Tallis Composer User Interface: Task Properties
Creating a simple task process
When you select a task in the process-description, the values of its properties are displayed in the Task Properties window. The title bar displays the task’s type and instance name.
Task properties can be categorised into four groups: general, task specific, scheduling, and runtime.
General Properties
Properties that differentiate the task from other tasks of the same type:
| Instance Name | An alphanumeric string representing the ID of the task. |
| Caption | A textual label that appears in the tree view and network view of the Composer; and as the task’s label when executing via the Tallis Engine. |
| Goal | A truth-valued expression indicating the intention of the task. |
| Description | A textual description of the task. |
Task Specific Properties
Properties that differentiate between tasks of different types:
Action
| Procedure | Defines the detailed action to perform. The Trigger List displays event triggers of other tasks in the same parent-plan. You can create a hyperlink that will in runtime enact one of these tasks by invoking its event trigger: Type a text string in the edit-box, select it, and then select the appropriate trigger. The View Mode can be either Plain Text (for entering ASCII text) or HTML (for entering HTML via an HTML editor). |
Enquiry
| Sources | Define the data items for which values must be supplied. Use this panel to create sources by linking to existing data definitions or by creating new ones. |
Decision
| Candidates tab | Candidates define the options to choose between. Use this tab to enter the names, descriptions, and priorities of the decision candidates. |
| Sources tab | Sources defined in this tab must be supplied with values before the decision is enacted. |
| Arguments tab | PROforma supports decision-making through a mechanism of generating arguments for and against candidates. Use this tab to define arguments for each candidate. |
| Decide tab | When a decision is enacted, the condition in the Recommendation Rule field determines whether or not a candidate is recommended. |
| Properties tab | Support Type determines the structure of the Support field in the Arguments tab.
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Plan
| Abort Condition | A truth-valued expression indicating the conditions under which the task should abort. Once this condition is met, the plan’s state is set to discarded. All tasks within the plan that have not been completed are discarded as well. |
| Terminate Condition | A truth-valued expression indicating the conditions under which the task should terminate. Once this condition is met, the plan’s state is set to completed. All tasks within the plan that have not been completed are discarded. |
| Plans: Using the abort and the terminate conditions to interrupt a process |
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Keystone
As it is a temporary placeholder, the Keystone doesn’t have task-specific properties.
Scheduling Properties
Properties that determine when a task should be enacted
| State trigger | A truth-valued expression indicating a condition that has to be met before the task can be enacted. As long as it isn’t met, the task remains dormant.State Triggers: Creating a task that runs only after something else happens |
| Event trigger | An alphanumeric string that enables the end-user to trigger a task during the enactment of the process-description. The event trigger is useful for creating processes that are not linear. During the enactment of the process-description, the end-user is able to decide which path to take by triggering the relevant task. Event Triggers: Offering the end-user a choice between tasks
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| Precondition | A truth-valued expression indicating a condition that has to be met before the task can be enacted. A task’s precondition is examined when, and only when, its scheduling constraints are met. If at that moment the precondition is false, the task is discarded.Preconditions: Creating a task that runs only if certain conditions are met
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Runtime Properties
Properties that affect the enactment scheme of the task
| Cycle until | An expression defining the conditions under which a task stops cycling. |
| Cycle Interval | An integer defining the time interval between cycles (the default time unit is hours). |
| Number of cycles | An integer defining the number of times a task is repeated.Cyclic Tasks: Creating a task that re-executes N times or until a certain condition is met |
| Optional | A task that is optional isn’t necessary for the completion of the guideline. By default, tasks are not optional. This means that their patent-plan can complete only if the task is completed or discarded. If a task is optional, its parent-plan can complete even if the task is dormant. |
| Automatic | A task that is automatic doesn’t request end-user confirmation. This property is only applicable to actions and decisions.Automatic Tasks: Creating a task that is confirmed automatically and is not displayed to the end-user |
| Postcondition | An assertion (expression) that is executed when the task has been performed (typically used for assigning a value to a data item – to specify information that is used by subsequent tasks. |
PROforma Tab
Displays the task properties in PROforma code (read-only).
Context Tab
The context tab is used to define parameters that provide further control over the enactment process (e.g. configuration parameters for data access, web enactment user interface, etc.)