Recurrence Property Pattern

• Description
• State-Based Pattern

Description

• Pattern in the original catalog
• Structured English Specification: [Scope], P [holds] repeatedly every t timeunits.
• Pattern Intent: This pattern describes a portion of a system's execution that contains an unspecified number of instances of a designated state, which must not be absent longer than the timebound.
• In the observers below, t is the time bound.

State-Based Pattern

Untimed

Globally

START --> GOAL

Before R

START --> GOAL

After Q

START --> GOAL

Between Q and R

This scope is hardly applicable.

VALIDATION --> (P_ or INIT)

After Q Until R

VALIDATE --> (P or R)

Timed

Globally

The following observer reaches an ERROR state when P is not true repeatedly in time. Whenever P is left, the clock is reset.

A[] not ERROR

Before R

The following observer reaches an ERROR state when P is not true repeatedly in time and afterwards it observes an R. Whenever P is left, the clock is reset. The ERROR state is unreachable once R happened.

A[] not ERROR

After Q

After observing Q, the following observer reaches an ERROR state when P is not true repeatedly in time. Whenever P is left, the clock is reset.

A[] not ERROR

Between Q and R

A[] not ERROR

After Q Until R

A[] not ERROR