Adding Tools to HIPE

Task, tools and variables

Tools are processing units that operate on specific data elements. The well-known Tasks are examples of tools within HIPE. If a data element is selected, a list of tools that can operate on that data should appear.

This section explains:

  • how you can make HIPE aware of an existing Task,
  • how your task can react better on an active data element,
  • the default task dialog and how you implement and contribute a dedicated the input dialog for your task,
  • how you can implement and contribute a specific parameter editor

Task Registry

Up to now you have made you task globally available to the system by specifying an instance of that task within the file of your sub-system, e.g.:

    # file

To make your task appear in the "Run Tools" view, you have to change the above by:

    from herschel.ia.task.views import TaskToolFactory

You can also specify that your task belongs to one or more categories:

    from herschel.ia.core.Tool import Category
    TaskToolFactory.register(MyTask(), [Category.IMAGE, Category.PACS]))
Your task will now be enabled whenever a session variable is selected which matches the type of the first input parameter within your task!

Within your task, you can control which parameter signs-up to be the prime parameter (the one which reacts on a selected data variable) by the Task API:

    class MyTask extends Task {
       MyTask() {
          prime=new TaskParameter("spectrum",SpecificProduct.class)
    public void setParameterValidator(ParameterValidator validator) {
	_validator = validator;

Prime input validation

The mechanism above makes you task to become a tool within the system and it appears whenever a variable of type SpecificProduct is selected.

Sometimes this may not be enough, e.g. is certain situations your task will only run on a SpecificProduct if it contains certain contents. A typical situation would be when a SPIRE reduction operates on a ObservationContext: such a task should not be listed whenever a HIFI observation is selected...

You can write a ParameterValidator to do just that:

    prime=new TaskParameter("spectrum",SpecificProduct.class)
    validator=new ParameterValidator() {
        public boolean isValid(Object value) {
            SpecificProduct s=(SpecificProduct)value;
            ...logic that would validate the contents of the value...

        public void validate(Object value) throws ParameterValidationException {
            if (!isValid(value)) throw new ParameterValidationException(reason);

In other words, rather than writing this logic within the pre-amble or execution block of your task, we recommend you to move that logic into the parameter validation. This way we achieve two things:

  • make the logic appear where it should be and therefore keeping the execution block of your task concentrated to the algorithm, and
  • make your task appear as a tool within HIPE that can be ran against specific data.

Task Input Dialog

Default dialog, drag-and-drop features, dedicated dialogs The application is generating a default input dialog for all registered tasks within the software. As the system does not know the intent of your task, it can only provide a dry-listing of all requested parameters; such a dialog may not be suitable for your purposes.

However, you may want to have more control over how the input parameters are presented to the user:

  • you may only want to provide a sub-set of parameters (and leave the full-set to expert users on the command-line)
  • you may want to organize your parameters by grouping them in tabs, or putting a border around a group of parameters
  • you may want to have more informative tooltips, labels or even input fields that are more suitable for your task.

For that you can implement a herschel.ia.task.gui.dialog.SignatureComponent and register it as follows (again in the

        id,                           # string
        implSignatureComponent,       # string
        implTask));                   # string
, where:
  • id is a unique identifier
  • implSignatureComponent - implementation of SignatureComponent interface
  • implTask - implementation of your task for which this input dialog applies
and the registry elements are defined as:
from herschel.ia.core import ExtensionRegistry, Extension

An example (which you can find in the prototype):


Note that your GUI component must have a default constructor!

Parameter Modifiers

TODO: Default modifiers, specialized modifiers

Task compliance

  • write user documentation (jtags)! That will be automatically picked up whenever a user asks the system for help on your task.
  • the name of the task should be a legal variable name in the global name-space. For example your instance of MyTask should report itself as e.g.: "myTask" and not "This is my task".
  • if your prime parameter is not the first parameter in your task, specify the prime parameter using the setPrimeInput method in the signature
  • write a parameter validator for your prime parameter if your task should be listed not only on prime data type but on prime data contents as well.

-- JorgoBakker - 21 Dec 2007

This topic: Public > DpHipe > DpHipeTools
Topic revision: r2 - 2007-12-23 - JorgoBakker
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