In Axis2 there are three kinds of configuration files to configure the system. First one configuration file is to configure whole system, second one is to configure a service and the third one is to configure a module.


Global Configuration
  • Writing axis2.xml

    • All the configuration that requires starting axis2 is obtained from axis2.xml. The way of specifying them is very simple and easy. The document is all about the proper way of specifying the configurations in axis2.xml. There are six top level elements that can be seen in the configuration file and those can be listed as follows;

    Parameter
    In axis2 a parameter is nothing but name value pair, each and every top level parameter available in the axis2.xml (direct sub elements of root element) will be transformed into properties in AxisConfiguration. Therefore the top level parameters in configuration document can be accessed via AxisConfiguration in the running system. The correct way of defining a parameter looks like what is shown below; 

     
  <parameter name="name of the parameter" >parameter value </parameter>

    Transport Receiver
    Depending on the underline transport that axis going to be run , need to have different transport receivers so the way of adding them to the system can be done as follows; 

     
<transportReceiver name="http" class="org.apache.axis2.transport.http.SimpleHTTPServer">
        <parameter name="port" >6060</parameter>
 </transportReceiver>
    The above elements shows the way of defining transport receivers in axis2.xml , here name attribute of the 'transportReceiver' element is the name of transport it can be http, tcp , smtp , commonshttp stc , and when the system starts up or when setting transport at the client side one can use these transport names to load the appropriate transport. Class attribute is to specify actual java class which implements required interfaces for the transport. Any transport can have zero or more parameters, and if there are any, then those parameters can be accessed via the corresponding transport receiver.

    Transport Senders
    As same as transport receivers it is possible to register transport senders in the system, and latter at the run time those senders can be used to send the messages. As an example consider Axis2 running under tomcat, then axis can use TCP transport senders to send message rather than HTTP. The way of specifying transport senders is as follows: 

     
<transportSender name="http" class="org.apache.axis2.transport.http.CommonsHTTPTransportSender">
        <parameter name="PROTOCOL" locked="xsd:false">HTTP/1.0</parameter>
 </transportSender>
    name: Name of the transport (it is possible to have http and http1 as transport name) Class: Implementation class of the corresponding transport. As same as transport receivers, transport senders can have zero or more parameters, and if there is any then it can be accessed via corresponding transport sender.

    Phase Order
    The specifying order of phases in execution chain has to be done using phase order element and it will be look like below; 

    <phaseOrder type="inflow">
         <phase name="TransportIn"/>
         …………………………………
         …………………………………….
</phaseOrder>
    type: the attribute represent type of the flow and which can only be one of the following

    In addition to that only child element allowed inside pahseOrder is phase element, which represents available phases in the execution chain. The way of specifying phase inside phaseOrder has to be done as follows; 

     <phase name="TransportIn"/>
    name: Name of the phase.
    There are number of things that one has to keep in mind when changing pahseOrder,

    Module References
    If you want to engage a module system wide you can do it by adding top level module element in axis2.xml. It should be look like following: 

    <module ref="addressing"/>
    ref: the module name which is going to be engage, system wide. Listeners (Observers) In Axis2 AxisConfiguration is observable so that one can register observers into that, and they will be automatically informed whenever a change occurs in AxisConfiuration. In the current implementation the observers are informed of the following events Registering Observers is very useful for additional features such as RSS feed generation which will provide service information to subscribers. The correct way of registering observers should be like below; 
    <listener class="org.apache.axis2.ObserverIMPL">
    <parameter name="RSS_URL" >http://127.0.0.1/rss</parameter>
  </listener>
    class: Represent an Implementation class of observer, and it should be note that the implementation class should implement AxisObserver interface, and the class has to be available in the classpath.


    Service Configuration
  • Writing service.xml

    • The description of service is specified using service.xml, each service archive file need to have service.xml in order to be a valid service. And which has to be available in META-INF directory of the archive file.
    A very simple service.xml is shown below: 

    <service name="Name of the service">
    <description> The description of the service  </description>

    <parameter name="ServiceClass"     locked="xsd:false">org.apache.axis2.sample.echo.EchoImpl</parameter>
    
  <inflow>
        <handler name="logging" class="org.apache.axis2.sample.handlers.LoggingHandler">
            <order phase="userphase1" phaseFirst="true"/>
        </handler>
    </inflow>
    <outflow/>
    <INfaultflow>….. </INfaultflow>
    <Outfaultflow> ….</Outfaultflow>

    <operation name="echoString">
        <module ref=" a module name "/>
        <messageReceiver class="org.apache.axis2.receivers.RawXMLINOutMessageReceiver"/>
    </operation>
  </service>
    service name: You can specify the name of the service, if you do not specify the service name then the archive file name will be the name of the service.
    description: This is an optional element if you want to display any description about the service via Axis2 web-admin module then the description can be specified here.

    Parameter:
    service.xml can have any number of top level parameters and all the specified parameters will be transformed into service properties in corresponding ServiceDescrption. There is a compulsory parameter in a service.xml called ServiceClass which specify the java class which really does the job and the class will be loaded by MessageReceiver.

    Flow :
    It is possible to add handlers into a flow directly form service.xml rather than engaging a modules and the way of doing that is through flow elements. It is possible to add any number of handlers into a flow and those handlers will be available in corresponding operations flows in the service (inflow consist of two parts, one part is up to post dispatch phase and other part is consisting of operation handlers)
    There are four types of valid flows that can be available in service.xml, and the adding the handles into them can be done by following the above procedure.
    Valid flows:

    Handler
    Handler element consists of compulsory and optional attribute and the way of defining a handler will be look like follows; 

    <handler name="handler1" class="handlerClass ">
            <order phase="userphase1" />
 </handler>
    Compulsory attributes
    name: name of the handler
    nlass: handler implementation class
    phase: name of the phase that the handler should stay in the execution chain

    Optional attributes :
    phaseLast: to indicate the handler is last handler of the phase
    phaseFirst: to indicate the handler is first handler of the phase.
    before : the handler should be invoked before the handler specified by before handler
    after: the handler should be invoked after the handler specified by after handler

    Operations
    All the operations you are going to exposeby the service has to be indicated in the service.xml and the correct way of specifying that should be as follows: 

        <operation name="echoString">
        <module ref=" a module name "/>
        <messageReceiver class="org.apache.axis2.receivers.RawXMLINOutMessageReceiver"/>
    </operation>
    Only compulsory attribute here is name, which represent the operation name that is going to be exposed. Any operation can contains module references, any number of parameters. The most interesting is that one can register custom message receiver per operation, then the registered message receiver will be the message receiver for the corresponding operation. If one does not specify the message receiver then the default message receiver will do the job.


    Module Configuration
  • Writing module.xml

    • The description of module is specified using module.xml, each module archive file need to have module.xml in order to be a valid module. And which has to be available in META-INF directory of the archive file.
    A very simple module.xml is shown below: 

    <module name="module1" class="org.apache.module.Module1Impl">
    <inflow>
        …………………….
    </inflow>
    <outflow>
       ………………………
    </outflow>

    <Outfaultflow>
       ………………………..
    </Outfaultflow>

    <INfaultflow>
      ………………………….
    </INfaultflow>

    <operation name="creatSeq" mep="MEP_URI_IN_OUT">
        <messageReceiver class="org.apache.axis2.receivers.RawXMLINOutMessageReceiver"/>
        <parameter name="para1" locked="xsd:true">10</parameter>
    </operation>
</module>
    name: This is a compulsory attribute and which indicates the name of the module
    class: This is an optional attribute which indicate module implementation class, a module may or may not contain module implementation class since the module can also be a collection of handlers. If a module contains an implementation class which implements the org.apache.axis2.modules.Module inteface where at the deployment time its init(); method will be called.

    parameter: Module can contains any number of parameters and all the listed parameters in the module.xml will be transformed into corresponding ModuleDescription of the module.

    flow: Flow concept is exactly the same as service flows.

    operations If a module wants to add an operation when it is engaged into a service it can be done by adding operation tag in module.xml and the way of specifying the operation is same as operation in service.xml.