The core of the Oracle9iWeb Services framework is the Web Service Broker, a J2EE execution engine deployed in Oracle9i Application Server.
Application developers can access the engine using the Oracle Web Services Java client APIs that provide
a level of abstraction over the communication protocol to connect to the execution engine (direct Java method calls,
PL/SQL calls, HTTP, HTTPS, or JMS (Java Message Service) messages).
Oracle's Web Services framework is based on open industry standards, defining four requirements: description, discovery,
request/response, and transport.
Requirement
,
|
Standard
|
Remarks
|
Description
|
WSDL
|
All service
attributes including input/output parameters, version,
provider, and
copyright/licensing information, are stored in registries.
The Oracle9i
Web Services framework supports two registries:
_
Service
Registry: stores service definitions
(called
service descriptors).
_
Application
Profile Registry: stores information about the
consumer
applications that are allowed to access services.
|
Discovery
|
UDDI.
LDAP
|
Search
registries for services with the desired characteristics.
_
Development-time:
Service descriptors can be published in
UDDI
registries (natively or in WSDL).
_
Run-time:
Service descriptors can be stored in Oracle Internet
Directory
(OID) for security, centralized management, and
lookup (via
LDAP).
|
Request/Response
|
XML
|
Request and
response formats are defined per service in XML
documents and
XML Schema documents
|
Transport
|
SOAP
ICE (See Note
1)
|
Send requests
to services and receive responses. Oracle9i Web Services framework
includes adapters for common transport
protocols and
supports custom adapters.
|
Note 1: Information and Content Exchange. A syndication protocol that standardizes interaction between information publishers
and subscribers via the Web
The illustration below shows how various parts of the Oracle9iWeb Services framework are related to one another. Starting
in the upper-left, Consumer Applications send XML Service Requests to the Web Services Client Library, using SOAP and
ICE. The Client Library provides Java and PL/SQL interfaces to the Web Services Broker. Interacting with the Broker for
Web Services and Database Services is accomplished though SOAP, Java reflection, or JDBC via software components
called adapters. When the Broker returns results to the Services, it dispatches them to the Consumer applications for display
to end-users. Software components called transformers allow the framework to support several output formats, including
HTML pages, and pages formatted for wireless and mobile devices.
The Oracle9i Web Services framework insulates developers from the complexity of interacting with multiple information
sources, protocols, and delivery channels. It is component-based to maximize re-use. It includes tools for creating, managing,
and monitoring services.
The following figure gives a developer's view of how various parts of the framework interact.
Working clockwise from the left, the steps are:
1. A Service Provider can start by reusing an existing Web or database application - ideally, one that returns results in
XML. If not, Oracle9i Web Services includes utilities that map HTML and other data sources to XML. Oracle9i Web
Services also includes a Creation Assistant that generates a simple service from a Web page.
2. Next, a Service Administrator uses a tool of choice (command-line utility or graphical Oracle Enterprise Manager) to
register the service, making it available to consumers.
3. Service Consumer Applications query the Service Registry to get the data required to find and invoke a service. Data
about Service Consumer Applications, including access privileges, is stored and maintained in the Application Profile
Registry.
4. Then, the Service Consumer Application interacts with the Web Services Broker, which uses an input transformer, if
needed, to convert the Consumer's request to a format it can use internally. When the service returns a result, the Web
Services Broker applies an output transformer, if needed, and dispatches the data to the Service Consumer application.
The Service Consumer Application can display the data to end-users, or use it in the flow of some business logic.
5. The Web Services Broker invokes the service via an adapter appropriate for the service's protocol (HTTP, SMTP, etc.).
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