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Session Pools

Session pools are a set of host sessions that you preconfigure for access by data objects. You can configure these host sessions with model variables and a starting entity, which provides faster host session allocaton and access to the host system because the host session can be logged on and waiting at the host application's main entry screen (entity) when a data object is ready to use it. This ability significantly enhances the Host Integrator's performance.

The Pools View

The Administrative Console provides a Pools view that contains the data you need to monitor your session pools.

To open the Pools view

  • From the Host Integrator perspective, open the View menu, and select Pools.

    This view shows pools that are associated with the objects you select in the Session Server Explorer or other views in the Administrative Console.

Creating Session Pools

To create a pool you must have at least one model deployed to the session server. You can deploy models using the Design Tool or on the command line. See the Design Tool help for instructions.

To create a session pool

  1. From the Session Server Explorer tree, select Pools under the appropriate session server, and then right-click and choose Add Pool.

    The Add Session Pool dialog box is displayed.

  2. Specify the name of the pool.

    When you create a new session pool, it is assigned, by default, the name Pool-1 (or whatever number is appropriate). You can specify any name you want.

  3. From the Models to use drop down list, select the model you want to associate with the new pool.

    The Start pool option is enabled by default. This option starts the pool as soon as it is created.

  4. Clear the Start pool checkbox to delay starting the pool and then click Next.

    The Session Pool Details panel displays.

  5. Determine the details for the new session pool.

    Session pool options include session management and host information. For complete descriptions of these settings, see Session Pool Details.

  6. Click Next to configure more advanced options or click Finish to complete creating the session pool.

  7. If needed, complete the Advanced Session Pool Details panel.(For descriptions of these settings, see Advanced Session Pool Details.

  8. Click Finish. The pool is added to the Pools view and it's associated session information is added to the Sessions view. You can open both of these views using the View menu.

You can add model variables to the session pool and set pool scheduling options using the Pool Properties page.

To open the property page

  • Click on the toolbar or right-click the pool name in the Session Server Explorer and choose Properties.

Viewing Session Pool Options

The following options are displayed in the Add Session Pool panels for each individual session pool:

Session Pool Details

Max concurrent sessions Specifies the maximum number of concurrent sessions that can be active in this pool. This is the "high water mark" for the number of sessions that can be created. The value you specify for this option cannot exceed the server's global setting Maximum concurrent sessions, or your licensed session limit. If the session pool has the maximum number of clients connected, any additional runtime client connection request will result in an exception. You can configure the server to automatically notify an administrator when this situation arises by using email configuration or SNMP configuration.

Initial idle sessions Specifies the number of sessions that are preloaded by the server. This is the number of sessions that a server should preconnect. The idle session count cannot exceed the server's global setting Maximum concurrent sessions or your licensed session limit, which is displayed as the maximum value for this option. If the session pool uses a model variable list, plan for enough model variable list entries for the expected (or maximum) number of concurrent sessions. Otherwise, when all entries are used, any attempt by an additional client to connect to the session pool will result in an exception.

Use Max pending sessions to control how quickly the sessions are preloaded.

Setting Initial idle sessions to a number equal to the expected number of concurrent sessions may provide better server performance.

Min idle sessions Minimum number of idle sessions to maintain.

Max idle sessions Maximum idle sessions cannot exceed the Maximum concurrent sessions defined for the pool, or your licensed session limit, which is displayed as the maximum value for this option.

Startup entity Specifies the entity the host session will be initialized to when a data object attaches to the host session. If the host session is returned to the pool when the data object releases it, it will automatically return to this entity for the next data object.

Host name Specifies the host the sessions in the pool connect to. The name specified here overrides the name stored in the model.

Host port Specifies the host port ID that the sessions in the pool connect to. The port ID specified here overrides the port ID stored in the model.

Advanced Session Pool Details

Connection throttle delay (seconds) The amount of time to wait since the last host connection before attempting another. This option is often set to zero; it is usually preferable to use Max Pending Sessions.

Max retry backoff (minutes) Each time there is an error starting host sessions in a pool, the pool waits for an increasing amount time before trying again (it backs off). This option limits the retry backoff so the delay doesn't become too long.

Max pending sessions The maximum number of sessions trying to connect to the host simultaneously. The actual number may be much less if the sessions start and login rapidly. The pools might not be able to keep up. This setting is intended to protect the host from a denial of service attack, not to guarantee performance.

Model Debug Messages Recording Specifies the model debug reporting status for the model. Options include Disabled, Record Errors, Record Error Sessions, and Record Everything. Use the Design Tool Model Debug Messages feature to troubleshoot and debug your model. Configure recording options on the Server Properties page of the Administrative Console.

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