PASSING THE PASSING THE WORDWORD

BYBY

FRANKLYN OMORUANFRANKLYN OMORUAN

Written specificationsWritten specifications

Manual is the external specification of Manual is the external specification of the productthe product

Prescribes and describes every detailPrescribes and describes every detail But not everything is described But not everything is described

including interfaceincluding interface Also refrain what the user does not Also refrain what the user does not

seesee Finest piece of manual is Gerry Finest piece of manual is Gerry

Blaauw’s appendix system 360 Blaauw’s appendix system 360

Written specifications Written specifications contd.contd.

Describes care and precisionDescribes care and precision Limits of system/360 compatibilityLimits of system/360 compatibility must show an implementation for must show an implementation for

any feature but not attempt to any feature but not attempt to dictate it. dictate it.

Formal DefinitionFormal Definition

Manual writer must strain himself Manual writer must strain himself and his language to achieve and his language to achieve precision neededprecision needed

Precision is the stock in tradePrecision is the stock in trade Has merits and demeritsHas merits and demerits Merits are formal definition are Merits are formal definition are

precise, complete and can show precise, complete and can show structured principles. structured principles.

DemeritsDemerits

The implementations may be over-The implementations may be over-prescribed even the externalsprescribed even the externals

Use of implementation as a formal Use of implementation as a formal definition is susceptible to confusiondefinition is susceptible to confusion

Must refrain from modification to Must refrain from modification to the implementation while it is the implementation while it is serving a standardserving a standard

Direct incorporationDirect incorporation

Technique for disseminating and Technique for disseminating and enforcing definition is available for enforcing definition is available for software architectsoftware architect

Useful for establishing syntax if not Useful for establishing syntax if not semantics of intermodule interfacessemantics of intermodule interfaces

Whole interface is referenced only Whole interface is referenced only by symbolic names, declaration can by symbolic names, declaration can be changed by adding new varables be changed by adding new varables with only recompilations with only recompilations

Conferences and CourtsConferences and Courts

Two levels of meeting Two levels of meeting Conference of all architects plus Conference of all architects plus

official representation official representation Chief system architect presidesChief system architect presides Emphasis on creativity rather that Emphasis on creativity rather that

mere decisionmere decision

Multiple Multiple ImplemanetationImplemanetation

System/360 had two important System/360 had two important advantagesadvantages

Enough time to work carefully and Enough time to work carefully and political cloutpolitical clout

Most computer projects there are Most computer projects there are time machine and manual do not time machine and manual do not agree agree

Telephone LogTelephone Log

No matter the precise specification No matter the precise specification many architectural interpretation many architectural interpretation question risesquestion rises

Are kept by architect, it records Are kept by architect, it records questions and every answer questions and every answer

It is informal but quick and It is informal but quick and comprehensive comprehensive

Product TestProduct Test

Daily adversary is the project Daily adversary is the project manager best friend.manager best friend.

Checks machine and programs Checks machine and programs against specification against specification

Pinpoints every conceivable defect Pinpoints every conceivable defect and discrepancies. and discrepancies.

summarysummary

What the chief architect produces What the chief architect produces are written specifications for the are written specifications for the system in the form of the manual. system in the form of the manual.

It should describe the external It should describe the external specifications of the system in detail, specifications of the system in detail, i.e., everything that the user sees. i.e., everything that the user sees.

The manual should be altered as The manual should be altered as feedback comes in from the feedback comes in from the implementation teams and the users. implementation teams and the users.