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With the deepening of the market-oriented reform of China's power system, the data sources for the technical support system of the power market are becoming more and more extensive, the data volume is increasing, and the data needs to be quickly queried and transmitted securely. The system architecture requirements of the application system are also required. Higher and higher. At the same time, the power system technical support system should also strictly classify all kinds of information according to the confidentiality level, and on this basis, take measures to ensure the integrity and security of various information and data. The traditional two-tier platform-based software system puts the interface and application logic on the client. Therefore, the requirements for the client are relatively high, and usually there is only one data source (RDBMS) and can only provide a comparison. Low security is no longer suitable for the development of technical support systems in the electricity market.
A multi-layered browser-server (B/S) architecture based on Internet/Intranet utilizes mature web application server (WAS) and transaction processing middleware to provide a web operating environment for applications. In the B/S structure, the user interface (ie, the browser) and the database are separated by the web server and the application server. The web server responds to the browser's requests for web pages, and the application server stores application logic. The web server and the application server cooperate to implement various functions of the server. This structure minimizes the complexity of the client and improves system compatibility. The lumped management at the server side ensures the security and stability of the system. This three-tier structure will effectively help the power market technology support system to achieve the near-term and long-term goals.
The study of multi-layer architecture programming technology at home and abroad has been very in-depth, but its application to the development of technical support systems for the power market is still lacking. Literature [3] introduced the architecture and reliability, timeliness, and security of the real-time information system of the electricity market using Web technology. Reference [4] refers to the application of the Internet in the electricity market mainly in the real-time information system. The web-based electricity market proposed in [5] is limited to Web server applications and does not have the concept of a logical application layer. The literature [6] describes the overall structure, function modules, network structure and software and hardware configuration of the power market technology support system based on multi-layer architecture, but it lacks detailed introduction to key technologies such as overall system design and software architecture.
This paper describes the multi-tier architecture design of the electricity market technical support system based on Internet/Intranet. Based on the practice of technical support system development in the power market, a specific implementation plan is proposed.
1 System Design 1.1 Internet/Intranet Structure The power market technical support system includes the technical support system at the main station end, ie, the power market trading center, and the subsystems at the plant and station side. The intranet of the power market technical support system consists of web servers, e-mail servers, database servers, and application servers and client-side PCs.
Plant-side and master-side users through the Internet. The browser accesses the Web server and invokes various power market business processing functions provided by the application server and the database server. The e-mail server provides e-mail sending and receiving services for each user in the power market technical support system.
In order to ensure the security of the technical support system for the power market, necessary security measures must be taken when the Intranet is connected to the Internet. The main means is to install a firewall.
1.2 System Architecture Figure 1 shows the software and hardware architecture of the power market technology support system based on Web technology proposed in this paper. It can be seen that the application logic of the system is centralized on the server side, and the server side is divided into a webpage server that responds to webpage requests and an application server that handles various business logics. The client is a simple browser, which is actually a "zero client" solution. The complete separation of the database server and the client ensures the data security of the system. 
Figure 2 shows the general structure of a traditional two-tier application system. It can be seen that the application's interface and application logic are on the client. Due to the dependence of the two-tier architecture on the client and its low operating efficiency, modern large-scale software systems are moving in a multi-layered and distributed direction. The power market technical support system will also certainly abandon the traditional two-tier structure. 
2.1J2EE Architecture The Internet/Intranet-based network programming technology has become the mainstream technology for the development of new-generation large-scale system software. The power market technology support system is no exception, and the system's scalability, operability, diversity, and availability And enough flexibility is the main consideration.
This platform currently has three kinds of technology implementations: 1 Sun Microsystems' Java 2 Enterprise Edition (J2EEJava2EnterpriseEdition), whose core technology is a component architecture based on Enterprise JavaBeans (EJBs); 2 OpenManagementGroup proposed The public object request broker architecture (common object request broker architecture); 3 Microsoft's distributed Internet application structure (WindowsDNA), the core technology is the use of COM cattle model to achieve the server-side component architecture (DCOM + MTS).
This article recommends that the power market technical support system technology solution adopts the first scheme, that is, J2EE. The advantages of comparing the other two schemes lie in the following aspects:
a. A large number of industry companies support unified industry standards. J2EE is an open platform co-sponsored by many well-known industry companies and has extensive support from the industry and numerous middleware software providers (such as IBM, Oracle, Inprise, Sun, Netscape, etc.).
b. Through the advanced middleware services to quickly open up the market and realize the concept of innovation. Advanced J2EE platform-based software products can easily use third-party developed middleware, thereby reducing the application developer's workload, allowing developers to focus on the development of their business logic that they are good at, without having to cover everything.
c. Better protection of investment and quick adaptation to changes. The development of technical support system software for the power market has seen rapid changes in technology requirements, and new functional requirements have emerged in an endless stream, often requiring deployment in complex heterogeneous systems. The server platform should have the ability to quickly adapt the client to this change. A well-designed JZEE application can be deployed in disparate operating systems with minimal changes.
2.2 WebLogic Application Server The components of the multi-layer structure used in the power market technical support system of this paper are shown in Table 1. 
BEA's WebLogic Application Server provides support for J2EE component technologies and services. Among them: Component technologies include Servlets, JavaServerPage, and Enterprise
JaveBeans; services include standard network communication protocols (HTTP, HTTPS, IIOP, etc.), database system access (JDBC), and messaging system services (JavaMessageService and JavaMail).
The system's application logic is encapsulated in these components (EJB or JavaBeans), and the WebLogic application server provides a complete management platform to manage the components, and provides a variety of service supply logic use. In this way, development time is greatly accelerated, and developers can focus on the development of specific application logic.
3 Several key technologies 3.1 Dynamic chart display In the power market technical support system, the dynamic chart display based on the browser page is a key technology that must be realized. The dynamic display and interactive operation of the charts brings intuitive interfaces and operational convenience to the operator of the technical support system in the power market.
There are two typical ways to implement dynamic chart display. The first method is to plot the data extracted from the database on the server side, generate a graphic file on the server side, and point the page's link to the graphic file. The biggest advantage of this method is that the generated graphics file is relatively small, suitable for users with slower network speeds (such as remote dial-up Internet access), but it cannot be interoperable, and it is not able to perform interactive operations, such as graphs, histograms, and pies. The transition between graphs is inflexible. The second method is to use embedded applets on the client to implement dynamic chart display. Applet is a Java client applet and is suitable for implementing some more complicated functions. After Apple compiles, it can be directly embedded in an HTML file. Running in a browser, it can provide a dynamic page to the user, and the user can realize the server in the page. Interactions. This article uses this method. However, because the Applet is a Java applet running on the client, it cannot access the data of the server itself. Therefore, how to realize the data exchange between the applet of the client and the servlet of the server is the core problem of realizing the technology.
There are 3 ways to achieve data communication between Applets and Servlets:
a. Use the URL/URLConneetion class. A URL is a type of URL connection that provides access to network resources. Because the identity of each servlet is unique, URL classes can be used to communicate with remote servlets.
b. Use Socket. Socket is an important way to achieve network programming. Socket communicates using the host name and server port number as identifiers. In the Java language, java is provided. Net. Socket and java. Net. ServerSocket class library, they complete encapsulation of the various sub-functions required for Socket programming, the former for the client, the latter for the server. Applet programming can use the functions encapsulated in the above two Socket classes to achieve data communication with the servlet.
C. Use RMI (remotemethodinvocation). RMI is a mechanism by which different Java virtual machines call each other's object functions and start each other's processes. Under this mechanism, when an object on a Java virtual machine invokes a function on another Java virtual machine, the program syntax rules used are the same as the syntax rules of function calls between objects on the local Java virtual machine. It is this mechanism that brings great convenience to system design and programming for distributed computing. As long as the RMI procedures are designed, it is not necessary to interrogate the network details under RMI such as TCP/IP, Socket, etc., not to worry about the underlying hardware and software environment. The communication between any two Java virtual machines is completely responsible by RMI. . Applets and servlets are objects that run on a Java virtual machine, so you can use RMI's powerful capabilities for remote communications.
3.2 Distributed Applications and Distributed Databases 3.2.1 Distributed Applications The power market technology support system can use WebLogic's distributed clustering technology, which distributes applications to different servers and then groups these servers into a cluster. (Domain) unified management, which not only realizes the distribution of applications, but also ensures the concentration of management.
Specifically, various application subsystems can be distributed to unused managed servers, and then an administrative server can be used to collectively manage the systems.
In this way, applications are distributed on different machines and form an architecture without coupling between them. The advantages are as follows:
a. Easy to maintain and manage. Each subsystem reads its own configuration file from the management server during initialization, and generates a database connection pool, a message queue service pool, and an application component thread pool. These connection pools and thread pools can be dynamically configured by the management server during runtime without restarting the server.
b, easy to upgrade and expand. Through the management server, you can create a managed server and dynamically publish new applications to new servers. If you find that a server is slow to respond to excessive traffic, you can dynamically add a new server to reduce the load.
The subsystem and the management server can communicate with each other through the JMS service. In this way, the monitoring program running on the management server can monitor the current running status of the entire system. Among them, a message communication service may be opened on each subsystem, and other systems may send a message to it or request it for its own desired message.
3.2.2 Distributed Database The power market technical support system uses a distributed database to implement distributed storage and unified management of data. Through the configuration of the database system, the data tables used by different application logics can be distributed to databases on different physical machines, which can improve the access efficiency. When the application establishes a database connection, only the unified database name needs to be input, and the distribution management server dynamically connects to the corresponding machine according to the data requested by the user. All this is transparent to the application of the linked database. The application itself does not care about where the data is stored.
3, 3 system application-level clustering and redundancy Through the clustering function of WebLogic application server, the system can form a cluster of multiple application subsystems to improve the reliability and scalability of the application. A cluster is transparent to the client. The cluster structure has the following advantages.
a. Extensibility. A multi-application server cluster has a much larger processing capacity than a single application server, and new servers can be added dynamically to increase processing power.
b. High reliability. A cluster uses multi-application server redundancy to prevent the entire system from crashing due to one of the servers. When one server crashes, other servers can continue to respond to client requests.
These features provided by WebLogic are transparent to both the writers and the users of the application. The application writer does not need to care about how the server is configured. It only needs to focus on the implementation of its own application logic. When the client sends a request to the server, it does not care about the internal processing of the server. A cluster can manage multiple controlled clusters. A controlled cluster provides a specific service interface in each server in the cluster. HTTP session state clusters and object clusters are controlled cluster types. In addition, there are managed clusters that provide cluster services for JMS message queues and JDBC connection pools.
3.4 Data Communication Service Management The dedicated data communication service management system of the power market technical support system introduced in this article is based on IBM's MQSeries communication middleware products and is mainly developed using the VC++ language. The data communication service program establishes a message processing mechanism based on "transaction-rule-task", constructs a standardized, data packetizing/unpacking/transporting communication interface (protocol) based on the Win32 platform, and strengthens the power market transaction center. The stability, safety, and reliability of data transmission between power plants.
The function of the data communication service management system is: Based on the "transaction-rule-task" message processing mechanism, the data that needs to be exchanged between the power market trading center and the power market technical support system of each power plant is abstractly described as the data exchange constraint. - Rules; assign executable rules to specific transactions; by defining the data tables to be processed by the firm, the task definition is completed; then, the data communication service program interprets the transaction rules in a timely manner and generates different message packets. Release the MQSeries message queue; the MQSeries channel is responsible for transmitting to the destination message queue. The destination data communication service program obtains the message packet from the queue and interprets the message packet as a meaningful database operation command to the destination. The database operates, or interprets the message packet as meaningful warning information for use by the corresponding application.
3.5 Network Transmission Security To ensure the security of data transmission and message transmission in power market trading centers and power plants, the power market technical support system can use TheJavaSecureSocketExtension (JSSE) architecture based on the SecureSocketsLayer (SSL) and TransportLayerSecurity (TLS) protocols. Network programming. Its functions include data encryption, server-side and client-side security authentication, and data integrity protection.
4 Examples This paper will combine the implementation of a pre-scheduling plan subsystem in an actual electricity market technical support system and explain the proposed solution more clearly. 
It can be seen from this example that the technical design of the power market technology support system based on Web technology proposed in this paper is feasible, and it can fully guarantee the high efficiency and safety of the system operation. Among them, SSL encryption technology is used to provide security for the TCP/IPSocket communication protocol.
Power Market Technical Support System Based on Internet/Intranet
0 Introduction The power market technical support system [1,2] is a huge information management system that aims to provide safe and powerful hardware and software support for the operation of the power market, and at the same time, it can reflect the general characteristics of power production and meet the basic laws of power system operation. 2 System Implementation This paper proposes a specific implementation scheme for a power market technical support system based on Internet/Intranet. The key technologies involved in this article are reflected in this example. Figure 3 shows the actual structure of the pre-scheduling plan management system. The client is an ordinary n browser. When the user performs functions such as viewing pre-scheduling plan result data and setting calculation parameters, a request is sent to the web server through the operation interface. The web server accesses the database through the application server and feeds back to the user; on the other hand, When the user executes the core algorithm of the pre-scheduling plan, the client sends a calculation request to the web server. The web server invokes the core algorithm on the calculation server, and receives the information returned by the client, and feeds back the information to the client; after the calculation is completed, The user can then access the web server through the client to view the calculation results. The division of labor among the servers involved in the entire process is clear, the burden is reasonable, and the security is fully guaranteed.