National Radio
Astronomy Observatory

H.1 The XML file

The key to getting your task into casapy is constructing a task interface description XML file.

Some XML basics, an xml element begins with <element> and ends with </element>. If an XML element contains no other XML element you may specify it via <element/>. An XML element may have zero or more attributes which are specified by attribute=”attribute value”. You must put the attribute value in quotes, i.e. <element myattribute=”attribute value”>.

All task xml files must start with this header information.

and the file must have the end tag

Inside a <task> tags you will need to specify the following elements.

<task>

Attributes

type required, allowed value is ”function”

name required

Subelements

shortdescription

required

description

required

input

optional

output

optional

returns

optional

constraints

optional

<shortdescription>

- required by <task>; A short one-line description describing your task

Attributes

None

Subelements

None

<description>

- required] by <task>, Also used by <param>a; A longer description describing your task with multiple lines

Attributes

None

Subelements

None

<input>

- optional element used by <task>; An input block specifies which parameters are used for input

Attributes

None

Subelements

<param>

, optional

<output> - optional

An output element that contains a list of parameters that are ”returned” by the task.

Attributes

None

Subelements

<param>

, optional

<returns> - optional

Value returned by the task

Attributes

type

optional; as specfied in <param>

Subelements

<description>

, optional

<constraints> - optional

A constraints element that lets you constrain params based on the values of other params.

Attributes

None

Subelements

<when>

, required.

<param> - optional

The input and output elements consist of param elements.

Attributes

type

, required; allowed values are record, variant, string int, double, bool, intArray, doubleArray, boolArray, stringArray

name

, required;

subparam

, optional; allowed values True, False, Yes or No.

kind

, optional;

mustexist

, optional; allowed values True, False, Yes or No.

All param elements require name and type attributes.

Subelements

<description>

, required;

<value>

, optional;

<allowed>

, optional;

<value> - optional

Value returned by the task

Attributes

type

, required; as specified in <param> attributes.

Subelements

<value>

, optional

<allowed>

- optional; Block of allowed values

Attributes

enum

, required; maybe enum or range. If specfied as enum only specific values are allowed If specified as range then the value tags may have min and max attributes.

Subelements

<value>

, optional

<when> - optional

When blocks allow value specific handling for parameters

Attributes

param

, required; Specifies special handling for a <param>

Subelements

<equals>

, optional

<notequals>

, optional

<equals> - optional

Reset parameters if equal to the specified value

Attributes

value

, required; the value of the parameter

Subelements

<default>

, required

<notequals> - optional

Reset specified parameters if not equal to the specified value

Attributes

value

, required; The value of the parameter

Subelements

<default>

, optional

<default> - optional

Resets default values for specified parameters

Attributes

param

, required; Name of the <param> to be reset.

Subelements

<value>

, required, the revised value of the <param>.

<example> - optional

An example block, typically in python

Attributes

lang optional; specifies the language of the example, defaults to python.

Subelements

None

More information about CASA may be found at the CASA web page

Copyright © 2010 Associated Universities Inc., Washington, D.C.

This code is available under the terms of the GNU General Public Lincense