Restructuring
Among the
' most urgent is-
sues in the CASE
industry today is '
the need to devel-
op better tools
for restructuring,
re-engineering
and reverseengi-
neering existing
applications code
into more easily

expandable,
maintainable

systems.

As outlined in
previous columns, restructuring involves
automatically converting unstructured
source code into structured code; reengi-
neering is used to standardize data defi:
nitions, remove redundancies and anom- ..
— alies in existing systems, and Finci
reimplement the application in a new
form; and reverse engineering is con-
cerned with extracting high-level specifi-

cations from existing code in the form >
of data and process models." Rea

Most computer-aided software engi-

neering (CASE) tools currently don't

provide facilities to restructure or re-en-
gineer existing code; they are focused on
automating the production of new appli-
cations. However, as much as 80 percent
of the pri ing effort in many in-:
formation-systems is) organizations is
directed toward the enhancement of ex-
isting applications. B.

'Tackling a Thorny Task .
Forward-engineering from graphical ..
design specifications using a convention:"
al CASE tool is much simpler to enact '
than true reverse-engineering, which de-
mands the extraction of specifications »
from existing systems. For instance,'' 1
more than 200 CASE vendors support:
the conventional forward-engineering |"
process, although very few vendors ' /''
have tackled the thorny task of reverse: '
engineering existing applications. In fact,

no vendor has yet solved this problem :.

,. for both the data and process sides of /
an application ;!": %W MJU
Organizations
nize the increasing
serving the value of past software in-
vestment through re-engineering the ex-
isting software base. Many organizations
have 10 million to 20 million lines of
code that must be maintained and en: «:
hanced for many more years; replacing

ward-engineering technigues is impracti:
cal at best. ia
The restructuring of existing code is '

one of the simplest methods available to |

reduce the cost of maintenance. Using :
products such as Language Technology
Ines Recoder or IBM's COBOL Structur-
ing Facility permits existing unstruc- .
tured COBOL programs to be restruc-
tured automatically,

As shown in the figure, these pro-
grams take spaghetti-code input and
proda pac structured code and

ocumentation as output, The resul
structured programs are identical ne
functionality to the original unstruc-
tured programs; however, the structured

this large body of code using only for..." v "she

bina:

nji

APPLIED INTELLIGENCE Či

Code Is a Sound Investment in the Future

code is typically 20 percent to 25 per:
cent less expensive to maintain.
In operation, the restructuring tool ex-

|ecutes a complex algorithm to automati-

cally structure the spaghetti code. First,
it reduces the program to an abstract,
control-flow design. This design is then
analyzed and redesigned to achieve a
cleanly structured control graph, which
is then run through a COBOL generator
to reimplement; the structured design.
Documentation is produced in the form ,
of structure charts, control:£flow dia--
grams and reports on problem areas in
the code, such as unreachable code, end-.
less loops and poor structure.
Specialized versions of these products

'tenance costs substantially by using
automated tools to analyze its portfolio
of COBOL programs, identify poorly
structured routines and automatically
restructure these programs. Metrics
tools provide an objective evaluation of
the cornplexity and guality of each pro-

' gram module.

As illustrated in the figure, the re-
structuring process does not extract
specifications from the restructured
code; it stopš short of making control-
flow information accessible to the pro-
grammer. :

Some restructuring tools do provide
interactive access to the controlflow di-
agrams produced as part of the restruc-

Restructuring and Reverse Engineering
Of Software Processes

Multiple Vendors Support Restructuring of Process Code;

Unstructured code —
PSA SA
Ri KA ii

Resiructuring

Restructuring
engine

Extracted
specifications

(Process
model)

Reverse engineering

Addition of system-design and business know-
ledge through human programming experls

No Vendor Yet Supports Its Complete Reverse Engineering

Redesigned code
and documentation

Restructured
code

Documen- | Project
tation manage-
generator | ment tool

specitications

(Process
model)

Repository

« Goals » Report designs
« Screen designs
» Strategies

dis j
MisRtnatiti ši
iIHRGrTO lani"

» Data models
« Specitications

» Process models

» Rules « Data structures

» Program structures

— Organizations ions are beginning to recognize the increasing
importance of preserving the value of past software

through

; iste
iron dev j

" are available to restructure IBM's Cus- '

' tomer Information Control System
| gram (CICS) commands, such as POSA s
Handle construct, which can cause hid: /'

/, den control flow jumps whenever a par- '

ticular type of error occurs. To provide
an objective measurement of the guality
of the code, additional tools such as the
Inspector from Language Technology. '
can be used to apply structure and com-
plexity metrics to existing code.
Organizations such as the Hartford In: .
surance Group of Hartford, Conn,, have '
used restructuring and metrics tools in
support of an applications-maintenance
center. The company has reduced main-

reengineering the existing software base.

turing process. These tools, among them
a new product called Chrysalis from
Language Technology and the
'Via/Center product set from Viasoft
Inc., extract controHlow information
from the code and make this informa-

| tion available to programmers on line.

Using this information, prograrmers

/ can evaluate the structure and organiza-

tion of the program, how control is
passed between modules and how logic
and data flow through the program. The
Pprogrammer can use this information to
enhance and malntain the program at
the structure-chart level. E
As shown in the figure, a desirable

nesel,

next step in the extraction of control in-
formation from existing code is to pro-
duce higher-level control abstractions,

by extracting process specifications in
the form of process models that are inde-
pendent of the implementation environ-
ment. These process specifications can
then be combined with high-level data

. models, which are stored in the reposi"

of a CASE tool, and then enhanced
at the design level and reimplemented in
any supported environment.

It is desirable to build systems that
will be easy to change in the future. A
major goal of software engineering is to
make systems easy to enhance and
maintain. Applications built today
should be fully based on normalized
data models in a CASE repository.

To design systems that will ease fu-
ture enhancement and migration, the
following technigues are recommended:
6 Use CASE tools for planning, analysis,
design and construction.

6 Use a code generator driven by the
CASE design tools.
e Adhere to the principles and prac:
tices of information engineering.
e Create procedure designs that are in-
dependent of technology, which is likely
to change.
e Employ a code generator that can
translate the designs into implementa-
tions with different technology (for ex:
ample, a tool that can generate code
and data descriptions for different data-
base environments).
€ Use fully normalized data models.
€ Use fully structured code built with
an action-diagram editor that is part of
a CASE environment.
€ Use a relational database whenever
possible.
€ Use application standards such as
IBM's Systems Application Architecture.
€ Use a database-management, system
with field independence and features
that enable changes to be made without
rewriting existing programs.
€ Avoid unusual hardware, operating
systems or facilities that could make fu-
ture migration difficult.
€ Plan to do future maintenance by re-
generation.
€ Make upper-level management fully
aware of the business reasons for using
soltware-engineering technigues and
automation in applications development.

Next week begins a series of articles
on key industry trends in computer
hardware, software, database environ-
ment, communications and methodolo-
gies that are having a profound impact,
on the computer industry. 8

tory

The concepts embodied, in reverse-engi-
neering are described in the CASE
volume dn The James Martin Report
Series. For more information on this
volume, call (800) 242-1240. For in-
formation on seminars, contaci (in the
United, States and Canada) Technology
Transfer Institute, 741 10th St., Santa
Monica, Calif. 90402 (213) 394-8305.
In Europe, contact Savant, 2 New St,
Carnforth, Lancs., LA5 9BX United
Kingdom (0524 734 505.