What is an enterprise service bus?
????? An enterprise service bus (ESB) is a pattern of middleware that unifies and connects services, applications and resources within a business. Put another way, it is the framework within which the capabilities of a business' applications are made available for reuse by other applications throughout the organization and beyond. The ESB is not a new software product — it's a new way of looking at how to integrate applications, coordinate resources and manipulate information. Unlike many previous approaches for connecting distributed applications, for example RPC or distributed objects, the ESB pattern enables the connection of software running in parallel on different platforms, written in different programming languages and using different programming models.
??? Examples of the enterprise service bus patterns exist today, built using existing integration tools available in the IBM Business Integration portfolio of products. For a business, an ESB can manage connectivity needs by providing standards based application integration with support for Web services, message based transport and mediation (transformation and routing) oriented toward a service based infrastructure (often referred to as a service oriented architecture).
Key characteristics of an enterprise service bus
An enterprise service bus can optimize information distribution within
an enterprise and beyond and may be built with integration middleware
products available today from IBM.
An enterprise service bus:
- Is standards-based
- Can enable all parts of a business to react instantly to new information
- Minimizes risk by using industry standard interfaces and protocols
- Overcomes differences in platform, software architecture and network protocols
- Assures delivery of transactions, even when systems and networks go off-line
- Re-routes, logs and enriches information without rewriting applications
- Provides an infrastructure that is highly distributed and yet can be managed centrally
- Can distribute data throughout your business and beyond to your customers and business partners
- Spans different operating systems, programming models, application types and locations
- Can be deployed incrementally, project by project, to better manage expense
- May combine new and existing technologies and standards
- Supports message, service and event oriented architecture
?? ????? ESB（Enterprise Service Bus，即企業服務總線）是傳統中間件技術與XML、Web服務等技術結合的產物。ESB提供了網絡中最基本的連接中樞，是構筑企業神經系統的必要元素。
??????? 企業服務總線ESB就是一種可以提供可靠的、有保證的消息技術的最新方法。ESB中間件產品利用的是Web服務標準和與公認的可靠消息MOM協議接口(例如IBM的WebSphere MQ、Tibco的Rendezvous和Sonic Software的SoniCMQ)。ESB產品的共有特性包括:連接異構的MOM、利用Web服務描述語言接口封裝MOM協議，以及在MOM傳輸層上傳送簡單對象應用協議(SOAP)傳輸流的能力。大多數ESB產品支持在分布式應用之間通過中間層如集成代理實現直接對等溝通。
?????? 企業服務總線（Enterprise Service Bus，ESB）的概念是從面向服務體系架構(Service -Oriented Architecture， SOA)發展而來的。SOA描述了一種IT基礎設施的應用集成模型，其中的軟構件集是以一種定義清晰的層次化結構相互耦合，其中，一個ESB是一個預先組裝的SOA實現，它包含了實現SOA分層目標所必需的基礎功能部件。