Download Downsizing: Client/Server Computing

Downsizing : Client/Server Computing
Joe Wang, The Upjohn Company, Kalamazoo, MI
(616)329-8421
Standardized interfaces for applications
allow users to make quick transitions to
other GUI-based applications.
ABSTRACT
Client/Server "fever" is spreading across Corporate
America like wild fire. Does your company want to
get on the bandwagon? Can you really save money
by using Client/Server technology? How much
productivity can you gain when you migrate your
system to the Client/Server platform?
2)
The Local Area Network (LAN) provides a
means to connect the new generation of
powerful personal workstations to other
LAN, midrange, and mainframe systems.
The ability to be connected to multiple
platforms allows the user to transparently
access data residing on different
platforms. Easy-to-use 4GL tools use
SOL commands as a generic means to
retrieve information or statistic, more
quickly, allowing us to react faster to
industry changes.
This paper gives answers to six key questions of
"Downsizing". It also provides practical advises on
selecting a Client/Server model which best ms your
shop and your SAS® applications.
1) Why do you want to downsize?
2) What is client/server?
3) What is the best Client/Network/Server Operating
System?
4) Is SAS portable?
5) What are the success factors?
6) What are the potential problems?
- With PC SAS
- Without PC SAS
3)
Flexible system configuration
Because of the low cost of the hardware
and software of the client/server, the end
user department can change/upgrade
hardware and software configuration
quickly based on the users' needs.
WHY DO YOU WANT TO DOWNSIZE?
In the past two decades, the emergence of advanced
personal computers and workstations, globally
connected local area networks and data
communications, distributed database management
software, and graphical user interfaces enable many
companies to migrate their applications from a
mainframe to client/server environment. There are
six major reasons for downsizing.
Easy data access
4)
User has more control
As technology moves processing power
and applications development tools to the
user department level, applications take
less development time and ongoing
support. End user departments have
more control on the system configuration
and priority of projects.
1) Better user interface
Graphical User Interface (GUI) has not only made
software systems more user friendly, they have
also set standards for application program
interfacing. GUI provides an end user with a
"point and click" type environment with pop-up
menus, scroll bars, and radio buttons.
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Users are now able to accomplish many
of the tasks and functions that previously
required the intervention of programmers.
5) Cost saving
Since the cost ratio of PCs and servers
are dropping every year, some experts believe
that client/server computing could be half as
expensive as minicomputer-based systems and
one-third as expensive as mainframe computing.
WHAT IS CLIENT/SERVER?
1) Definition of Client/Server
The key aspect of Client/Server
computing is the capability of one or more
computers (Clients) to access (via
networks) and utilize one or more
computers (Servers) to perform a task.
(Figure 1) In short, the server provides a
service to the client. For example, the
clients can be 486 PCs running Windows
3.1 and the servers are SUN SPARC
workstations running UNIX. The SUN
SPARC workstations provide printing, file
management, and program execution
services.
In general, when migrating to a client/server,
users save cost in tenms of host hardware,
maintenance, and licensing fees.
6)
Re-engineer the business process
With this new enabling technology, Client/Server,
business executives should be able to redesign
the business process to coordinate crossfunctional workflow, infonmation technology,
people and organization, policy and regulation,
and physical infrastructure. The end result is to
build more flexible and effective process to deliver
more value to the organization's customers.
While downsizing may offer more power on the
desktop for less cost, most organizations still have
large investments in mainframe hardware, software,
and data. Many downsizing strategies do not totally
eliminate traditional mainframe systems, but rather
attempt to select the most appropriate platfonm or mix
of platfonms for a business enterprise.
2)
Closer look
There are five layers between the client
and the server:
Client
===========================
Programming interfaces
Client/Server enabling services
Client/Server core services
SAS* Server
Communications backplane formats &
Client/Server
Server
protocols
UNIX:
Network transport
multi-sesslon
compubng
IBM*\lMICMS.
singig.oossion
Server
The application programming interfaces is
the layer that users see and work with.
.-riiting
Client
The enabling services, such as database
management, workflow routing,
transaction management, and document
linking, enable users to build their
applications.
Figure 1
Client/Server
The core services provide definition,
directory, and security facilities.
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A communication backplane deliver the content of
messages between clients and servers.
Examples includes remote procedure calls, X.400
electronic mail, and object request brokers.
A network transport provides communications
between clients and servers. TCPIIP, NovelJ®s
IPX, and IBM®>s SNA are the most popular
transport.
IS SAS PORTABLE?
Ves, SAS is portable among dtlferent
computer platfonns. Vou can port your SAS
programs from a PC to a mini or a
mainframe. Nevertheless, there are two
things you need to pay attention to:
1) MuHi-platfonn version compatibilny
Surround all these layers are application
development tools and management tools. These
tools allow users to manage their client/server
project more effectively and efficiently.
WHAT IS THE BEST CLIENT/NETWORK/SERVER
OPERATING SYSTEM?
Not all versions of SAS are compatible
under different operating systems. For
example, SAS 608 on IBM VM/CMS is
compatible only with SAS 609 on SUN
Solaris.
2)
Picking the best operating system for your company's
clientlserver platform can be tough and tricky
especially when you plan to move mission-crnical
applications to this platform. When you pick the best
operating system, you need to pick them for the
client, the network, and the server.
Novell Knhwear has about 60% of the Network
operating system market. Knnwear 4.x provides
robust messaging, distributed security and directory
services, and the fastest file and print service and
allows users to easily manage large enterprise
networks. Nevertheless, the new MicroSoft Windows
NT 3.5 bundled wnh the BackOffice provides a
superb client/server support. BackOffice offers Sal
Server, SNA Server, Systems Management Server,
and Mail Server which based on Windows NT. More
and more companies are migrating their Knnwear
servers to NT servers.
Unix vendors are untlying themselves wnh the Spec
1170, Common Desktop Environment, and better PC
connection to stay alive.
Platfonn dependent system options
Before you migrate your SAS programs to
another computer platfonn, h is a good
practice to consolidate the platfonn
dependent code like FilENAME,
LlBNAME, macro library, and WORK
library together in one place, test the new
code on the old platfonn, move the code
to the new platfonn, and change all
platfonn dependent code accordingly.
WHAT ARE THE SUCCESS FACTORS?
In order to successfully implement a client
server project, certain key criteria are required
as follows.
1) Upper management support and push
Support from the upper management is
extremely important when unforeseeable
technical problems are encountered or
when the implementation slows down.
2) Top priorny project
As for the best operating system for a client, there is
no definne winner yet. OS/2 Warp 3 is more robust,
but n only supports a subset of the Win32 API.
Windows NT is secure and robust, but h demands at
least 12 MB of memory. Windows 95 will run all 16bit Windows application in a single address space,
which makes h less robust than OS/2 and NT.
,V',:-
Make sure your client/server projects
have top priorhy. This will guarantee the
high level of support from management
and participation from users.
3) Parallel processes
During the implementation, keep the old
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environment along with the new environment for
performance comparisons until the new process
has stabilized.
character for running batch programs on
DOS.
2) Slow implementation
4)
Incremental release
Incremental release the new programming
environment in order to ease the transition.
5) Productive project team
A productive project team which consists of
managers, system engineers, lead analysts, and
the project leader with different knowledge.
WHAT ARE THE POTENTIAL PROBLEMS?
1) IBM/UNIX/DOS file formats incompatibility
This might be the most difficult problem for you to
solve if you are not aware of that IBM, UNIX, and
DOS have different file formats/EOl (End Of
Line) characters. The following are scenarios
which might happen:
a) When uploading PC files to VM/CMS, the
whole file may become one long record
sometimes.
b) When using the PC editor to create REXX
programs, the uni-REXX interpreter on Unix may
not execute these programs.
Client/Server is a new concept and
technology for programmers in many
company. Some programmers are not
familiar with Unix or PC. When key
programmers are asked to migrate their
applications to this new platform, some
might respond with the following:
a) No time to leam or migrate
b) New technology is too hard to learn
c) New system/technology is not robust
and error-free
People resist changes because they feel
more comfortable in the environment they
know the best and this resistance can
definitely slow down the implementation.
3) Bad vendors' technical service
In the client/server environment, You
purchase hardware/ software products
from many different vendors. When a
problem arises, the in-house Information
Center and Computing Service units may
not know the solution. The vendors'
technical service become vital to the
success of the project.
4) High development/maintenance cost
c) When using the PC editor to create DOS
batch programs, DOS may not execute these
programs.
Unlike the mainframe environment which
users can solely rely on one vendors
service, the client/server environment
requires users to integrate
hardware/software from many vendors.
Users need to have a well defined
plan/schedule on training and
implementation to avoid potential high
development/maintenance cost.
The key to these problems is the IBM/UNIX/DOS
file format incompatibility -- namely, the choice of
the End Of Line (EOl) character. The PC editor
allows users to specify either the Unix or DOS
EOl for a file. For files with the Unix EOl,
PC/FTP (the network file transfer program)
assumes that the file has the DOS EOl when the
file is uploaded to VM/CMS. Therefore, the Unix
EOL is ignored and the file becomes one long
record when it is transferred to VM/CMS.
TWO CUE NT/SERVER MODELS
For solving scenarios 2 and 3, the trick was to
specify the Unix EOL character for running uniREXX programs on Unix and the DOS EOL
Two client/server models are layed out below.
Which model you pick is based on the type of
SAS application that you run in your
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company. If your application is interactive oriented,
pick model 1). If you can run your applications in
batch mode, pick model 2). But remember that these
two models require different network bandwidth,
hardware power, and software license.
1)
W~h
PC SAS - interactive oriented
PCWEEKLABS, "Guide to Operating
Systems", PCWEEK, November 14, 1994,
p.125-t63
For the SAS users who can not live without using
the Display Manager to edit programs, subm~ a
portion of program to run, fsview/fsedit a data set,
this is a perfect solution.
Further equipped w~h SAS's remote compute,
data transfer, and remote library services, users
can build various types of client/server
applications. Depending the size and frequency
of the data transferred between a client and a
server, a high bandwidth network is needed to
keep a reasonable response time. A PC wnh fast
CPU and large hard disk is also required ij users
want to run analysis against the data resides on
the hard disk.
W~hout
Marion, William (1994), Client/Server
Strategies
Rymer, John R., "Networking's silly putty",
Communications Week, June 20, 1994, p.4849
This model has four major components,
a) SAS OMS
b) remote compute service
c) data transfer service
d) remote library service
2)
REFERENCES
PC SAS - batch oriented
This model has three major components,
a) MS Windows program editor
b) remote shell
c) NFS mount
For this model, a MS Windows program edftor is
the focal point. Users edit programs reside on
the Unix server's directories mounted to the PC
as local drives. Then, users remotely subm~ the
program to a Unix server for execution. They can
browse SAS log and listing files from the same
program ednor when the execution is done. The
setup of this model will be cheaper than the first
model because ~ does not requfte a high-end PC,
PC SAS, and high bandwidth network.
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Wang, Joe, ·SAS Server: Client/Server
Computing", Proceedings of the Ninetheenth
Annual SAS Users Group International
Conference
SAS is a registered trademark or trademark
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countries. IBM and VM/CMS are registered
trademarks or trademarkS of Inte~tional
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Other brand and product names are
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