IS550: Software requirements engineering

Dr. Azeddine Chikh

5. Special interfaces - combined styles

Soren Lauesen, "Software Requirements: Styles & Techniques"Addison-Wesley Professional 2002,  608 pp, ISBN-10: 0201745704 - ISBN-13: 9780201745702

                 

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0. Introduction

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The most important product interfaces is usually the interactive interface to the user.

The discussions in the previous chapter were primarily related to the user interface

Many of the requirements styles could deal with other product interfaces (reports, platform, external technical systems) as well.

1. Reports

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Highlights

Often hundreds of reports

Specify the clearly necessary reports

Postpone the rest, but specify the framework for making them

External reportsR1: Product shall produce pay slips with layout as in app. xx.

Specific purpose

Existing reports - vague purpose

Reports on demand

R2: Product shall print forecasts of room occupation for monthly roster planning. Format for instance as xx.

R3: Supplier shall provide a list of built-in reports.

R4: Supplier shall develop up to 200 simple reports (like yy) at a price of $_____ per report and up to 50 complex reports (like zz) at a price of $_____ per report.

R5: Product shall include a report generator.Reports like yy can be developed by:

ordinary user? yes/nosuper user? yes/nocustomer’s IT dept? yes/no

1. Reports

2. Platform requirements

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Highlights

What the product shall run on, now and in the future.

Dealing with existing and planned platforms

We have a platformR1: Product shall run on Pentíum PC’s with 128 MB. Many older PC’s still

used, so tasks 2.1 to 2.5 must be supported on 80486 with 64 MB.

R2: Our IT staff have expertice in Oracle. Product must use same database platform.

R3: Product shall run on MS Windows release xx.yy. Supplier shall for 3 years port his product to new releases within ___ months from release date.

We want a new platform anywayR4: Customer expects to switch to client-server running OS zz.

Supplier shall specify server memory and server speed needed to obtain capacity and response time for Rxx.

We want software and hardware (maybe)R5: Supplier shall deliver hardware + software. Supplier shall upgrade

if capacity becomes inadequate for the load specified in xx.

R6: Product shall run on Pentium PC’s with 128 MB. As an option, total delivery may include the PC’s and hardware support.

2. Platform requirements

3. Product integration – non technical customers

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Highlights

Find someone else to integrate the products

Specify the user to be supported, or specify the desired commercial products

Who can integrate?

Hotelsystem

Accountsystem

Customer???

Customer’sIT dept

Productsupplier

Maincontractor

?

?

3. Product integration – non technical customers

Integration reqs, domain-level

Sub-tasks:1. Get guest invoices

2. Post on accounts

Problem: Same posted twice or forgotten.3. Send invoices . . .Variants:1a. We have several hotels and want shared accounting.

Example solution:Automatic transfer from hotel system to Wonder-Account xx.yy.Account numbers defined in a database table.Unbroken sequence of numbers.

Data transmission.

Task: 5.1 Daily accountingPurpose: Balance with bank account . . .

Send out invoices to company customersFrequency: Daily

R1: The product shall support task 5.1.

3. Product integration – non technical customers

Integration reqs, product-level

We have a commercial productR2: Customer uses WonderAccount xx.yy. Hotel system shall ensure

transfer within next day. Shall transfer . . . once and only once.

We want a new commercial productR3: Customer wants new account system. Supplier shall specify the

systems he integrates with and the degree of transfer reliability.

R4: Supplier shall specify detailed interface forchosen account system.

Consortium modelR5: Supplier shall deliver hotel system plus account system. Account

system shall provide standard account facilities.

We have a tailor-made systemR6: Customer uses old mainframe system YY for accounting. Hotel system

must ensure daily transfers, once and only once.

Let the supplier study YY documentation?Document the interface?Let YY developer be main contractor?

3. Product integration – non technical customers

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Highlights

Product integration is a main contractor’s job

Technical interfaces are a design issue

Divide total product into sub-products, using what is available

4. Product integration – main contractor

Hotelsystem

Accountsystem

Telephonesystem

Sub-contractorJoint design workThe optimal split.Exists? Willing?Cost vs. market

DB sys

Embedded3rd partyproduct

Main contractor

Visible3rd partyproduct

4. Product integration – main contractor

5. Technical interfaces

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Highlights

Many ways to specify the technical interface

Prototype and test the communication early

Hotelsystem

Accountsystem

Communication channelPhysical channel:

File, TCP/IP, object calls . . .

Message formats: Data descr, call params

Protocol: State diagram, sequence diagramformal data descr, SDL . . .

Semantics: about what? E/R, tasks, activity diagrams

Verify early:Functionalprototypes

5. Technical interfaces