When solving the information transmission problem of a monitoring system, some difficulties were encountered, mainly due to the variety of data types in the system, the direction of sending, and the complexity of control. The introduction of XML files simplifies this issue.

1. Data communication of monitoring system

Data communication is the use of data transmission technology to transfer data information between two terminals according to a certain communication protocol. It can achieve data and information transmission between computers, computers and terminals, as well as between terminals. In distributed monitoring systems, data communication is the most fundamental issue. As shown in Figure 1, it is a typical model of a site based remote monitoring system.

 

In this system, there are basically three situations where the monitoring center and the site need to send data to each other:

(1) Site → Monitoring Center

Such as on-site data collected by the site, captured image information, alarm information, and confirmation response information sent back by the site after receiving data from the monitoring center.

(2) Monitoring Center → Station

Such as the basic data and system operating parameters sent by the monitoring center to the site, the confirmation response information sent back by the monitoring center after receiving the data from the site, and the remote control instructions given by the monitoring center to the site.

(3) Site → Site

Some transactions may require two sites to complete together (such as tare weight at site A and gross weight at site B, where the two sites need to exchange data to obtain net weight values), so data will also be sent between sites, and these data monitoring centers are not concerned.

From this, it can be seen that there are multiple types of data to be sent to each other in this site monitoring system, including 531X121PCRALG1, and the data transmission is random, messy, and dynamic, with different contents, formats, and a wide variety of types. In addition, the monitoring center can connect to the Internet through a local area network and have a fixed IP address, while the site uses ADSL connection, and its IP address is usually not fixed. When using the Socket communication mechanism as the data channel of the system, the monitoring center is treated as a Socket Server to start listening, and the site can only act as a Socket Client and actively connect to the Server. If data needs to be transmitted between sites, it can only be forwarded through the monitoring center, which further increases the complexity of sending and receiving data between the monitoring center and the sites.

2 XML and Its Characteristics

XML (Extensible Markup Language) is an extensible markup language similar to HTML, but unlike HTML, XML tags are not pre-defined and users can and must define tags themselves. XML is a flexible and effective way to describe and store data, which can clearly represent what data is, what data is available, and how data is organized. XML is a standard text format for representing structured information on the Web, widely used for network data exchange, and has the advantage of being easy to generate data.

XML supports almost all major languages in the world, and texts from different languages can be mixed and used in the same document. Software that applies XML can handle any combination of these languages. All of this will make XML an open standard for data representation, which is independent of machine platforms, vendors, and programming languages.

XML has been introduced into many network protocols, such as 531X121PCRALG1, to provide a standard method for communication between two software, such as the Simple Object Access Protocol (SOAP) and the XML RPC specification.

XML data is stored in plain text format, providing a software and hardware independent method of sharing data, so XML data files can be utilized by more users and devices, rather than just browsers based on HTML standards.

XML is a bridge between different systems.