Apache Synapse

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# Quick start guide

This guide will demonstrate two sample applications covering the basic and the most common usage scenarios of Synapse; which is Message mediation and Service mediation (i.e. using Proxy services). You will be guided through a step by step approach to get a feeling about Synapse from the absolute beginning.

### Pre-requisites

You should have following pre-requisites installed on your system to follow through this guide

- A Java 2 SE - JDK or JRE of version 1.4.2 or higher
- Apache Ant http://ant.apache.org

Note: To use the bundled https transport, you will need a Java 2 SE runtime of version 1.5 or later. If you are using a J2SE below 1.5 and does not require the https transport, you may comment out the following section from your repository/conf/axis2.xml and samples/axis2Server/repository/conf/axis2.xml configuration files.

    ...
       <transportReceiver name="https"...      ...   </transportReceiver>
       ...
       <transportSender name="https"...      ...   </transportSender>
    ....

## Message Mediation

In this example Synapse will be used to simply log all the messages passing through it. Although this simple scenario only performs logging, it demonstrates the basics of message mediation, where the logging functionality could be replaced with any combination of advanced mediations such as transformations, content based routing as well as bridging between different communication protocols etc. So, let's start with the basics.

### Download

Our first task is to download Synapse. Open a web browser and access the following URL: http://ws.apache.org/synapse/download.cgi. You will then see the list of available releases. Click on the 1.0 version, and you will be directed to the Synapse 1.0 release download page. Now download the 'Standard binary distribution' ZIP or tar.gz archive compatible with your operating system.

### Installation

Synapse can be installed just by extracting the downloaded binary archive.. A directory named synapse-1.0 will be created in the selected parent directory, containing all the files required for Synapse. We will refer to this directory as <synapse-home> from now on.

### Running the sample

Synapse ships with a set of sample clients and services to demonstrate some of its core capabilities. Hence, you will need to run three programs to get an idea of message mediation. The destination server that hosts the ultimate service to be invoked to service the client, the client itself, and Synapse, which acts as the intermediary to bridge between the client and the server.

#### Starting the sample Axis2 server

In this case we are using a standalone Axis2 web services engine as the server. You don't have to get it now, it is already bundled with your Synapse distribution. But we have to deploy a sample service for which client can send requests. Go to <synapse-home>/samples/axis2Server/src/SimpleStockQuoteService directory. Run "ant" to build and deploy this service to the sample Axis2 server.

    user@host:/opt/synapse/samples/axis2Server$ cd src/SimpleStockQuoteService/
    user@host:/opt/synapse/samples/axis2Server/src/SimpleStockQuoteService$ ant
    Buildfile: build.xml

    clean:
       [delete] Deleting directory /home/asankha/java/synapse-1.0-RC1-SNAPSHOT/samples/axis2Server/src/SimpleStockQuoteService/temp

    init:
        [mkdir] Created dir: /home/asankha/java/synapse-1.0-RC1-SNAPSHOT/samples/axis2Server/src/SimpleStockQuoteService/temp
        [mkdir] Created dir: /home/asankha/java/synapse-1.0-RC1-SNAPSHOT/samples/axis2Server/src/SimpleStockQuoteService/temp/classes

    compile-all:
        [javac] Compiling 9 source files to /home/asankha/java/synapse-1.0-RC1-SNAPSHOT/samples/axis2Server/src/SimpleStockQuoteService/temp/classes

    build-service:
        [mkdir] Created dir: /home/asankha/java/synapse-1.0-RC1-SNAPSHOT/samples/axis2Server/src/SimpleStockQuoteService/temp/SimpleStockQuote
        [mkdir] Created dir: /home/asankha/java/synapse-1.0-RC1-SNAPSHOT/samples/axis2Server/src/SimpleStockQuoteService/temp/SimpleStockQuote/META-INF
         [copy] Copying 1 file to /home/asankha/java/synapse-1.0-RC1-SNAPSHOT/samples/axis2Server/src/SimpleStockQuoteService/temp/SimpleStockQuote/META-INF
         [copy] Copying 1 file to /home/asankha/java/synapse-1.0-RC1-SNAPSHOT/samples/axis2Server/src/SimpleStockQuoteService/temp/SimpleStockQuote/META-INF
         [copy] Copying 9 files to /home/asankha/java/synapse-1.0-RC1-SNAPSHOT/samples/axis2Server/src/SimpleStockQuoteService/temp/SimpleStockQuote
          [jar] Building jar: /home/asankha/java/synapse-1.0-RC1-SNAPSHOT/samples/axis2Server/repository/services/SimpleStockQuoteService.aar

    BUILD SUCCESSFUL
    Total time: 1 second

Now go to <synapse-home>/samples/axis2Server directory and start the server using the following command. This will start Axis2 server on port 9000 (http).

Linux / Unix: . axis2server.sh

Windows: axis2server.bat

You will see the following messages on the console.

    user@host:/opt/synapse/samples/axis2Server$ ./axis2server.sh
     Using JAVA_HOME:   /opt/jdk1.5_06
     Using AXIS2 Repository :   /home/asankha/java/synapse-1.0-RC1-SNAPSHOT/samples/axis2Server/repository
     Using AXIS2 Configuration :   /home/asankha/java/synapse-1.0-RC1-SNAPSHOT/samples/axis2Server/repository/conf/axis2.xml
    [SimpleAxisServer] Using the Axis2 Repository : /home/asankha/java/synapse-1.0-RC1-SNAPSHOT/samples/axis2Server/repository
    [SimpleAxisServer] Using the Axis2 Configuration File : /home/asankha/java/synapse-1.0-RC1-SNAPSHOT/samples/axis2Server/repository/conf/axis2.xml
    [main] INFO  HttpCoreNIOSender - HTTPS Sender starting
    [main] INFO  HttpCoreNIOSender - HTTP Sender starting
    [main] INFO  HttpCoreNIOListener - HTTPS Listener starting on port : 9002
    [main] INFO  HttpCoreNIOListener - HTTP Listener starting on port : 9000

#### Starting Synapse

Now it's time to start Synapse. In this scenario we are starting Synapse using the sample configuration found in synapse_sample_0.xml (i.e. in repository/conf/sample) and listed below. It is configured to log and pass through, all the messages.

    <definitions xmlns="http://ws.apache.org/ns/synapse">    <log level="full"/>     <send/>
    </definitions>

Go to <synapse-home>/bin directory and type the command given below. Synapse will be started on port 8080 (http) and 8443 (https - under JDK 1.5)

Linux / Unix: . synapse.sh -sample 0

Windows: synapse.bat -sample 0

Following messages will be displayed on the console to indicate the successfull startup of Synapse.

    user@host:/opt/synapse/bin$ ./synapse.sh -sample 0
    Starting Synapse/Java ...
    Using SYNAPSE_HOME:    /opt/synapse
    Using JAVA_HOME:       /opt/jdk1.5_06
    Using SYNAPSE_XML:     -Dsynapse.xml=/opt/synapse/repository/conf/sample/synapse_sample_0.xml
    [SynapseServer] Using the Axis2 Repository /opt/synapse/repository
    [main] INFO  SynapseModule - Initializing the Synapse configuration ...
    ...
    [main] INFO  SynapseConfigurationBuilder - Loaded Synapse configuration from : /opt/synapse/repository/conf/sample/synapse_sample_0.xml
    [main] INFO  SynapseModule - Deploying the Synapse service..
    [main] INFO  SynapseModule - Deploying Proxy services...
    [main] INFO  SynapseModule - Synapse initialized successfully...!
    [main] ERROR SandeshaModule - Could not load module policies. Using default values.
    [main] INFO  HttpCoreNIOSender - HTTPS Sender starting
    [main] INFO  HttpCoreNIOSender - HTTP Sender starting
    [main] INFO  HttpCoreNIOListener - HTTPS Listener starting on port : 8443
    [SynapseServer] Starting transport https on port 8443
    [main] INFO  HttpCoreNIOListener - HTTP Listener starting on port : 8080
    [SynapseServer] Starting transport http on port 8080
    [SynapseServer] Ready

#### Run the client

Now the final step, running the client. Go to <synapse-home>/samples/axis2Client directory and type the following command

    user@host:/opt/synapse/samples/axis2Client$ ant stockquote -Daddurl=http://localhost:9000/soap/SimpleStockQuoteService -Dtrpurl=http://localhost:8080 -Dmode=quote -Dsymbol=IBM
    Buildfile: build.xml

    init:

    compile:

    stockquote:
         [java] Standard :: Stock price = $175.56196739870038

    BUILD SUCCESSFUL

This sends a request for a stock quote for the symbol IBM and sets the transport URL to Synapse (http://localhost:8080) and the WS-Addressing EPR set that of the actual server (http://localhost:9000/soap/SimpleStockQuoteService). The actual wire level http message sent by the client is as follows, and is sent over port 8080 to the Synapse instance on localhost.

    POST / HTTP/1.1
    Content-Type: text/xml; charset=UTF-8
    SOAPAction: "urn:getQuote"
    User-Agent: Axis2
    Host: 127.0.0.1
    Transfer-Encoding: chunked

    218
    <?xml version='1.0' encoding='UTF-8'?>
       <soapenv:Envelope xmlns:wsa="http://www.w3.org/2005/08/addressing" xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">
          <soapenv:Header>
             <wsa:To>http://localhost:9000/soap/SimpleStockQuoteService</wsa:To>
             <wsa:MessageID>urn:uuid:D538B21E30B32BB8291177589283717</wsa:MessageID>
             <wsa:Action>urn:getQuote</wsa:Action>
          </soapenv:Header>
          <soapenv:Body>
             <m0:getQuote xmlns:m0="http://services.samples/xsd">
                <m0:request>
                   <m0:symbol>IBM</m0:symbol>
                </m0:request>
             </m0:getQuote>
          </soapenv:Body>
       </soapenv:Envelope>0

Now take a look at the console running Synapse. You will see that all the details of the mediation are logged along with all the SOAP messages passed through Synapse - as Synapse is running on debug mode by default.

    [I/O reactor worker thread 5] INFO  PipeImpl - Using native OS Pipes for event-driven to stream IO bridging
    [HttpServerWorker-1] DEBUG SynapseMessageReceiver - Synapse received a new message for message mediation...
    [HttpServerWorker-1] DEBUG SynapseMessageReceiver - Received To: http://localhost:9000/soap/SimpleStockQuoteService
    [HttpServerWorker-1] DEBUG SynapseMessageReceiver - SOAPAction: urn:getQuote
    [HttpServerWorker-1] DEBUG SynapseMessageReceiver - WSA-Action: urn:getQuote
    [HttpServerWorker-1] DEBUG SynapseMessageReceiver - Body :
    <?xml version='1.0' encoding='utf-8'?><soapenv:Envelope xmlns:wsa="http://www.w3.org/2005/08/addressing" xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"><soapenv:Header><wsa:To>http://localhost:9000/soap/SimpleStockQuoteService</wsa:To><wsa:MessageID>urn:uuid:32748ED82860C9DBDE1177504004875</wsa:MessageID><wsa:Action>urn:getQuote</wsa:Action></soapenv:Header><soapenv:Body><m0:getQuote xmlns:m0="http://services.samples/xsd"><m0:request><m0:symbol>IBM</m0:symbol></m0:request></m0:getQuote></soapenv:Body></soapenv:Envelope>
    [HttpServerWorker-1] DEBUG SequenceMediator - Sequence mediator <main> :: mediate()
    [HttpServerWorker-1] DEBUG AbstractListMediator - Implicit Sequence <SequenceMediator> :: mediate()
    [HttpServerWorker-1] DEBUG LogMediator - Log mediator :: mediate()
    [HttpServerWorker-1] INFO  LogMediator - To : http://localhost:9000/soap/SimpleStockQuoteService, MessageID : urn:uuid:32748ED82860C9DBDE1177504004875, Action : urn:getQuote, Envelope: <?xml version='1.0' encoding='utf-8'?><soapenv:Envelope xmlns:wsa="http://www.w3.org/2005/08/addressing" xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"><soapenv:Header><wsa:To>http://localhost:9000/soap/SimpleStockQuoteService</wsa:To><wsa:MessageID>urn:uuid:32748ED82860C9DBDE1177504004875</wsa:MessageID><wsa:Action>urn:getQuote</wsa:Action></soapenv:Header><soapenv:Body><m0:getQuote xmlns:m0="http://services.samples/xsd"><m0:request><m0:symbol>IBM</m0:symbol></m0:request></m0:getQuote></soapenv:Body></soapenv:Envelope>
    [HttpServerWorker-1] DEBUG SendMediator - Send mediator :: mediate()
    [HttpServerWorker-1] DEBUG SendMediator - Sending message using implicit message properties..
    [HttpServerWorker-1] DEBUG SendMediator - Sending To: http://localhost:9000/soap/SimpleStockQuoteService
    [HttpServerWorker-1] DEBUG SendMediator - SOAPAction: urn:getQuote
    [HttpServerWorker-1] DEBUG SendMediator - Body :
    <?xml version='1.0' encoding='utf-8'?><soapenv:Envelope xmlns:wsa="http://www.w3.org/2005/08/addressing" xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"><soapenv:Header><wsa:To>http://localhost:9000/soap/SimpleStockQuoteService</wsa:To><wsa:MessageID>urn:uuid:32748ED82860C9DBDE1177504004875</wsa:MessageID><wsa:Action>urn:getQuote</wsa:Action></soapenv:Header><soapenv:Body><m0:getQuote xmlns:m0="http://services.samples/xsd"><m0:request><m0:symbol>IBM</m0:symbol></m0:request></m0:getQuote></soapenv:Body></soapenv:Envelope>
    [HttpServerWorker-1] DEBUG Axis2FlexibleMEPClient - sending [add = false] [sec = false] [rm = false] [ to Address: http://localhost:9000/soap/SimpleStockQuoteService]
    [HttpClientWorker-1] DEBUG SynapseCallbackReceiver - Synapse received an asynchronous response message
    [HttpClientWorker-1] DEBUG SynapseCallbackReceiver - Received To: null
    [HttpClientWorker-1] DEBUG SynapseCallbackReceiver - SOAPAction: null
    [HttpClientWorker-1] DEBUG SynapseCallbackReceiver - WSA-Action: null
    [HttpClientWorker-1] DEBUG SynapseCallbackReceiver - Body :
    <?xml version='1.0' encoding='utf-8'?><soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"><soapenv:Body><soapenv:Envelope><soapenv:Body><ns:getQuoteResponse xmlns:ns="http://services.samples/xsd"><ns:return><ns:change>3.9759712191629117</ns:change><ns:earnings>-9.463240695957264</ns:earnings><ns:high>97.0893936590198</ns:high><ns:last>93.87052890651084</ns:last><ns:lastTradeTimestamp>Wed Apr 25 18:26:46 LKT 2007</ns:lastTradeTimestamp><ns:low>96.4856592398509</ns:low><ns:marketCap>5.572519121414568E7</ns:marketCap><ns:name>IBM Company</ns:name><ns:open>-92.43795414108462</ns:open><ns:peRatio>-18.381880013551893</ns:peRatio><ns:percentageChange>-4.5174961332793435</ns:percentageChange><ns:prevClose>-88.01271991962221</ns:prevClose><ns:symbol>IBM</ns:symbol><ns:volume>15381</ns:volume></ns:return></ns:getQuoteResponse></soapenv:Body></soapenv:Envelope></soapenv:Body></soapenv:Envelope>
    [HttpClientWorker-1] DEBUG SequenceMediator - Sequence mediator <main> :: mediate()
    [HttpClientWorker-1] DEBUG AbstractListMediator - Implicit Sequence <SequenceMediator> :: mediate()
    [HttpClientWorker-1] DEBUG LogMediator - Log mediator :: mediate()
    [HttpClientWorker-1] INFO  LogMediator - Envelope: <?xml version='1.0' encoding='utf-8'?><soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"><soapenv:Body><soapenv:Envelope><soapenv:Body><ns:getQuoteResponse xmlns:ns="http://services.samples/xsd"><ns:return><ns:change>3.9759712191629117</ns:change><ns:earnings>-9.463240695957264</ns:earnings><ns:high>97.0893936590198</ns:high><ns:last>93.87052890651084</ns:last><ns:lastTradeTimestamp>Wed Apr 25 18:26:46 LKT 2007</ns:lastTradeTimestamp><ns:low>96.4856592398509</ns:low><ns:marketCap>5.572519121414568E7</ns:marketCap><ns:name>IBM Company</ns:name><ns:open>-92.43795414108462</ns:open><ns:peRatio>-18.381880013551893</ns:peRatio><ns:percentageChange>-4.5174961332793435</ns:percentageChange><ns:prevClose>-88.01271991962221</ns:prevClose><ns:symbol>IBM</ns:symbol><ns:volume>15381</ns:volume></ns:return></ns:getQuoteResponse></soapenv:Body></soapenv:Envelope></soapenv:Body></soapenv:Envelope>
    [HttpClientWorker-1] DEBUG SendMediator - Send mediator :: mediate()
    [HttpClientWorker-1] DEBUG SendMediator - Sending message using implicit message properties..
    [HttpClientWorker-1] DEBUG SendMediator - Sending To: null
    [HttpClientWorker-1] DEBUG SendMediator - SOAPAction: null
    [HttpClientWorker-1] DEBUG SendMediator - Body :
    <?xml version='1.0' encoding='utf-8'?><soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"><soapenv:Body><soapenv:Envelope><soapenv:Body><ns:getQuoteResponse xmlns:ns="http://services.samples/xsd"><ns:return><ns:change>3.9759712191629117</ns:change><ns:earnings>-9.463240695957264</ns:earnings><ns:high>97.0893936590198</ns:high><ns:last>93.87052890651084</ns:last><ns:lastTradeTimestamp>Wed Apr 25 18:26:46 LKT 2007</ns:lastTradeTimestamp><ns:low>96.4856592398509</ns:low><ns:marketCap>5.572519121414568E7</ns:marketCap><ns:name>IBM Company</ns:name><ns:open>-92.43795414108462</ns:open><ns:peRatio>-18.381880013551893</ns:peRatio><ns:percentageChange>-4.5174961332793435</ns:percentageChange><ns:prevClose>-88.01271991962221</ns:prevClose><ns:symbol>IBM</ns:symbol><ns:volume>15381</ns:volume></ns:return></ns:getQuoteResponse></soapenv:Body></soapenv:Envelope></soapenv:Body></soapenv:Envelope>

You have successfully completed the first part of this guide. Now let's look at the next scenario, proxy services.

## Proxy Services

As the name implies, a proxy service acts as a service hosted in Synapse, and typically fronts an existing service endpoint. A proxy service can be created and exposed on a different transport, schema, WSDL, or QoS (such as WS-Security, WS-Reliable Messaging) aspect than the real service and could mediate the messages before being delivered to the actual endpoint, and the responses before they reach the client.

Clients can send requests for proxy services directly to Synapse, as the client sees as if they are hosted on it, and for example can perform ?wsdl and view the WSDL of the virtual proxy service. But in the Synapse configuration, such requests can be handled in anyway you like. Most obvious thing would be to do some processing to the message and send it to the actual service, probably running on a different computer. But it is not neccessary to always send the message to the actual service. You may list any combination of tasks to be performed on the messages received for the proxy service and terminate the flow or send some messge back to the client even without sending it to an actual service. Let's explore a simple proxy services scenario step by step to get a better feeling. As you have downloaded and installed Synapse in the previous section, now you can start directly on the sample.

### Running the sample

As in the previous section, there should be three entities running to demonstrate proxy services, the server, client and Synapse. Let's start with the server.

#### Starting the sample Axis2 server

As you have built and deployed the SimpleStockQuote service in the previous section, you can simply start the server by switching to the <synapse-home>/samples/axis2Server directory and running the following command.

Linux / Unix: . axis2server.sh

Windows: axis2server.bat

You can see the console messages as in the previous section.

#### Starting Synapse

We have to start Synapse with a configuration containing a proxy service definition. In this case we are using the synapse_sample_100.xml, so that you don't have to write the configuration your self.

    <definitions xmlns="http://ws.apache.org/ns/synapse">
        <proxy name="StockQuoteProxy">
            <target>
                <endpoint>
                    <address uri="http://localhost:9000/soap/SimpleStockQuoteService"/>
                </endpoint>
                <outSequence>
                    <send/>
                </outSequence>
            </target>
            <publishWSDL uri="file:repository/conf/sample/resources/proxy/sample_proxy_1.wsdl"/>
        </proxy>
    </definitions>

The above configuration will expose a proxy service named StockQuoteProxy and specifies an endpoint (http://localhost:9000/soap/SimpleStockQuoteService) as the target for the proxy service. Therefore, messages coming to the proxy service will be directed to the address http://localhost:9000/soap/SimpleStockQuoteService specified in the endpoint. There is also an out sequence for the proxy service, which is applicable for response messages. In the out sequence, we just send the messages back to the client. The publishWSDL tag specifies an WSDL to be published for this proxy service. Let's start Synapse with this sample configuration by running the below command from the <synapse-home>/bin directory. It is possible to specify a sequence of mediation for incoming messages instead of a target endpoint, and many other possibilities and options are available to configure proxy services. These are explained in the samples and configuration guides.

Linux / Unix: . synapse.sh -sample 100

Windows: synapse.bat -sample 100

Synapse will display a set of messages as in the previous section describing the steps of starting procedure. Before running the client, it is time to observe another feature of proxy services. That is diplaying the published WSDL. Just open a web browser and point it to the address http://localhost:8080/soap/StockQuoteProxy?wsdl. You will see the sample_proxy_1.wsdl specified in the configuration but containing the correct EPR for the service over http/s.

#### Run the client

Now it is time to see it in action. Go to the <synapse-home>/samples/axis2Clients directory and type the following command:

ant stockquote -Dtrpurl=http://localhost:8080/soap/StockQuoteProxy -Dmode=quote -Dsymbol=IBM

The above command sends a stockquote request directly to the provided transport endpoint at: http://localhost:8080/soap/StockQuoteProxy. You will see the response from the server displayed on the console as follows:

Standard :: Stock price = $165.32687331383468

This quick guide illustrates the simple use case of proxy services. Please refer to samples #100 and above in the Samples guide, for indepth coverage of more advanced use cases.

Yes, you are done with a quick look at Synapse. Now it is time to go deeper and reveal the advanced features of Synapse. You can browse through the samples for your interested areas. If you have any issue regarding Synapse as a user, feel free ask it in the Synapse user mailing list (http://ws.apache.org/synapse/mail-lists.html).