net.sf.taverna.example
Class WorkflowLauncherWrapper

java.lang.Object
  net.sf.taverna.example.WorkflowLauncherWrapper

public class WorkflowLauncherWrapper
extends java.lang.Object

A simplified example application demonstrating how to invoke the Taverna API through Raven, without the need to bootstrap the application.

Its main point is to demonstrate populating an Repository instance with the system artifacts and external artifacts required to execute a workflow. Workflow execution is the most popular request, but this technique can also be applied to access other parts of the Taverna API.

The system artifacts relate to the artifacts that already exist within the applications classpath. Correctly defining these ensures that the applications classloader is used to create instances of classes contained within these artifacts. This prevents Raven creating instances through its own classloaders leading to ClassCastException or similar errors. These artifacts are defined in buildSystemArtifactSet()

Since you necessarily will be accessing parts of Taverna's API, you will need to include the relevant artifacts on your application's classpath to be able to access the classes. If you access other parts of Taverna than this example shows, you will need to add those artifacts to buildSystemArtifactSet() as well.

For instance, if you are constructing a new workflow using the API, and you need access to a SoaplabProcessor, you will need to both list taverna-soaplab-processor as a system artifact and include it and its dependencies in your application's classpath.

The external artifacts relate to artifacts that exist outside of the application as SPI plugin points, ie. artifacts that are not on the application's classpath. For the purpose of this example this is the Processors that are needed during workflow execution. These artifacts are defined in buildExternalArtifactSet(). Depending on which parts of Taverna's API you are invoking, you might have to include more artifacts from Taverna's distribution profile.

Because these artifacts are not defined in the application they, and their dependencies, need to be downloaded when the application is first run and are downloaded to the local repository location defined by the method getRepositoryBaseFile(), and ultimately the runtime argument -basedir if provided.

The external artifacts are downloaded from the remote repository locations defined in buildRepositoryLocationSet().

The key to this approach is initialising a Repository using the API call:

 Repository repository = LocalRepository.getRepository(localrepository,
                applicationClassloader, systemArtifacts);
 

Then making sure the local repository is up to date with a call:

 repository.update();
 

The repository is then registered with the TavernaSPIRegistry with the call:

 TavernaSPIRegistry.setRepository(repository);
 

This all takes place within initialiseRepository()

Note that for simplicity in this example the external artifacts and remote repositories have been hardcoded and would normally be better defined separately in a file. For the same reason, exception handling has also been kept to a minimum.

There is nothing requiring you to use this mechanism from an main(String[]) method started from the command line, this is just to make this example self-contained and simple. As long as you include the necessary dependencies this example should be easily ported to be used within a servlet container such as Tomcat.

To use:

First build using maven together with the appassembler plugin:

 mvn package appassembler:assemble
 

Then navigate to the target/appassembler/bin directory and run the runme[.bat] command:

 runme [-inputdoc <path to input doc>
        -outputdoc <path to output doc>
        -basedir <path to local repository download dir>]
        -workflow <path to workflow scufl file>.
 

Author:

Stuart Owen, Stian Soiland

Field Summary

static java.lang.String

TAVERNA_BASE_VERSION The version of Taverna core components that is used, for instance 1.6.2.0.

Constructor Summary

WorkflowLauncherWrapper()

Method Summary

static void	main(java.lang.String[] args)
void	run(java.lang.String[] args) The execution entry point, called by main(String[])

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

TAVERNA_BASE_VERSION

public static final java.lang.String TAVERNA_BASE_VERSION

The version of Taverna core components that is used, for instance 1.6.2.0.

(Note that although processors and plugins might be updated by their minor-minor version, say a SoaplabProcessor can be in version 1.6.2.1, the core components listed by buildSystemArtifactSet() would still be 1.6.2.0, and thus this constant would also be 1.6.2.0. You might have to update use of TAVERNA_BASE_VERSION in buildExternalArtifactSet() if you want a newer version of a processor or similar.)

This version has to match the version of the real dependency you have to Taverna libraries on your classpath (ie. the pom.xml dependencies).

See Also:

Constant Field Values

Constructor Detail

WorkflowLauncherWrapper

public WorkflowLauncherWrapper()

Method Detail

main

public static void main(java.lang.String[] args)

run

public void run(java.lang.String[] args)
         throws java.lang.Exception

The execution entry point, called by main(String[])

Parameters:

args - the arguments as passed to main(String[])

Throws:

java.lang.Exception - if anything goes wrong