Application Block Structure Function Analysis on Smart Clients (2)

3. Updater Application Block: This module is mainly responsible for automatic updating of programs. In the fat client mode, it is very troublesome to deploy and update programs. Especially when there are hundreds of clients, we have to process them one by one, in this way, we will waste a lot of time and energy, and it is very easy to make mistakes. The Updater Application Block provides a good solution. Each time the client starts, the program checks the version of the file to be updated, if the server version is later than the current client version, the user is prompted whether to update the program. If confirmed, the latest client program is automatically obtained from the server.

4. Configure Application Block: in the Application Block automatically updated above, you will be certain to question how the program judges the version of the current client file and what files to update. At this time, the Configure Application Block is used. This module provides us with a series of processing XML files. The formats of these XML files have some basic definitions, in this example, we can set our configuration information so that we can use these files to obtain some information about the current client.

5. caching Application Block: In this application block, Microsoft encapsulates their recommended cache mechanism for us. Since we are using a smart client to develop distributed programs, cache data is very important for programs. There are two caching mechanisms: short-term data caching, that is, storing data in the memory; and long-term data caching, most of the data is stored in our hard disk. For how to cache these two mechanisms, we need to consider a lot in the process of programming, because if it is stored in the memory, it is fast, but easy to lose, although the data stored in the hard disk is not easy to lose, there is a slow speed problem. How to balance the two is a difficult problem. In this application block, Microsoft basically puts forward some principles for solving this problem.

6. Logging Application Block: in our program, to avoid operations by illegal users, or to record all operations performed by users, we must record the operations performed by the program. The recorded records are generally stored in a file, which is generally called a log. In a Smart Client, many operations such as file update and version check will automatically generate a very detailed log file. This log file is in XML format. That is to say, we can easily read, write, and analyze it, and import it into the database.

7. Security Application Block: Because smart clients want to implement remote collaborative work, data transmission over the network is inevitable. Users are generally concerned about security issues. Once some sensitive data or confidential data is lost on the Internet, the consequences are unimaginable. To solve this problem, Microsoft provides a variety of security solutions in the Security Application Block, including how to authorize users and how to encrypt files, how to verify the validity of a user. There are also a lot of applications in the Smart Client. For example, when we want to perform automatic updates, the server will first use a key to verify the legitimacy of the client, only verified clients can download the updated files correctly.

8. Exception management application block: in the actual running process of the program, many unexpected situations are inevitable, that is, the exceptions we call. A program's handling of exceptions is also a major user-friendly standard. This application block provides a variety of options. When an exception occurs, it may be handled in a defined manner, or the process may be terminated by writing the log file; the processing may also be handed over to the user for manual selection. In this way, we can flexibly handle exceptions so that program functions can be better implemented.

In short, the preceding application blocks are interconnected and mutually dependent, forming a whole. In this way, an intelligent client system can be formed. We believe that in the near future, this system will bring us a brand new experience.