Tallis Training

Enquiries, Sources and Data Definitions: Overview

Collecting data

Enquiries are tasks that collect information from agents, whether end-users or software components, to be used later in the process. An enquiry can hold several requests for data, each known as a source.

Each source is based on a data definition, which defines the structure of the data that the source is requesting. A data definition will typically define the following attributes:

  • Name
  • Caption
  • Description
  • Data Type
  • Range
  • Default Value
  • Selection Mode

Data definitions can be thought of as templates for sources. The key difference between a source and a data definition is that a source only exists within the context of an enquiry (or a decision); therefore a source has an additional attribute, which isn’t part of the data definition:

  • Status

The status of a source determines the behaviour of the enquiry during enactment. When the status is mandatory, the enquiry will remain in progress until all the data is collected, and only then complete. When the status is optional, the enquiry will complete as soon as all the mandatory sources are supplied with values.

This means that the same data definition can cause different behaviours in different enquires.

When a piece of data is collected during runtime enactment, it is held in an instance of a data definition, and referred to as a data item.

Note: The current version of Tallis allows for only one instance of a data item per data definition.

The figure below describes the relationships between enquiries, sources, data definitions and data items:

  • Different enquiries can have a common source.
  • Each source is based on a singular data definition.
  • One instance of data item per data definition is formed during runtime enactment.


  • Data definitions that are not used by sources are not saved with the process-description.
  • Data definitions can be saved separately in data definition libraries (.dd files) to facilitate reuse.
  • Data definitions can be imported into a process-description either from a library or from another process-description.

Learn more about:

Browse through process-description samples:

If you have installed the Tallis Toolset, you can find these samples in the World > Samples folder in the ACL Web Repository.

See Also

  • Collecting data
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