Using Tallis for the first time? A series of step-by-step tutorials will take you through the process of constructing a computerised guideline, using as an example a simplified diagnosis and treatment protocol for patients presenting with unexplained weight loss. Click here to start.

Do you want some sources to be disabled unless the end-user selects a certain value for another source? Would you like to display several enquiries on a single page? Learn to modify the appearace of tasks in the web enactment. Click here to start.

Creating a simple task process
Watch a basic process created and run. The process contains (a) an enquiry that gathers data (b) a decision between two options – based on the data gathered (c) two actions, only one of which runs – depending on the results of the decision.

State Triggers: creating a task that runs only after something else happens
State triggers can be used to construct a dataflow: a dynamic process in which tasks do not necessarily follow one another, but rather monitor the state and the data changes in the process-description and become active in response to these changes.

Preconditions: creating a task that runs only if certain conditions are met
A precondition is an expression that has to be met before the task can be executed. A task’s precondition is checked at the point where a task is being considered for enactment, that is, when its scheduling constraints are met. If at that point the precondition is true, the task becomes active. Otherwise, it is discarded, and is not activated again even if its precondition subsequently becomes true.

Frequently used expressions
Several PROforma task attributes hold expressions. This clip looks at frequently used expressions and assertions for preconditions, state triggers and postconditions.