Middleware Client settings

Deadlock Retry Count

The number of times a deadlock scenario must be retried before returning an error to the caller.

Deadlock Retry Wait Max

The maximum time (in milliseconds) a deadlock must wait before retrying. The default wait time is randomly chosen between 0 and the configured maximum wait time.

Listen Backlog

Specifies the number of pending accept requests to be queued. If the listen backlog queue fills up, new socket requests will be rejected.

Max Concurrent Calls

A Windows Communication Foundation (WCF) throttling setting that limits the number of calls that can be made against the MES middleware host.

Max Concurrent Instances

A WCF throttling setting that limits the number of instances that can be made against the MES middleware host. It is recommended that this value be set to 100 x the number of processors on the server. For example, if the server has eight processors, the value of this setting should be 800.

Max Concurrent Sessions

A WCF throttling setting that limits the number of sessions that can be made against the MES middleware host.

Max Connections

The maximum number of connections allowed to be pending dispatch on the MES middleware server.

Max Message Size

The maximum size of the message (in MB) that you can exchange between the client and the server.

Receive Timeout

The amount of time in seconds that the client must wait before receiving data from the server.

Send Timeout

The amount of time in seconds that the client must wait when sending a command to the server.

Transaction Timeout

The maximum time that a transaction may take to execute (in seconds). All the commands within the transaction must complete within this time.

Optimizing MES Middleware Client–Host Communication

The defaults for the settings Listen Backlog, Max Concurrent Calls, Max Concurrent Instances, Max Concurrent Sessions, and Max Connections have been selected to optimize the reliability of communication between the MES middleware client proxies and the MES middleware host. The defaults are the recommended settings for medium and large systems, and also work without causing communication issues for small systems.

If these settings are changed to lower values, transaction processing issues might occur, as indicated by the following error message: TCP Provider: No connection could be made because the target node actively refused it.

For example, the WCF throttling settings limit the number of calls, sessions, and instances that can be made against a service. Setting limits on these helps to avoid DOS (denial of service) attacks as they help to prevent the server from being overwhelmed. However, if the setting values are too low, the server can be underutilized.

To further ensure optimal communication between MES middleware proxy clients and the middleware host, it is recommended that there be no devices between the client and host nodes, such as load balancers or NATs (network address translators).