A Distributed Architecture Helps Integrate CASE Tools

fourth of a six-
- column series
on tntegrated
Po An ti
systems engi
neering (I-
CASE) technolo-
gy, eramines the
architecture of .
an I-CASE tool.
last week's col- .
umn, CASE si
"tools can support

MATI
| Z tne full life-cycle.

process of a sij system, from
planning, analysis and design to code |.
generation and maintenance.

The architecture of I/CASE tools vpi ;
cally consists of PC-based, front-end .
workstations tightly coupled to main-:
frame-based, back-end code and data-
base generators. The front-end
workstations are used for planning, '''''
analysis and design functions. The back )
end system supports automatic code '.''/':
generation, documentation generation, ""
database generation di penal ii
agement aids.

Analysts using f rontend CASE tools se

;

their own workstation, and, to provide
local completeness and consistency TE:

dia and knowledge Coordinator | in that;
workstation.

edge base across a large development or,
information-engineering effort reguires '
substantial computing power and is ike-

trols the central encyclopedia. A distrib-'

The accompanying illustration shows: dE
— the architecture of a typical multitiered ""

cal area networks, departmental mini-'

the information provided by different
tools used by the developer. The depart- "

tains a central encyclopedia with a '

sures consistency among the work of.
' different developers. ie

From the central encyclopedia, the de- '
veloper can check out a hyperview, or a
set of objects, duplicating them into his,"
or her own encyclopedia. From that, '
point, the developer can work with the

tion thats coordinated in the work- iioii
station. '

When satisfied with the new informa:
tion, the developer then checks it, back

coordinated with central informallon.
That's how consisten

across a large zs Or multiple
projects in an information-e »nginec
environment.

Pe a dei lesi
pe rtv Local neg

- store and

ha E

must be able to get a fast response tor, |

-checking, there should be an encyelope ii ji H ša
ly to be done on the machine that con: "::

computers and corporate mainframes. dij , M š | G
Each PC workstation contains a local" M
encyclopedia and knowledge coordina- '''
tor, thereby ensuring consistency among ". ;
mental minicomputer or mainframe con- Vi
knowledge coordinator that in turn s Nje m k

di. "MRENE

duplicate set and create new informa-'' ji | impossib

ga Be: Pi hi s
ea

into the central encyclopedia, where it is  cyclo

ava sna sea to] "on thed

JANUARY 30, 1989

APPLJED INTELLIGENCE

An encyclopedia at the minicomputer .

level can be used to accumulate and an-
alyze design specifications for an entire

-, project. Design information that is to be
- ' shared across an entire organization,
' such as enterprise models, data models

and process models, can be stored in a
corporate encyelopedia. at the main-

': frame level. '''-'''

Building and integratini the informa-

tion systems needed in an enterprise are

achieved by synthesizing the models and
designs of many paš throughout the

' enterprise.

CASE tools with a zminii encyclope-

dia make this possible. The amount and.

complexity of information in an enter-

A prise is so great that synthesis is almost

Distributed Architecture

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uted architecture is thus desirable.' "''' Et GE repro

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ocelens in the projectrjeve or central en-
opedia. |

dovede. PERNE
esign, he or she will extract whatever
information in the central encyclopedia

-a data model. 1

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E oordinitina, the com nine knowledge base
ose a large development or aaa o el eU
is ia with a distributed architecture. .

common data model.

|— internal consistency as possible in
ik team le unfumillar with the entire set of | m Pok

'ey is unlikely to be achieved, The James Martin Producti: Series,

a evolution of CASE built. an infor m service dobni guar-
; teriy,

najet odel se y, iS available through High Pro-

design. For exampl some- <
ing dne deal ot a pu h

k also to oper
s of objects and zones of internal consis-
;  tency and, possibly, interfaces belega

, Zones t t are agreed to be inconšistent. 8305. In Europe, contact Savant, 2
j There are usually multiple versions of New St., Carnforth, Lanecs., LAS 9BX
gn. The workbench should enable United Kingdom (0524) 734 505.
1 |
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already in the encyclopedia.

The designer thus extracts informa-
tion from the central encyclopedia into
his local encyclopedia, works on it in
the local environment; and then inte-
grates it with the knowledge in the cen:
tral encyclopedia.

When the design is coordinated and
approvaed, it will reside in the central
encyclopedia and may affect the work
of other designers. There may be many
local encyclopedias all being used in
conjunetion with the central encyclo-
pedia. |

The central encyclopedia contains
many hyperviews that may overlap. In
other words, they use many common ob-
jects and employ data derived from a

multiple versions of designs to be stored
and archived. The graphics representa-
tions on the screen should be able to
show all inconsistencies between two
hyperviews or between versions of the
same hyperview. This can be done with
highlighting, reverse video or color.
Different designs are often worked on

simultaneously by independent teams.
Because of this independent develop-
ment, hyperviews may contain contlict-
ing information. They may contain in-
compatible descriptions of the same
objects.

A goal of development with CASE
systems should be to remove such in-
compatibility. Incompatibility is mini-
mized by using the descriptions of data
and other objects that are already in the
central encyclopedia, whenever possible.

Sometimes a design cannot be
changed, however; at least, not, guickly.
Often, a design is frozen while the pro-
gramming of that system is done. The

objects are software modules or pack-
zb ii) Ni: | ages that cannot. be modified. The ency-
NOE: bi aii, clopedia should have knowledge about
EM what can and cannot be modified.

Corbo tate Often a bridge is needed hetween
rale znojelopedla subsystems that are incompatible. Good
bitev s Š design has uncomplicated interfaces.

TU The bridge ought to be no more than the
conversion of data that passes from one
subsystem to another. The encyclopedia
should make clear the different incom-
patible versions of data, and the dia-
grams should show the data conversions
necessary to build bridges between sepa-
rate systems or different hyperviews.

Coordinating Development

A data administrator has the task of
coordinating the logical representations
of the corporation's data. An extension
of this task is the general coordination
of what is in the encyclopedia. I will re-
fer to the person responsible for this
task as the development coordinator.

Like the data administrator, the devel-
opment coordinator needs computerized
tools to help him analyze and coordinate
the knowledge. He or she will examine
many perspectives, helping to synthesize
them into as consistent, a whole as pos-
sible. He may be regarded as the custo-
dian of the central encyclopedia.

The development coordinator ought to
report at a suitably high level, typically
to the vice president of information ser-
vices. He has a dotted-line link to the in-
formation center, development, center
and the project managers, and is respon-
sible for ensuring that they use the en-
cyclopedia and link into the data model,
bič and that the best possible coordination
of systems is achieved.

Next:s week's column will discuss the
functional characteristics you should
look for in a CASE tool. H

- zi s]
a ME

zde NE a ji, LEM ' a.
L ai o CE k i-i air: z ja
rah a NINE I
PENE JIM MA PRRALMA., kali deje m či U

David Hannum

i

| 4

l
k bi

— The objective is to achieve as much

' knowledge stored in the encyclopedia. In
a large organization, complete consisten.

ductivity Software Inc., af Marble-
head, Mass. 1-800-242-1240. For infor-
mation on seminars, please contact (in
the United States and Canada) Tech-
nology Transfer Institute, 741 10th St.,
Santa Monica, Calif. 90402 (213) 394-

need to be designed to enable an enter:
prise to work toward consistency, but

ate with different versions "