[CONF] Apache ServiceMix: servicemix-scripting (page edited)

Thu, 12 Jun 2008 03:40:05 -0700

Page Edited : SM : servicemix-scripting

servicemix-scripting has been edited by Lars Heinemann (Jun 12, 2008).

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Content:

ServiceMix Scripting

The ServiceMix Scripting component provides support for processing scripts using JSR-223.

Availability

Note that this component is only available in releases >= 3.3.

What is JSR-223

JSR-223 is some kind of abstraction layer for using different scripting languages from inside java. You can code the script caller class once and use it with
every available JSR-223 compliant script engine / language.

Have a look at the project site to get an overview what languages are available and what dependencies they have.
https://scripting.dev.java.net/

The servicemix-scripting engine is packaged with the following engines:

  • Groovy (1.5.6)
  • JRuby (1.1.2)
  • Rhino _javascript_ (1.7R1)

You don't need to care about dependencies for these 3 languages. For every other language take care to put the dependencies into your SU or the container classpath.

Installation

Installing the servicemix-scripting component can be done in several ways:

  • drop the installer zip in an hotdeploy directory monitored by ServiceMix
  • using ant tasks

Note that when using ant tasks, the component is not started, you will have to start it manually using ant tasks or a console.

Creation

You can use Maven to create a service unit.

mvn archetype:create \
    -DarchetypeGroupId=org.apache.servicemix.tooling \
    -DarchetypeArtifactId=servicemix-scripting-service-unit \
    -DgroupId=com.mycompany.myproduct \
    -DartifactId=mycomponent.artifact


or simply use the smx-arch tool from ServiceMix's bin folder.




Endpoints



Endpoint


<scripting:endpoint service="test:myScriptingService" 
             endpoint="scriptingEndpoint"
             script="classpath:MyGroovyScript.groovy" />






Message Exchange Pattern


The endpoint can handle InOnly and InOut MEP.




The following table shows the additional configuration possibilities of the endpoint.



endpoint attributes





 Name 		
 Type 	
 Description 							
 Default 				




 marshaler		
 class		
 org.apache.servicemix.scripting.ScriptingMarshalerSupport	
 DefaultScriptingMarshaler			




 script		
 String		
 Spring Resource for the script file 		
 null (must be spec'd)			




 language		
 String		
 script language to use (groovy, jruby, js etc)		
 autodetect (via file extension)			




 logResourceBundle		
 String		
 Log Resource Bundle for Script Logger 		
 null 			




 scriptLogger		
 class   
 java.util.logging.Logger 		
 null 			




 disableOutput		
 boolean		
 flag if out message should be sent 		
 true 			




 bindings		
 class		
 java.util.Map		
 null 			







For all xbean file endpoint configuration take a look at Xml schemas




The script resource


The script resource can be defined in different ways:




 
script="classpath:MyScript.js"
  OR  
script="file:///home/lhein/scripts/groovy/MyGroovyScript.groovy"



 



The user bindings


You can specify user bindings to be available from inside the script as variables. For doing this you can specify the 

attribute bindings inside the endpoint's configuration.

The bindings object is a simple Map<String, Object> which contains key - value pairs.



Example:




<beans xmlns:scripting="http://servicemix.apache.org/scripting/1.0"
       xmlns:test="http://servicemix.apache.org/test"
       xmlns:util="http://www.springframework.org/schema/util">
       
    <!-- _javascript_ JSR-223 Endpoint  -->
    <scripting:endpoint
        service="test:js-jsr223" 
        endpoint="endpoint"
        script="classpath:MyJavaScriptFile.js"
        bindings="#myCustomBindings">
    </scripting:endpoint>
            
    <util:map id="myCustomBindings">
        <entry key="company" value="My Company" />
        <entry key="logo" value="/home/lhein/myLogo.png" />
    </util:map>   

</beans>






These values (company and logo) are available from within the MyJavaScriptFile.js via a global variable called "bindings".

You could now just do the following inside your _javascript_: (adapt this for other languages)





var companyName = bindings.get("company");
var companyLogoPath = bindings.get("logo");







Marshalers



You can write your own marshalers to have a possibility to influence the bahviour of the engine.

To do this you simply need to subclass the org.apache.servicemix.scripting.DefaultScriptingMarshaler or even create a new class 

implementing the interface ScriptingMarshalerSupport if you don't want to start from scratch.



onStartup (...)


This method is called by the endpoint when the endpoint is starting.




onShutdown (...)


This method is called by the endpoint when the endpoint is shutting down.




getScriptCode (...)


This method is called to get the input stream for the script defined in script attribute of the xbean configuration.




registerUserBeans (...)


This method is called after all scope variables of the endpoint where set, just before starting the script.




After finishing your marshaler you can simply configure your endpoints to use it:



Marshaler example


<scripting:endpoint service="test:myScriptService" 
             endpoint="scriptingEndpoint"
             script="classpath:MyScript.rb" > 

    <property name="marshaler">
        <bean class="com.mycompany.MyScriptingMarshaler" />
    </property>

</scripting:endpoint>






Global variables



While inside the script you have a access to the following variables / objects:






Variable
Description
Type




 componentContext 
 The JBI Component Context 
 javax.jbi.component.ComponentContext 




 deliveryChannel 
 the Delivery Channel 
 javax.jbi.messaging.DeliveryChannel 




 exchange 
 The JBI Message Exchange 
 javax.jbi.messaging.MessageExchange 




 inMessage 
 The in message 
 javax.jbi.messaging.NormalizedMessage 




 log 
 The script logger object 
 java.util.logging.Logger 




 endpoint 
 the scripting endpoint which executes the script 
 org.apache.servicemix.scripting.ScriptingEndpoint 




 endpointname 
 the name of this endpoint 
 java.lang.String 




 servicename 
 the name of this service 
 java.lang.String 




 interfacename 
 the name of this interface 
 java.lang.String 




 script 
 the absolute path of the script or the script itself if path can't be determined 
 java.lang.String or org.springframework.core.io.Resource 




 bindings 
 a map containing user defined values
java.util.Map<String,Object>







Migration from ScriptComponent / GroovyComponent



The servicemix-scripting is a full replacement of the leightweight components for "script" and "groovy". 

As the leightweight components are no longer maintained and also won't work in ServiceMix 4 you are strongly encouraged to switch to this new engine.



What are the differences?



The GroovyComponent knew a binding / variable called builder which in fact was a DOMBuilder. This variable isn't available now. To have it again you could write your own marshaler and provide such a variable in the registerUserBeans(...) method.



Both components, GroovyComponent and ScriptComponent, knew the following configuration attributes:



    
	
  • scriptEngineName
    • 
	
  • compiledScript
    • 
	
  • scriptText
    • 





These attributes are no longer available. 

Instead of scriptEngineName you could use the language attribute to define the language to use. 



Instead of scriptText you could write your own marshaler overriding the getScriptCode (...) method to provide your scriptText.

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