PASSING THE WORD BY FRANKLYN OMORUAN

Written specifications Manual is the external specification of the product Manual is the external specification of the product Prescribes and describes every detail Prescribes and describes every detail But not everything is described including interface But not everything is described including interface Also refrain what the user does not see Also refrain what the user does not see Finest piece of manual is Gerry Blaauw’s appendix system 360 Finest piece of manual is Gerry Blaauw’s appendix system 360

Written specifications contd. Describes care and precision Describes care and precision Limits of system/360 compatibility Limits of system/360 compatibility must show an implementation for any feature but not attempt to dictate it. must show an implementation for any feature but not attempt to dictate it.

Formal Definition Manual writer must strain himself and his language to achieve precision needed Manual writer must strain himself and his language to achieve precision needed Precision is the stock in trade Precision is the stock in trade Has merits and demerits Has merits and demerits Merits are formal definition are precise, complete and can show structured principles. Merits are formal definition are precise, complete and can show structured principles.

Demerits The implementations may be over-prescribed even the externals The implementations may be over-prescribed even the externals Use of implementation as a formal definition is susceptible to confusion Use of implementation as a formal definition is susceptible to confusion Must refrain from modification to the implementation while it is serving a standard Must refrain from modification to the implementation while it is serving a standard

Direct incorporation Technique for disseminating and enforcing definition is available for software architect Technique for disseminating and enforcing definition is available for software architect Useful for establishing syntax if not semantics of intermodule interfaces Useful for establishing syntax if not semantics of intermodule interfaces Whole interface is referenced only by symbolic names, declaration can be changed by adding new varables with only recompilations Whole interface is referenced only by symbolic names, declaration can be changed by adding new varables with only recompilations

Conferences and Courts Two levels of meeting Two levels of meeting Conference of all architects plus official representation Conference of all architects plus official representation Chief system architect presides Chief system architect presides Emphasis on creativity rather that mere decision Emphasis on creativity rather that mere decision

Multiple Implemanetation System/360 had two important advantages System/360 had two important advantages Enough time to work carefully and political clout Enough time to work carefully and political clout Most computer projects there are time machine and manual do not agree Most computer projects there are time machine and manual do not agree

Telephone Log No matter the precise specification many architectural interpretation question rises No matter the precise specification many architectural interpretation question rises Are kept by architect, it records questions and every answer Are kept by architect, it records questions and every answer It is informal but quick and comprehensive It is informal but quick and comprehensive

Product Test Daily adversary is the project manager best friend. Daily adversary is the project manager best friend. Checks machine and programs against specification Checks machine and programs against specification Pinpoints every conceivable defect and discrepancies. Pinpoints every conceivable defect and discrepancies.

summary What the chief architect produces are written specifications for the system in the form of the manual. What the chief architect produces are written specifications for the system in the form of the manual. It should describe the external specifications of the system in detail, i.e., everything that the user sees. It should describe the external specifications of the system in detail, i.e., everything that the user sees. The manual should be altered as feedback comes in from the implementation teams and the users. The manual should be altered as feedback comes in from the implementation teams and the users.