Server Process

A server process is a program that directly interacts with the Oracle server. Once a user has established a connection, a server process is started to handle the user processes requests. A server process can be either a dedicated server process or a shared server process. In a dedicated server environment, the server process handles the request of a single user process. Once a user process disconnects, the server process is terminated. In ashared server environment, the server process handles the request of several user processes. The server process communicates with the Oracle server using the Oracle Program Interface Server processes (or the server portion of combined user/server processes) created on behalf of each user's application can perform one or more of the following:

• Parse and run SQL statements issued through the application
• Read necessary data blocks from datafiles on disk into the shared database buffers of the SGA, if the blocks are not already present in the SGA
• Return results in such a way that the application can process the information

Related Post:- 

• User Process
• Background Process 

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User Process

User Processes

When a user runs an Oracle tool Oracle creates a user process to run the user's application. A database user who needs to request information from the database must first make a connection with the Oracle server. The connection is requested using a database interface tool, such as SQL*Plus, and beginning the user process. The user process does not interact directly with the Oracle server. Rather it generates calls through the user program interface (UPI), which creates a session and starts a server process

Connections and Sessions

The terms "connection" and "session" are closely related to the term "user process", but are very different in meaning.

A connection is a communication pathway between a user process and an Oracle instance. A communication pathway is established using available interprocess communication mechanisms (on a computer that executes both the user process and Oracle) or network software (when different computers execute the database application and Oracle, and communicate via a network).

A session is a specific connection of a user to an Oracle instance via a user process. For example, when a user starts SQL*Plus, the user must provide a valid username and password and then a session is established for that user. A session lasts from the time the user connects until the time the user disconnects or exits the database application.

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• Server Process 
• Background Process 

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Introduction to processes

All connected Oracle users must execute two modules of code to access an Oracle database instance:

• Application or Oracle tool 
• Oracle server code 

These code modules are executed by processes. A process is a "thread of control" or a mechanism in an operating system that can execute a series of steps. (Some operating systems use the terms job or task. A process normally has its own private memory area in which it runs.

The process structure varies for different Oracle configurations, depending on the operating system and the choice of Oracle options. There are some processes 

• User Process 
• Server Process
• Background Process 

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