ACL     Access Control List. A mean of determining the appropriate access rights to a given object depending on certain aspects of the process that is making the request.

Action Classes     A component that is responsible for doing a certain type of work after a receipt of a message inside the ESB.

Bus     A subsystem that transfers data between computer components inside a computer or between computers. Unlike a point-to-point connection, a bus can logically connect several components over the same structure.

Content Based Router (CBR)     A pluggable service inside the ESB that provides capabilities for message routing based on the content of the message.

CORBA     Common Object Request Broker Architecture. A standard defined by the Object Management Group that enables software components written in multiple computer languages and running on multiple computers to interoperate.

CORBA IDL     CORBA Interface Definition Language. A computer language used to describe a software component's interface. It describes an interface in a language-neutral way, enabling communication between software components written in different languages.

EAI     Enterprise Application Integration. A practice that makes use of software and computer systems architectural principles to integrate a set of different enterprise computer applications.

Endpoint Reference (EPR)     A standard XML structure used to identify and address services inside the ESB. This includes the destination address of the message, any additional parameters (reference properties) necessary to route the message to the destination, and optional metadata (reference parameters) about the service.

ESB     Enterprise Service Bus. An abstraction layer on top of an implementation of an enterprise messaging system that provides the features with which Service Oriented Architectures may be implemented.

Fault     A type of message that express an error condition inside a Web Service. Similar to the Exception object in some programming languages.

Gateway     A specialized ESB listener process that can accept messages from non-ESB clients and services and route them to the required destination inside the ESB, taking care of the appropriate bridging of message types and EPRs.

J2EE/JEE     Java Platform Enterprise Edition (formerly known as Java 2 Platform Enterprise Edition). A programming platform, based on the Java language, for developing and running distributed multi-tier Java applications. It is based largely on modular software components running on an application server.

JBI     Java Business Integration. An API that provides a standard pluggable architecture to build integration systems that hosts service producers and consumers components. Components interoperate through mediated normalized message exchanges.

JMS     Java Message Service. An API for sending messages between two or more systems.

JTA     Java Transaction API. An API that allows distributed transactions to be done across multiple XA resources

Listener Classes     A component that encapsulates the endpoints for message reception on the ESB.

Message     A data item that is sent (usually asynchronously) to a communication endpoint. This concept is the higher-level version of a datagram except that messages can be larger than a packet and can optionally be made reliable, durable, secure, and/or transacted.

Message Factory     A service inside the ESB that can build specific types of messages according to their serialization capabilities.

Message Store     A pluggable service inside the ESB that persists messages for auditing and tracking purposes.

MOM     Message Oriented Middleware. A software component that makes possible inter-application communication relying on asynchronous message-passing.

Quality of Service     A term that refers to control mechanisms that can provide different priority to different users or data flows, or guarantee a certain level of performance to a data flow in accordance with requests from the application program.

RPC     Remote Procedure Call. A protocol that allows a computer program running on one computer to call a subroutine on another computer without the programmer explicitly coding the details for this interaction.

SCA     Service Component Architecture. A set of specifications that describe a model for building applications and systems using Service-Oriented Architecture. It encourages an SOA organization of applications based on components that offer their capabilities through service-oriented interfaces and which consume functions offered by other components through service-oriented interfaces, called service references.

Service Registry     A persistent repository of Service information. Used by ESB components to publish, discover and consume services.

SOA     Service Oriented Architecture. A perspective of software architecture that defines the use of loosely coupled software services to support the requirements of the business processes and software users. In an SOA environment, resources on a network are made available as independent services that can be accessed without knowledge of their underlying platform implementation.

SOAP     A protocol for exchanging XML-based messages over computer network, normally using HTTP. SOAP forms the foundation layer of the Web services stack, providing the basic messaging framework.

Transformation Service     A pluggable service inside the ESB that provides capabilities for transforming messages from one data format to another.

UDDI     Universal Description, Discovery, and Integration. A platform-independent, XML-based registry and core Web Services standard. It is designed to be interrogated by SOAP messages and to provide access to Web Services Description Language documents describing the protocol bindings and message formats required to interact with the web services listed in its directory.

WS-Addressing     A Web Service specification for addressing web services and messages in a transport-neutral manner. This specification enables messaging systems to support message transmission through networks that include processing nodes such as endpoint managers, firewalls, and gateways.

WS-BPEL     Web Services Business Process Execution Language. A choreography language for the formal specification of business processes and business interaction protocols using Web Services. Thus BPEL's messaging facilities depend on the use of Web Services Description Language (WSDL) 1.1 to describe incoming and outgoing messages.

WS-Context     A Web Service specification that provides a definition, a structuring mechanism, and a software service definition for organizing and sharing context across multiple Web Services endpoints.The context contains information (such as a unique identifier) that allows a series of operations to share a common outcome.

WSDL     Web Services Description Language. An XML format for describing the public interface to a Web services based on how to communicate using the web service; namely, the protocol bindings and message formats required to interact with it.

WS-Policy     A Web Service specification that allows web services to advertise their policies (on security, Quality of Service, etc.) and for web service consumers to specify their policy requirements.

WS-Security     A Web Service specification that provides a set of mechanisms to secure SOAP message exchanges. Specifically, it describes enhancements to provide quality of protection through the application of message integrity, message confidentiality, and single message authentication to SOAP messages.

WS-Trust     A Web Service specification that uses the secure messaging mechanisms of WS-Security to define additional primitives and extensions for the issuance, exchange and validation of security tokens.

XA     An X/Open specification for distributed transaction processing. It describes the interface between the global transaction manager and the local resource manager to support a two-phase commit protocol.

XML     Extensible Markup Language. A general-purpose markup language that supports a wide variety of applications. Its primary purpose is to facilitate the sharing of data across different information systems.