Classification in terms of architecture
- Two-tier file-server systems. In such case the server usually performs function of data storage (storage of executive files is also possible), and data processing is done on a client PC. Number of clients is limited due to restrictions of simultaneous access and changes in one file. The main disadvantages of such type are: absence of 100% database integrity, low security level, low performance.
- Two-tier client-server systems, all computing is done on DBMS server, protected by server's OS. The main disadvantages of this type are: low speed and impossibility to use complex computing algorithms. Here we should point out that there are a plethora of solutions working as a file-server type, despite client-server tools are used. Such solutions are usually used when there is a need to transfer performance of a complex computing algorithm from server to a client work place.
- Multi-tier systems, the functions of data processing are distributed to one or several separate servers; it allows separating functions of storage, processing and data presentation to make process more effective. At the present stage such solutions have all necessary functionality.