Generate BPEL for Oracle workflow engine

BPEL stand for Business Process Execution Language, which is used to describe business process as well as executing the process. This topic is going to introduce the major steps of generating BPEL for Oracle workflow engine.

Drawing BPEL Business Process Diagram
As the name implies, BPEL Business Process Diagram is a Business Process Diagram for BPEL (Business Process Execution Language). It is used to model business process and make it executable.
	Creating Participant for Pool
	According to the specification of BPEL, each BEPL is described by WSDL. Within BPEL Business Process Diagram, there a something similar Participant of Pool. The below steps demonstrate how to create Participant for Pool by using template.
	1.	Open or create Business Process Diagram.
	2.	Open Specification of Pool.
	3.	Create Participant using template.
	4.	Click OK several times to apply and close all dialogs.
		Create option Creation result Create Participant... Empty Participant Create asynchronous Participant... Participant of asynchronous template Create synchronous Participant... Participant of synchronous template
	Asynchronous Participant
	When using asynchronous Participant, the BPEL process will become asynchronous at runtime. As implied by the name, interaction of asynchronous process may not reply immediately. Therefore, another operation should be defined for the callback purpose. In our asynchronous template, two sets of partnerLinkType, portType and operation are included, which to be used for caller and callback.
	Synchronous Participant
	Opposite to asynchronous Participant, synchronous Participant will cause BPEL process become synchronous at runtime. Any interaction of synchronous Participant must reply immediately. Therefore, only one operation is required and the synchronous template is including only one set of partnerLinkType, portType and operation.
	Creating and setting Partner Link
	Partner Link is a reference of Web Service used within BPEL. In BPEL Business Process Diagram, Pool is used to define Partner Link.
	1.	Open Specification of Pool.
	2.	Normally, Pool with Partner Link will be set as black box.
	3.	Create Partner Link.
	4.	Since Partner Link is separated from Pool, name of Partner Link should be maintained manually.
	5.	Participant of Partner Link is used to describe which Web Service it refers to.
	6.	Partner Link Type of Partner Link represents the interaction of BPEL and Web Service.
	7.	My Role and Partner Role is used for identifying responsibility of interaction. In synchronous process, only one role is required because it is a single direction invocation. In asynchronous process, two roles are required which describe caller role and callback role.
		Role Description My Role The role of current business process. Partner Role The role of opposite side such as client application or Web Service.

Setting BPEL properties
For executing the business process, some related properties are required to set. Basic properties are described in the example below.
	Simple Example
	In the example, the Business Process will start by receiving a message. Then it will make some modification to the message. Finally, the modified message will return back.
	1.	Draw Business Process.
	2.	Start by receive a message.
		I. Open Specification of Task. II. Check Instantiate if message will create a process instance. Since process will start when message is received, Instantiate should be checked. III. Open Specification of Task Type. IV. Select Partner Link of receiving message. Since message is from other to current process, the Partner Link should be "Client" which is the Web Service interface of current process. V. Select Operation to be invoked by other. VI. Select the corresponding Varaible. Since the Variable does not exist, create one for it. VII. Select the corresponding Message. Select Process1_RequestMessage since the Operation required it as input message. VIII. Click OK several times to apply and close all dialog boxes.
	3.	Modify the received message.
		I. Open Specification of Task. II. Create Assignment. III. Create From. IV. Create To. V. Select Varaible to be copied from. VI. Select Part of Variable to be copied from. VII. Input Query of the value to be copied from. VIII. Create To Variable. Create a Variable for storing modified message and return back. IX. Select the corresponding Message. Select Process1_ResponseMessage since the Operation for return required it as input message. X. Select Part of Variable to be copied to. XI. Input Query of the value to be copied to. XII. Click OK several times to apply and close all dialog boxes.
	4.	Return modified message back.
		I. Open Specification of Task. II. Open Specification of Task Type. III. Check Reply if process is synchronous. Since process is asynchronous, it should not be checked. IV. Select Partner Link of return message. V. Select Operation to be used for return. VI. Select the corresponding Varaible. VII. Click OK several times to apply and close all dialog boxes.
	Properties Reference
	The tables below show BPEL related properties with description.
		Business Process Diagram Location Property Description Dependence General:Tab Participant Web Service interface of BPEL   BPEL:Tab → Variable:Tab   List of global Variable   BPEL:Tab → Correlation Sets:Tab   List of global Correlation Set   Variable Location Property Description Dependence BPEL:Tab Message Message type of Variable   Correlation Set Location Property Description Dependence BPEL:Tab →Properties:Tab   List of selected Property   Unspecified Task Location Property Description Dependence Assignments:Tab   List of Copy Rule   Assignment (Copy Rule) Location Property Description Dependence BPEL:Tab From From of Copy Rule   Same as above To To of Copy Rule   From Variable, To Variable Location Property Description Dependence BPEL:Tab Variable Variable to be copied   Same as above Part Copy Part of Variable Variable Same as above Query Query of copy value   From Expression Location Property Description Dependence BPEL:Tab Expression Expression of copy value   From Property, To Property Location Property Description Dependence BPEL:Tab Property Property to be copied   From Partner Link Location Property Description Dependence BPEL:Tab Partner Link Target Partner Link   Same as above End Point Reference Role of Partner Link   To Partner Link Location Property Description Dependence BPEL:Tab Partner Link Target Partner Link   Receive Task Location Property Description Dependence General:Tab → Type:Specification - → BPEL:Tab - - → General:Tab Partner Link Target Partner Link   Same as above Operation Operation to be invoked Partner Link Same as above Variable Variable for receive message Operation General:Tab → Type:Specification - → BPEL:Tab - - → Correlations:Tab   List of Correlations   Correlation Location Property Description Dependence BPEL:Tab Initiate Is initiate   Same as above Set Correlation Set used   Same as above Pattern Pattern of Correlation Task Type Intermediate Event Type Reply Send Task Location Property Description Dependence General:Tab → Type:Specification - → BPEL:Tab - - → General:Tab Reply Act as Reply or Invoke   Same as above Partner Link Target Partner Link   Same as above Operation Operation to be invoked Partner Link Reply Same as above Variable Variable to be used Operation Reply General:Tab → Type:Specification - → BPEL:Tab - - → Correlations:Tab   List of Correlations   Service, User, Script, Manual Task Location Property Description Dependence General:Tab → Type:Specification - → BPEL:Tab - - → General:Tab Partner Link Target Partner Link   Same as above Operation Operation to be invoked Partner Link Same as above Input Variable Variable for send message Operation Same as above Output Variable Variable for receive message Operation General:Tab → Type:Specification - → BPEL:Tab - - → Correlations:Tab   Correlations   Timer Intermediate Event Location Property Description Dependence General:Tab → Trigger:Specification - → BPEL:Tab For Time duration of executing time   Same as above For's Expression Expression of time duration of executing time   Same as above Until Fixed time   Same as above Until's Expression Expression of fixed time   Error Intermediate Event Location Property Description Dependence General:Tab → Trigger:Specification - → BPEL:Tab Fault Target Fault type   Same as above Fault Variable Variable to be used   Compensation Intermediate Event Location Property Description Dependence General:Tab → Trigger:Specification - → BPEL:Tab Scope Scope to be compensated   Message, Rule, Link Intermediate Event Location Property Description Dependence General:Tab → Type:Specification - → BPEL:Tab - - → General:Tab Reply Act as Reply or Invoke   Same as above Partner Link Target Partner Link   Same as above Operation Operation to be invoked Partner Link Reply Same as above Variable Variable to be used Operation Reply General:Tab → Type:Specification - → BPEL:Tab - - → Correlations:Tab   List of Correlations   Embedded Sub Process Location Property Description Dependence General:Tab → Type:Specification - → BPEL:Tab - - → Variable:Tab   List of local Variable   General:Tab → Type:Specification - → BPEL:Tab - - → Correlation Sets:Tab   List of local Correlation Set   Data Gateway Location Property Description Dependence General:Tab → Type:Specification - → BPEL:Tab While Is while or do-while   Event Gateway Location Property Description Dependence General:Tab → Type:Specification - → General:Tab Initiate Is initiate

Generating Oracle BPEL
Since Oracle BPEL is one of the supported target server, generating BPEL for Oracle is simple. However, as only basic validation is provided, an invalid BPEL may also be generated and it may fail at deployment generation.
1.	Open Export Dialog.
2.	Select Output Directory.
3.	Select Target Server.
4.	Configure Target Server.
	I.	Select Oracle BPEL Home.
	II.	Input Partner Link Map.
5.	Check Auto Overwrite if overwrite existing files.
6.	Start Export.
7.	Wait until export finished.
8.	Review Export Result. Double click on the list item may open a dialog with file content.
9.	Debug Feature. Since it is not easy to debug a diagram with message only, an export details is provided.
	Export Details
	Export Details is the actual steps of exporting BPEL for debugging usage. In exporting BPEL, there are six major procedures. Each procedure depends on its previous procedure and will be executed one by one. Any errors within the procedure will be stored, and then try to continue the procedure. If procedure has error occurred, the next procedure will not be executed and the whole progress will be canceled.
	The Export Trace dialog box is used to display the steps of each procedure. In other words, it show the diagram?s execution sequence of each procedure. With the Export Trace dialog box, it is possible to show details by double-clicking on a list item. However, some items are not possible to visualize. Therefore, double-clicking on those items will have no effect.

Deploying and testing BPEL
After generated Oracle BPEL, a BPEL suitcase bpel_*.jar will be created by bpelc at the selected output directory. If file does not exist, there must be problem with the diagram. Please refer to the export details and try to fix it.
	Deploy BPEL into Oracle
	1.	Open browser and login to Oracle BPEL console.
	2.	Click Deploy New Process on Dashboard.
	3.	Select created BPEL suitcase and click deploy.
	4.	Click deployed process.
	5.	Input value for message.
	6.	Create process instance by sending message.
	7.	View the flow of instance.
	8.	View returned message.

Samples

Click on the link below to download:
• The VP project of the Simple Example.
		simple_example.zip
• The exported BPEL suitcase.
		bpel_process1_v2006_07_28_41487.jar
• The BPEL file exported from Simple Example.vpp.
		process1.bpel
• The WSDL file exported from Simple Example.vpp.
		process1_participant.wsdl
• The BPEL suitcase descriptor file exported from Simple Example.vpp.
		bpel.xml