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.
You should have following pre-requisites installed on your system to follow through this guide
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.
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 latest version, and you will be directed to the Synapse release download page. Now download the 'Standard binary distribution' ZIP or tar.gz archive compatible with your operating system.
Synapse can be installed just by extracting the downloaded binary archive.. A directory named synapse with the release number 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.
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.
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-1.1.1/samples/axis2Server$ cd src/SimpleStockQuoteService/
user@host:/opt/synapse-1.1.1/samples/axis2Server/src/SimpleStockQuoteService$ ant
Buildfile: build.xml
clean:
init:
[mkdir] Created dir: /opt/synapse-1.1.1/samples/axis2Server/src/SimpleStockQuoteService/temp
[mkdir] Created dir: /opt/synapse-1.1.1/samples/axis2Server/src/SimpleStockQuoteService/temp/classes
[mkdir] Created dir: /opt/synapse-1.1.1/samples/axis2Server/repository/services
compile-all:
[javac] Compiling 9 source files to /opt/synapse-1.1.1/samples/axis2Server/src/SimpleStockQuoteService/temp/classes
build-service:
[mkdir] Created dir: /opt/synapse-1.1.1/samples/axis2Server/src/SimpleStockQuoteService/temp/SimpleStockQuote
[mkdir] Created dir: /opt/synapse-1.1.1/samples/axis2Server/src/SimpleStockQuoteService/temp/SimpleStockQuote/META-INF
[copy] Copying 1 file to /opt/synapse-1.1.1/samples/axis2Server/src/SimpleStockQuoteService/temp/SimpleStockQuote/META-INF
[copy] Copying 1 file to /opt/synapse-1.1.1/samples/axis2Server/src/SimpleStockQuoteService/temp/SimpleStockQuote/META-INF
[copy] Copying 9 files to /opt/synapse-1.1.1/samples/axis2Server/src/SimpleStockQuoteService/temp/SimpleStockQuote
[jar] Building jar: /opt/synapse-1.1.1/samples/axis2Server/repository/services/SimpleStockQuoteService.aar
BUILD SUCCESSFUL
Total time: 2 seconds
user@host:/opt/synapse-1.1.1/samples/axis2Server/src/SimpleStockQuoteService$
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-1.1.1/samples/axis2Server$ ./axis2server.sh Using Bouncy castle JAR for Java 1.5 Using JAVA_HOME: /opt/jdk1.5_06 Using AXIS2 Repository : /opt/synapse-1.1.1/samples/axis2Server/repository Using AXIS2 Configuration : /opt/synapse-1.1.1/samples/axis2Server/repository/conf/axis2.xml 2007-11-05 14:36:41,462 [-] [main] INFO SimpleHTTPServer [SimpleAxisServer] Starting [SimpleAxisServer] Using the Axis2 Repository : /opt/synapse-1.1.1/samples/axis2Server/repository [SimpleAxisServer] Using the Axis2 Configuration File : /opt/synapse-1.1.1/samples/axis2Server/repository/conf/axis2.xml 2007-11-05 14:36:43,864 [-] [main] INFO HttpCoreNIOSender HTTPS Sender starting 2007-11-05 14:36:43,891 [-] [main] INFO HttpCoreNIOSender HTTP Sender starting 2007-11-05 14:36:44,288 [-] [main] INFO HttpCoreNIOListener HTTPS Listener starting on port : 9002 2007-11-05 14:36:44,298 [-] [main] INFO HttpCoreNIOListener HTTP Listener starting on port : 9000 2007-11-05 14:36:44,350 [-] [main] INFO SimpleHTTPServer [SimpleAxisServer] Started
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-1.1.1/bin$ ./synapse.sh -sample 0 Using Bouncy castle JAR for Java 1.5 Starting Synapse/Java ... Using SYNAPSE_HOME: /opt/synapse-1.1.1 Using JAVA_HOME: /opt/jdk1.5_06 Using SYNAPSE_XML: -Dsynapse.xml=/opt/synapse-1.1.1/repository/conf/sample/synapse_sample_0.xml 2007-11-05 14:58:55,029 [-] [main] INFO ServerManager Using the Axis2 Repository /opt/synapse-1.1.1/repository 2007-11-05 14:58:56,617 [-] [main] INFO SynapseInitializationModule Initializing Synapse at : Mon Nov 05 14:58:56 LKT 2007 2007-11-05 14:58:56,618 [127.0.1.1-asankha] [main] INFO SynapseInitializationModule Loading mediator extensions... 2007-11-05 14:58:56,619 [127.0.1.1-asankha] [main] INFO SynapseInitializationModule Initializing the Synapse configuration ... 2007-11-05 14:58:56,624 [127.0.1.1-asankha] [main] INFO XMLConfigurationBuilder Generating the Synapse configuration model by parsing the XML configuration 2007-11-05 14:58:56,717 [127.0.1.1-asankha] [main] INFO SynapseConfigurationBuilder Loaded Synapse configuration from : /opt/synapse-1.1/repository/conf/sample/synapse_sample_0.xml 2007-11-05 14:58:56,724 [127.0.1.1-asankha] [main] INFO SynapseInitializationModule Deploying the Synapse service.. 2007-11-05 14:58:56,740 [127.0.1.1-asankha] [main] INFO SynapseInitializationModule Initializing Sandesha 2... 2007-11-05 14:58:56,801 [127.0.1.1-asankha] [main] INFO SynapseInitializationModule Deploying Proxy services... 2007-11-05 14:58:56,801 [127.0.1.1-asankha] [main] INFO SynapseInitializationModule Synapse initialized successfully...! 2007-11-05 14:58:56,886 [127.0.1.1-asankha] [main] INFO HttpCoreNIOSender HTTPS Sender starting 2007-11-05 14:58:56,887 [127.0.1.1-asankha] [main] INFO HttpCoreNIOSender HTTP Sender starting 2007-11-05 14:58:57,039 [127.0.1.1-asankha] [main] INFO HttpCoreNIOListener HTTPS Listener starting on port : 8443 2007-11-05 14:58:57,040 [127.0.1.1-asankha] [main] INFO ServerManager Starting transport https on port 8443 2007-11-05 14:58:57,041 [127.0.1.1-asankha] [main] INFO HttpCoreNIOListener HTTP Listener starting on port : 8080 2007-11-05 14:58:57,041 [127.0.1.1-asankha] [main] INFO ServerManager Starting transport http on port 8080 2007-11-05 14:58:57,085 [127.0.1.1-asankha] [main] INFO ServerManager Starting transport vfs 2007-11-05 14:58:57,086 [127.0.1.1-asankha] [main] INFO ServerManager Ready for processing
Now the final step, running the client. Go to <synapse-home>/samples/axis2Client directory and type the following command
user@host:/opt/synapse-1.1.1/samples/axis2Client$ ant stockquote -Daddurl=http://localhost:9000/soap/SimpleStockQuoteService -Dtrpurl=http://localhost:8080 -Dmode=quote -Dsymbol=IBM
Buildfile: build.xml
init:
[mkdir] Created dir: /opt/synapse-1.1.1/samples/axis2Client/target/classes
compile:
[javac] Compiling 10 source files to /opt/synapse-1.1.1/samples/axis2Client/target/classes
stockquote:
[java] Standard :: Stock price = $91.09641757880443
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. If you execute Synapse in debug mode by editing the lib/log4j.properties "log4j.category.org.apache.synapse" as "DEBUG" instead of INFO, you will see more information as follows after a restart and replay of the above scenario again.
2007-11-05 15:03:51,082 [127.0.1.1-asankha] [I/O dispatcher 3] INFO PipeImpl Using native OS Pipes for event-driven to stream IO bridging 2007-11-05 15:03:51,206 [127.0.1.1-asankha] [HttpServerWorker-1] DEBUG SynapseMessageReceiver Synapse received a new message for message mediation... 2007-11-05 15:03:51,206 [127.0.1.1-asankha] [HttpServerWorker-1] DEBUG SynapseMessageReceiver Received To: http://localhost:9000/soap/SimpleStockQuoteService 2007-11-05 15:03:51,206 [127.0.1.1-asankha] [HttpServerWorker-1] DEBUG SynapseMessageReceiver SOAPAction: urn:getQuote 2007-11-05 15:03:51,206 [127.0.1.1-asankha] [HttpServerWorker-1] DEBUG SynapseMessageReceiver WSA-Action: urn:getQuote 2007-11-05 15:03:51,206 [127.0.1.1-asankha] [HttpServerWorker-1] DEBUG Axis2SynapseEnvironment Injecting MessageContext 2007-11-05 15:03:51,207 [127.0.1.1-asankha] [HttpServerWorker-1] DEBUG Axis2SynapseEnvironment Using Main Sequence for injected message 2007-11-05 15:03:51,207 [127.0.1.1-asankha] [HttpServerWorker-1] DEBUG SequenceMediator Start : Sequence <main> 2007-11-05 15:03:51,207 [127.0.1.1-asankha] [HttpServerWorker-1] DEBUG SequenceMediator Sequence <SequenceMediator> :: mediate() 2007-11-05 15:03:51,207 [127.0.1.1-asankha] [HttpServerWorker-1] DEBUG LogMediator Start : Log mediator 2007-11-05 15:03:51,231 [127.0.1.1-asankha] [HttpServerWorker-1] INFO LogMediator To: http://localhost:9000/soap/SimpleStockQuoteService, WSAction: urn:getQuote, SOAPAction: urn:getQuote, ReplyTo: http://www.w3.org/2005/08/addressing/anonymous, MessageID: urn:uuid:DB76240DF26CE9AF1D1194253430879, Direction: request, Envelope: <?xml version='1.0' encoding='utf-8'?><soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/" xmlns:wsa="http://www.w3.org/2005/08/addressing"><soapenv:Header><wsa:To>http://localhost:9000/soap/SimpleStockQuoteService</wsa:To><wsa:MessageID>urn:uuid:DB76240DF26CE9AF1D1194253430879</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> 2007-11-05 15:03:51,250 [127.0.1.1-asankha] [HttpServerWorker-1] DEBUG LogMediator End : Log mediator 2007-11-05 15:03:51,250 [127.0.1.1-asankha] [HttpServerWorker-1] DEBUG SendMediator Start : Send mediator 2007-11-05 15:03:51,250 [127.0.1.1-asankha] [HttpServerWorker-1] DEBUG SendMediator Sending request message using implicit message properties.. Sending To: http://localhost:9000/soap/SimpleStockQuoteService SOAPAction: urn:getQuote 2007-11-05 15:03:51,254 [127.0.1.1-asankha] [HttpServerWorker-1] DEBUG Axis2FlexibleMEPClient Sending [add = false] [sec = false] [rm = false] [ to Address: http://localhost:9000/soap/SimpleStockQuoteService] 2007-11-05 15:03:51,302 [127.0.1.1-asankha] [HttpServerWorker-1] INFO TimeoutHandler This engine will expire all callbacks after : 86400 seconds, irrespective of the timeout action, after the specified or optional timeout 2007-11-05 15:03:51,356 [127.0.1.1-asankha] [HttpServerWorker-1] DEBUG SendMediator End : Send mediator 2007-11-05 15:03:51,356 [127.0.1.1-asankha] [HttpServerWorker-1] DEBUG SequenceMediator End : Sequence <main> 2007-11-05 15:03:51,398 [127.0.1.1-asankha] [HttpClientWorker-1] DEBUG SynapseCallbackReceiver Synapse received an asynchronous response message 2007-11-05 15:03:51,400 [127.0.1.1-asankha] [HttpClientWorker-1] DEBUG SynapseCallbackReceiver Received To: null 2007-11-05 15:03:51,400 [127.0.1.1-asankha] [HttpClientWorker-1] DEBUG SynapseCallbackReceiver SOAPAction: null 2007-11-05 15:03:51,400 [127.0.1.1-asankha] [HttpClientWorker-1] DEBUG SynapseCallbackReceiver WSA-Action: null 2007-11-05 15:03:51,402 [127.0.1.1-asankha] [HttpClientWorker-1] DEBUG SynapseCallbackReceiver Body : <?xml version='1.0' encoding='utf-8'?><soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"><soapenv:Body><ns:getQuoteResponse xmlns:ns="http://services.samples/xsd"><ns:return type="samples.services.GetQuoteResponse"><ns:change>4.03627430702446</ns:change><ns:earnings>-9.467701672785129</ns:earnings><ns:high>191.83014686803938</ns:high><ns:last>185.42637586281398</ns:last><ns:lastTradeTimestamp>Mon Nov 05 15:03:51 LKT 2007</ns:lastTradeTimestamp><ns:low>193.2690208751758</ns:low><ns:marketCap>-1737393.107878862</ns:marketCap><ns:name>IBM Company</ns:name><ns:open>-183.2632780777984</ns:open><ns:peRatio>-17.430497030284027</ns:peRatio><ns:percentageChange>1.9749680728382655</ns:percentageChange><ns:prevClose>204.37162314344914</ns:prevClose><ns:symbol>IBM</ns:symbol><ns:volume>6695</ns:volume></ns:return></ns:getQuoteResponse></soapenv:Body></soapenv:Envelope> 2007-11-05 15:03:51,404 [127.0.1.1-asankha] [HttpClientWorker-1] DEBUG Axis2SynapseEnvironment Injecting MessageContext 2007-11-05 15:03:51,404 [127.0.1.1-asankha] [HttpClientWorker-1] DEBUG Axis2SynapseEnvironment Using Main Sequence for injected message 2007-11-05 15:03:51,404 [127.0.1.1-asankha] [HttpClientWorker-1] DEBUG SequenceMediator Start : Sequence <main> 2007-11-05 15:03:51,404 [127.0.1.1-asankha] [HttpClientWorker-1] DEBUG SequenceMediator Sequence <SequenceMediator> :: mediate() 2007-11-05 15:03:51,404 [127.0.1.1-asankha] [HttpClientWorker-1] DEBUG LogMediator Start : Log mediator 2007-11-05 15:03:51,405 [127.0.1.1-asankha] [HttpClientWorker-1] INFO LogMediator To: http://www.w3.org/2005/08/addressing/anonymous, MessageID: urn:uuid:A6510AF6BD288D8DFB1194253431259544001-942151716, Direction: response, Envelope: <?xml version='1.0' encoding='utf-8'?><soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"><soapenv:Body><ns:getQuoteResponse xmlns:ns="http://services.samples/xsd"><ns:return type="samples.services.GetQuoteResponse"><ns:change>4.03627430702446</ns:change><ns:earnings>-9.467701672785129</ns:earnings><ns:high>191.83014686803938</ns:high><ns:last>185.42637586281398</ns:last><ns:lastTradeTimestamp>Mon Nov 05 15:03:51 LKT 2007</ns:lastTradeTimestamp><ns:low>193.2690208751758</ns:low><ns:marketCap>-1737393.107878862</ns:marketCap><ns:name>IBM Company</ns:name><ns:open>-183.2632780777984</ns:open><ns:peRatio>-17.430497030284027</ns:peRatio><ns:percentageChange>1.9749680728382655</ns:percentageChange><ns:prevClose>204.37162314344914</ns:prevClose><ns:symbol>IBM</ns:symbol><ns:volume>6695</ns:volume></ns:return></ns:getQuoteResponse></soapenv:Body></soapenv:Envelope> 2007-11-05 15:03:51,405 [127.0.1.1-asankha] [HttpClientWorker-1] DEBUG LogMediator End : Log mediator 2007-11-05 15:03:51,405 [127.0.1.1-asankha] [HttpClientWorker-1] DEBUG SendMediator Start : Send mediator 2007-11-05 15:03:51,405 [127.0.1.1-asankha] [HttpClientWorker-1] DEBUG SendMediator Sending response message using implicit message properties.. Sending To: http://www.w3.org/2005/08/addressing/anonymous SOAPAction: null 2007-11-05 15:03:51,408 [127.0.1.1-asankha] [HttpClientWorker-1] DEBUG SendMediator End : Send mediator 2007-11-05 15:03:51,408 [127.0.1.1-asankha] [HttpClientWorker-1] DEBUG SequenceMediator End : Sequence <main>
You have successfully completed the first part of this guide. Now let's look at the next scenario, 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 necessary 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 java 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.
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.
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.
We have to start Synapse with a configuration containing a proxy service definition. In this case we are using the synapse_sample_150.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 150
Windows: synapse.bat -sample 150
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 displaying 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.
Now it is time to see it in action. Go to the <synapse-home>/samples/axis2Clients directory and type the following command:
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:
This quick guide illustrates the simple use case of proxy services. Please refer to samples #150 and above in the Samples guide, for in depth 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).