Establish an XML-based network service using J2EE
1 Overview
Web service is a new specification for the B2B interaction model using the XML standard. It provides a foundation for concepts and architectures. These can be achieved by means of different platforms and products. Today, developers can use Java 2 Platform, Enterprise Edition (J2EE) to establish XML-based network services. We can use existing J2EE technology to create a complete, interoperable network service suitable for XML. There is no need to reconstruct a fundamental architecture, nor does it need to establish an enhanced J2EE system, and developers can create complex and powerful network services.
2 introduction
Network Services Receive other systems from Internet or intranet through lightweight, non-dependent developers, making all systems that can connect between systems that can be connected to Internet. With the maturity of these technologies, network services will be able to include more special features suitable for multi-part B2B cooperation.
Network services have begun to perform in a very intelligent and dynamic manner. These "smart" network services will understand the contents of each request and dynamically generate return results under different situations. These services can adjust themselves according to user authentication, parameter selection, location and other information, and give the requesting reason. Multiple services can be dynamically combined together, work together to generate a unified customized solution, which can be transparent to users completely, and users only need to know the final integrated structure.
In the construction of a business website, there are three main challenges to build network services, they are:
l Establish a client layer, which enables Applets, applications, business partners, and PDA users to connect and use this network service.
l Implement network services, including workflow logic, data transfer logic, business logic, and data access logic. It is the basis for providing functional support for customers in the background.
l Connect to the backend system, which may include one or more databases, existing corporate information systems, business partners published network services, and a public, userken library shared by multiple systems.
Web Services is actually an interface based on XML for business, applications, and system services. In fact, it is a new concept based on a series of existing technology. How to build a web service? The following technique has been widely recognized in the industry.
l Serving providers build, organize and release network services. Its means is diverse, and can be done using programming languages (such as Delphi, Java, C #, etc.), middleware, or other special platforms.
l Service providers provide service description with WSDL (The Web Services Description Language). The WSDL document provides a service description to third parties.
l Services The service provider registers network services to the UDDI (Universal Description, Discovery, and Integration). UDDI enables developers to publish services and can search for other people from other people. Users will search for services by searching for the UDDI registry.
The client application is bound to the network service and activate the network service accordingly by SOAP (THE Simple Object Access Protocol). SOAP provides parameters and return results in XML format and transmits with HTTP. All network services communicate through SOAP.
Figure 1 depicts an architecture of a J2EE based network service system. It should be noted that many APIs are not displayed in this figure, they are used to analyze and communications. However, this figure depicts the main standards, protocols, and primary subsystems based on J2EE network service systems.
Figure 1 Based on the main subsystems and protocols in the network service system of J2EE
