On a application level, the two most common architectures are:
As internet computing becomes more prevalent in computing environments, many database management systems are moving to a multitier environment.
An system can easily take advantage of distributed processing by using its client/server architecture. In this architecture, the database system has two parts: a front-end or a client, and a back-end or a server.
The client is a database application that initiates a request for an operation to be performed on the database server. It requests, processes, and presents data managed by the server. The client workstation can be optimized for its job. For example, the client might not need large disk capacity, or it might benefit from graphic capabilities. Often, the client runs on a different computer than the database server. Many clients can simultaneously run against one server.
The server runs Oracle Database software and handles the functions required for concurrent, shared data access. The server receives and processes requests that originate from client applications. The computer that manages the server can be optimized for its duties. For example, the server computer can have large disk capacity and fast processors.
A traditional multitier architecture has the following components:
This architecture enables use of an application server to do the following:
If proxy authentication is being used, then the identity of the client is maintained throughout all tiers of the connection.
Service-oriented architecture (SOA) is a multitier architecture in which application functionality is encapsulated in services. SOA services are usually implemented as Web services. Web services can be accessed with the HTTP protocol and are based on a set of XML-based open standards, such as WSDL and SOAP.