Oracle Enterprise Service Bus contains the following components:
■ ESB Server
The ESB Server is the runtime server which listens on the control topic for updates
from the ESB Metadata Server and updates its cache.
■ Oracle ESB Control
The Oracle ESB Control provides a Web-based interface for managing,
administering, and monitoring services that you have registered with the ESB
Metadata Server.
■ ESB Metadata Server
The database that holds your ESB metadata such as schemas, transformations, and
routing rules. The ESB Metadata Server is the server to which you register the ESB
services that you have designed using Oracle JDeveloper and configured using
Oracle ESB Control.
■ Oracle JDeveloper
Oracle JDeveloper is a graphical and user-friendly way to model, edit, and design
the services that comprise an Oracle Enterprise Service Bus system.
Oracle ESB Architecture
ESB services are designed and configured with Oracle JDeveloper and Oracle ESB
Control user interfaces. The ESB project which contains the services is registered to the
ESB Server. The ESB Server supports multiple protocol bindings including
HTTP/SOAP, JMS, JCA, WSIF, and Java that ensure guaranteed, reliable message
delivery using synchronous/asynchronous, request/reply or publish/subscribe
models. However, the ESB Server does not support Remote Method Invocation (RMI).
Oracle ESB DT(Design Time)
When an ESB project is registered with the ESB server, ESB files created in Oracle
JDeveloper or Oracle ESB Control are deployed to the design time metadata server.
The following JMS topics are running on the design time metadata server: control,
monitor, resubmit, and defer. Also running on the metadata server are the following
servlets: console, WSIL, design time, WebDav, and SOAP provider.
The created or updated service definition files are translated and captured in a
relational form in the ORAESB schema in the database repository while the XSD, XSL,
WSDL, and map files are written to the file system. The service definition files have
pointers to the XSD, XSL, WSDL, and map files.
Oracle ESB RT (Run Time)
An ESB runtime server, or multiple servers in a cluster, accesses the control topic file
on the design metadata server to cache the information for the ESB runtime services.
ESB runtime servers listen on the control topic to get notified of any metadata changes.
These notifications result into reload of cached metadata for the entities that changed.
The ESB runtime server contains the following: server execution, memory cache, JMS
error topic, XML/XSL engine, and JCA adapter agents.
At runtime, the ESB message flow is initiated by an inbound adapter polling or
listening for an event, such as a file copied to the directory specified for an inbound
file adapter. The ESB flow is also initiated when an external SOAP/HTTP process
invokes the Web service associated with an ESB routing service.
Note:--
If execution is synchronous, then Oracle Enterprise Service Bus
invokes the target service immediately; control is not returned to the routing
service until the message has been received by the target service for processing.
If execution is asynchronous, then Oracle Enterprise Service Bus
uses JMS for delivering the message to the target service, which will be invoked at
a later time. Control is returned to the routing service immediately, before the
target service has received the message.
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