Talking about SOAP (1)
With the continuous development of computer technology, the environment facing modern enterprises is increasingly complex, and most of their information systems are multi-platform, multi-system complex systems. This requires a wide range of compatibility, which can support different system platforms, data formats, and a variety of connection methods, requiring the system to be loosely coupled, cross-platform, and language And unrelated to a particular interface and provide reliable access to the web application. As the heterogeneous calculation environment is increasing, interoperability between various systems is necessary, requiring the system to seamlessly communicate and share data, thereby eliminating huge information sharing in the Internet environment, realizing information sharing, Data exchange, meet the consistency of information. Web Services hopes that different systems can call each other with "Software Dialogue", breaking the Software Application, Websites, and Various Devices, and implement "web seamless integration" goals.
What is soap?
SOAP (Simple Object Access Protocol) Simple Object Access Protocol is a simple protocol to exchange information in a dispersion or distributed environment, which is an XML-based protocol that includes four parts: SOAP package (Envelop), package definitions What is the content in the message, who is sent, who should accept and process it and how to handle their framework; SOAP coding rule (Encoding rules), used to indicate an instance of the data type required to use; SOAP RPC (RPC REPRESENT), representing the protocol; SOAP Binding, using underlying protocol. Although these four parts are part of the SOAP, as a whole, they are defined, but they are functionally intersecting, independent of each other. In particular, envelopes and coding rules are defined in different XML namespaces, which makes it easier to define. The two main design goals of SOAP are simplicity and scalability. This means that some of the traditional message systems or distributed object systems will not be part of the SOAP specification. For example: distributed garbage collection (Distributed garbage collection), bulk transfer message (Boxcarring or batching of messages), object reference, object activation (Objects-by-reference (which requires distributed garbage collection)) (Activation (which requires objects- BY-REFERENCE))))))))))))))) SOAP Message Example: 1. The first example clarifies a simple communication information in SOAP, including two elements that are not SOAP definitions but the application defined: header element AlertControl and body block element Alert. The header element includes two parameters: priority and expires. The body block element includes information of actual transmission. (Example 1)
2. The SOAP communication is related to the underlying different protocols and different exchange formats. The following example SOAP uses HTTP as the underlying communication protocol, so that you can use the Request / Response mechanism to transfer information. The SOAP / HTTP request includes a block element of getLastTradeprice, which carries a string parameter and Ticker symbol, returns a floating point number in the SOAP response. The XML name is used to distinguish SOAP flags and application-specific flags. (Example 2) 3. Example 3 shows the STOCKQUOTE SOAP service information, a response message made to the request of Example 2. (EXAMPLE 3)
The difference between SOAP and CORBA, COM / DCOM?
When SOAP has just been raised, many people put forward questions: What is the difference between SOAP and CORBA and DCOM? · Corba (Common Object Request Broker Architecture) Public Object Request Agent Architecture is a standard or-oriented application system specification that is developed by OMG organization. Several parts of the object request proxy ORB, object service, public facilities, domain interfaces, and application interfaces. Its core part is an object request proxy ORB (Object Request Broker). ORB provides a mechanism that allows for a transparent request and response by this mechanism. Distributed, interoperable objects can utilize ORB configurations to be interoperable. ORB can be seen as a middleware that establishes a client / service relationship between an object. Based on ORB, customer can transparently call the method of service objects, which can run on the same machine with customers, or run over other machines to interact with customers through the network. The ORB intercepts the request sent by the customer and is responsible for finding the service object that implements the request on the software bus, then completes the parameters, method call, and returns the final result. CORBA 1.1 is published by the object management organization in 1991. Define Interface Definition Language (IDL) and Apply Programming Interface (API) to activate the interaction of the client / server by implementing the object request agent (ORB). Corba 2.0 issued the implementation of how to span different ORB providers in December 1994 to communicate. · COM / DCOM (Component Object Model) is the distributed component object model standard proposed by Microsoft, supports communication between the LAN, WAN, and even an object of different computers on the Internet. DCOM-based applications, components, tools, etc., handle low-level detail issues of network protocols, without having to pay too many network protocol details, allowing users to concentrate on solving the problems required by users. DCOM is located between the components of the application, and the components are glued together with the unasual way to form a complete feature application. Comparison of SOAP and CORBA, DCOM / COM. First, it is pointed out that SOAP does not replace CORBA, COM / DCOM, and the concept of three. COM / DCOM is a component model, CORBA is a service standard for distributed applications. CORBA and DCOM establish a service, service objects to execute client calls. SOAP is a communication protocol based on XML and HTTP distributed objects, which is a protocol for communications in COM / DCOM and CORBA objects. In fact, the two can be combined with SOAP interoperability and CORBA powerful execution capabilities. OMG (Object Management Group Responsible for the Corba Specification) is paying attention to this development. Corba applications and DCOM applications cannot achieve interoperability, and both cannot work together. Because in the ORPC (Object RPC) protocol, use ObjRef to represent a reference to run objects; in CORBA / IIOP (Internet Inter-ORB Protocol), use the exchange interoperable object reference to IOR (Interoperable Object Reference) represents a server Object references. Unfortunately, the IOR and Objref cannot be associated. However, using SOAP can be implemented on the vertical application level level integration, which can be better integrated with CORBA, and DCOM is a whole.
