Databases Reference
In-Depth Information
Session Management
Analysis Services uses sessions to manage state, the current set of updated data (writeback
data) and calculations available while it executes a command. A command received by
Analysis Services can be executed in a stateless session, in which the command executes
independent of other commands, or in a stateful session, in which the command's execu-
tion can depend on the results or activities of another command in that session. For
example, you can create a calculated member that is temporarily available to you, and
then send a request that uses the calculated member. The request depends on the previous
command that created the calculated member. Therefore, the session is stateful. (For infor-
mation about calculated members, see Chapter 12, “Cube-Based MDX Calculations.”)
The session manager subsystem of Analysis Services manages sessions on the server. A
Session
object makes it possible to share data between requests. There is a many-to-many
relationship among client connections and session objects created on the server. You can
create many sessions from a single client connection; a client can work with a single
session through multiple connections. The only limitation is that the users who initiate
connections should have the same credentials. Figure 26.2 illustrates client applications
connecting to the server through session objects, one session object for each connection.
Server
Client
Session
Client
Client
Connection
Request
Begin
Transaction
Command
Command
Command
Commit/Rollback
Transaction
Session
Request
Session
Request
Connection
Command
Command
Command
Command
Command
Command
FIGURE 26.2
Sessions on the server are managed by the session manager subsystem.
When a client application connects to the server, the session manager creates a
Session
object; Analysis Services assigns a unique identifier to that
Session
object, and establishes
the connection. The client application can create a new session, work with an existing
one, or not create a session. (For information about the application programming interface
[API] that enables a client application to create and end sessions, see Chapter 32.)
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