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The iTask system (iTasks) is a task-oriented programming toolkit for programming workflow support applications in Clean.

With this toolkit workflows can be speficied using combinators in a very high level declarative monadic style. Workflows consist of typed tasks that produce results that can be passed as parameters to other tasks. Tasks are constructed by combining single steps sequentially or in parallel. From iTask specifications, executable workflow support systems are generated automatically.

The iTask2 GUI

This latest version features:

  • A highly declarative API for specification of dynamic workflows
  • A rich Ajax client interface for working on tasks
  • Automatically generated editors for entering and updating data in workflows.
  • A JSON based service API for spawning and interacting with running workflow instances
  • The possibility to change running workflow instances

Snapshot for CEFP 2013 Course

For the CEFP course, a snapshot of Clean 2.4 + iTasks for 32-bit windows is available that works out of the box. You can download it here:

Here are some additional resources:

  1. [1]: a framework for the Ligretto case study (
 WARNING SPOILERS AHEAD: if you really want to implement the case study yourself, then do not download this version!! This is a complete implementation of the Ligretto case study!!
  1. [2]: brief explanation of the Ligretto case study and the above framework.
  2. [3] the lab assignments.
 NOTE: assignment 6 has been reduced in size.
  1. [4]: the first lecture slides
  2. [5]: the second lecture slides

Get from subversion

The iTask system is actively developed, but not regularly released. You can get the development trunk from our subversion repository. You can get started with iTasks by following the following three steps:

  1. Install a Clean 2.4 system for 32-bit Windows.
  2. Check out the iTask trunk to a directory named 'iTasks-SDK' in your Clean 2.4 directory.
  3. Follow the setup instructions in README.txt


Documentation of iTasks is still mostly done in scientific papers (look for iTasks on the Publications page). On this Wiki the following additional resources are available:


The iTask system works with most browsers. IE 9 is a known exception, we are working on that.

Using the iTask system with Firefox can be very slow. This is caused by a delay that is added by Firefox for all events for localhost. There are several solutions and workarounds:

  1. type as url: about:config
  2. search for v6, you will see network.dns.disableIPv6
  3. toggle the value of this parameter to True.

Read more