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systems based on SES model

Takaaki Koshiro

Scho ol of information,

Japan Advanced Institute of Science and Technology

February 15, 2001

Keywords: SES mo del,Embedded system, RTOS.

Today,theobject-orientedapproachwhichiswidelyusedisoneofthemostprogressed

approach for software development. In the embedded system developments, we have to

take their sp ecic non-functional properties such as time and hardware constraints into

consideration. Many development methods for embedded systems have been proposed,

and OCTOPUSis one of such metho ds. OCTOPUSprop osedimplicit concurrentmodel

and explicit concurrent mo del. We model a target system without considering asyn-

chronousand synchronousfactors inthe implicitconcurrentmodel. Then,inthe explicit

concurrent mo del, we mo del the target system with considering these factors from the

constructed implicit concurrent model. However, how to implement software from the

implicitconcurrent model is not fully explained.

In this research, we adopt the SES mo del as design metho d. The SES mo del is an

object-oriented method for time-critical embedded systems proposed by Aoki. In this

approach, we construct SES mo del,then we implement software on real-time op erating

system from the design mo del. The SES model consists of pro cess sequences. We refer

to each of the sequences as a SES which is an abbreviation of synchronous execution

sequence. This approach also provides templates for implementing software on RTOS

from SES mo del. In this pap er, We prop osed a to ol which automatically generates a

programfromSES mo delusingtemplate. SoftwareonRTOSconsistsofasetoftasksand

schedulingalgorithm. These tasksare executed concurrently accordingto the scheduling

algorithm. Our a program generator which generates an executable program which is

executed on RTOS from a set of the SESs, a set of the tasks, and scheduling algolithm.

As SES mo del did not have enough notion to implement such software, I extended SES

mo del so that we can describe ab out tasks and schedule algolithmas follows.

1. Iintro ducedthenotation whichspeciesanaspecttoassignSESsappearinginSES

mo del to tasks

Copyright c

2001byTakaakiKoshiro

I found that we can automatically generate a program from SES mo del with these two

asp ects, and we can execute this program by implementing processes app earing in the

SES model. We implemented a telephone system using this program generator. The

constructed SES mo del contains eleven states and fteen SESs. We succeeded in gener-

ating an executable program on RTOS. However, it is still dicult to describe complete

sp ecication tob e dened. Forexample ,SES mo del andthe program generator can not

deal with tasks comminications. These problems are takenas a future works.