So you want to enter the brave new world of Distributed Computing.
But you have a huge baggage of existing applications that you can't
throw away. Not to worry! This article will show you the various options
available to leverage those existing applications and still not miss
the technology bus.
Web services are the logical next step in the evolution of e-business.
The new era of distributed computing is all about using Internet technologies
and standards to create applications that span the globe, cutting across
time zones and cultures, and serving diverse markets. The Web services
vision is one where everything is viewed as a service that can be dynamically
discovered and consumed, using messaging on the network. Businesses
can sell their services to others by publishing them on the Web.
Enterprises have made significant investments in older applications
that were developed when there were no open standards. These applications
use proprietary technologies that are not interoperable with each other.
These applications will continue to be useful in the future and cannot
be discarded.
Existing applications are also quite complex in nature. For example,
a payroll system developed in the US may take into account certain US
labor laws when doing its processing. The same application, when offered
worldwide, has to offer a more generic interface so that users from
other countries can be accommodated. These interfaces also have to be
simplified to allow for maximum flexibility.
Lets say, Company ABC has an inventory management system sitting on
a mainframe computer. This system provides up-to-date information about
the company's product lines and items in stock. The company's sales
representatives need to have real-time access to this information to
perform their functions more effectively.
The company has a Windows 2000 Advanced Server with the Dot Net Runtime
installed. This server is connected to the Internet and through the
firewall, to the internal network of the company. To enable Internet
access to the mainframe legacy application, we need to build Web Service
Adapters that will expose the application's functionality through the
<link> Simple Object Access Protocol (SOAP) <link>.
Click on the diagram for a larger view.
A Web Service Adapter is a wrapper program that will talk to the legacy
application using its native protocol at one end, and talk to the rest
of the world using SOAP, at the other end.
The Web Service Adapter can be built using Microsoft VisualStudio.NET
that makes creation of Web Services a snap. Since a typical inventory
application will have a lot of functionalities, a number of such web
service adapters need to be created, each exposing a specific functionality.
These web services will be published using the Web Services Description
Language (WSDL).
The company's sales representatives will use applications that access
this web service over the internet using a simple URL like http://www.abc.com/services/inventory/CurrentOrders.asmx.
The web server will transfer the request to the web services adapter,
which, through the Dot Net runtime, will talk to the legacy application
and return the required data. This whole process will be totally transparent
to the end user. The company's legacy application will be now employed
gainfully to reap all the benefits of the internet-enabled applications
without having to start from scratch.
We at Stylus, with our deep understanding of how the web works,
can help enterprises migrate their legacy applications to the web painlessly
and effectively. We work on the cutting edge web technologies and bring
our rich experience of developing effective enterprise solutions, to
help you realize your goals.
Useful Links:
http://www-106.ibm.com/developerworks/webservices/library/ws-legacy/
In addition to Creating Web Services from existing applications, we
also offer other services like Business Process Engineering, Porting Legacy
applications to the web and Enterprise Application Integration. Please
contact us here
for more details.
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