Guest speaker:
Joe Pluta, Pluta Brothers Design Inc.
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
This is a review of the various technologies for
Web-enabling legacy applications. Companies
Web-enable for many different reasons, and
there are many different options. Some of them
you may not have even considered. So, rather
than rehash just the most popular techniques,
this presentation will attempt to address all of
your Web-enabling options. I’ll also try to give
you some idea of the available products.
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
The Options
Replacing
Refacing
Rewriting
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Replacing
If your existing system is out of date and
unable to cope with your requirements,
you may want to consider replacing it.
Many vendors can supply you with
ready-made Web-enabled systems.
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Refacing
Traditional Model
Terminal Emulation
Thin-Client Computing
Screen Scraping
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Traditional Model
RPG
Program
EXFMT
Workstation
Data
Management
5250 data
stream
5250
Terminal
Display
File
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Terminal Emulation
RPG
Program
EXFMT
Workstation
Data
Management
5250 data
stream
5250
Emulator
Display
File
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Terminal
Emulation
Many vendors
Client Access Express
Mochasoft
Rumba
Shareware and Freeware 5250
Emulators
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Terminal
Emulation
Can now be done over VPN
Virtual Private Network
Secure, Stable, Reliable
Speed depends on Internet
connection
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Thin Client Computing
RPG
Program
EXFMT
Workstation
Data
Management
Display
File
© 2003 Pluta Brothers Design, Inc.
Thin-Client
Terminal
Server
5250 data
stream
TCP/IP
5250
Emulator
Thin
Client
http://www.plutabrothers.com
Thin-Client Computing
Citrix MetaFrame
GraphOn WinBridge
Microsoft Terminal Server
SCO Tarantella
Virtual Network Computing
Wyse Winterm
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Screen Scrapers
RPG
Program
EXFMT
Workstation
Data
Management
5250 data
stream
Screen
Scraper
Client
Display
File
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Screen Scrapers
Providers dwindling:
Core Technology
Jacada
Seagull
Zephyr
© 2003 Pluta Brothers Design, Inc.
Gone:
Easel
Flashpoint
Mozart
http://www.plutabrothers.com
To Scrape or not to scrape
Pros:
No source changes
Desktop integration
Cons:
Fewer vendors
The interactive tax
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
CFINT: The Interactive Tax
CFINT is a system job that consumes
CPU resources when it recognizes that
your interactive workload exceeds the
interactive CPW rating of your machine.
This governor is indiscriminate: When
CFINT kicks in, all of your jobs, batch and
interactive, come nearly to a standstill.
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
CFINT: The Interactive Tax
Most new iSeries models now offer only
two options for interactive CPW:
Standard models have zero interactive
capability
Advanced edition servers have full
interactive capabilities
Except for the very smallest iSeries
model, there is no middle ground.
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
How Much Does CFINT Cost?
To determine the direct cost of interactive
CPW, go to the following IBM Web page:
http://www.iseries.ibm.com/servlet/factFind
This page compares the costs of various
iSeries configurations.
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
How Much Does CFINT Cost?
The 810-0869 is a 2700 CPW machine.
With zero interactive this model costs
$50,000, while the same machine with
max interactive costs $245,000 – nearly
five times the cost.
higher
CFINT makes your hardware costs
.
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
IBM Options
Screen Scrapers
Host Publisher
Host On-Demand
HATS
Like all screen scrapers, the IBM screen
scraper solutions require interactive CPW.
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
IBM Options
RPG
Program
EXFMT
Workstation
Data
Management
Display
File
Data Buffers
Java Beans
and Java
ServerPages
WebFacing
Runtime
(WAS)
HTML
Browser
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
IBM Options
Until just recently, WebFacing also used
interactive resources. Now, however, on
the newer server models WebFacing will
not require interactive CPW.
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Interactive Technologies
Except for the new WebFacing offering, these
are all interactive techniques that require no
modifications to the legacy systems. These
have an initial cost/benefit advantage.
However, the new IBM pricing model has
made interactive solutions too expensive for
many businesses to maintain.
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Rewriting
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Rewriting
Two architectures:
Client/Server
Application logic on client, makes
requests to servers on the host
Examples: ODBC or Web services
Server/Client
Application logic on server, makes
requests to client to present data
Examples: X-Windows or good old 5250
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Client/Server
Business logic encapsulated in
servers or replaced by ODBC calls
Application logic moves to client
Three client options:
Remote database
Thick client
Browser-based
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Remote Database
AS/400
Workstation
DB2
ODBC
Support
ODBC
based
application
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Remote Database
Remote database designs are relatively less
flexible than other architectures. Because the
client must have complete knowledge of the
database layout, changes to business rules that
affect your database can be difficult to deploy.
Remote database is best suited for ad hoc user
queries, and not for mission-critical enterprise
applications.
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Thick Client
AS/400
Server
Workstation
Program
Call
Support
Client/
Server
Application
Server
Server
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Browser Based
AS/400
Server
Workstation
Web
Application
Server
Web
browser
Server
xxxx
xxxx
xxxx
Application
and
business
logic
Server
© 2003 Pluta Brothers Design, Inc.
Note: This interface uses
only HTML, so no
sophisticated graphics
are supported.
http://www.plutabrothers.com
Other
The other client/server architectures share the
same concept: business logic is encapsulated in
servers. Whether exposed via program call or
Web service, or encapsulated in Java classes,
these server programs are probably the ultimate
goal of a complete rewrite.
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Other
Unfortunately, there are no tools today that can
directly mine business logic, although some
companies are beginning to claim that ability.
Certain 4GL vendors also claim to be able to
encapsulate your business rules. But in most
cases, a true client/server design will require a
significant investment in rewrite (which also
means re-testing).
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Server/Client
Application logic unchanged
I/O requests replaced by API calls
Three UI options:
Thick client on workstation
Thick client applet
CGI or servlet/JSP to browser
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Browser Technologies
Static Web pages
Common Gateway Interface
Servlets
JavaServer Pages
JSP and servlets
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Static HTML
Workstation
AS/400
HTTP
Request
Web Server
Web
Browser
HTML
Data
Static HTML
Pages
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Common Gateway Interface
Workstation
AS/400
HTTP
Request
Web
Browser
HTML
Data
© 2003 Pluta Brothers Design, Inc.
Web Server
CGI Program
(RPG, Perl, …)
Database
Data
http://www.plutabrothers.com
Servlet
Workstation
AS/400
HTTP
Request
Web
Browser
HTML
Data
© 2003 Pluta Brothers Design, Inc.
Web Server
Servlet
(Java)
Database
Data
http://www.plutabrothers.com
JavaServer Pages
Workstation
AS/400
HTTP
Request
Web Server
Database
Data
Web
Browser
HTML
Data
JSP Processor
JavaServer
Pages
© 2003 Pluta Brothers Design, Inc.
JavaBeans
http://www.plutabrothers.com
Servlet/JSP
Workstation
AS/400
HTTP
Request
Web
Browser
Web Server
Servlet
HTML
Data
JSP Processor
JavaServer
Pages
© 2003 Pluta Brothers Design, Inc.
Database
Data
JavaBeans
http://www.plutabrothers.com
Server/Client
Application logic unchanged
I/O requests replaced by API calls
Three UI options:
Thick client on workstation
Thick client applet
CGI or servlet/JSP to browser
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
e
Serv r/Client - CGI
AS/400
Workstation
HTTP Server
Application
rewritten to
replace
workstation I/O
with CGI calls.
Web
browser
xxxx
xxxx
xxxx
Note: This interface uses
only HTML, so no
sophisticated graphics
are supported.
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
e
Serv r/Client - CGI
Replace I/O with CGI calls
Requires an HTTP server
Several vendors
FreeStyle/400
LegacyWeb
Relational Web
© 2003 Pluta Brothers Design, Inc.
(*)
http://www.plutabrothers.com
Server/Client - Thick Client
AS/400
Application
Client
Workstation
Server
Client
APIs
© 2003 Pluta Brothers Design, Inc.
Thick
Client
UI
Server
http://www.plutabrothers.com
e
Serv r/Client – Thick Client
Replace I/O with server/client API
May require additional software
Jacada
PSC/400
Seagull
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Server/Client - Applet
AS/400
Application
Client
Server
Client
APIs
© 2003 Pluta Brothers Design, Inc.
Workstation
HTTP
Server
UI
Server
Applet
Web
browser
http://www.plutabrothers.com
Server/Client - Servlet/JSP
AS/400
Application
Client
Server
Client
APIs
Workstation
Web
Appl.
Server
Web
browser
xxxx
xxxx
xxxx
Servlet
Java
Server
Page
© 2003 Pluta Brothers Design, Inc.
Note: This interface uses
only HTML, so no
sophisticated graphics
are supported.
http://www.plutabrothers.com
e
Serv r/Client – Servlet/JSP
Replace I/O with server/client API
Requires Web Application Server
May require additional software
Jacada
Jaci/400
PSC/400
Seagull
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
e
Serv r/Client – Servlet/JSP
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
e
Serv r/Client – Servlet/JSP
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
e
Serv r/Client – Servlet/JSP
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
Emulation
Thin Client
Scrapers
WebFacing
C/S
S/C CGI
S/C thick
S/C browser
Dialup
Y
N
(N)
(N)
Y
Y
Y
Y
Batch
N
N
N
(Y)
Y
Y
Y
Y
Thick Client
N
N
Y
N
Y
N
Y
N
© 2003 Pluta Brothers Design, Inc.
Browser
N
(N)
N
Y
Y
Y
N
Y
No Source
Y
Y
Y
(N)
N
N
(N)
(N)
Time
+
++
++
++++
+++
+++
+
Cost
++
+++
+
++
+++
http://www.plutabrothers.com
e
Serv r/Client – Servlet/JSP
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com
e
Serv r/Client – Servlet/JSP
© 2003 Pluta Brothers Design, Inc.
http://www.plutabrothers.com