Comparison between WebServices and other technologies

Compare WebServices with other technologies. Read the comparison between WebServices and other technologies. XMLHTTP and SOAP: XML are the core technologies of webserivces and the key to SOAP implementation; XMLHTTP is designed based on XML. In terms of implementation: XMLHTTP is browser-based. XML words can be transmitted to the server as long as Internet Explorer is available.

XMLHTTP and SOAP:

XMLIs the core foundation of web serivcesTechnologyIs the key to SOAP implementation, while XMLHTTP is designed based on XML. In terms of implementation: XMLHTTP is browser-based. XML strings can be transmitted to the server as long as Internet Explorer is available, which is highly universal. However, browsers are not used for XMLHTTP. they are intended for public users. if you can use XML to perform various operations, it will inevitably affect users. For example, the browser corresponding to the previous version of msxml can access the XML document of the client (designed for XMLHTTP at the beginning), which means that the local file system can be accessed through XMLHTTP technology. Later, microsoft defined it as a vulnerability, and now it cannot work. Of course, you can also write client programs, but limited to Visual programs. they can call the APIs in msxml. However, the server can be asp, jsp, or servlet, all of which convert xml strings into xml documents.Object.

SOAP is a communication protocol in XML format. It includes the following: the SOAP envelope defines the agreement describing the message content, and implies the message processing method; protocol binding provides a set of common mechanisms for transmitting the SOAP envelope through the underlying protocol. the encoding rule is to map various application data types to tag-based XML representation.MethodThe RPC mechanism provides a method to indicate remote process calls and return values. It has no clear relationship with other protocols, and his province is an agreement. It can be bound to http. stmp, tcp, and other protocols. SOAP messages are XML documents and can contain attachments. they can generate SOAP messages based on W3C-defined APIs. of course, microsoft's. net platform also supports SOAP. SOAP + HTTP is similar to XMLHTTP. when it provides better and more powerful implementation functions, it is scalable and universal in distributed collaborative communication, more importantly, it has become a key technology for Web Services and line communication.

SOAP and RMI, CORBA, COM

Both RMI and COM are implementation methods of distributed applications, which define the communication between components. Because they are just a system (for exampleJavaA series of programs written) Communication Conventions between programs, and communication requires the support of specific platforms. in addition to the efficient communication within the system, it cannot be associated with other systems.

To solve this communication problem, CORBA designed a proxy request model (using the IDL language) to communicate with each other. However, it seems to be a repair and cannot solve the fundamental problem, the system becomes more and more complex, and the use of CORBA is only effective in restoring the value of the old system. Neither of them can pass through the firewall. SOAP + HTTP is a firewall-friendly protocol that can be passed through the firewall.

SOAP is a protocol unrelated to specific implementations. it transmits data in XML format based on XML format, making the system loose. In this way, the readability of XML is used in the application, and XML documents are parsed to implement the application, which greatly improves the system interoperability (communication with different systems ). In addition, the business logic of each unit in the system is clear, which is highly portable and reusable.

UDDI and JNDI

UDDI is a service registration management protocol. the UDDI registration center is used to register a service. you can use WSDL to register a service. by searching for a service in the UDDI registration center, you can obtain the WSDL document, according to the WSDL document, obtain the method for accessing the service and use SOAP to communicate with the service. It can useDatabaseOr you can useOpen sourceOr company (IBMAnd so on. XML is used for representation. When a user queries, the details can be returned in XML format. Its access program is just a process of looking down at a level. The service it registers is generic and has nothing to do with the platform, and the registration method is generic XML format. It can be orientedInternet, Or Interanet provides a variety of services for a variety of users.

JNDI is the naming Directory of the Java service. it records the access directory of EJB and DataSource in the form of a tree. The program can locate the service through JDNI and RMI. The specific deployment files are used. after the server is started, it automatically creates JNDI based on the deployment file and supports query of RMI and naming services (implemented by the server itself ). Then RNI can access these components. Its idea is similar to that of UDDI, but it is bound to a specific system platform and is completely bound by a service (related to a program, which should not be called a service, but a component, the implementation method is simple. Therefore, UDDI is more dynamic and easier to operate than JNDI.

Configuration files for WSDD and EJB

For CMP-type object beans, WSDD is similar to its configuration file. However, it describes the ing between data and the database and does not involve methods. there are access methods implemented at the underlying layer of the server system. WSDD defines the service access interface. it supports the identification interface and data transmission at the underlying system level of web services.