Brief description of connection management related code samples.

Creating a connection is an expensive database operation which involves several background operations such as network communication, reading connection strings, authentication, transaction enlistment, foreground process creation and memory allocation. Each of these processes contributes to the amount of time and resources taken to create a connection object. Repeated connection creation and destruction will significantly impact Java application scalability.

"Connection Management" code samples explain various ways of connecting to an Oracle Database and explain use-cases to be considered while choosing the connection management strategy. The section below provides more details on specific connection management strategy.

This sample shows how to connect to a simple DataSource (oracle.jdbc.pool.OracleDataSource) and how to set connection related properties such as defaultRowPrefetch, defaultBatchValue etc.,

The server-side Type 2 (T2S) driver (aka KPRB driver) is for Java in the database. It uses database session directly for accessing local data. T2S driver is used for better performance because it cuts network traffic between the Java code and the RDBMS SQL engine.

The server side Type 4(T4S) driver (aka thin/T4 driver) is used for code running Java in database session needing access to another session either on the same RDBMS instance/server or on a remote RDBMS instance/server.

This sample shows connecting to the Oracle Database using Proxy authentication or N-tier authentication. Proxy authentication is the process of using a middle tier for user authentication. Proxy connections can be created using any one of the following options. (a) USER NAME: Done by supplying the user name or the password or both. (b) DISTINGUISHED NAME: This is a global name in lieu of the password of the user being proxied for. (c) CERTIFICATE:More encrypted way of passing the credentials of the user, who is to be proxied, to the database.

DRCP can be used with or without a client side connection pool. Either UCP or any other third party connection pool (eg., C3P0) can be used as client side pool. Note that, when UCP is used, it takes care of attaching and releasing server connections. There is no need to explicitly call attachServerConnection()/detachServerConnection() with UCP.

Universal Connection Pool (UCP) is a client side connection pool. UCP furnishes a rich set of features to support scalability in single database instance as well as built-in features to support high-availability and scalability in RAC and Active Data Guard environments. UCP along with RAC, RAC One and ADG is a tested and certified combination for handling database failovers. Refer to this sample for using UCP and setting UCP properties such as minPoolSize, maxPoolSize, etc.

Database Resident Connection Pool (DRCP) is the server side connection pool. DRCP should be used in a scenario when there are a number of middle tiers but the number of active connections is fairly less than the number of open connections. DRCP when used along with and Universal Connection Pool(UCP) as the client side connection pool improves the performance. The sample shows UCP with DRCP in action. The purpose of the client-side pooling mechanism is to maintain the connections to Connection Broker. Client-side connection pools must attach and detach connections to the connection broker through attachServerConnection() and detachServerConnection(). DRCP should be used in a scenario when there are a number of middle tiers but the number of active connections is fairly less than th number of open connections.