Interaction Fragment Properties

You can modify an object's properties from its property sheet. To open an interaction fragment property sheet, double-click its diagram symbol in the top-left corner near the operator tag. The following sections detail the property sheet tabs that contain the properties most commonly entered for interaction fragments.

The General Tab contains the following properties:

Property	Description
Operator	Specifies the type of fragment. You can choose between: Alternative (alt) – the fragment is split into two or more mutually exclusive regions, each of which has an associated guard condition. Only the messages from one of these regions will be executed at runtime. Assertion (assert) – the interaction must occur exactly as indicated or it will be invalid. Break (break) – if the associated condition is true, the parent interaction terminates at the end of the fragment. Consider (consider) – only the messages shown are significant. Critical Region (critical) – no other messages can intervene until these messages are completed. Ignore (ignore) – some insignificant messages are not shown. Loop (loop) – the interaction fragment will be repeated a number of times. Negative (neg) – the interaction is invalid and cannot happen. Option (opt) – the interaction only occurs if the guard condition is satisfied. Parallel (par) – the fragment is split into two or more regions, all of which will be executed in parallel at runtime. Strict Sequencing (strict) – the ordering of messages is strictly enforced. Weak Sequencing (seq) – the ordering of messages is enforced on each lifeline, but not between lifelines. The operator type is shown in the top left corner of the interaction fragment symbol.
Stereotype	Extends the semantics of the object beyond the core UML definition.
Condition	Specifies any condition associated with the fragment. This may be the evaluation of a variable, such as: X > 3 Or, for a loop fragment, the specification of the minimum and (optionally) maximum number of times that the loop will run. For example: 1,10 For the Consider or Ignore operators, this field lists the associated messages. This field is not available if the fragment does not support conditions.

Property

Description

Operator

Specifies the type of fragment. You can choose between:

Alternative (alt) – the fragment is split into two or more mutually exclusive regions, each of which has an associated guard condition. Only the messages from one of these regions will be executed at runtime.
Assertion (assert) – the interaction must occur exactly as indicated or it will be invalid.
Break (break) – if the associated condition is true, the parent interaction terminates at the end of the fragment.
Consider (consider) – only the messages shown are significant.
Critical Region (critical) – no other messages can intervene until these messages are completed.
Ignore (ignore) – some insignificant messages are not shown.
Loop (loop) – the interaction fragment will be repeated a number of times.
Negative (neg) – the interaction is invalid and cannot happen.
Option (opt) – the interaction only occurs if the guard condition is satisfied.
Parallel (par) – the fragment is split into two or more regions, all of which will be executed in parallel at runtime.
Strict Sequencing (strict) – the ordering of messages is strictly enforced.
Weak Sequencing (seq) – the ordering of messages is enforced on each lifeline, but not between lifelines.

The operator type is shown in the top left corner of the interaction fragment symbol.

Stereotype

Extends the semantics of the object beyond the core UML definition.

Condition

Specifies any condition associated with the fragment. This may be the evaluation of a variable, such as:

X > 3

Or, for a loop fragment, the specification of the minimum and (optionally) maximum number of times that the loop will run. For example:

1,10

For the Consider or Ignore operators, this field lists the associated messages.

This field is not available if the fragment does not support conditions.

Sub-Regions Tab

The Interaction Sub-Regions Tab lists the regions contained within the fragment. It is only displayed if you select an operator that requires more than one region. You can add or delete regions and (if appropriate) specify conditions for them.