viernes, octubre 23, 2009

Apuntes sobre Factorías de Software, II

De lo comentado antes, queda la impresión de que durante la época temprana del desarrollo del software, múltiples líneas de acción tendieron a darle sustento sistemático a su concepción y construcción, y en este contexto, la idea de aplicar el concepto de factoría fue una vía consistente de trabajo; primero iniciada en Estados Unidos, luego tomada con fuerza por Japón, y finalmente continuada en Europa. Tanto M. Cusumano como Y. Matsumoto señalan la conferencia de la NATO sobre Ingeniería de Software en 1968, como el punto de partida de los intentos de construír el software a modo de una factoría desde la Ingeniería de Software.
Ya se habló de Bob Bemer y M.D. Mcllroy, cuyos antecedentes se remontan a fines de los 60, y cuyas afirmaciones van en el sentido de mejorar procesos y procedimientos, medir, estandarizar herramientas de productividad, y establecer técnicas de reutilización del código.
Cusumano recoje a Mcllroy sobre reutilización de código, tan temprano como 1968:
The most important characteristic of a software components industry is that it will offer families of routines for any given job. No user of a particular member of a family should pay a penality, in unwanted generality, for the fact that he is employing a standard model routine. In other words, the purchaser of a component from a family will choose one tailored to his exact needs. He will consult a catalogue offering routines in varying degrees of precision, robustness, time-space performance, and generality. He will be
confident that each routine in the family is of high quality--reliable and efficient. He will expect the routine to be intelligible, doubtless expressed in a higher level language appropriate to the purpose of the component, though not necessarily instantly compilable in any processor he has for his machine. He will expect families of routines to be constructed on rational principles so that families fit together as building blocks. In sort, he should be able safely to regard components as black boxes.

[Citado por Cusumano en The Software Factory: Origins and popularity in Japan: M.D. Mcllroy, "Mass Produced Software Components," in Peter Naur and Brian Randell, eds., Software Engineering: Report on a Conference Sonsored by the NATO Science Committee, Brussels, Scientific Affairs Division, NATO, January 1969]
En este y otros papeles, Cusumano recoje a Bemer sobre métricas y factorías:
[A] software factory should be a programming environment residing upon and controlled by a computer. Program construction, checkout and usage should be done entirely within this environment, and by using the tools contained in the environment... A factory... has measures and controls for productivity and quality. Financial records are kept for costing and scheduling. Thus management is able to estimate from previous data... Among the tools to be available in the environment should be: compilers for machine-independent languages; simulators, instrumentation devices, and test cases as accumulated; documentation tools -- automatic flow-charters, text editors, indexers; accounting function devices; linkage and interface verifiers; code filters (and many others).

[Cusumano, en
The Software Factory: Origins and popularity in Japan: R.W. Bemer, "Position Papers for Panel Discussion -- The Economics of Program Production," Information Processing 68, Amersterdam, North-Holland, 1969, pp. 1626-1627]
Objetivos semejantes impulsaron el desarrollo de las fábricas de software de Hitachi, Toshiba, NEC, Fujitsu, a partir de la década de 1970, y las de SDC de Rand Corporation en Estados Unidos. Estas acciones fueron analizadas detalladamente por Michael Cusumano, que entrega también una buena bibliografía sobre los esfuerzos dedicados desde los 60 hasta los 90. Particularmente destaca el trabajo de Matsumoto en Toshiba:
An RD group responsible for industrial systems software in Toshiba, led by Dr. Yoshihiro Matsumoto, introduced an organization and process in 1977 integrating tools, methods, management and personnel systems with a physical layout for work stations (...). The strategy for utilizing this infrastructure centered around four policies: (1) standardize the development process, to reduce variations among individuals and individual projects; (2) reuse existing designs and code when building new systems, to reduce redundant work and maximize productivity; (3) introduce standardized and integrated tools, to raise the performance levels of the average programmer; and (4) provide extensive training and career-development tracks for programmers, to relieve the shortage of skilled engineers.

Perhaps the most delicate feature of Toshiba's Factory was its organizational structure, a matrix imposed over product departments from several operating groups and divisions, all located on one site, Toshiba's Fuchu Works. Established in 1940 and set on 198 acres in the western outskirts of Tokyo, the Fucnu Works in 1991 had at least 8000 employees working primarily in four areas: Information Processing and Control Systems, Energy Systems, Industrial Equipment, and Semiconductors (Printed Circuit Board Division). Operating departments within the divisions corresponded roughly to 19 product lines, including systems for information and control in public utilities, factories, power-generation plants, and various industrial and transportation equipment. Each department contained sections for hardware and software design as well as for manufacturing, testing, quality assurance, and product control.

Similarities in the type of software the Fuchu Works built from project to project allowed Toshiba to deliver "semi-customized" programs that combined reusable designs and code with newly written modules, rather than writing all software from scratch. Toshiba also relied heavily on a standardized tool and methodology set, the Software Engineering Workbench (SWB), developed gradually after 1976and modelled after AT&T's UNIX Programmers Workbench. Toshiba utilized its customized version of the UNIX operating system as well as a full complement of tools for design-support, reusable module identification, code generation, documentation and maintenance, testing, and project-management. Important features of the Toshiba methodology were the design of new program modules (ideally limited to 50 lines) for reusability, the requirement that programmers deposit a certain number of reusable modules in a library each month, and the factoring in of reuse objectives into project schedules and budgets (Matsumura et al., 1987).

Software productivity at the Toshiba Software Factory rose from 1390 delivered equivalent-assembler source lines or EASL per person per month in 1976 to over 3100 in 1985, while reuse levels (lines of delivered code taken from existing software) increased from 13% in 1979 to 48% in 1985. The 3130 lines of EASL source code per month per employee translate into approximately 1000 lines of Fortran, the most common language Toshiba used in 1985 -- considerably more than the 300 lines or so of new code per month commonly cited for U. S. programmers making similar real-time applications. Quality levels (defined as the number of major faults detected after final testing) also improved dramatically after the opening of the factory, ranging from 7 to 20 per 1000 lines of delivered code converted to EASL to .2 to .05 in 1985 (the range depended on quality-control practices as well as the reliability requirements and the amount of testing customers contracted for) (Cusumano, 1991: 240).

Toshiba data indicated that reusability was the major reason for productivity and quality improvements. The organization Toshiba created to promote reuse and overcome short-term concerns of project managers and development personnel (such as the longer time required to write and document reusable software) relied on Software Reusing Parts Steering Committees and a Software Reusing Parts Manufacturing Department and Software Reusing Parts Center. The factory formed a steering committee for different areas (with different members, depending on the application) to determine if customers had a common set of needs suitable for a package, and then allocated funds from the Fuchu Works' budget for these special projects. Some packages were usable in different departments, although most served specific applications. The Reusing Parts Manufacturing Department and Parts Center evaluated new software (and documentation) to make certain it met factory standards; after certification, engineers registered the software in department or factory reuse
databases (libraries). Registered items required a key-word phrase to representthe functionality of the part or correspond to a specific object, as well as reuse documentation that explained the part's basic characteristics.
[Cusumano, The Software Factory: An Entry for the Encyclopedia of Software Engineering]
Al documento mencionado en la nota anterior, se agregan otros tres consultados del mismo autor, todos en el mismo sentido:

The Software Factory: Origins and popularity in Japan, Cusumano, Massachusetts Institute of Technology (MIT), Sloan School of Management, Working Papers (WP2036-88)

A quantitative analysis of U.S. and japanese Software-Engineering practice and performance, Cusumano y Chris F. Kemerer, en Management Science, Volumen 36 , número 11, 1990

The Software Factory: An Entry for the Encyclopedia of Software Engineering, Cusumano, Massachusetts Institute of Technology (MIT), Sloan School of Management, Working papers, (WP3268-91)

En resumen, las décadas de los 80 y 90, en estos y otros papeles, se revelan como un laboratorio precursor tratando de elevar la productividad especialmente en la industria japonesa: un aspecto fundamental es el papel motor de sus empresas, y la colaboración con instituciones de investigación universitaria. De paso, merecen un comentario aparte (será otro día) las observaciones de Cusumano sobre las diferencias de enfoque entre Japón y Estados Unidos.
Visto en perspectiva, este esfuerzo por plasmar factorías de software colaboró, junto a otras líneas de acción, a prefigurar áreas de investigación que ya nos son mucho más familiares: el impulso del análisis y diseño orientado a objetos, y el desarrollo de componentes. Digamos que desde el punto de vista histórico, las factorías están lejos de representar un retroceso en la forma de encarar la construcción de software. Matsumoto por ejemplo, muestra en la continuidad de su propia actividad cómo este pensamiento siempre estuvo en primera línea de la investigación acerca de mejores vías para la construcción de software.

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