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Overview of the ServiceMix 2.x HTTP Binding Example

The following procedure describes how to run the HTTP Binding example and provides details regarding what it does. For information on the business use case, please refer to: Use Case for HTTP Binding.

The HTTP Binding example illustrates:

  • use of declarative programming
  • how to perform HTTP binding in ServiceMix

The source code for the HTTP Binding example is located in the ServiceMix installation directory under the examples\http-binding directory in the servicemix.xml file. It is recommended that you refer to the source code while reading this document.

This example shows how to use the HTTP bindings to handle a simple HTTP post. One component acts as the HTTP server thahttp://docs.codehaus.org/display/SM/Http+Binding+Ja
Viewt listens on http://localhost:8912 while another invokes a remote service implemented as a URLEndpoint. A simple HTTP client is provided so that a simple post can be set to the server.

Running the HTTP Binding Example

  1. From a command shell, go to the HTTP Binding example directory: 
    cd [servicemix_install_dir]\examples\http-binding
    where servicemix_install_dir is the directory in which ServiceMix was installed.
  2. Then type: 
    [servicemix_install_dir]\bin\servicemix servicemix.xml
  3. To start sending and receiving of messages from the HTTP server, send an initial message. To do this, compile and run a simple HTTP client. The client is built and run from source code using Ant. Execute Ant from the HTTP Binding directory: servicemix_install_dir\examples\http-binding. To run the HTTP client type: 
    ant

    Ant will compile and run the simple HTTP client, HttpClient, which performs a simple post on the HTTP Server into the ServiceMix container before returning the results to the console.

Stopping the HTTP Binding Example

To terminate the HTTP Binding example, type "CTRL-C" in the command shell in which it is running and answer "y" to the "Terminate batch job (y/n)?" question.

How it Works

The diagram below illustrates the flow of messages through the HTTP Binding components:

HTTP Binding Example Message Flow Diagram


Messages flow through the components as follows:

  1. HttpClient, a java standalone program connects to http://localhost:8912 through URLConnection class. It then sends the file "request.xml" to this port.
  2. httpReceiver, an http server, being a listenser on http://localhost:8912 receives the message.
  3. It then sends the message to stockQuote as specified in its destinationService property, via NMR.
  4. stockQuote sends in into another service, soapEndpoint for processing.
  5. soapEndpoint sends the response to stockQuote.
  6. stockQuote send the response to httpReceiver via NMR.
  7. httpReceiver sends the response to http://localhost:8912.
  8. HttpClient reads the response.
  9. The response is printed on the console.

Typical output looks like the following:

Output of servicemix servicemix.xml 

  
Loading ServiceMix from file: C:\exist\servicemix\servicemix-2.0.2\examples\http
-binding\servicemix.xml
17:34:34.768 EVENT  Starting Jetty/4.2.20RC0
17:34:34.848 EVENT  Started ServletHttpContext[/]
17:34:34.858 EVENT  Started SocketListener on 127.0.0.1:8912
17:34:34.858 EVENT  Started org.mortbay.jetty.Server@1f06dc3

Output of HttpClient.java 

Buildfile: build.xml

init:

compile:

run:
     [echo] Running example client
     [java] <?xml version="1.0" encoding="UTF-8"?><soap:Envelope xmlns:soap="htt
p://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSch
ema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:soapenc="http:/
/schemas.xmlsoap.org/soap/encoding/" soap:encodingStyle="http://schemas.xmlsoap.
org/soap/encoding/"><soap:Body><n:getQuoteResponse xmlns:n="urn:xmethods-delayed
-quotes"><Result xsi:type="xsd:float">88.8</Result></n:getQuoteResponse></soap:B
ody></soap:Envelope>asdf

BUILD SUCCESSFUL
Total time: 6 seconds

Details

The following table provides more details about the function of each component and bean in the servicemix.xml file.

Component or Bean ID

Description

jbi

jbi is the "id" of the JBI container and provides the basic infrastructure services for the following components:
httpReceiver and stockQuote. During initialization, several singletons are instantiated: URLEndpoint and jbi.
After initialization, the components in the jbi container are activated.

httpReceiver

This component is an http server that is set to listen at

http://localhost/8912

. It forwards the message it receives from this url to stockQuote as specified in its property destinationService.

stockQuote

This is a SaajBinding component that invokes an endpoint service called soapEndpoint. It is implemented by the SaajBinding class which converts an inbound JBI message into a SAAJ (Soap With Attachments for Java) request-response and outputs the response back into httpReceiver. This provides a message centric way of invoking SOAP services inside providers such as Apache Axis

soapEndpoint

A URLEndpoint object contains a URL, which is used to make connections to the remote party. A standalone client can pass a URLEndpoint object to the SOAPConnection method call to send a message.

Useful Code Hints

This section describes the start-up sequence and how the ServiceMix container interacts with the HTTP Binding application. The Java class files are located in the servicemix-2.0.2.jar file in the ServiceMix installation directory. To look at the Java source code, unjar and decompile the .class files or download the source code. Please note: the downloadable source code is slightly different than the compiled binary code.

Viewing the Java source code is recommended for understanding the information in this section.

  1. The ServiceMix container reads the servicemix.xml file and instantiates the components specified through SpringJBIContainer.
  2. SpringJBIContainer registers the components and the activationSpecs in its afterPropertiesSet method. In this case, httpReceiver and stockQuote are registered as activationSpecs.
  3. SpringJBIContainer uses ActivationSpec class as the container for component specific properties such as routing information.

Some of its ActivationSpec's methods are:
setId - takes the spring:id=jbi and sets the id of the container to "jbi"
setcomponentName - sets componentName to httpReceiver on first invocation and "stockQuote" in the next
setEndpoint - sets the endpoint properties from the servicemix.xml file
setService - sets the service properties from xml file
setDestinationService = sets the destinationService for each component

HttpConnector Details
stockQuote Details

Related Documentation

For more information on the following topics please see:


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