  There is a growing interest in adopting object technologies for the
development of real-time control systems. Several commercial tools, currently
available, provide object-oriented modeling and design support for real-time
control systems. While these products provide many useful facilities, such as
visualization tools and automatic code generation, they are all weak in
addressing the central characteristic of real-time control systems design,
i.e., providing support for a designer to reason about timeliness properties.
We believe an approach that integrates the advancements in both object modeling
and design methods and real-time scheduling theory is the key to successful use
of object technology for real-time software. Surprisingly several past
approaches to integrate the two either restrict the object models, or do not
allow sophisticated schedulability analysis techniques. This study shows how
schedulability analysis can be integrated with UML for Real-Time (UML-RT) to
deal with timing properties in real time control systems. More specifically, we
develop the schedulability and feasibility analysis modeling for the external
messages that may suffer release jitter due to being dispatched by a tick
driven scheduler in real-time control system and we also develop the
scheduliablity modeling for sporadic activities, where messages arrive
sporadically then execute periodically for some bounded time. This method can
be used to cope with timing constraints in realistic and complex real-time
control systems. Using this method, a designer can quickly evaluate the impact
of various implementation decisions on schedulability. In conjunction with
automatic code-generation, we believe that this will greatly streamline the
design and development of real-time control systems software.
