What are Web services?
Web services
are modular applications that interact with one another across the
Internet. Web services are based on shared, open and emerging technology
standards and protocols (such as SOAP, UDDI and WSDL) and can communicate, interact and integrate
with other applications, no matter how those applications are implemented.
What is the Web services gateway?
The
gateway provides you with a single point of control, access and validation
of Web service requests, and allows you to control which services
are available to different groups of Web service users. You use the
gateway to make available controlled sets of Web services for use
within your organization and by external users. The services that
each gateway instance makes available as Web services can be a mixture
of internal services that are directly available at service integration
bus
destinations and
external Web services. This approach provides the following benefits:
- The gateway service is made available at a different Web address
to the target service, so you can replace or relocate the target service
without changing the details for the associated gateway service.
- You can have more than one target service (that is, more than
one implementation of the same logical service) for each gateway service.
- The gateway service can be made available on a different service
integration bus to the target service.
- The gateway provides a common interface to the services in each
set. Your gateway service users need not know where each underlying
service is located, or whether the underlying service is being provided
internally or sourced externally, or whether there are multiple target
services available for a single gateway service.
How does the Web services gateway work?
When
you create
a gateway service, you map an existing destination
that hosts a target service (either an internal service or an external
Web service) to a new Web service that seems to be provided by the
gateway.
Who should use the Web services gateway?
An
enterprise that chooses to share its resources selectively with its
business partners and customers, or an enterprise that uses external
Web services and wants to make them available internally. IT managers
and developers, who deploy resources, can also benefit from this technology.
What business problems are solved by the Web
services gateway?
The gateway solves the following business
problems:
- Securely "externalizing" Web services: Business
applications that are exposed as Web services can be used by any Web
service-enabled tool, regardless of the implementation details. To
better integrate your business processes, you might want to expose
these assets to business partners, customers and suppliers who are
outside the firewall. The gateway lets clients from outside the firewall
use Web services that are hosted within your enterprise. Using the
gateway, you can control access to each of these services.
- Better return on investment: Any number of partners
can reuse a process that you develop as a Web service.
- Use of existing infrastructure: With the gateway,
you can make readily available as Web services any combination of
your existing internal services and external Web services, no matter
how each of those existing services are currently accessed (for example
through a service integration bus destination, a Web address or a
UDDI registry).
- Protocol transformation: You might use one particular
messaging protocol to invoke Web services, while your partners use
some other protocol. Using the Web services gateway, you can trap
the request from the client and transform it to another messaging
protocol.
How do I migrate from a previous version of
the gateway?
You use a wsadmin command script to migrate
a WebSphere® Application
Server Version 5 gateway to the new gateway capability that is provided
in Version 6 by completing the steps described in Migrating a complete gateway
configuration.
Can a gateway that is fully integrated within IBM service integration technologies
co-exist with a previous version of the gateway?
A WebSphere Application Server
Version 6 cell can contain both Version 5 and Version 6 application
servers, so you can continue to use Version 5 gateways that are deployed
to Version 5 application servers even if you migrate the cell from
a Version 5 to a Version 6 deployment manager. However, before you
migrate the cell you must preserve the gateway configuration as described
in Co-existing
with previous gateway versions.