Implementing TimeOuts in Bpel Using Pick(On Message,On Alaram)

                                       

                                    

                                                 In this blog ,I wanna  discuss how to create a pick activity to select to continue a process or wait, create wait activities to set an expiration time, create OnEvent branches in BPEL 1.0 to wait for message arrival, and set timeouts on synchronous processes.

The pick activity provides two branches, each one with a condition. The branch that has its condition satisfied first is executed

    

• onMessage
  This condition has code for receiving a reply in the form of a web service. The onMessage code matches the code for receiving a response from the  web service before a timeout was added.
  
• onAlarm
  This condition has code for a timeout of one minute. This time is defined as PT1M, which means to wait one minute before timing out. In this timeout setting:
  
  • S stands for seconds
  • M for one minute
  • H for hour
  • D for day
  • Y for year
    
    
    
    
     Note:The pick activity condition that completes first is the one that the BPEL process service component executes. The other branch then is not executed.

 An onMessage branch is similar to a receive activity in that it receives operations. However, you can define a pick activity with multiple onMessage branches that can wait for similar partner links and port types, but have different operations. Therefore, separate threads and parallel processes can be invoked for each operation. This differs from the receive activity in which there is only one operation. Another difference is that you can create a new instance of a business process with a receive activity (by selecting the Create Instance checkbox), but you cannot do this with a pick activity.

In this Example - A BPEL process(Process1) client: uses an Invoke to send an asynchronous request to the service (BPEL Process 2), and a Pick activity with:
- An onMessage branch to receive the response (callback)
- An onAlarm branch to manage the timeout condition if it occurs before the response is
received

 Create a BPEL project PICK_DemoPjct

Artifacts required is a simpleXSD : picksample.xsd

 <xsd:element name="EmployeeDetails">
<xsd:complexType>
<xsd:sequence>
 <xsd:element name="EmpID" type="xsd:string" />
  <xsd:element name="Salary" type="xsd:string" />
</xsd:sequence>
</xsd:complexType>
</xsd:element>
<xsd:element name="EmpdetailsResponse">
<xsd:complexType>
<xsd:sequence>
 <xsd:element name="EmpID" type="xsd:string" />
 <xsd:element name="MessageStatus1" type="xsd:string" />
 <xsd:element name="MessageStatus2" type="xsd:string" />

</xsd:sequence>
</xsd:complexType>
</xsd:element>
</xsd:schema>

Step 1:  Design the BPEL Process 1 name it "PickSyncBpelProcess" by selecting "SynchronousBPEL Process"  as Template

Input,Output are the elements from the above picksample.xsd

Step 2:   Design the BPEL Process 2 name it "PickAsyncBpelProcess" by selecting "ASynchronousBPEL Process"  as Template

 Input,Output are the elements from the above picksample.xsd

 Note : Exposed as a soap Service is unchecked

  

 Connect the BPEL process1 to BPEL process2 as shown below, design composite as below

 Step 3:  Now we will edit BPEL Process 2  "PickAsyncBpelProces"

In this Process Drop Assign activity between Receive and Callback and a delay activity (Waiit_1) between Assign and Callback.Assign activity just assign input to output.

Step 4:  Now Configure the Wait activity to 5 seconds.It Means after Assign_1 activity there will be a delay of 5 seconds

What happens when you create wait activity<wait (for="duration-expr" | until="deadline-expr")standard-attributes>standard-elements</wait> 

in our case:  <wait name="Wait1" for="'PT5S'"/> 

the duration value bpelx:for="'PT5M'" specifies that the activity expects an inbound message to arrive 

no later than five minutesafter the activity has started execution.

Step 5:  Now we will edit BPEL Process 1   "PickSyncBpelProces"

                         1. Add Invoke activity to Call BPEL Process 2 "PickAyncBpelProces"

                         2. Add Pick activity.Pickout activity has 2 type of outcome , OnMessage and 
OnAlarm. Set An onMessage branch to receive the response (callback) and 
an onAlarm branch to manage the timeout condition if it occurs before the 
response is received.

Create a Variable for Callback  response to receive

reply from AsyncBpelprocess "PickAyncBpelProces"

  3.Add Assign Activity Assign_1 with OnMessage branch and Assign activity 
Assign_1 with the OnAlarm activity.

   4.  In Assign_1 activity , assign MessageStatus1 element of "EmpdetailsResponse" of OutputMessageType 
with value  'OnMsg' and  MessageStatus2 element with value 'BPEL_Pick'    

    5.In Assign_2 activity , assign MessageStatus1 element of "EmpdetailsResponse" 

OutputMessageType with value  'On_ALARM' that indicate that it is Time out Activity.

   6.Configure the OnAlarm activity of Pick activity and set the time = 59 
seconds.That means if the OnMessage Branch has not been process within 59 
seconds that BPEL will trigger the OnAlaram branch of theflow

 
6. Add Assign_3 to map input to invoke inputVariable of   "PickAsyncBpelProces"

 

 Step 6:  Now our PICK_DemoPjct is ready to test 

Run the BPEL Process .Please note that in BPEL Process we have a delay of 5 seconds and OnAlaram branch in Process1 will trigger only if OnMessage will not get any response with in 59 seconds.

In Our case since delay in Process 2 is 5 seconds , On Message will get response in 5seconds and output will Print the variable assign in Assign activity_2 .

MessageStatus1 and  MessageStatus2  value 'BPEL_Pick' 

Step 7: Now we will tweet the code to test OnAlarm Branch 

 Once again configure the delay (Wait_1) activity of the BPEL process 2 and set the dealy time = 2 minutes .That means Process2 will take 2 minutes of dealy  between Assign and callback.

Run the BPEL Process 

                                                                                                              By Deepthi Reddy