A small introduction to the three-layer database and application server (Delphi&BCB)
Author: Zeng Mu Dark Shark 2002
Ben Shark spent 10 yuan to buy two e-book databases, and three C++ BUILDER5 advanced programming technology for 100 yuan <<Database and MIDAS programming>>
<<IDE and OPP Programming>><<COM, CORBA and Internet Programming>>Xu Xinhua People's Posts and Telecommunications Press learned and took a look here.
Everyone doesn't know much about application servers, so I'll explain my understanding.
Application server solves two main problems
In a client/server mode: the database server is responsible for the connection problem (Brother Xiang Yu encountered it)
Second, the website needs to dynamically update data and databases to connect to the Internet
I won’t talk about other applications.
The first mode application environment is mainly in the LAN: client program + application server + database
The second mode of application is on the Internet: browser + WEB server + application server + database
A browser can be used in a LAN, and a client program can be used in the Internet.
It can be imagined that large data flows can be used in a local area network, and small data flows must be used in the Internet.
Where are the rules applied?
After adopting the application server, everyone reached a consensus and submitted the rules on the client.
Some people put rules into application servers, which can reduce the workload of the database.
I think the rules still allow the database to be managed, and the database has a better ability than ours.
Only some very old databases have very low management rules, perhaps not relational databases
The application server has to deal with the rules.
It is best for the application server to be responsible for the connection, monitoring of data traffic, and providing high-quality services to the client.
Better compatibility with different types of old-fashioned databases.
There are currently three types of application servers
Microsoft's decentralized type: spread across different technologies.
Database vendors: They sell application servers (special type) together when they sell databases.
Independent software vendor: a separate application server developed.
Suitable for different situations.
And we, I think, are developing independent application servers that can provide better flexibility and compatibility.
Everyone should pay attention to the future when developing.
C++Builder5 provides us with various parts for development clients and application servers.
Application server-side parts: TDataSetPRovider+BDE method parts (Table, Query...)+ADO(ADOTable......). odbc is still through BDE parts; I haven't seen SQL link
ADO parts are not rich without BDE sessions, batch movement, cache updates, and nested tables; there are no InterBase transactions, database information, monitoring, and events.
BDE was released very complicated and disobedient, and even if there was an installer, it was ashamed. I hope C++Builder6 can enhance ADO function. Is Deiithl6 unanswerable?
Client
TDataSource+TClientDataSet+{TDCOMConnection;TSocketConnection;TWebConnection;TCorbaConnction;TSimpleObjectBroker}
Five different ways to connect to the application server.
TDCOMConnection When publishing using DCOM technology, pay attention to the NT server name and domain name settings, and the application server must also register DCOM with the client.
TSocketConnection: Using TCP/IP method, you can use NT domain name servers without using. If you connect to the application server with security problems, you must start ScktSrver.EXE to listen.
TWebConnection:
Using HTTP, it connects to the WEB server and passes data to the application server. When publishing, the client needs Wininet.dll to be installed with IE3 or above system;
The WEB server must be IIS4 UP or Netscap enterprise3.6 up
The WEB server must have HTTPsrvr.dll;
TWebConnection->URL="HTTP://MIDASHOST.ORG/scripts/httpsrvr.dll
TSimpleObject: TOLEnterpriseConnection Simple Version is for backward compatibility. The advantage is that it can be selected randomly to make the application server load balancing, consisting of 4 parts.
1Broker.exe
2ObjFact.exe
3OLECFG.exe
4OLEntExp.exe
1+2 is placed on the application server Broker.exe to run first; 3 and 4 are configuration tools. ClientDataset+DCOM+Simpleobject cannot be used alone
TCorbaConnction: I don’t have this guy! !
All clients must publish MIDAS.DLL at the same time. I won’t say much about the specific situation. Newspaper News said that when joining the WTO, companies need to use information systems. I have learned that information systems are very complicated and involve management methods and interpersonal relationships, but for database support, the three-layer database must be the first. We have heroes and a place to use them, VC VB is still a little tender