A system that implements a queue for executing long-running tasks with logging facilities.

Description

Introduction

This extension provides a system based on the XWiki scheduler that is able to run execute-once long-running tasks in the background. It also provide reporting and logging facilities so that the user can have a clue about the progress status. The main use case for this extension is large batch import of data into the wiki.

Recent versions of XWiki (>= 4.0) have a component that provides similar functionalities. If you are using such a version you might be interested in looking at the Job Module

Architecture

This extension defines two types of entities: tasks, ask executors and a task executor manager.

• A task is a document containing information about the task to be executed. The page, for example could contain, as attachments, the files to be processed or the object defining the parameters for the process that will execute this task. A task is identified by an object of type TaskClass which is used to define the following properties: the executor that will handle the task, and the status of the task: SUSPENDED, READY, RUNNING, DONE or ERROR

• A task executor is document containing a Groovy script that implements the logic for processing a given task. A task executor defines a function run that takes three parameters: a logger, the XWiki API object and the task document.

• A task executor manager is a scheduler job that takes care of executing tasks. What it does is quite straightforward: when called, it looks for a task that is READY to run and it executes it in a well defined context. It also takes care of handling the task status, logging and error management. By default the task executor manager executes one task per invocation. Subsequent invocations will execute new tasks depending on the maxConcurrentTasks settings. At any given moment there will always be at most maxConcurrentTasks in the RUNNING state. This setting is configurable in the document TaskExecutorCode.TaskExecutorManagerJobConfiguration and by default it is set to 1.

• Every task has a private log where it can log its progress. Task logs can be accessed from the TaskExecutorCode.WebHome page, or by using the TaskExecutorCode.ShowLog page, passing the query parameter log with the log name, or also using the *showlog log="..."* macro in wiki pages. The task log name is its document name with the .log suffix (e.g., if a task document is defined in the Tasks space and has the SimpleTask name, then its log name will be Tasks.SimpleTask.log)

Prerequisites & Installation Instructions

We recommend using the Extension Manager to install this extension (Make sure that the text "Installable with the Extension Manager" is displayed at the top right location on this page to know if this extension can be installed with the Extension Manager). Note that installing Extensions when being offline is currently not supported and you'd need to use some complex manual method.

You can also use the following manual method, which is useful if this extension cannot be installed with the Extension Manager or if you're using an old version of XWiki that doesn't have the Extension Manager:

1. Log in the wiki with a user having Administration rights
2. Go to the Administration page and select the Import category
3. Follow the on-screen instructions to upload the downloaded XAR
4. Click on the uploaded XAR and follow the instructions
5. You'll also need to install all dependent Extensions that are not already installed in your wiki

Release Notes

v1.0

Initial release