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.