating through files.

9.1.2 Understanding Correlation Set Contents and Concepts

This section provides an overview of key correlation set concepts.

The correct BPEL instance using correlation sets is obtained as follows:

• A BPEL process provides a construct called a correlation set to allow for custom correlation.

• A correlation set is a collection of properties used by the BPEL process service engine to identify the correct process to receive a message.

• Each property in the correlation set can be mapped to an element in one or more message types through property aliases. Figure 9-1 provides an overview.

  Figure 9-1 Correlation Sets

  
  Description of "Figure 9-1 Correlation Sets"

Note the following key correlation guidelines:

• Only the process receiving the message is concerned about correlation. As long as the sending service includes sufficient information in the message to correlate it with previous activities, the sender does not need to be aware that correlation is occurring.

• Correlation properties must be unique for the duration of the life of the BPEL process that sets them.

• Ensure that no two processes are working with the same correlation tokens. For example, using social security numbers to correlate an expense claims process is not recommended if you start two separate instances of the process.

• Properties can be made up values or actual business identifiers such as purchase orders or numbers. They do not need to be strings; they can be any reasonable XML type.

Key correlation concept attributes are as follows. You set these attributes in Oracle JDeveloper when designing a correlation set with the Correlation wizard:

• An initiate attribute is set as follows:

  • yes: The correlation set is initiated with the values of the properties available in the message being transferred.

  • no: The correlation set validates the value of the property available in the message.

• A pattern attribute is set as follows:

  • in (for BPEL 1.1) or response (for BPEL 2.0): The correlation property is set and validated on the incoming message.

  • out (for BPEL 1.1) or request (for BPEL 2.0): The correlation property is set and validated on the outgoing BPEL message.

  • out-in (for BPEL 1.1) or request-response (for BPEL 2.0): The correlation property is set and validated on both incoming and outgoing messages.

• Property aliases map a global property to a field in a specific message part. This action enables the property name to become an alias for the message part and location. The alias can be used in XPath expressions.

9.1.3 Overview of Correlation Set Creation

Table 9-1 provides an overview of the steps for creating a correlation set. References to the pages of the Correlation wizard on which you perform these steps and examples of values to set are provided.

Table 9-1 Correlation Set Creation Overview

Step	Correlation Wizard Page	Example
Create a correlation set with property names and types to correlate the exchange.	Set this information on the Correlation wizard - Define Correlation Set page. See Figure 9-2.	Create a phonenumber correlation set with property names and types: username of type string userordernumber of type int IsGift of type boolean
Add the correlation to the invoke or receive activity that begins the conversation and set Initiate to yes.	Select the activity and set the Initiate attribute on the Correlation wizard - Initiate Settings page. See Figure 9-3.	Select the internalReceive receive activity and set Initiate to yes.
Create property alias mappings to appropriate elements in each message. They must have the same value in both messages of the conversation. The elements can be different names and in different structures in the two messages, but they must contain the same value for correlation to work.	Set this information on the Correlation wizard - Property Aliases page. See Figure 9-7. Two editors available on this page enable you to create the property alias mappings: Alias Editor (Figure 9-4) Alias Drag and Drop Editor (Figure 9-5)	Define the property aliases to populate the correlation set property values at runtime: Map alias username to the name message element Map alias userordernumber to the poNumber message element Map alias IsGift to the gift message element.
Add the same correlation set with its property to additional activities. Do not set them to initiate. The BPEL process uses this to select the correct process instance. Set the pattern accordingly.	Set on the Activity Correlation Editor - Initiate Tab. See Figure 9-10.	Select the internalCallback invoke activity: Set Initiate to no Set Pattern to request

9.2 Creating Correlation Sets in Oracle JDeveloper

You can create correlation sets on the following activities and branches.

• Receive activity

• Reply activity

• Invoke activity

• onMessage branch

• onEvent branch

There are two methods for creating correlations sets in Oracle JDeveloper:

• Automatically through the Correlation wizard in an activity

• Manually through the Correlations tab in an activity

9.2.1 How to Create a Correlation Set with the Correlation Wizard

To create a correlation set with the Correlation wizard:

1. Right-click an applicable activity (such as a receive activity), and select Setup Correlation.

   The Correlation wizard - Define Correlation Set page is displayed.

2. Provide responses appropriate to your environment, then click Next. Table 9-2 provides details.

   Table 9-2 Correlation Wizard - Define Correlation Set Page

   Field	Description
   Create Correlation Set	Select to create a new correlation set.
   Choose Existing Correlation Set	Select an existing correlation set in which to include the selected activity.
   Name	Enter the name of the correlation set you want to create.
   Scope	Displays the scope or process in which to create the new correlation set.
   Properties	Click Add to create a new property in the Name column of the Properties table or click Browse to select an existing property. Click the Type column, then click the ellipses to invoke the Type Chooser dialog for selecting the property type (for example, integer, boolean, or some other type).

   When complete, the Correlation wizard - Define Correlation Set page looks as shown in Figure 9-2.

   Figure 9-2 Correlation Wizard - Define Correlation Set Page

   
   Description of "Figure 9-2 Correlation Wizard - Define Correlation Set Page"

   The Correlation wizard - Initiate Settings page is displayed.

3. Provide responses appropriate to your environment, then click Next. Table 9-3 provides details.

   Table 9-3 Correlation Wizard - Initiate Settings Page

   Field	Description
   Activity	Displays the activity on which the correlation is set.
   initiate	Select whether this activity is the initiator in the correlation set. When set to yes, the correlation set is initiated with the values of the properties occurring in the message being sent or received.

   When complete, the Correlation wizard - Initiate Settings page looks as shown in Figure 9-3.

   Figure 9-3 Correlation Wizard - Initiate Settings Page

   
   Description of "Figure 9-3 Correlation Wizard - Initiate Settings Page"

   The Correlation wizard - Property Aliases page is displayed for mapping properties to values. The properties defined previously in the Define Correlation Set page of the wizard are displayed in the Property Aliases table.

   Property aliases enable you to map a property to a field in a specific message part of a variable. This action enables the property to become an alias for the message part and location.

4. Click a property in the table and select a method for mapping the message part of the variable to the property. Table 9-4 provides details.

   Table 9-4 Methods for Mapping the Variable Message Part to a Property

   To Use The...	Go to Step...
   Alias Editor	5
   Alias Drag and Drop Editor	6

5. Click the Edit (first) icon to invoke the Alias Editor dialog.

   1. Expand the variable.

   2. Select the message part to represent the property, and click OK. Figure 9-4 provides details.

      Figure 9-4 Alias Editor

      
      Description of "Figure 9-4 Alias Editor"

6. Click the Alias Drag and Drop Editor (second) icon to invoke the Alias Drag and Drop Editor dialog.

   1. Expand the variable.

   2. Select the message part to represent the property.

   3. Drag and drop the message part onto the property row in the Correlation wizard - Property Aliases page. Figure 9-5 provides details.

      Figure 9-5 Alias Drag and Drop Editor

      
      Description of "Figure 9-5 Alias Drag and Drop Editor"

      Existing property aliases are listed in the lower part of the Correlation wizard - Property Aliases page, as shown in Figure 9-6. For this example, there are no existing property aliases.

      Figure 9-6 Correlation Wizard - Property Aliases Page - Lower Part

      
      Description of "Figure 9-6 Correlation Wizard - Property Aliases Page - Lower Part"

   4. When complete, click Next.

7. Select additional properties to map to specific message parts of variables.

   When complete, the Correlation wizard - Property Aliases page looks as shown in Figure 9-7. The properties created in Figure 9-2 are displayed in the Property column. The message elements to which the properties were mapped with either the Alias Editor (Figure 9-4) or Alias Drag and Drop Editor (Figure 9-5) are displayed in the Query column.

   Figure 9-7 Correlation Wizard - Property Aliases Page

   
   Description of "Figure 9-7 Correlation Wizard - Property Aliases Page"

8. Click Next.

   The Correlation wizard - Correlated Activities page is displayed. Figure 9-8 provides details.

   Figure 9-8 Correlation Wizard - Property Aliases Page (Without Activity)

   
   Description of "Figure 9-8 Correlation Wizard - Property Aliases Page (Without Activity)"

9. Click the Add icon to add more activities to this correlation set (multiple activities can correlate on the correlation set).

   The Activity Browser dialog is displayed.

10. Select the activity to add, and click OK. Figure 9-9 provides details.

    Figure 9-9 Activity Browser for Selecting an Activity

    
    Description of "Figure 9-9 Activity Browser for Selecting an Activity"

    The activity is added to the Correlation Activities field of the Correlation wizard - Correlated Activities page.

11. In the Correlation Activities field, select the activity and click Edit to invoke the Initiate tab of the Activity Correlation Editor dialog. Figure 9-10 provides details.

    Figure 9-10 Activity Correlation Editor - Initiate Tab

    
    Description of "Figure 9-10 Activity Correlation Editor - Initiate Tab"

12. Select appropriate values in the Initiate and Pattern lists. For this example:

    • Select no from the Initiate list (because the correlation set validates the value of the property available in the message).

    • Select request from the Pattern list (because the correlation property is set and validated on the outgoing BPEL message).

    For BPEL 2.0, you can select response if the correlation applies to an inbound message, request if the correlation applies to an outbound message, or request-response if the correlation applies to both outbound and inbound messages.

    For BPEL 1.1, you can select in if the correlation applies to an inbound message (response), out if the correlation applies to an outbound message (request), or out-in if the correlation applies to both inbound and outbound messages. (response and request).

13. Click the Aliases tab.

14. Repeat Step 4 through Step 7 to select a property and map the message part of the variable to the property.

    When complete, the Alias dialog looks similar to that shown in Figure 9-11.

    Figure 9-11 Activity Correlation Editor - Alias Tab

    
    Description of "Figure 9-11 Activity Correlation Editor - Alias Tab"

15. Click OK to return to the Correlation wizard - Correlated Activities page, which looks as shown in Figure 9-12.

    Figure 9-12 Correlation Wizard - Correlated Activities Page (With Selected Activity)

    
    Description of "Figure 9-12 Correlation Wizard - Correlated Activities Page (With Selected Activity)"

16. Click Next to review the correlation set details in the Activities, Correlation Set, and Alias tabs.

    • Activities: Displays the activities involved in the correlation and their roles (for example, the receive activity is the initiator and the invoke activity is the responder).

    • Correlation Set: Displays the name of the correlation set.

    • Aliases: Displays the property aliases defined for the activities in the correlation set.

    Figure 9-13 provides details.

    Figure 9-13 Correlation Wizard - Summary Page

    
    Description of "Figure 9-13 Correlation Wizard - Summary Page"

17. Click Finish.

    The correlation set is created.

18. In the Structure window, view the correlation set, properties, and property aliases you defined in the Correlation wizard.

19. In Oracle BPEL Designer, click the Correlations tab of one of the participating activities to view the details you defined (for example, the receive activity). Figure 9-14 provides details.

    Figure 9-14 Correlation Tab of Receive Activity

    
    Description of "Figure 9-14 Correlation Tab of Receive Activity"

20. If you want to find out which activities are used in a correlation set, perform the following steps.

    1. Click the Search icon above Oracle BPEL Designer, and select Correlation Search.

       The Correlation Set Chooser dialog is displayed.

    2. Select the correlation set, and click OK.

    3. In the Correlation Search dialog, click OK.

       The activities using the correlation sets are displayed in the Log window.

21. If you want to add additional activities to an existing correlation set, right-click the activity, and select Setup Correlation.

    The Correlation wizard - Define Correlation Set page is displayed.

22. Select Choose Existing Correlation Set.

23. From the Correlation Sets list, select the correlation set, and click OK.

24. Define the activity by following the pages in the Correlation wizard.

9.2.2 How to Manually Create Correlation Sets From the Correlations Tab

This section describes the steps to manually create correlation sets in an asynchronous service. This example illustrates how to use correlation sets for a process having three receive activities with no associated invoke activities.

9.2.2.1 Step 1: Creating a Project

To create a project:

1. Start Oracle JDeveloper.
2. From the File main menu, select New > Applications.
3. Select SOA Application, and click OK.

   The Create SOA Application Wizard appears.

4. In the Application Name field, enter a name (for this example, MyCorrelationSetApp is entered).
5. Accept the default values for all remaining settings, and click Next.
6. In the Project Name field, enter a name (for this example, MyCorrelationSetComposite is entered).
7. Accept the default values for all remaining settings, and click Next.
8. In the Composite Template section, select Composite With BPEL Process, and click Finish.

   The Create BPEL Process dialog appears.

9. Enter the values shown in Table 9-5.

   Table 9-5 Create BPEL Process Dialog Fields and Values

   Field	Value
   Name	Enter a name (for this example, MyCorrelationSet is entered).
   Template	Select Asynchronous BPEL Process.
   Expose as a SOAP Service	Select the check box. After process creation, note the SOAP service that appears in the Exposed Services swimlane. This service provides the entry point to the composite application from the outside world.

10. Accept the default values for all remaining settings, and click OK.

9.2.2.2 Step 2: Configuring Partner Links and File Adapter Services

You now create three partner links that use the SOAP service.

This section contains these topics:

• You create an initial partner link with an adapter service for reading a loan application.

• You create a second partner link with an adapter service for reading an application response.

• You create a third partner link with an adapter service for reading a customer response.

9.2.2.2.1 Creating an Initial Partner Link and File Adapter Service

To create an initial partner link and file adapter service:

1. Double-click the MyCorrelationSet BPEL process.
2. In the Components window, expand BPEL Constructs.
3. Drag an initial Partner Link activity into the right swimlane of the designer.
4. Click the third icon at the top (the Service Wizard icon). This starts the Adapter Configuration Wizard, as shown in Figure 9-15.

   Figure 9-15 Adapter Configuration Wizard Startup

   
   Description of "Figure 9-15 Adapter Configuration Wizard Startup"
5. In the Configure Service or Adapter dialog, select File and click OK.
6. In the Name field of the File Adapter Reference dialog, enter a name (for this example, FirstReceive is entered) and click Next.
7. In the Adapter Interface dialog, accept the default settings and click Next.
8. In the Operation dialog, select Read File as the Operation Type and click Next. The Operation Name field is automatically filled in with Read.
9. Above the Directory for Incoming Files (physical path) field, click Browse.
10. Select a directory from which to read files (for this example, C:\files\receiveprocess\FirstInputDir is selected).
11. Click Select.
12. Click Next.
13. In the File Filtering dialog, enter appropriate file filtering parameters.
14. Click Next.
15. In the File Polling dialog, enter appropriate file polling parameters.
16. Click Next.
17. In the Messages dialog, click Browse next to the URL field to display the Type Chooser dialog.
18. Select an appropriate XSD schema file. For this example, Book1_4.xsd is the schema and LoanAppl is the schema element selected.
19. Click OK.

    The URL field (Book1_4.xsd for this example) and the Schema Element field (LoanAppl for this example) are filled in.

20. Click Next.
21. Click Finish.

    You are returned to the Partner Link dialog. All other fields are automatically completed. The dialog looks as shown in Table 9-6:

    Table 9-6 Partner Link Dialog Fields and Values

    Field	Value
    Name	FirstReceive
    WSDL URL	directory_path/FirstReceive.wsdl
    Partner Link Type	Read_plt
    Partner Role	Leave unspecified.
    My Role	Read_role

22. Click OK.

9.2.2.2.2 Creating a Second Partner Link and File Adapter Service

To create a second partner link and file adapter service:

1. Drag a second Partner Link activity beneath the FirstReceive partner link activity.
2. At the top, click the third icon (the Service Wizard icon).
3. In the Configure Service or Adapter dialog, select File and click OK.
4. In the Name field of the File Adapter Reference dialog, enter a name (for this example, SecondFileRead is entered) and click Next. This name must be unique from the one you entered in Step 6 of Creating an Initial Partner Link and File Adapter Service.
5. In the Adapter Interface dialog, accept the default settings and click Next.
6. In the Operation dialog, select Read File as the Operation Type.
7. In the Operation Name field, change the name (for this example, Read1 is entered).
8. Click Next.
9. Select Directory Names are Specified as Physical Path.
10. Above the Directory for Incoming Files (physical path) field, click Browse.
11. Select a directory from which to read files (for this example, C:\files\receiveprocess\SecondInputDir is entered).
12. Click Select.
13. Click Next.
14. Enter appropriate file filtering parameters in the File Filtering dialog.
15. Click Next.
16. Enter appropriate file polling parameters in the File Polling dialog.
17. Click Next.
18. Next to the URL field in the Messages dialog, click Browse to display the Type Chooser dialog.
19. Select an appropriate XSD schema file. For this example, Book1_5.xsd is the schema and LoanAppResponse is the schema element selected.
20. Click OK.

    The URL field (Book1_5.xsd for this example) and the Schema Element field (LoanAppResponse for this example) are filled in.

21. Click Next.
22. Click Finish.

    You are returned to the Partner Link dialog. All other fields are automatically completed. The dialog looks as shown in Table 9-7:

    Table 9-7 Partner Link Dialog Fields and Values

    Field	Value
    Name	SecondReceive
    WSDL URL	directory_path/SecondFileRead.wsdl
    Partner Link Type	Read1_plt
    Partner Role	Leave unspecified.
    My Role	Read1_role

23. Click OK.

9.2.2.2.2.1 Creating a Third Partner Link and File Adapter Service

To create a third partner link and file adapter service:

1. Drag a third Partner Link activity beneath the SecondReceive partner link activity.
2. At the top, click the third icon (the Service Wizard icon).
3. In the Configure Service or Adapter dialog, select File and click OK.
4. In the Name field of the File Adapter Reference dialog, enter a name (for this example, ThirdFileRead is entered) and click Next. This name must be unique from the one you entered in Step 6 of Creating an Initial Partner Link and File Adapter Service and Step 4 of Creating a Second Partner Link and File Adapter Service.
5. In the Adapter Interface dialog, accept the default settings and click Next.
6. In the Operation dialog, select Read File as the Operation Type.
7. In the Operation Name field, change the name (for this example, Read2 is entered). This name must be unique.
8. Click Next.
9. Select Directory Names are Specified as Physical Path.
10. Above the Directory for Incoming Files (physical path) field, click Browse.
11. Select a directory from which to read files (for this example, C:\files\receiveprocess\ThirdInputDir is entered).
12. Click Select.
13. Click Next.
14. Enter appropriate file filtering parameters in the File Filtering dialog.
15. Click Next.
16. Enter appropriate file polling parameters in the File Polling dialog.
17. Click Next.
18. Next to the URL field in the Messages dialog, click Browse to display the Type Chooser dialog.
19. Select an appropriate XSD schema file. For this example, Book1_6.xsd is the schema and CustResponse is the schema element selected.
20. Click OK.

    The URL field (Book1_6.xsd for this example) and the Schema Element field (CustResponse for this example) are filled in.

21. Click Next.
22. Click Finish.

    You are returned to the Partner Link dialog. All other fields are automatically completed. The dialog looks as shown in Table 9-8:

    Table 9-8 Partner Link Dialog Fields and Values

    Field	Value
    Name	ThirdReceive
    WSDL URL	directory_path/ThirdFileRead.wsdl
    Partner Link Type	Read2_plt
    Partner Role	Leave unspecified.
    My Role	Read2_role

23. Click OK.

9.2.2.3 Step 3: Creating Three Receive Activities

You now create three receive activities; one for each partner link. The receive activities specify the partner link from which to receive information.

9.2.2.3.1 Creating an Initial Receive Activity

To create an initial receive activity:

1. In the Components window, expand BPEL Constructs.
2. Drag a Receive activity beneath the receiveInput receive activity in the designer.
3. Click the receive activity to display its property fields in the Property Inspector or double-click the receive icon to display the Receive dialog.

   For information about editing activities in the Property Inspector, see How to Edit BPEL Activities in the Property Inspector.

4. Enter the details described in Table 9-9 to associate the first partner link (FirstReceive) with the first receive activity:

   Table 9-9 Receive Dialog Fields and Values

   Field	Value
   Name	receiveFirst
   Partner Link	FirstReceive
   Create Instance	Select this check box.

   The Operation (Read) field is automatically filled in.

5. To the right of the Variable field, click the first icon. This is the automatic variable creation icon.
6. In the Create Variable dialog, click OK.

   A variable named receiveFirst_Read_InputVariable is automatically created in the Variable field.

7. Ensure that you selected the Create Instance check box, as described in Step 4.
8. Click OK.

9.2.2.3.2 Creating a Second Receive Activity

To create a second receive activity:

1. From the Components window, drag a second Receive activity beneath the receiveFirst receive activity.
2. Double-click the receive icon to display the Receive dialog.
3. Enter the details described in Table 9-10 to associate the second partner link (SecondReceive) with the second receive activity:

   Table 9-10 Receive Dialog Fields and Values

   Field	Value
   Name	receiveSecond
   Partner Link	SecondFileRead
   Create Instance	Do not select this check box.

   The Operation (Read1) field is automatically filled in.

4. To the right of the Variable field, click the first icon.
5. In the Create Variable dialog, click OK.

   A variable named receiveSecond_Read1_InputVariable is automatically created in the Variable field.

6. Click OK.

9.2.2.3.2.1 Creating a Third Receive Activity

To create a third receive activity:

1. From the Components window, drag a third Receive activity beneath the receiveSecond receive activity.
2. Double-click the receive icon to display the Receive dialog.
3. Enter the details described in Table 9-11 to associate the third partner link (ThirdReceive) with the third receive activity:

   Table 9-11 Receive Dialog Fields and Values

   Field	Value
   Name	receiveThird
   Partner Link	ThirdFileRead
   Create Instance	Do not select this check box.

   The Operation (Read2) field is automatically filled in.

4. To the right of the Variable field, click the first icon.
5. In the Create Variable dialog, click OK.

   A variable named receiveThird_Read2_InputVariable is automatically created in the Variable field.

6. Click OK.

   Each receive activity is now associated with a specific partner link.

9.2.2.4 Step 4: Creating Correlation Sets

You now create correlation sets. A set of correlation tokens is a set of properties shared by all messages in the correlated group.

9.2.2.4.1 Creating an Initial Correlation Set

To create an initial correlation set:

1. In the Structure window of Oracle JDeveloper, right-click Correlation Sets and select Expand All Child Nodes.
2. In the second Correlation Sets folder, right-click and select Create Correlation Set.
3. In the Name field of the Create Correlation Set dialog, enter CorrelationSet1.
4. In the Properties section, click the Add icon to display the Property Chooser dialog.
5. Select Properties, then click the Add icon (first icon at the top) to display the Create Property dialog.
6. In the Name field, enter NameCorr.
7. To the right of the Type field, click the Browse icon.
8. In the Type Chooser dialog, select string and click OK.
9. Click OK in each dialog to close the Create Property dialog, the Property Chooser dialog, and the Create Correlation Set dialog.

9.2.2.4.2 Creating a Second Correlation Set

To create a second correlation set:

1. Return to the Correlation Sets section in the Structure window of Oracle JDeveloper.
2. Right-click the Correlation Sets folder and select Create Correlation Set.
3. In the Name field of the Create Correlation Set dialog, enter CorrelationSet2.
4. In the Properties section, click the Add icon to display the Property Chooser dialog.
5. Select Properties, then click the Add icon to display the Create Property dialog.
6. In the Name field, enter IDCorr.
7. To the right of the Type field, click the Browse icon.
8. In the Type Chooser dialog, select double and click OK.
9. Click OK in each dialog to close the Create Property dialog, the Property Chooser dialog, and the Create Correlation Set dialog.

9.2.2.5 Step 5: Associating Correlation Sets with Receive Activities

You now associate the correlation sets with the receive activities. You perform the following correlation set tasks:

• For the first correlated group, the first and second receive activities are correlated with the CorrelationSet1 correlation set.

• For the second correlated group, the second and third receive activities are correlated with the CorrelationSet2 correlation set.

9.2.2.5.1 Associating the First Correlation Set with a Receive Activity

To associate the first correlation set with a receive activity:

1. Double-click the receiveFirst receive activity to display the Receive dialog.
2. Click the Correlations tab.
3. Click the Add icon to display the correlation set dropdown list.
4. Select CorrelationSet1.
5. Click the Initiate column to display a dropdown list, and select yes. When set to yes, the set is initiated with the values of the properties occurring in the message being exchanged.
6. Click OK.

9.2.2.5.2 Associating the Second Correlation Set with a Receive Activity

To associate the second correlation set with a receive activity:

1. Double-click the receiveSecond receive activity to display the Receive dialog.
2. Click the Correlations tab.
3. Click the Add icon to display the correlation set dropdown list.
4. Select CorrelationSet2, then click OK.
5. Click the Initiate column to display a dropdown list, and select yes.
6. Click Add again and select CorrelationSet1.
7. Click OK.
8. Click the Initiate column to display a dropdown list, and select no for CorrelationSet1.
9. Click OK.

   This groups the first and second receive activities into a correlated group.

9.2.2.5.3 Associating the Third Correlation Set with a Receive Activity

To associate the third correlation set with a receive activity:

1. Double-click the receiveThird receive activity to display the Receive dialog.
2. Click the Correlations tab.
3. Click the Add icon.
4. Select CorrelationSet2.
5. Set the Initiate column to no for CorrelationSet2.
6. Click OK.

   This groups the second and third receive activities into a second correlated group.

9.2.2.6 Step 6: Creating Property Aliases

Property aliases enable you to map a global property to a field in a specific message part. This action enables the property name to become an alias for the message part and location. The alias can be used in XPath expressions.

9.2.2.6.1 Creating Property Aliases for NameCorr

You create the following two property aliases for the NameCorr correlation set:

• Map NameCorr to the LoanAppl message type part of the receiveFirst receive activity. This receive activity is associated with the FirstReceive partner link (defined by the FirstReceive.wsdl file).

• Map NameCorr to the incoming LoanAppResponse message type part of the receiveSecond receive activity. This receive activity is associated with the SecondReceive partner link (defined by the SecondFileRead.wsdl file).

To create property aliases for NameCorr:

1. In the Structure window of Oracle JDeveloper, right-click Property Aliases.
2. Select Create Property Alias.
3. From the Property list, select NameCorr.
4. Expand and select Message Types > Partner Link > FirstReceive > FirstReceive.wsdl > Message Types > LoanAppl_msg > Part - LoanAppl.
5. In the Query field, press Ctrl+Space to define the following XPath expression:

   /ns2:LoanAppl/ns2:Name
   

6. Click OK.
7. Repeat Step 1 through Step 3 to create a second property alias for NameCorr.
8. Expand and select Message Types > Project WSDL Files > SecondFileRead.wsdl > Message Types > LoanAppResponse_msg > Part - LoanAppResponse.
9. In the Query field, press Ctrl+Space to define the following XPath expression:

   /ns4:LoanAppResponse/ns4:APR
   

10. Click OK.

9.2.2.6.2 Creating Property Aliases for IDCorr

You create the following two property aliases for the IDCorr correlation set:

• Map IDCorr to the LoanAppResponse message type part of the receiveSecond receive activity. This receive activity is associated with the SecondReceive partner link (defined by the SecondFileRead.wsdl file).

• Map IDCorr to the CustResponse message type part of the receiveThird receive activity. This receive activity is associated with the ThirdReceive partner link (defined by the ThirdFileRead.wsdl file).

To create property aliases for IDCorr:

1. In the Structure window, right-click Property Aliases.
2. Select Create Property Alias.
3. In the Property list, select IDCorr.
4. Expand and select Message Types > Project WSDL Files > SecondFileRead.wsdl > Message Types > LoanAppResponse_msg > Part - LoanAppResponse.
5. In the Query field, press Ctrl+Space to define the following XPath expression:

   /ns4:LoanAppResponse/ns4:APR
   

6. Click OK.
7. Repeat Step 1 through Step 3 to create a second property alias for IDCorr.
8. Expand and select Message Types > Project WSDL Files > ThirdFileRead.wsdl > Message Types > CustResponse_msg > Part - CustResponse.
9. In the Query field, press Ctrl+Space to define the following XPath expression:

   /ns6:CustResponse/ns6:APR
   

   Design is now complete.

10. Click OK.

9.2.2.7 Step 7: Reviewing WSDL File Content

To review WSDL file content:

1. Refresh the Applications window.

   The NameCorr and IDCorr correlation set properties are defined in the MyCorrelationSet_Properties.wsdl file in the Applications window.

   <definitions
        name="properties"
        targetNamespace="http://xmlns.oracle.com/MyCorrelationSet/correlationset"
        xmlns="http://schemas.xmlsoap.org/wsdl/"
        xmlns:bpws="http://schemas.xmlsoap.org/ws/2003/03/business-process/"
        xmlns:plnk="http://schemas.xmlsoap.org/ws/2003/05/partner-link/"
        xmlns:xsd="http://www.w3.org/2001/XMLSchema">
       <bpws:property name="NameCorr" type="xsd:string"/>
       <bpws:property name="IDCorr" type="xsd:double"/>
   </definitions>
   

   The property aliases are defined in the MyCorrelationSet.wsdl file.

   <bpws:propertyAlias propertyName="ns1:NameCorr"
    messageType="ns3:LoanAppl_msg"
    part="LoanAppl" query="/ns2:LoanAppl/ns2:Name"/>
   
   <bpws:propertyAlias propertyName="ns1:NameCorr" 
    messageType="ns5:LoanAppResponse_msg" 
    part="LoanAppResponse" query="/ns4:LoanAppResponse/ns4:APR"/>
   
   <bpws:propertyAlias propertyName="ns1:IDCorr" 
    messageType="ns5:LoanAppResponse_msg" 
    part="LoanAppResponse" query="/ns4:LoanAppResponse/ns4:APR"/>
   
   <bpws:propertyAlias propertyName="ns1:IDCorr" 
    messageType="ns7:CustResponse_msg" 
    part="CustResponse" query="/ns6:CustResponse/ns6:APR"/>

   Because the BPEL process service component is not created as a web services provider in this example, the MyCorrelationSet.wsdl file is not referenced in the BPEL process service component. Therefore, you must import the MyCorrelationSet.wsdl file inside the FirstReceive.wsdl file to reference the correlation sets defined in the former WSDL.

   <import namespace="http://xmlns.oracle.com/MyCorrelationSet"
    location="MyCorrelationSet.wsdl"/>

9.2.3 What You May Need to Know About Conversion IDs and Different Composite Revisions

Do not use the same conversion ID for different revisions of a SOA composite application. When correlation sets are used in a BPEL process, you have explicit control over the conversation ID value. Oracle SOA Suite does not interfere or add restrictions on conversation ID value generation. This situation means that even though it appears that Oracle SOA Suite is generating the same conversation ID for different revisions, you actually control this behavior. Oracle SOA Suite does not restrict you from using the same conversation ID for different instances of different revisions.

If you do not use correlation sets, the conversation ID generated is unique and this is not a problem because Oracle SOA Suite decides which conversation ID to generate, and not you.

Oracle SOA Suite does not execute a revision check for callback routing. Routing of callback messages is only based on the following:

• Conversation ID: This is calculated based on the input value and correlation set. If you use the same correlation set for two revisions of processes and enter the same input when creating an instance, both revisions subscribe using the same conversation ID. This causes confusion when a callback for one revision is delivered to another revision.

• Operation name (is the same for both revisions).

• BPEL service component name (is also the same for both revisions).

The concept of a revision number is applicable to Oracle SOA composite applications, and is not part of the BPEL specification. This is why it is not used as part of the routing decision.

There is another complication in which adding a revision as part of callback routing causes problems. When sending a callback, you also specify the endpoint URL. If the endpoint URL does not contain the composite revision (which is extremely likely), the message is assumed to be routed to the default revision. If Oracle SOA Suite runtime adds a revision check as part of callback routing, the callback for the nondefault revision instance is never possible.

For example, assume you have the following BPEL process:

• An entry receive activity named receive_1 (on which a correlation set is used)

• An invoke activity, which invokes a web service

• A receive activity named receive_2

Assume you perform the following steps:

1. Deploy revision 1.0 of composite_A, which includes a BPEL component.

2. Create an instance of revision 1.0, which is using a correlation set, and input a value of 123, which generates conv_id = "123".

   This process now invokes a web service through a one-way invoke activity and then waits on the receive_2 activity for a callback to arrive.

3. Deploy revision 2.0 of composite_A, which now becomes the default revision.

   A web service sends a callback for the instance for revision 1.0. However, as a part of its URL, it does not specify the revision number. You typically create a callback so that the URL does not use the revision number. This is because web services are external and you cannot change web service settings to continue using a revision tag because it is internal to Oracle SOA Suite and is a concept that the external world does not understand.

   Since a revision number is not specified, the SOA server assumes that the revision number must be 2.0 and, if the routing of the callback takes the revision number into account, it cannot forward this callback intended for 1.0 to the correct revision 1.0. Instead, it attempts to route it to the default revision of 2.0, which does not have any instance waiting for the callback.

   You cannot route callback messages based on revisions. You only receive the option to route callback messages based on the conversion ID (if the correlation set is not used, then even this is not under your control), operation name, and component name.

   For these reasons, different instances must use different conversation IDs (which means different input is used for creating a conversion ID) to avoid confusion, and routing should be solely based on a conversation ID.

9.2.4 What You May Need to Know About Setting Correlations for an IMA Using a fromParts Element With Multiple Parts

Assume you have the following scenario:

• A BPEL 2.0 process with a WSDL message type that has multiple parts that are identical in type.

• A property alias has been defined based on the element type of the above part.

For a process that has an inbound message activity (IMA) (for example, a receive activity, onMessage branch of a scope or pick activity, or onEvent branch of a scope activity in BPEL 2.0) that uses the fromParts element with fromParts defined for each part, correlations cannot be defined because the runtime environment cannot determine the part to which to apply the property alias.

For more information about mapping WSDL message parts with the toParts and fromParts elements, see Mapping WSDL Message Parts in BPEL 2.0.

9.3 Routing Messages to the Same Instance

Oracle BPEL Process Manager supports a message aggregation feature. When multiple messages are routed to the same process/partner link/operation name, the first message is routed to create a new instance and subsequent messages can be routed to continue the created instance using a midprocess receive activity.

Message aggregation enables you to use the same operation (or event name) in an entry receive activity and a midprocess receive activity.

Note:

• This feature only performs aggregation, and not resequencing. This feature does not resequence messages arriving out of order into an ordered format. Therefore, the first message only means the first message processed. This may be different from the first message in a time sequence order.

• You must use correlation sets to take advantage of the message aggregation feature.

• Synchronous operations as ambiguous calls (at both beginning and midprocess receive activities) are supported. However, this is not a recommended use of this feature and should be avoided.

9.3.1 How to Configure BPEL Process Instance Creation

You can control the number of instances to create and use to route messages with the reenableAggregationOnComplete property.

To configure BPEL process instance creation:

1. In the SOA Composite Editor, select the BPEL process service component, as shown in Figure 9-16.

   Figure 9-16 Selected BPEL Process Service Component

   
   Description of "Figure 9-16 Selected BPEL Process Service Component"
2. Go to the Property Inspector in the lower right corner of Oracle JDeveloper. If the Property Inspector is not displayed, select Property Inspector from the View main menu.
3. In the Properties section, click the Add icon, as shown in Figure 9-17.

   Figure 9-17 Property Inspector

   
   Description of "Figure 9-17 Property Inspector"

   The Create Property dialog is displayed.

4. In the Name field, enter the bpel.config.reenableAggregationOnComplete deployment descriptor property. The prefix of bpel.config is required for this type of deployment descriptor.
5. In the Value field, enter true, as described in Table 9-12.

   Table 9-12 reenableAggregationOnComplete Property Settings

   Value	Description	Example
   true	Creates a new instance to handle messages. However, there is a window between messages coming in and instance completion. This can result in messages remaining in the DLV_MESSAGE table. This setting can result in the occurrence of race conditions. For more information, see Table 9-13.	You invoke messages 1 through 4 for a client using the initiate operation. This results in the following actions: Two instances of the BPEL process are created and completed. Messages 1 and 2 are routed to the first instance and messages 3 and 4 are routed to the second instance.
   false	This is the default behavior. This setting causes the aggregation feature to be disabled. Only one instance is created. Messages that are not handled by the instance remain in the DLV_MESSAGE table. This setting is recommended for most environments.	You invoke messages 1 through 4 for a client using the initiate operation. One instance of the BPEL process is created and completed. Do not attempt to route multiple messages using the same correlation set to one BPEL instance.

   Figure 9-18 shows the completed Create Property dialog.

   Figure 9-18 Create Property Dialog

   
   Description of "Figure 9-18 Create Property Dialog"
6. Click OK.

   The reenableAggregationOnComplete property with the bpel.config prefix looks as follows in the composite.xml file.

   <composite name="Aggregation" revision="1.0" label="2011-07-10_13-52-24_174"
    mode="active" state="on">
   . . .
   . . .
   <component name="Aggregation" version="1.1">
       <implementation.bpel src="Aggregation.bpel"/>
         <property name="bpel.config.reenableAggregationOnComplete" type="xs:string"
                 many="false" override="may">true</property>
     </component>
   . . .
   . . .
   </composite>

9.3.2 How to Use the Same Operation in Entry and Midprocess Receive Activities

Assume you create a correlation set as shown in the example that follows. All messages to Oracle BPEL Process Manager are routed to the same operation name. The messages have the same correlation ID. The interface WSDL does not differentiate between the entry activity (receiveInput) and the midprocess receive activity (Continue_Receive). All messages are processed using the initiate operation. A single instance is created to which to route all messages.

This differs from releases before 11g Release 1 11.1.1.6, in which you needed to define different operation names on the same partner link. The process had to expose two operations and the caller had to choose the correct operation name.

<receive name="receiveInput" partnerLink="client" portType="client:BPELProcess1"
 operation="initiate" variable="inputVariable" createInstance="yes">
 <correlations>
  <correlation initiate="yes" set="CorrelationSet_1"/>
 </correlations>
</receive>

<!-- Asynchronous callback to the requester. (Note: the callback location and
 correlation id is transparently handled using WS-addressing.) -->
<assign name="Assign_1">
 <copy>
  <from variable="inputVariable" part="payload"
 query="/client:BPELProcess1ProcessRequest/client:input"/>
  <to variable="Invoke_1_initiate_InputVariable" part="payload"
 query="/ns1:BPELProcess2ProcessRequest/ns1:input"/>
 </copy>
</assign>

<receive name="Continue_Receive" partnerLink="client"
 portType="client:BPELProcess1" operation="initiate" variable="inputVariable"
 createInstance="no">
 <correlations>
  <correlation initiate="no" set="CorrelationSet_1"/>
 </correlations>
</receive>

For event delivery network (EDN) business events, you substitute the operation attribute with bpelx:eventName in both the entry and midprocess receive activities.

bpelx:eventName="ns3:initiateEvent"/>

Information is maintained in the DLV_AGGREGATION table:

• Conversation ID

• Domain name

• Component name and type

• Composite name, label, and revision

• State

• Received date

• CI key

• Primary key

This information can be deleted from this table with the purge scripts or from the Auto Purge page in Oracle Enterprise Manager Fusion Middleware Control. For more information about both of these options, see the Administering Oracle SOA Suite and Oracle Business Process Management Suite.

9.3.3 How to Route a Message to a New or Existing Instance when Using Correlation Sets

For a BPEL process using correlation sets, the correct routing is performed. The message can be either of the following:

• An invoke message creating a new instance

• A callback message continuing an existing instance

Figure 9-19 shows entry and midprocess receive activities using the same operation (process).

Figure 9-19 Routing a New Message to a New or Existing Instance

Description of "Figure 9-19 Routing a New Message to a New or Existing Instance"

The following provides an example of the entry and midprocess receive activities using the same operation (process).

<receive name="receiveInput" partnerLink="client" portType="client:BPELProcess1"
 operation="process" variable="inputVariable" createInstance="yes">
 <correlations>
  <correlation initiate="yes" set="CorrelationSet_1"/>
 </correlations>
</receive>

<!-- some business logic -->

<while name="While_1" condition=*loop for 3 iterations*>
 <sequence name="Sequence_1">
  <receive name="Continue_Receive" partnerLink="client"
 portType="client:BPELProcess1" operation="process" variable="inputVariable"
 createInstance="no">
   <correlations>
    <correlation initiate="no" set="CorrelationSet_1"/>
   </correlations>
  </receive>

<!-- some business logic -->

 </sequence>
</while>

In the initial scenario in the preceding example, the following actions occur in BPEL process P1:

• A partner provides four messages (message 1, message 2, message 3, and message 4) for the same partner (correlation ID 101).

• Message 1 creates a new instance of BPEL process P1. This message is marked as an invoke message.

• Messages 2, 3, and 4 are received using the Continue_Receive activity. These messages are marked as callback messages.

• The instance closes because three iterations of the while loop are expected.

Assume now that additional messages are routed, which can potentially cause race conditions to occur. Table 9-13 provides details.

Table 9-13 Message Delivery Scenarios

Scenario	Description	Marked as Invoke Message	Marked as Callback Message
1	Assume the partner now provides message 5 for the same correlation ID (101). Message 5 creates a new instance of BPEL process P1 and waits on the Continue_Receive activity inside the while loop for three more messages (6, 7, and 8).	Message 1 Message 5	Message 2 Message 3 Message 4 Message 6 Message 7 Message 8
2	If messages 4 and 5 are received within a small time window, it is possible that message 4 is closing the instance BPEL process P1 and message 5 is routed as a callback to that instance. This scenario can cause a race condition. For example: When message 6 arrives, it is routed to the entry receive activity of the new instance. Messages 7 and 8 are routed to the Continue_Receive activity. Message 5 is routed to the Continue_Receive activity only by the recovery part of the BPEL process service engine. This is because it initially was routed to a closed instance and could not be handled.	Message 1 Message 6	Message 2 Message 3 Message 4 Message 5 Message 7 Message 8
3	This is similar to scenario 2. However, in this case, messages 7, 8, and 9 are not received. For example: Message 5 becomes an unhandled callback message waiting for a subscriber. BPEL process service engine recovery tries to process message 5 and fails because there is no subscriber available. There are several options for message recovery. Limit recovery of callback messages with the System MBean Browser property maxRecoverAttempt in Oracle Enterprise Manager Fusion Middleware Control. This count specifies the number of attempts made by automatic recovery to recover an invoke/callback message. Once the number of recover attempts exceeds this count, the state of the message is changed to exhausted. For more information, see Section "Configuring Automatic Recovery Attempts for Invoke and Callback Messages" in Administering Oracle SOA Suite and Oracle Business Process Management Suite. Write a custom SQL script to check that the criteriaCallback has state set to 0. The correlation value for this callback exists in CORRELATION_GROUP in a closed state (state = 0). This indicates that the callback message is marked for a closed aggregation instance. You can cancel/purge these instances based on business logic. Note: BPEL is designed as a conversation-based system. At any point in which unsolicited messages are not being handled, the application is always aware of the messages coming as part of correlation aggregation and chooses to subscribe and process or ignore the message as required by business needs.	Message 1 Message 6	Message 2 Message 3 Message 4 Message 5