Invoke activity

Chapter 17 Working with WS-BPEL 2.0

Invoke activity

The invoke activity allows the business process to initiate a message sent to a partner, the partner can respond or not. It can include:

Fault handlers to handle message faults returned by the operations
A compensation handler
Implicit assignments named <toParts> and <fromParts> elements

The <toParts> element provides an alternative to explicitly create multi-part WSDL messages from the contents of WS-BPEL variables. Each <copy> operation copies data from the variable (indicated in the "fromVariable" attribute) into the part of the anonymous temporary WSDL variable, which is referenced in the "part" attribute of the <toPart> element.

The <fromParts> element is similar to the <toParts> element. The <fromParts> element is used to retrieve data from an incoming multi-part WSDL message and place it into individual WS-BPEL variables. Each <copy> operation copies the data at the part of the anonymous temporary WSDL variable, which is referenced in the "part" attribute of the <fromPart> element into the variable indicated in the "toVariable" attribute.

The virtual <assign> created as a consequence of the <fromParts> or <toParts> elements occurs as part of the scope of the <invoke> activity and therefore any fault that is thrown are caught by an <invoke>'s inline fault handler when defined.

Syntax

<invoke name="InvokeCreditOrg" partnerLink="CreditOrg" portType="cc:CheckCreditPT" operation="CheckCreditOp">
   <correlations>
      <correlation set="AccountKey" initiate="yes" pattern="request"/>
   </correlations>
   <fromParts>
      <fromPart part="message" toVariable="transfer"/>
   </fromParts>
   <toParts>
      <toPart part="account" fromVariable="personnal" />
   </toParts>
</invoke>

Mapping

You design an invoke activity in any of the following ways:

Process object with the following properties:
Process property Value

Implementation type Execute operation

Action type Invoke operation

Implemented by Operation defined under a service provider within the same model
Right-click an <<empty>> process or a process without any stereotype and select the Change to Assign command
Drag the operation from the Browser and drop it on a process in the diagram window then set the appropriate action type

Process property	Value
Implementation type	Execute operation
Action type	Invoke operation
Implemented by	Operation defined under a service provider within the same model

Extended attributes

The following extended attributes apply to the invoke activity and are available from its property sheet:

Name	Internal code	Description
Join Condition	joinCondition	Join condition
Suppress Join Failure	suppressJoinFailure	Avoids propagation of Join Failure exceptions
Multiple Correlation	MultipleCorrelation	Defines BPEL Invoke, Receive or Reply activities using several correlations.
First correlation pattern	InCorrelationPattern	When the first correlation is used by the invoke activity, it can be a request, a response or a request-response
Second correlation pattern	OutCorrelationPattern	When the second correlation is used by the invoke activity, it can be a request, a response or a request-response
—	InCorrelationInitiate	When the first correlation is used by the invoke activity, the initiate attribute can take yes, no or join value.
—	OutCorrelationInitiate	When the second correlation is used by the invoke activity, the initiate attribute can take yes, no or join value
—	expressionLanguage	Specifies the expression language used in expressions

When the invoked operation is a One-Way operation, the Message mapping attribute of the Sent message corresponds to the invoke variable defined for the BPEL invoke activity and the Correlation key attribute corresponds to the correlation element of the BPEL activity:

When the invoked operation is a Request-Response operation, the Message mapping of the Received message corresponds to the input variable defined for the invoke activity and the Message mapping of the Sent message corresponds to the output variable.