Borland's MIDAS Technology
Borland has gained the premium of people's membership after launching Delphi. Every new version of Delphi has provided users with new, better functions. For example, Delphi 1.0 version This user has provided a new visualization programming, which enables users to quickly develop Windows3.1 application procedures. Delphi 2.0 adds a variety of high efficiency data such as data module. Now in the third generation version of Delphi 3 - - Multi-layer structured 32-bit fast-faster development tools have brought all new multi-layer structure concepts. ---- As early as 1980, the first data library management system is now now, the Database will be quietly started. At that time, the idea was to control the relationship system library, which is generally referred to as a single-layered structure (1 -tier). Data launched by this structural library program occupation calculator resources, in the 80-year-in-chief period, the data library should be used to start switching C / S structure, which is the two-layer structure (2 -tier). This structure is not a wide range of uses in the past ten years, and it is successful. However, after the back of the two-layer C / S finitecture, it is gradually exposed to the lack of the frame. The most clear questionnaires in it are now telescological and maintenance of the application. For example, how a multinational business is scattered on a very slow network in a very slow network, how to control data unity and integrity; once the application has any changes, the maintenance personnel must modify each client. application. ---- New Generation Database Treatment System In the C / S structure of the community, adding the application program server - - this new structure is what the N -Tier or Multi -tier is described. The application program servement includes the interface of the unified interface, the establishment of business rules and the rules of data processing logic. Multi-layer application service techniques allow for a division application program, and there is no need to install a complete set of data library tools on the local plan to deploy data on another machine. At the same time, it allows the operational rules and the process to enter the integration of management, and distributes the dynamic regulation of the process load on the entire network. ---- The public is known, the application program of the development server is much more difficult than the procedure of opening a single pure application level, and there are many system services need to be considered. If there is no good tool, it is only a kind of reason to do a complex multi-layer structure.
In order to make this idea, the Borland company launched the techniques and tools required for the development of multi-layered structures - -Midas. Multilayer Subject Application Services --- - There are two kinds of solutions for Midas. Midas is the abbreviation of Multi -tier Distributed Application Services Suite (Multi-Layer Package Application Services Pack), which also explains the real quality of MIDAS technology. It is also because it is too long, many people are more willing to solve it into Multi -tier Made Easy, which is also MIDAS. Multi -tiered computing is the artistic language of the industry, and Multi -Tier is the technical language used by the Borland company. The Borland typical three-layer junction is as follows: The first layer is the database server, the second layer is the application server, the third layer is a thin passenger machine. ---- Database servers are databases such as Interbase, Oracle, Sybase, MS SQL Server, and application server and thin passenger machine are set up by Delphi. In most cases, data library access software (examples such as BDE, SQL * NET, etc.) are running on the same machine. ---- Application server mainly Borland-based distributed data technology, at least two contents: ---- 1. Built in the Delphi component; ---- 2. Olenterprise products provide distributed computing and load balancing Super support. ---- Inside the Delphi component, you can easily connect two machines with DCOM, SOCKET or OLENTERPRISE, and transfer the data set between the two. Olenterprise tools provide DCOM's optional method simplified the two machines, especially for two running Windows 95 machines. Olenterprise enables access to Object Broker, which allows random spaceloads in several servers. In addition, it is also possible to load server tools on several machines. Each time it is connected, Broker will select a machine. For example, if you have 100 clients and 3 server, Object Broker will randomly distribute to 3 server, with approximately 33 clients per servor. Broker will provide support when servers are often closed. The write a few lines of code can be provided to provide the server error handling, and the client is switched from the server from the present question to the other normal running server.
Another Broker will not attempt to connect a new client to a closed server, and it will automatically connect to a servers that are running in it. ---- Sub-forming data set can read the remote data in the case where the client does not have any data library tools in the customer. Some users can have this question: It can also observe the data set on the remote machine without any data set in the client. Why should I use a subset of equivalendal data? This is because the function of the browser is far from the function of Borland distribution data set. If there is no strong third-party tool (such as intRabuilder), it is uncommon to increase the bunch of browses, or in the browser to join or build a one-to-many relationship table is not often difficult. However, these functions can be simply realized in the multi-layer application in Delphi, and Delphi's compilation should be more faster than Based on HTML, it is easier to answer. ---- Distributed Data Set Allows all standard Delphi components to be used in client applications, including database tools, but clients do not need to load BDE, ODBC, or any database class library (such as Oracle SQL * Net, Sybase Ct -Lib et al) Wait) . When some of the places on the network need to be a BDE or similar engine, but the customer is not loaded. Briefly, now you need a set of server-side data library tools, each customer can use it. ---- Sub-formal data set is a method of shrinking the network of network. After downloading the data from the server side, the client is operated in the client and does not have to initialize any network transactions, eliminating the need to change the server side. This means that multiple records can be edited, inserted, and delete multiple records in the case where the network is easy. When changing the server data, you can send multiple data packets to the network in the pre-selected time period. ---- Another except that the customer is disconnected from the network, still can use the "Briefcase Model" to access the data. The operation steps are as follows: First copy a remote data library to the magnetic disk, then turn off the meter, re-introduce it, disconnect the network connection, edit the data, and then reconnect the net network and modify the database. All these can be completed at a customer who has no large data library tool. This is the way to operate, and the client does not have to connect to the server every moment. This is not constant for the lack of the lap-type calculation machine and the smallest site that wants to keep the data library. ---- The other party of Midas technology is to provide access to the data library coverage condition.
When the data is unloaded from the server, a set of self-execution of the beam condition can be unloaded at the same time. The strip condition can help the program to ensure the data of the user. When you are renewed to the network, the data can be correctly modified. If you can't send a wrong mistake when you change the database, the built-in machine system will help the program report and the wrong misconduct. For example, if another user has changed the record you are trying to change, you will see a list of options that tell you. A pre-established form in Delphi Object Repository can make your application procedure simply realize the wrong handling. Another heavy function of the Borland multi-layer calculation is to disperse the load of the data library into multiple servers. In this way, once a mistake is wrong, it can be restored. In summary, these technologies are present in three Broker: ---- The first kind of Remote Data Broker, the essence of the Remote Data Broker structure is to make each client no longer need BDE, replaced by a centralized BDE To reduce the overhead and complexity required for each customer in BDE in a centralized manner. ---- The second name is called constraint brroker, and the role it plays is a completeness and data of the authority of the country. ---- The third is Business Object Broker, and its purpose is to give some key business applications to provide a quick and trusted use of environment. In order to satisfy this high-level, Business Object Broker will automatically use the program to make appropriate divisions, and reproduce the important business rules to each interval to achieve the requirements of the speed. The real tool ---- Borland provides four Delphi tool helper households. The first two are in the server side: ---- 1. The remote data module is like a standard data module, which does not transmit data to the previous application, and will be transmitted to the specific area on the network. It is especially transfining simple data modules into a COM object, allowing you to access the DC library through the DCOM. ---- 2. The TPROVIDER component is like a TTable component that can reside in the standard data module, residing in the remote data module, is not true, TPROVIDER issues data tables on the network. TTable and Tquery components include provider attributes. However, if you do it as an independent component, there will be a greater spiritual activity and strength.
