Petals Getting started - day 5 - EIP Orchestration

Hi ! Today is you last day. You will create a simple process: bufferize messages, and execute all of them in one time with MathOperations. You will use EIP chains for this.

This tutorial is based on the use case: Bufferize operations with EIP.

Any question, any problem? Find the solution on the EIP tutorial discussion. 

Integration process definition

You will use Enterprise Integration Patterns (EIP, see below for explanations) to create this process:

• Several messages are sent to an EIPAggregator pattern, which bufferizes all the incoming messages.
• A trigger message is sent to EipAggregator.
• The EipAggregator sends an aggregated message to EipSPlitter.
• The EipSplitter splits the aggregated message back into multiple messages.
• The EipSPlitter sends the multiple messages to the operation AddIntegers of the MathOperations service.
• The MathOperations.AddIntegers operation processes the messages and sends the responses.

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What is EIP ?
A set of design patterns for enterprise application integration.

What is Agregator pattern ?
What is Splitter Pattern ?
Read EIP Aggregator and EIP SPlitter documentation to understand those patterns.

Configure EIP Splitter

1. Launch Petals Studio.
2. Click File > New > Service-Unit Project.
3. Select Use a Petals technical Service > EIP > Your_EIP_Version.
4. Configure Splitter Service-Unit with following configuration:

   Parameter name	Value
   JBI properties	Note: EIP does not need a WSDL
   Interface namespace:	http://test.petalslink.com
   InterfaceName:	EipSplitterInterface
   Service Namespace:	http://test.petalslink.com
   Service Name:	EipSplitter
   End-point Name:	EipSplitterEndpoint
   Project Name and Location
   Project Name:	su-EIP-EipSplitter-provide
   Chain calls (1)
   Eip:	Splitter
   Chain calls (2)
   Selected Pattern: splitter	see below for configuration

5. Click Add > Edit. It displays the window "EIP: Invoked Service 1".
6. Click Select a service.
7. Double click MathOperations implements MathOperations @ MathOperationsPort.
8. Fill the following properties for Invoked Service 1:

   Service Identifiers	auto-configured
   Invocation Properties
   Operation Namespace:	http://test.petalslink.com
   Operation:	AddIntegers
   Mep:	InOut
   Routing Condition
   XPath Condition	//*[local-name()="AddIntegers"]

9. Click Ok > Next > Finish.

Configure EIP Aggregator

1. Create another New Service-Unit Project for EIP Technical Service with the following configuration:

   Parameter name	Value
   JBI propertie
   Interface Namespace:	http://test.petalslink.com
   Interface Name:	EipAggregatorInterface
   Service Namespace:	http://test.petalslink.com
   Service Name:	EipAggregator
   End-point Name:	EipAggregatorEndpoint
   Project Name and Location
   Project Name:	su-EIP-EipAggregator-provide
   Chain calls (1)
   Eip:	Aggregator
   Aggregator Correlation:	boolean(/*[local-name()="AddIntegers"])
   Chain calls (2)
   Selected Pattern: aggregator	see below for configuration

2. Click Add > Edit. It displays the window "EIP: Invoked Service 1".
3. Click Select a service.
4. Double click EipSplitter implements EipSplitterInterface @ EipSplitterEndpoint.
5. Fill the following properties for Invoked Service 1:

   Service Identifiers	auto-configured
   Invocation Properties
   Operation Namespace:	http://test.petalslink.com
   Operation:	AddIntegers
   Mep:	InOut
   Routing Condition
   XPath Condition	boolean(/*[local-name()="AddIntegers"]/*[local-name()="equals"])

6. Click Ok > Next > Finish.

Create and deploy an EIP Service Assembly

Beacause EipSplitter and EipAggregator are tight-coupled, they can be packaged in one Service Assembly, without loosing felxibility. This is especially adapted with EIP, which can chain lots of EIP Service-Units.

1. Click File > New > Service Assembly Project.

   Service Assembly
   Name:	sa-Eip-AggregatorSplitter
   Artifact ID:	sa-Eip-AggregatorSplitter

2. Click Next.
3. Check su-EIP-EipSplitter-provide and su-EIP-EipAggregator-provide.
4. Click Finish.
5. Fast-export the Service Assembly for Petals.
6. Download Petals-SE-EIP.
7. Deploy Petals-SE-EIP in Petals ESB.
8. Deploy sa-Eip-AggregatorSplitter in Petals ESB.

Understand XPath expressions

What is XPath ?
Run this tutorial (takes ~30 min) for Xpath : http://www.w3schools.com/XPath/default.asp
Look at XPath expressions used in EipSplitter and EipAggregator. Try to understand them. XPath is essential to use Petals-SE-EIP.

EIP Agregator conditions:

1. Elements which satisfy "aggregator-correlation" are aggregated

   <eip:aggregator-correlation>boolean(/*[local-name()="AddIntegers"])</eip:aggregator-correlation>

   Elements inside <AddIntegers> will be aggregated.

2. When "test" is true, aggregated message is sent.

   <eip:test>boolean(/*[local-name()="AddIntegers"]/*[local-name()="equals"])</eip:test>

   When <AddIntegers> contains the <equals> element, the aggregated message is sent to the next service, and buffer cleared.

EIP Splitter conditions:

1. Elements which satisfy "test" are extracted and sent to the next service.

   <eip:test>//*[local-name()="AddIntegers"]</eip:test>

   <AddIntegers> elements are split and sent one by one.

Test the EIP chain

1. Check that sa-jsr181-MathOperations-provide (from last day tutorial) is deployed in Petals ESB. If not, deploy it.
2. Deploy sa-Eip-AggregatorSplitter in Petals ESB.
3. Go to Webconsole > Server: 0 > Test > Send
4. Send following messages to Endpoint EipAggregatorEndpoint, with MEP InOut:
   Message 1

   <AddIntegers xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >
   <integer1>1</integer1>
   <integer2>2</integer2>
   </AddIntegers>
   

   Response message

   <result xmlns="http://petals.ow2.org/petals-se-eip/aggregator">Aggregator: the content is buffered by the pattern</result>
   

   Message 2

   <AddIntegers xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >
   <integer1>3</integer1>
   <integer2>4</integer2>
   </AddIntegers>
   

   Message 3

   <AddIntegers xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >
   <integer1>5</integer1>
   <integer2>6</integer2>
   </AddIntegers>
   

5. Send trigger message:
   Message 4 - Trigger

   <AddIntegers xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" >
   <equals/>
   </AddIntegers>
   

   Response message

   <result xmlns="http://petals.ow2.org/petals-se-eip/splitter">
   <dlwmin:AddIntegersResponse xmlns:dlwmin="http://test.petalslink.com" xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
   <returnMessage xmlns="">3</returnMessage>
   </dlwmin:AddIntegersResponse>
   <dlwmin:AddIntegersResponse xmlns:dlwmin="http://test.petalslink.com" xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
   <returnMessage xmlns="">7</returnMessage>
   </dlwmin:AddIntegersResponse>
   <dlwmin:AddIntegersResponse xmlns:dlwmin="http://test.petalslink.com" xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
   <returnMessage xmlns="">11</returnMessage>
   </dlwmin:AddIntegersResponse>
   </result>
   

More about orchestration

Orchestration alternatives:

You can orchestrate services in Petals with either BPEL, SCA, JSR181, EIP or POJO. Read this Orchestration Whitepaper to learn more.

Main differences between orchestration technologies:

• EIP: Good performances. But complicated and best-suited for integration projects than SOA (WSDL are not required).
• BPEL: Based on XML and WSDL. Standard. Requires some time to be mastered.
• SCA: Another approach of orchestration. Java code, based on WSDL and dependency injections offered by the SCA Java specification.
• POJO or JSR181: Needs advanced Java programmation.
• Custom JBI Component: Need of programming skills with Java. Best performances. Hard to maintain. Not mandatory a good practice.

Finished !
Bravo, you successfully ran the Petals Getting Started Guide.

Want to know more ?

• Tell me what additional tutorial you would like.
• Ask for advises and help on the forum.
• Trainings gives advanced knowledge on Petals ESB. They talk more about SOA, and real project problems.

For all this, just contact me!
mathieu.lebreton@petalslink.com