Libris Britannia 4/science library(b).zip/science library(b)/PROGRAMM/DB_CLIPP/2838A.ZIP/FEATURES.DOC

Text File | 1989-10-17 | 17KB | 292 lines

                           MODEL-S: A NEW MILESTONE
                          IN APPLICATION DEVELOPMENT


          The critical phases of the software development which affect the
     resulting applications the most and are difficult to rectify after the
     system is built, are the specification, design, and iterative testing,
     which together establish the detailed technical requirements. MODEL-S
     Version 2.0 is PC-SYSTEMS' solution to these problems. It enables rapid
     development of a working model of the application and is capable of
     delivering the final product from the model.The application is easily
     built, readily modifiable, and expandable. MODEL-S solution capitalizes on
     the strengths of both user and software developer to increase their
     productivity, reduce overall project costs, and ensure user satisfaction.

     The need to increase productivity of MIS coupled with the tremendous
growth and change has driven the computer industry to explore new and better
software development techniques. This has resulted in the adaptation of many
proven development methodologies from other disciplines. These methodologies,
in a modified form, provide methodology for development, management, and
control of application software. For example, "top-down" system design and
"bottom-up" programming are analogous to the engineering design of a structure
from the roof down to it's foundations; whereas, actual construction starts at
the foundation and proceeds upward. Another example is CASE tools which
generate system's "blue prints" much like those of other engineering
disciplines.

     Although many new development tools have been introduced over the years,
the fundamental elements of system development remained intact. Considering the
application development cycle, the user is still expected to define system
requirements before system design is started. The approved design is coded,
tested at various levels, and implemented pending user approval. Most aspects
of development were and still are exclusively controlled by MIS.

     The computer industry recognized the need to improve and refine the
software development process by producing a variety of software tools to assist
MIS. The industry has progressed from manual flowcharting and decision tables
to computerized structured methodologies which streamline system analysis.
Along with this, newer software products that range from report generators to
4GL, increased MIS productivity. The availability of these products has
promoted the use of prototyping, which is an iterative development process
consisting of system planning, incremental development of a working model, and
implementation of the final product.

     Unlike engineering disciplines, industry is experiencing unprecedented
growth in computer literacy. Engineering remains and will likely continue to
remain the exclusive domain of the engineers. Even though computer software and
programming is proliferating beyond the bounds of MIS, industry still faces
fundamental problems: business people have the solutions to their business
problems, but it is very difficult to decide precisely what and how to build,
and establish up-front the detailed technical requirements. Conversely, MIS
which has both the tools and knowledge to develop the application, does not
necessarily have a thorough understanding of the business beyond the specified
requirements. The case in point is application development practices that are
prevalent in the industry.

     The solution to these problems lies in the formation of a meaningful
partnership between users and developers. A partnership in which both take
active roles in all aspect of the process. Tools must be created to capitalize
on the strengths of users and developers to complement rather compete with each
other. Users should be able to "see" and "feel" the system before they are
expected to make final decisions about development and implementation. Users
should not be burdened with DP jargon, design methodologies and programming
languages. On the other hand, the developer should be provided with more
complete set of specification requirements for the system. Developers should
have a better "feel" for what problems the system is designed to solve. Such
tools would assist in reducing system backlog and increase the productivity of
the developer through increased automation of the development cycle.

     Rapid prototyping is a technique that can greatly assist in achieving the
desired partnership between users and developers. Its deliverable is a
partially specified working model of an application; it can be tested for
completeness during the building phase, easily and quickly modified, and
capable of evolving into a final product. Before describing this technique, it
is essential to define the terms "model", "prototype", and "final product". Too
often these terms are used interchangeably to describe the same process or
activity. A "model" is a simulation of the applications; whereas, the
"prototype" is a real working system which consists of major system components
but may require enhancements and/or refinements. The "final product" is the
finished product which contains all the required functions and refinements. To
illustrate this, consider the car, a model of which can be tested for modern
design, air-dynamic qualities, but cannot be driven. The prototype version of
the car is a real car - driven and tested in a controlled environment. This
prototype is usually modified before it is mass produced (remember Ford's
Model-T ?). Similarly, the model of an application "looks" and "behaves" as if
it was the actual working system. It simulates the manner in which certain
parts of the fully developed system should function. A prototype provides the
real system with most (or all) of the components. It may still require
modifications and final tuning.

     Benefits of rapid prototyping are numerous: fast implementation of new
ideas, timely detection of design flaws, reduction of development time/cost by
as much as 10% to 50%, more complete design, and thus real savings over entire
life of application, not just its development.

     After a three-year research and development effort, PC-Systems has
developed a PC-based, called MODEL-S. It employs rapid prototyping as well as
the latest user interface techniques. Model building is based on the principle
of design approximations which enables the developer to rapidly build a working
model and modify parts of it without affecting other parts of the model.
Modifications are fast and easy, because the model does not require the
presence of all the information before it becomes executable. Fine tuning of
the model is an iterative process; the model is tested (executed) and modified
repeatedly until it operates according to specifications. User interface
includes powerful yet easy to use design tools which simplify the model
building process. After completion of the model, user can automatically create
a customized dBASE III Plus application (i.e. programs and files).

     This technique speeds up the development cycle, increases user
satisfaction and reduces maintenance. Most of the "traditional" development
backlog is a direct result of the diversion of resources to system maintenance
(more than 70% during the system's life cycle). MODEL-S alleviates this problem
by enabling both user and developer to modify the model and "see" the effect of
change on the system prior to implementation. The application can easily be re-
generated and incorporated into the production environment with reduced effort.

     After exhaustive study of available software products, it is our
conclusion that there is no product comparable to MODEL-S on the market today.
The products that address application development are Computer Aided Software
Engineering (CASE) tools, presentation/demonstration software, and Data Base
Management Systems (DBMS).

     Among the new tools available today, the most visible are CASE tools which
enable the system analyst to graphically design and analyze the system for
correctness, and thus automate manual design techniques. This does not increase
the user participation by much. It is still impossible for the user, even
working with a software engineer, to specify completely the exact requirements
of a modern software product before some versions of this product have been
built and tried.

     The latest DBMS products enable the professional programmers to create the
subset of the actual application to further clarify and confirm user
perspective of the system. This approach is  costly and time consuming; it is
merely an extension of the traditional development methodology.

     Presentation/demonstration software can be used to simulate applications,
and are simply sequences of screens that take the user through the "motions".
These too are not working models and cannot be used as development tools let
alone generation of the application. The same applies to computer-based
training software products which provide the vehicle to train people.

     Although presentations (demos) and computer based training courses can
also be produced by MODEL-S, its primary purpose is to address the needs of the
application user and developer. MODEL-S enables to:

■    Build the model rapidly, using the latest user interface techniques such
     as screen painting, windowing, pop-up and pull-down menus, color,
     character graphics and much more.

■    Execute the model in either interactive or automatic mode. In interactive
     mode, the model reacts to user response at each step of execution.

■    Set up logic to control model flow during execution. This is done by
     evaluating user response such as a key stroke, or the contents of data
     fields or computed values from any part (file) of the model. All this is
     accomplished in non-procedural manner.

■    Define multi-file relationship for data base applications. This provides
     relational capabilities which enables generation of DBMS applications.

■    Generate data base prototype from the model. Version 2.0 of MODEL-S
     enables generation of customized applications in dBASE III Plus and in PC-
     SYSTEM's DREAM relational data base management system.

■    Import/export ASCII files with MODEL-S. This allows for the interfacing
     with any system with ASCII file capabilities.

■    Generate a control diagram which shows overall model scheme and all
     possible paths that may be taken during execution. The diagrams can be
     displayed, printed, or plotted in various forms.

■    Connect models to form super models. This feature enables models or
     segments of models to be connected to other models with ease.

■    Execute the model (and the final application) starting with any screen.
     Furthermore, MODEL-S allows to override normal model flow, "jump" to the
     desired screen and continue uninterrupted.

■    Create presentations, demos and computer based training courses using the
     windowing, color, and character graphics.

     Usage of MODEL-S does not require knowledge of data processing
terminology, data base design or computer programming. The only requirement is
the ability to define the application and break it down to interconnected
blocks (called frames) which represent the application functions. The frame may
be designed as menu, data entry panel, or report. Each frame is built
independently of other frames. All the required specifications are built into
the frame including screen layout, formatting and editing rules as well as the
interconnections (flow) between current frame and others. This capability
enables the user to place the frame anywhere in the model without affecting the
functionality of other frames. This feature is particularly important during
model building, because a change made to one frame does not require adjustments
to other frames. This simplifies the building process and allows effective use
of iterations without paying the price of change.

     The major features of MODEL-S are outlined below.

Frame building:
     ■ Powerful yet easy to use frame painting function.
     ■ Full implementation of color.
     ■ Function to copy information from other frames or DOS files to current
       frame.
     ■ Character graphics.
     ■ Field formatting and editing, including value/range check as well as
       table lookup.
     ■ Windowing.

Controls:
     ■ Flow logic in the form of IF ... THEN ...
     ■ Report generation, including sort, breaks and totals.
     ■ Condensed display of model paths.
     ■ Reference to external data fields which enables use of fields from
       several files while executing current frame.
     ■ Computations.
     ■ Relational operations for report generation.

Execution:
     ■ Start execution with any frame.
     ■ Override normal flow.

Interface:
     ■ Generation of dBASE III Plus applications (i.e programs and files).
     ■ Generation of PC-SYSTEM's DREAM DBMS screens.
     ■ Import/export of ASCII files.
     ■ Interface to DIAGRAM MASTER graphic software for generating model flow
       chart.

Other:
     ■ System parameter specifications.
     ■ Catalog maintenance.
     ■ On-line, contents specific help.
     ■ Electronic note pad.
     ■ MODEL-S run time modules for running demos/presentations
     ■ Interrupt keys.
     ■ Much more...

     Although MODEL-S is a PC-based software, it enables development of models
with up to 200 frames each. Models can be connected to form super models, thus
limiting model size to the capacity of the storage (hard disk) medium. Frame
size is 60 rows by 160 columns (9600 characters in all). A frame can
accommodate up to 200 titles and data fields and may be linked to as many as 60
other frames.

     The functions described above are clear indication as to the completeness
of MODEL-S. It contains all the necessary functions to build the model and
generate a prototype without programming. Furthermore, MODEL-S allows expansion
of code generation to other languages. PC-SYSTEMS plans to include additional
interfaces to other computer software products and languages.

     In conclusion, here is a product that automates the development process
yet does not require data processing expertise. This enables users to become
full partners in the development process. Using MODEL-S, the user can "see" and
"feel" the proposed system; this gives the opportunity to put ideas to work
while enabling the MIS developer to better understand system requirements. This
is a key factor for the user; it ensures that the application is implemented
correctly the first time, with full user satisfaction.

     The benefits to the MIS developer are just as significant. Both user and
developer will perceive the specifications, which are jointly developed, as
being complete. Automatic generation of code will further shorten the
development cycle as well as project backlog and will help implement systems on
schedule, within budget and with complete satisfaction.

                         About PC-SYSTEMS

     PC-SYSTEMS software company has devoted its resources in the past six
years to research and development of PC-based productivity software. The
driving force behind these efforts has been the demands of both the business
community and MIS to increase productivity by improving system development
efficiency at reduced cost. The main objective of PC-SYSTEMS is to develop a
low risk, high productivity tools that will minimize cost while improving the
end product.

     PC-SYSTEMS is currently marketing three (3) software products:

■ MODEL-S This product is the key software of PC-SYSTEMS.

■ DREAM   Data Retrieval, Entry And Management system which is a menu driven
          relational DBMS. It puts power in the hand of the user without
          programming.

■ PSP     Professional Screen Painting manager which enables development of
          menus, on-line help, electronic note pad and other general purpose
          screen and save them on file. PSP comes with programming toolkit
          which enables programmers to imbed PSP subroutines in their custom
          programs and retrieve PSP screens with CALL statements.

     PC-SYSTEM will continue to support its many satisfied users and is
planning to enhance and improve its products. Future plans include expansion of
MODEL-S to the main frame arena to satisfy the growing demand for modeling and
prototyping among developers.