Plugins.md

Task Plugins

The Task entities defined in a Processor definition can be implemented as dedicated native java plugins or as scripts written in Perl, Python or Shell scripting languages.

Native plugins

Dedicated native java plugins can be developed by implementing the GenericTaskInterface process method defined in the DES library

GenericTaskInterface Interface

public interface GenericTaskInterface {

	/**
	 * 
	 * @param basepath Basepath as configured in DistributionServer.ini
	 * @param aoi_name AOI name contained in the $processor.processor_config.xml
	 * @param processor_name Processor name related to the $processor.processor_config.xml
	 * @param entity_name Name of executing entity (Task, Consumer, etc.)
	 * @param parameters Parameters as defined by <Parameter>
	 * @param args List of arguments of the Task (String or Hashtables, to be checked by the plugin)
	 * @param files List of files of the Task IFF <FileType>regexp</FileType> is defined, else null
	 * @return ExitCodes
	 */
	public int process(String basepath, String aoi_name,
			String processor_name, String entity_name, Hashtable parameters, Object[] args, String[] files);
	
}

The implemented plugin should be packaged as a jar file and placed in the DES ./plugins directory where it is automatically loaded at Runtime.

The plugin can be executed in a given Processor Task with the following definition:

Example:

<Task name="renameFiles" type="class" active="yes" priority="NORM">
	<Command>class</Command>
	<FileType>SAMPLE.*.AA.txt</FileType>
	<Parameter>edu.eurac.distributionserver.tasks.generic.FileRename</Parameter>
	<FilePrefix>RENAME</FilePrefix>
</Task>

The parameters can be passed to the Task plugin with one of the following options:

• By using a custom keyword tag eg. FilePrefix in the Task definition and then accessing the parameter with the Hashtable parameters in the Interface

    String file_prefix = (String)parameters.get("FilePrefix");

• By using the Parameter tag in the Task definition and than referencing the parameter with the Object[] args type in the Interface

    String classname = (String)args[1];

Note: Note: args[0] is the class name

Script plugins

If a given Task is implemented with a scripting language (Perl, Python, Shell), the script must consider the following input parameters:

[BASE_PATH] [AOI] [PROCESSOR] [Parameter_1] [Parameter_N] ... [$FILE*]

IFF a FileType filtering is defined for the Task, the last parameter, defined above as $FILE, is the filename of the 1st file filtered by the Task execution. In this case the script will be executed N times, for each file filtered by the FileType regular expression.

Example:

#!/usr/bin/perl -w

# This script is part of the Task plugin collection available for the DES (Data Exchange Server)
# version: 1.0
# usage: testPerlExitCode.pl [base_path] [aoi] [procesosr_name] [Sleep] [ExitCodeToReturn]

#main
print "running testPerlExitCode.pl\n";
my $base_path = "null";
my $aoi = "null";
my $processor_name = "null";
my $sleep_sec = 1; # 1 second default 
my $exit_code = -1;
print "Parameters: @ARGV\n";
if(scalar(@ARGV) < 4){
	print "missing arguments!\n";
	print "usage: testPerlExitCode.pl [base_path] [aoi] [Sleep] [ExitCode]\n";
	exit -1;
}else{
	$base_path = $ARGV[0];
	$aoi = $ARGV[1];
	$processor_name = $ARGV[2];
	$sleep_sec = $ARGV[3];
	$exit_code = $ARGV[4];
	print "base_path: $base_path, aoi: $aoi, processor_name: $processor_name, Sleep: $sleep_sec , ExitCode: $exit_code\n";
	print "sleep $sleep_sec seconds...\n";
	sleep $sleep_sec;
	exit $exit_code;
}

The Task definition for the script above is:

<Task name="testExitCode" type="cmd" active="yes" priority="NORM">
	<EMail>mail@host.yourdomain</EMail>
	<NotifyEmail>OnError</NotifyEmail>
	<Command>perl</Command>
	<Parameter>./test_data/scripts/testPerlExitCode.pl</Parameter>
	<Parameter>@mySleep</Parameter>
	<Parameter>@myExitCode</Parameter>
</Task>