MarkLogic Server's 'DatabaseClient' instance represents a database connection sharable across threads. The connection is stateless, except that authentication is done the first time a client interacts with the database via a Document Manager, Query Manager, or other manager. For instance: you may instantiate a DatabaseClient as follows:
// Create the database client
DatabaseClient client = DatabaseClientFactory.newClient(host, port,
user, password, authType);
And release it as follows:
// release the client
Details on DatabaseClient Usage
To use the Java Client API efficiently, it helps to know a little bit about what goes on behind the scenes.
You specify the enode or load balancer host when you create a database client object. Internally, the database client object instantiates an Apache HttpClient object to communicate with the host.
The internal Apache HttpClient object creates a connection pool for the host. The connection pool makes it possible to reuse a single persistent HTTP connection for many requests, typically improving performance.
Setting up the connection pool has a cost, however.
As a result, we strongly recommend that applications create one database client for each unique combination of host, database, and user. Applications should share the database client across threads. In addition, applications should keep a reference to the database client for the entire life of the application interaction with that host.
For instance, a servlet might create the database client during initialization and release the database client during destruction. The same servlet may also use two separate database client instances with different permissions, one for read-only users and one with read/write permissions for editors. In the latter case, both client instances are used throughout the life of the servlet and destroyed during client destruction.