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The Document Message EIP is used to reliably transfer a data structure between applications. The Command Message EIP allows you to invoke only a specific client through the ESB, while the Document Message EIP sends the entire data unit to the receiver. For more information, refer to see http://www.eaipatterns.com/DocumentMessage.html.
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This example demonstrates how the ESB transmits an entire message from a client to a sample Axis2 server as a document message. Then the Axis2 server processes it the message and identifies which operation to invoke.
The following diagram
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depicts this process.
Figure 2: Example scenario of the Document Message EIP
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| Document Message EIP (Figure 1) | Document Message Example Scenario (Figure 2) |
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| Sender | Stock Quote Client |
| Document Message | Proxy Service |
| Receiver | Simple Stock Quote Service |
The ESB
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configuration
Given below is the ESB configuration for simulating the example scenario explained above.
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The configuration elements
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The elements used in the above ESB configuration are explained below.
- Proxy Service - The proxy service takes requests a request and forwards them it to the back-end service, abstracting the routing logic from the client. In this example scenario, the proxy service just forwards requests the request to the back-end service, following the Document Message EIP style.
Simulating the example scenario
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You need to set up the ESB, and the back-end service:
- Download the
Document-Message_1.0.0.zipfile, which includes the ESB configuration described above. See Setting up the Environment for instructions on setting up the ESB and the back-end service.
Info When you set up the environment, note that you only need to start one instance of the back-end service (Stock Quote Service) to simulate this example.
Executing the sample
Send the following Let's send a request to the ESB , by using a SOAP client: Note that the entire request will be passed to the back-end Axis2 Server, and the client will receive the response in return.
Request command:
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using the Stock Quote Client application. Find out more about the Stock Quote Client from the ESB documentation.
- Open a new terminal, and navigate to the
<ESB_HOME>/samples/axis2Client/directory. The Stock Quote client application is stored in this directory. Execute the following command to send the request to the ESB.
Code Block ant stockquote -Dtrpurl=http://localhost:8280/services/DocumentMessageProxy
Analyzing the output
Stock Quote Client output:
Standard :: Stock price = $72.78678053494932
Axis2 server console output:
When you execute the command above, the ESB first receives the message and then routes it to the back-end service (StockQuoteService). The following output will be printed on the Axis2 server's console:
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samples.services.SimpleStockQuoteService :: Generating quote for : IBM |
The generated stock quote will then be sent to the client application (Stock Quote Client). The following output will be printed on the client application's console:
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Standard :: Stock price = $72.42070059233666 |