SE-381 Homework 1: Informal Requirements Specification

Fall quarter 2003-2004

Dr. Mark J. Sebern

Developed with support from the National Science Foundation

Introduction

The purpose of this exercise is to prepare a (non-formal) requirements specification for a software system, to be used as a baseline for later work in formal specification.

Assignment details

Introduction

This is a team (3-4 members) project; you may not do it as an individual.

Because this exercise concentrates on the specification and documentation of requirements, rather than on eliciting them from clients or stakeholders, the problem domain is one that you should already be familiar with. You are expected to take into account your own knowledge of the problem domain in completing this work. The members of your team may have differing views about the requirements. You should reach some kind of consensus about the requirements and document them as well as you can. There is more than one possible "right answer" for this project.

System description

Study this overview of the system you are to specify. It is taken from a similar problem addressed at the Fourth International Workshop on Software Specification and Design, April 3-4, 1987, Monterey, California.

• An n-elevator system is to be installed in a building with m floors. The elevators and the control mechanism are supplied by the manufacturer. The internal mechanisms of these are assumed (given).
• The problem concerns the logic to move elevators between floors according to the following constraints:
  1. Each elevator has a set of buttons, one for each floor. These illuminate when pressed and cause the elevator to visit the corresponding floor. The illumination is cancelled when the corresponding floor is visited by the elevator.
  2. Each floor has two buttons (except the top and bottom floors), one to request upward travel and one to request downward travel. These buttons illuminate when pressed. The illumination is cancelled when an elevator visits the floor and is either moving in the desired direction or has no outstanding requests.
  3. When an elevator has no requests to service, it should remain at its final destination with its doors closed and await further requests. (An alternative would be to specify a floor to which the elevator should return under these conditions.)
  4. All requests for elevators from floors must be serviced eventually, with all floors being given equal priority.
  5. All requests for floors within an elevator must be serviced eventually, with floors being serviced sequentially in the direction of travel.
  6. Each elevator has an emergency button that, when pressed, causes a warning signal to be sent to the site manager. The elevator is then deemed "out of service." Each elevator has a mechanism to cancel its "out of service" status.

It is likely that you have are familiar with elevator systems similar to the one described here. You should use your own experience to help you understand the details of the system for which you are trying to specify the requirements.

Report

Prepare your report using LaTeX. (You'll need LaTeX throughout the course, and LaTeX is still commonly used to prepare papers for technical journals and conferences, so this assignment will help you gain familiarity and expertise in using it.)

• Document your understanding of the system requirements.
  • Focus primarily on requirements related to controlling the movement of each elevator in response to passenger inputs and related factors.
  • Since you are preparing an informal (or non-formal) specification, your document will be mostly textual in nature.
  • If you wish, you may include tables or diagrams. However, this will likely require learning about additional features of LaTeX. Concentrate first on the content, and only worry about more complex formatting if you have the time to do so.
• Add a section to your specification describing any difficulties you encountered, or any questions that you still have.

If you have questions about the assignment, please consult the instructor.

Report submission

Your report should consist of the following:

• The LaTeX (".tex") specification source file; name it Name1Name2Name3Name4HW2.tex, where NameX is the last name (NOT username) of each team member.
• The PDF document you created from it; name it Name1Name2Name3Name4HW2.pdf.

The report is due before class on the day specified in the course schedule.

If you have questions about the assignment, please consult the instructor (in person or by email) as soon as possible.

Email your report to the instructor. Be sure to keep your own copy for safekeeping.

This page was last updated on Sunday, 07-Sep-2003 18:03:09 CDT.

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