Category: Content Server

In December 2016, we discussed how to call Java code from OScript . Now, we’ll discuss the other way round, how to call OScript from Java. This can be quite useful, if you want to use your business logic implemented in java against the content server.

The Java code must be put in the ojlib directory (see the previous post on this topic).

As always, if you want to deploy your java code within a module, do this

• Build your code into jar files.
• Add the jar files in OTHOME/ojlib/ or OTHOME/module/yourmodule_yourversions/ojlib/ directory (and their subdirectories) to be recognized by Content Serverk JVM’s application classloader.

The base thing is, you call OScript built-in functions through the OScriptObject.runScript method from a java coding.

For example, the java code

OScriptObject.runScript("echo","System.ThreadID()");

will display the unique integer for the current thread ID at the console (or in the logs, if you do not use CSIDE)

You can call all OScript functions and scripts. This example will list all nodes in the enterprise workspace

     // List nodes in the Enterprise workspace.
            result = (Map<String,Object>) OScriptObject.runScript( "$LLIAPI.NodeUtil.ListNodes",
				prgCtx,
				"(ParentID=:A1)",
				args );

prgCtx is the standard rogram Context, args is the ArrayList containing the arguments and A1 points to the first entry in the args array to be used as ParentID.

The next example can be used to get the current user from java coding, extract its userID and then derives the user name from ths user id. A standard logger is used to log the output, replace this with the logger of your preference.

    public static String getUserName( OScriptObject prgCtx )
    throws Exception
    {
        String retval = " user not found";
        
        try
        {        
            // get the user session object
            OScriptObject uSession = (OScriptObject) prgCtx.invokeScript( "USession" );
            // get the userID from the User Session
            Integer userID = (Integer) uSession.getFeature( "fUserId" );
            // display it
            logger.log( Level.INFO, "UserID is " + userID );
            
            retval = "The current login User: " + userID;
            
            // Get the Users name from the User ID
            Map<String,Object> status = (Map<String,Object>)
			OScriptObject.runScript( "$LLIAPI.UsersPkg.NameGetByID", uSession, 1000 );
			
            logger.log( Level.INFO, String.valueOf( status ) );
            logger.log( Level.INFO, (String) status.get( "Name" ) );
        }
        catch( Exception e )
        {
            logger.log( Level.SEVERE, "Caught Exception", e );
            throw e;
        }
        
        return retval;
    }

In the next posting on this topic, we’ll discuss the Mappings from JAVA to OScript and vice versa.

Sometimes it would be nice to use existing Java coding from a module instead of recoding this in OScript.

There is a facility in the content server which does exactly this bridging from OScript to Java, the so called JavaObject class. You’ll find the exact documentation in the “OScript API/Build-In Package Index”

In this first post of the series we’ll discuss the  basic calls from OScript.

First, you need some Java Code, compiled and in the form of a jar. Put this jar either in OTHOME/ojlib or (much better) in a ojlib directory in your module structure. After installing the module, the jar(s) are copied automatically to the OTHOME/ojlib. Then, the jvm classloader will find your jar(s).

From OScript it is possible to access static classes and instances.

Static

Dynamic InvokeStaticMethod(String classname, String methodName, List parameters)

Dynamic GetStaticField( String classname, String fieldName)

Dynamic SetStaticField( String className, String  fieldName, Dynamic value)

The return values are either Error or Dynamic if the call is successful.

Dynamic

JavaObject New (String className, List parameters)

Instance

Dynamic GetField(String fieldname)

Dynamic SetField(String fieldname, Dynamic value)

Dynamic InvokeMethod(String methodName, List parameter)

The return values are either Error or Dynamic if the call is successful.

An example

function void javaTest()

   JavaObject myObject

   myObject = JavaObject.new("my.own.package.class")
 
   Dynamic res = myObject.InvokeMethod("myMethod",{"aa","bb})

   if (isError(res))

     echo ("Init failed")

     return

   end

   Dynamic res1 = myObject.GetField("myResult")

   if (IsError(res)) 

     echo("Calculation failed")

     return

   end

   echo("The result is "+res1)

end

In the next post we’ll discuss how to get the JNI exceptions and the error stack from the jvm.