Ajax core XMLHTTP component information page 1/2

I. Remote Database Management Technology
Remote database monitoring is an important part of modern Internet-Based WAN applications. First, let's briefly review the development process and method of the remote database management technology on the Internet: (recommended Article: AJAX)

Early Database Remote Management by writing CGI-BIN module. But the CGI-BIN running speed is slow, maintenance is inconvenient, and now has been basically abandoned.

Over the past few years, there have been a lot of applications using the Component Object Model (COM), and the results are also very good. However, if a third-party server is used (the author's website is built on a third-party virtual host), the server often does not allow users to register their own components for confidentiality or other commercial reasons.

In recent years, Microsoft launched the. NET platform and SUN's J2EE platform are both very high-end remote database management and service platforms. It can provide excellent multi-Tier (n-Tier) application services. Where ,. NET Simple Object Access Protocol (SOAP) uses Hypertext Transfer Protocol (HTTP) and Extensible Markup Language (XML) cross-system (such as Windows-Linux) communication service methods have been widely accepted and used by developers. Many large applications, such as Enterprise resource planning (ERP), are built on such a large platform. However, for small and medium-sized applications, such as the construction and maintenance of a website, such a large application platform seems to be too costly.

Microsoft, once lagging behind in Internet technology and Java technology, is ahead in XML application development. The XMLHTTP protocol in her XML Parser (MSXML) is a very convenient and practical client/service communication pipeline. The combined use of XMLHTTP and ActiveX Data Objects (ActiveX Data Objects, ADO/ADOX) can easily achieve remote database management.

2. Database Remote Management System

The task process of remote database management is as follows:

1. The client sends a command to the server to query or modify the database structure and data.

2. The server accepts and executes the relevant commands and returns the results to the client.

3. The client accepts and displays the command execution result returned by the server.

Two key steps for achieving remote database management are:

1. The data channel for command upload and result transfer between the client and the server is implemented by XMLHTTP.

2. The Command Transmission and result return between the server and the database are completed by the ADO/ADOX interface serving as the middle layer.

Iii. Use of XMLHTTP

As the name implies, XMLHTTP is a hypertext transfer protocol for transmitting XML data.

In fact, the data transmission process of XMLHTTP is more flexible:

It can upload instructions in XML format, strings, streams, or an unsigned integer array. It can also be a URL parameter.

The output result can be XML data, a string, a stream, or an unsigned integer array.

For more information, see the link at the end of the article.

The client calls XMLHTTP in five steps:

1. Create an XMLHTTP object

2. Open the connection with the server, and define the command sending method, Service webpage (URL), and request permissions.

The client opens a connection to the Service webpage of the server through the Open command. Like normal HTTP Command Transmission, you can use the "GET" method or "POST" method to direct to the Service webpage of the server.

3. Send commands.

4. Wait for and receive the processing results returned by the server.

5. Release the XMLHTTP object