4. Getting started with DEMO Transaction Pattern

Prerequisite

Before starting to use the DEMO transaction pattern gain knowledge about it by reading a book or following a course.

Start with a VISI framework

Translating a VISI transaction to a DEMO transaction pattern is not straight forward, and cannot be done automatically. The framework designer needs to have knowledge about the VISI transaction and interpret the name of VISI messages. As a first step the VISI messages need to be tagged with the default actions from the DEMO transaction pattern (request, decline, quit, promise, state, reject, stop, accept). Also the designer needs to search for the modelling in a VISI transaction of a revoke by means of a VISI message ("intrekking melding").

Second step is to determine which of the default actions of the DEMO transaction pattern are not available a VISI messages. These actions are added to the framework as implicit actions (see chapter ...).

Third step it to cut a VISI transaction up into one or more default DEMO transaction patterns.

Fourth step is to check if every action is only used once in a DEMO transaction pattern. For example if there are two different message with are a state these messages need to be combined, or the ransaction needs to be split in two transactions. Such messages can be two state message: 1) "positief advies", 2) "negatief advies". This can be combined into one message "advies". The message contains an simple element with the type of advise: "positief" or "negatief".

The appendix "Bijlage A Translate VISI to DST method" expands on this method of translating VISI transactions to DEMO transactions. The appendix "Bijlage B Translate VISI to DST example" gives an extensive example of how to translate one VISI transaction into several DEMO transaction patterns.