Special interfaces

Chapter 5

Reports

Reports on screen and paper are a form of one way communication between product and userHard to specify

Many types of reports are necessary and it is important to specify these correctly

Reports

Reports

Some reports must specify external format requirements

“The product shall produce pay slips with the layout shown in Figure xx. The pay slips should be available on paper as well as comma separated files”

Some reports relate to well-defined tasks

Reports

Beware of existing reports with vague purposes

COTS systems may have built in reports that could be used and this will save costs

Reports on demand; is there a report generator and how easy it is to use

Platform requirements

Platform is a combination of HW and SW on which the system will run’HW, OS, network, DB (mostly COTS)

We already have a platformWe plan to buy a new platformWe want the platform as part of the

productCan be strategic or obvious

Platform requirements

We already have a platform

Typical for small projectsPentium with xx Mhz and xx RAM, etc

“Since the customer’s IT staff have expertise in Oracle, which is used for other applications, the product shall use the same DB platform”

Specify platform products and release numbers

We want a new platform

Typical when major changes in IT strategy are involved

Platform requirements are closely related to speed and capacity

Response time requirements dependent on platform speed and memory requirements

We want SW and HW

Typical for dedicated systems for one specific purpose

Could be a multipurpose system where the supplier takes care of maintenance and support

“the supplier shall deliver the necessary HW and SW, and shall upgrade if necessary as load increases” ISP

We want SW, maybe HW

Customer may not have made up his mind

Combined HW/SW or not?In this case, specify HW as an option

and decide later“the client part of the product shall

run on Pentiums. As an option, the total delivery may include PCs..”

Product integration

What if the customer has little IT skills?External products – your system has to

communicate with these other systemsIntegration of two or more products

leads to complexityWhat should be said about the other

system?

Who integrates?

Who is responsible for the adjustments and settings for the whole system?Customer responsible for the

integrationAvoid if possibleEndless problems for non-specialists

Who integrates?

Customer’s IT departmentFine if they have the technical expertiseCustomer should regard the IT department

as his main contractor and supplier

External supplierUsually best choiceSupplier may have a product and used to

integrating itSome SW houses and good at “glue code”

Who can integrate?

Integration requirements, domain level

Integrating with a commercial product

“The customer us using WonderAccount xx for his financial accounting. The hotel system must ensure that today’s invoice transactions are transferred automatically to WonderAccount with the next day. Each transaction must be transferred once and only once”

Integrating with a new commercial product

What if the customer wants several new products at once and he wants to integrate them?

“The hotel system supplier shall list the accounting systems with which his system can integrate….”

Consortium model; delivering an integrated product

Suppliers may form a consortium that together deliver the integrated product

Consortium might reduce to a single supplier

Best for large systems where many products have to be integrated

Integration requirements – product level

Product integration – main contractor

Main contractor may be hired to help a customer integrate some products in an ad hoc manner, or he may develop a new product of his own that builds on other products

Product developers use integration with third parties more and more because they offer increasingly complex and intelligent services

Product integration – main contractor

Main contractor will have the responsibility for the integrationWrites requirements for each

subcontractorSpecify technical interfaces between the

productsMain contractor ultimately

responsible for customer requirements

Main contractor

Technical interfaces

Technical interfaces between a product and an external product is always one or more communication channels Physical channel; how is data

communicated/Data transmissionInter-object callsSnail mail

Technical interfaces

Messages; how is the message identity or the event communicated?Which formats are involved?

ProtocolsWhat are the possible message sequences,

error recovery, etc?Semantics

What do they communicate about?

Technical interfaces

Examples of channels

File transferHotel accounting system

Object calls3D graphics package

Network communicationRemote process control

Channel descriptions

Physical channelTCP/IP

MessagesData expressions, data dictionary

ProtocolSDL (telecom)

SemanticsDFD, use cases, etc

“Hard” requirements

Hard requirements in a technical interfacemessage formatsProtocolsPhysical channel

Crucial when two independent organizations develop separate parts of the whole