What Is an Enterprise Service Bus?

The Enterprise Service Bus, or ESB, is called Enterprise Service Bus. It refers to the combination of traditional middleware technology and XML, Web services and other technologies. The ESB provides the most basic connection hub in the network and is an essential element for building an enterprise's nervous system.

Service-oriented architecture has gradually become the mainstream technology for IT integration. Service-oriented architecture (SOA) is a software system design method that provides services to end-user applications or other services through published and discoverable interfaces.

SOA divides IT architecture into component layer, Web service layer, and business process layer. The component layer includes various application components, which are usually technology-related specific implementations. Various specific distributed component technologies (CORBA, COM / DCOM, J2EE) can be used to implement the application components at the component layer. Generally, the component layer in a complex IT environment uses multiple distributed component technologies at the same time, and the interconnection barriers between different implementation technologies have brought great difficulties to application integration, and then formed islands of information. SOA introduced the Web services layer to solve the application integration problem in this case. Web services are independent of various distributed component technologies. It uses a standard XML-based Service Description Language (WSDL) to define and encapsulate discrete business functions. Various distributed component technologies that support Web services The business components on it can be published as Web services and the corresponding WSDL documents can be generated, and only the information described by the WSDL can be used to call the Web services, that is, the business functions described by the WSDL. Web services have been widely used in system integration. In SOA, the business components that need to enter the system integration link are mapped as Web services, forming a Web service layer. The business process layer is on top of the Web service layer, and the business process is realized through the orchestration of Web services. The business process layer can call business components based on various distributed component technologies through the Web service layer, which realizes the application integration of complex IT system environments.

In the three-layer model of the SOA's component layer, Web service layer, and business process layer, the component layer uses specific distributed component technology to implement business functions, and the Web service layer provides a technology-independent universal access method for the component layer, shielding The differences between the specific technologies at the component layer highlight the encapsulation of business logic. The business components in the component layer and the web services in the web service layer constitute the main reusable parts of the enterprise IT architecture. They should remain relatively stable. The business process layer arranges the services to adapt to changes in business requirements. Mapping business components at the component layer to services at the Web service layer is a key step in the successful implementation of SOA. At present, for specific business components, the industry widely uses the built-in support for Web services specific to distributed component technology to implement components and services. Mapping. This mapping method is highly dependent on the specific distributed component technology itself, and lacks flexibility in the process of use and customization. When a web service implementation requires the implementation of business components in multiple distributed component technologies, this mapping Method will not support ^[1]

The Enterprise Service Bus (ESB) is a key part of the infrastructure used when building a service-oriented architecture (SOA) solution. It is a set of infrastructure functions implemented and supported by SOA through middleware technology. ESB supports services, messages, and event-based interactions in a heterogeneous environment, with appropriate service levels and manageability. In short, the ESB provides the ability to connect new and existing software applications within and across the enterprise, enabling a rich set of features to enable management and monitoring of interactions between applications. In the SOA layered model, the ESB is used between the component layer and the service layer. It can connect and integrate components on different platforms through multiple communication protocols and map them into services at the service layer.

As a key part of the SOA infrastructure, the functions of the ESB are mainly reflected in communication, service interaction, application integration, service quality, security, and management and monitoring. In terms of communication, the ESB can support message routing / addressing, support multiple communication technologies, communication protocols (such as JMS, HTTP), support publish / subscribe communication modes, and can handle request / response, synchronous, and asynchronous messaging methods. It also requires that messages be delivered in a reliable manner. In terms of service interaction, the services published on the ESB use the current standard Web Services Description Language (WebServicesDescriptionLanguage) to define Web services, and the ESB is usually equipped with a service directory and discovery mechanism. The important function of the ESB is to integrate different systems. It must be able to support multiple ways to access the ESB (such as connecting ESB, WebService, CORBA, and legacy systems accessed using Socket and other methods to the ESB system), and map the accessed systems Into Web services. When integrating different systems, quality of service issues must be considered, such as transactional and message delivery reliability. For key web services, the ESB needs to send messages in an encrypted manner and must verify the permissions of the visitor. As a complex subsystem of the SOA infrastructure, ESB software must also be equipped with corresponding management and monitoring functions for system management, logging, measurement, and monitoring of the ESB software itself. At present, research on enterprise service buses at home and abroad is relatively active. IBM's ISV, BEA's AquaLogicServiceBus, open source Mule, and Sun's draft JBI specification are all concrete implementations of enterprise service buses. However, these companies' ESB implementations are more focused on supporting their own brand products, and they have not given enough consideration to how to integrate more distributed component technologies.

1. Bus basic service framework: It provides basic technical means to ensure system consistency, security, reliability, and performance and expansion capabilities.

2,

1.Availability and reliability

Support cluster physical deployment to ensure high availability of the system and support long-term stable operation of the system.

Performance and scalability

Supporting the system's processing capability can still leave a sufficient margin while meeting the peak requirements of system performance indicators.

3.Extensibility and flexibility

Support system expansion deployment and separate deployment of multiple logical units. Provides management functions for system maintenance and parameter configuration.

4.Security

Provide security authentication and authorization mechanisms, provide non-repudiation and confidentiality, and support security standards.