The maintenance of the system has been scattered from the client to the server, which enhances the stability and efficiency of the system. In the process of enterprise informatization, small and medium-sized manufacturing companies usually start with warehouse management systems. In such an enterprise, the existing system is a manual system, which has many defects such as information storage redundancy, time-consuming information query, and lagging out-of-stock warning. In severe cases, it even affects the normal production. When developing warehouse management information systems, due to the poor scalability of the traditional two-tier database system and the difficulty of management, people gradually turned their attention to the new three-tier database technology. This article introduces the warehouse management system under the Web mode of developing a three-tier structure with Delphi5.0 with examples.
Three-tier structure introduction The biggest advantage of using a three-tier database can be summarized in two points: one is the centralized data processing mechanism; the second is to simplify the client program. Three-tier database applications can be divided into the following three tiers. Client program: used to provide a user interface, is a "thin" client program. Application server: It is used to manage the data transmitted between the client and the database server. It is a key to the industrial engineering in the three-tier architecture and plays a role of inheritance. Database server: used to provide a database system.
If you combine the three-tier database structure with Web technology, you can also publish the application system to the Internet.
Delphi5.0 can create an application server or a "thin" client program, develop the client program as a client program (Activeform), embed it in a web page for people to download, and then run it locally. Developing the client in this way further simplifies the client's installation and configuration, making the client's installation simpler to use a browser to download a control from a web page and run it on the web page, and put all system maintenance work on the server side.
The principle of developing a three-tier Web structure with Delphi Delphi's support for a three-tier architecture is mainly due to its MIDAS technology. Its principle is shown in Figure 2.
Schematics.
1) Client program In this way, the client program is embedded as an Activeform in a web page for people to download, and is designed as an Activeform client program. As for which MIDAS connection control to choose, it depends on the communication protocol. We use a connection component (TsocketConnection) (based on the TCP / IP protocol, because the environment that supports TCP / IP is the Host property to locate the computer where the application server is located.
2) Application server The key control of the application server is the remote data module. One or more data supply interfaces (TdataSetProvider) are generally placed on the remote data module to provide the data supply interface. The database asks the database to create an alias, and the application server uses the data set component name to establish a connection with the remote database.
The warehouse management system has realized the comprehensive management of five warehouses. Among them: 1) System management menu: used by warehouse supervisors, including operator management, basic code management, unit code management, inventory model settings, and system initialization.
2) Material warehouse (hardware, electronics, steel) menu: including warehouse management, warehouse management, procurement, inventory and monthly reports, query statistics.
3) Finished product warehouse menu: including warehouse management, product warehouse, inventory and monthly report, query statistics.
4) Semi-finished product warehouse menu: including warehouse management, warehouse management, inventory and monthly report.
5) Inquiry statistics menu: including inquiries of basic codes and unit codes and cost statistics.
The design of the three-tier Web method 1) Create a database server. The database server uses SQL Server 7.0 on Windows NT 4.0 and mainly includes 7 libraries: â‘ System library (system): including some basic common code, such as Min Xilin, Zhang Lihou: use Delphi5 0Develop a three-tier structured Web method for warehouse management system product codes, supplier codes, customer codes, outsourcing factory codes, department codes, production lot numbers, maintenance lot numbers, sales contract numbers, operator codes, etc.
â‘¡Hardware storehouse (wj): contains hardware export account, hardware deposit account, hardware material code.
â‘¢Steel warehouse (gc): Contains steel export account, steel deposit account, steel material code, and steel conversion table.
â‘£Electronic library (dz): Contains the electronic inventory account, electronic inventory account, and electronic material code.
⑤Finished product warehouse (cp): Contains the finished product inventory account, finished product inventory account, and finished product material code.
â‘¥ Semi-finished product warehouse (bcp): Contains semi-finished goods export account, semi-finished product storage account, semi-finished product material code.
⑦Backup (backup): store the data to be backed up.
2) Establishment of application server To create a three-tier Web system, first create an application server and register it. Only when the application server is registered and running normally can the client program be created.
Here is an example material matching table query. Since the accessories used for each product come from different warehouses, such as the product with the specification number 2188, the hardware warehouse needs to provide several types of accessories, the steel warehouse also needs to provide several types of accessories, and the electronic warehouse also needs to provide.
When the workshop comes to pick up materials, as long as it is a production plan, the hardware warehouse and other warehouses should see the product specifications and models and then check how many accessories should be given to the workshop from the computer.
To make the system work, we must first connect Delphi and SQLServer. This requires using BDE. Start the BDE database alias in Delphi, and set the parameters in the Definition page on the right.
When creating an application server: â‘¡ Put a data set control, such as TTable, on the remote data module, and make related settings to enable it to access the remote SQL database and specify the database to be accessed.
â‘£ Save and compile the application server.
3) Establishment of client program This system is a Web system, using the structure shown in Figure 1, that is, its development steps are as follows: â‘¡ Put in the connection component, select TSocketConnection in the system, set its ServerName property, specify and connect the application service. As long as the application server is registered and running normally, this can be selected directly from its drop-down list.
â‘¢ Put in the client data set component (TClientDataSet), its Remoteserver is the connection component of the previous step, additionally set the ProviderName property, and select it from the drop-down list.
④ Put in the data source component (TDataSource), set ⑤ save in the user interface design component such as TDBGrid, and its TDataSource property points to the data source of the previous step.
Options ", set options related to Web publishing, mainly to specify the distribution to the Web server.
When the Activeform is modified, it must be included in this number when it is republished, so that the browser will re-download it if it encounters a new version, otherwise it will only remain intact forever, the material matching query form obtained in the browser.
Key program for querying supporting materials in different warehouses of a product (1) Client data request program (client is put into the data set industrial engineering (2) application server response program (application server is put into the warehouse based on the three-tier structure Web mode The management system realizes the effective management of various types of inventory information. Considering the low computer application ability of most enterprise library managers, putting the system maintenance function on the server side is managed by the corresponding professional, which undoubtedly enhances the stability and efficiency of system operation In addition, when the process of enterprise informatization develops to develop other subsystems, each subsystem can have its own database server, application server, and client. Because BDE can set the remote database alias, the client connection component can be passed through such as TCP / IP and other protocols to connect to the application server, so the access of each layer between subsystems is very convenient, so this method should have broad application prospects.
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