What is an ESB in the IT industry?

    What is ESB?  
 An ESB is called an enterprise service bus. It is a product of the combination of traditional middleware technologies and XML, web services, and other technologies. ESB provides the most basic connection hub in the network and is a necessary element for building an enterprise's neural system. The emergence of ESB has changed the traditional software architecture and can provide cheaper solutions than traditional middleware Products. At the same time, it can eliminate technical differences between different applications, it allows different application servers to coordinate operations and realize communication and integration between different services. In terms of functions, ESB provides event-driven, document-oriented processing modes, and distributed operation management mechanisms. It supports Content-based routing and filtering, it has the ability to transmit complex data and can provide a series of standard interfaces. Five basic functions of ESB: 1) metadata management of services: Registration and addressing management of services within the bus scope. 2) transmission service: ensure the correct delivery of messages between business processes connected through the Enterprise bus. transmission also includes content-based routing. 3) intermediary: Provides service routing and locating services with location transparency, multiple message transmission modes, and supports widely used transmission protocols. 4) various service integration methods: such as JCA, web services, messaging, and adaptor. 5) service and event management support: for example, service call recording, measurement and monitoring data; event detection, trigger and distribution functions; Eight extended functions of ESB: 1) service-oriented metadata management: He must understand the two ends of the intermediary, that is, the request of the service and the request's requirements for the service, as well as the service provider and description of the service provided by him; 2) Mediation: it must have a mechanism to complete mediation functions, such as protocol conversion; 3) Communication: service publishing, subscription, response to requests, synchronous asynchronous messages, routing and addressing; 4) Integration: Legacy system adapters, service orchestration and ing, protocol conversion, data transformation, and Enterprise Application Integration Middleware continuity. 5) service interaction: Service Interface Definition, service implementation replacement, service message model, Service Catalog and discovery. 6) Service Security: authentication and authorization, non-repudiation and confidentiality, and support of security standards; 7) Service Quality: transactions, service deliverables, etc.; 8) Service level: performance and availability. Two of the most common functions in ESB are message conversion and message routing.