Web services are a technology that invokes services or applications
using Internet standards and protocols. You can read this topic to learn about
the core technologies on which Web services are developed and implemented.
If you have an existing application, and you want to make the service that
your application provides available to others - either within your own organization
or beyond it - you can use Web services technologies to provide a standard
Web interface for your service. Web services can be defined as middleware
that connects applications together no matter how each application is implemented
or where it is located.
Web services operate at a level of abstraction that is similar to the Internet;
they can work with any operating system, hardware platform or programming
language that can be Web-enabled and are one of the technologies that you
can use to implement a service-oriented architecture (SOA).
newfeatThe WebSphere Application
Server Version 6.1 Feature Pack for Web Services introduces additional Web
services standards that support interoperable and reliable Web services applications.
These additional standards support asynchronous messaging, which means
that your applications can exchange messages reliably even if one of the parties
is temporarily offline, busy, or not available. You can be confident that
your communication is reliable and reaches its destination while interoperating
with other vendors.
The core technologies on which Web services are developed and implemented
include:
WebSphere Application Server also provides other mechanisms that can help
you get the most out of your Web services:
- A private Universal Description,
Discovery and Integration (UDDI) registry
- A private UDDI registry provides a way to publish and discover information
about Web services that are available within and through your organization.
You can use it to make your Web services available to people within your organization,
or beyond your organization. A group of companies can use it to share their
Web services, or to make them available to others outside the group. At its
simplest, a private UDDI registry does for Web services what a business telephone
directory does for business addresses and telephone numbers. However, a private
UDDI registry is much more than just a directory. It needs to be in order
to harness the considerable power and flexibility of Web services. If you
publish your Web service to UDDI, you make it available for other people or
applications to discover and reuse. This saves development time, effort and
cost, and helps minimize the need to maintain several different implementations
of the same application.
- A Web Services Invocation Framework
(WSIF)
- SOAP bindings for Web services are part of the WSDL specification. So
when you think of using a Web service, you probably think of assembling a
SOAP message and sending it across the network to the service endpoint, using
some SOAP client API. The WSDL specification allows for extensibility points
which can describe alternate ways of invoking a Web service. A WSIF client
can make use of these non-SOAP descriptions to invoke a service in a more
efficient way. For example, a Web service provider might offer a SOAP binding
for the service and a local Java binding that allows you to treat the local
service implementation (a Java class) as a Web service. If the client is deployed
in the same environment as the service, then the local Java binding for the
service can be used. This provides more efficient communication with the service
by making direct Java calls rather than sending and receiving SOAP messages.
- To deploy a Web service as a WSIF-enabled service, you first develop and
deploy the Web service, then you develop the WSIF client based on the WSDL
document for that Web service.
- Web services and service integration technologies
Web
services can use the service integration bus and the Web services gateway
to provide a single point of control, access, and validation of Web service
requests and to allow control of Web services that are available to different
groups of Web service users.
With service integration bus-enabled Web
services, you can achieve the following goals:
- Take an internally-hosted service that is available at a bus destination,
and make it available as a Web service.
- Take an externally-hosted Web service, and make it available internally
at a bus destination.
- Use the Web services
gateway to map an existing service - either an internal service, or an external
Web service - to a new Web service that appears to be provided by the gateway.
For more information, see Enabling Web services through service integration technologies.
- WS-Notification
WS-Notification enables Web services to use the "publish and subscribe" messaging
pattern. In this pattern a producing application inserts (publishes) a message
(event notification) into the messaging system, having marked it with a topic
that indicates the subject area of the message. Consuming applications that
have subscribed to the topic and have the appropriate authority, receive an
independent copy of the message that was published by the producing application.
WS-Notification
also allows interchange of event notification between WS-Notification applications
and other clients of the service integration bus. By exploiting other service
integration bus functionality, you can also use this function to interchange
messages with other IBM publish and subscribe brokers such as Event Broker
or Message Broker.
Learn more about WS-Notification.
- WS-Reliable Messaging
- With WS-Reliable Messaging, you can make your SOAP over HTTP-based Web
services interoperable and reliable without having to write custom code. For
more information, see Adding assured
delivery to Web services through WS-Reliable Messaging.
- WS-Security 1.1 enhancements
- The WS-Security 1.1 standard brings several new enhancements to the security
component, including Web Services Secure Conversation (WS-SecureConversation)
and Web services policy sets.
- Web Services SecureConversation (WS-SecureConversation)
- WS-SecureConversation provides a secured session for long running message
exchanges and leveraging of the symmetric cryptographic algorithm. The symmetric
cryptographic algorithm provides better performance and throughput when compared
to the asymmetric cryptographic algorithm.
- Web Services Addressing (WS-Addressing) enhancements
Web Services Addressing (WS-Addressing) is a Worldwide Web Consortium
(W3C) specification that aids interoperability between Web services by defining
a standard way to address Web services and provide addressing information
in messages. The WS-Addressing specification introduces two primary concepts:
endpoint references and message addressing properties.
- Web Services Distributed Management (WSDM)
- Web Services Distributed Management (WSDM) is an OASIS approved standard
that supports managing resources through a standardized Web service interface.
Your environment, such as WebSphere Application Server host or an operating
system host that has an exposed resource as a Web service within a single
interface is used to manage and control resources. WSDM provides a new way
to expose the internal product administration functions for a Web service
interface.