keep_awake

[TCPW],[TCPMGR],[progname]
keep_awake=1

Applies on Windows CE devices from release 4.621

Windows CE devices are typically configured to go into suspend mode automatically, after only a few minutes of user inactivity. This may be inappropriate if the device is running background processes that are communicating with another computer over a network. From release 4.621 DP4 can prevent Windows CE devices suspending while DP4 network activity is taking place. Note that this new functionality is enabled by default, but there are situations where it may be preferable to disable it.

DP4 prevents devices suspending automatically by resetting to zero the timer that measures the time since the last user activity, whenever certain types of network activity take place. DP4 does not prevent user-initiated suspends (for example the user presses an Off button), and only prevents automatic suspends while it detects significant network activity from DP4 programs.

There are currently three places where keep_awake can be specified:

• [TCPW]

  Unless you specify keep_awake=0 in the [TCPW] section, then, whenever a DP4 program calls the database manager across the network, the inactivity timer is reset. If DP4 is loaded in the named connection configuration calls passed to tcpw.wce but destined for the local machine are ignored. However, in a multiple resilience configuration, calls destined for the local machine do also reset the timer.

• [TCPMGR]

  Unless you specify keep_awake=0 in the [TCPMGR] section, then the inactivity timer is reset whenever TCPMGR receives a message other than a network "keepalive".

  If your application includes some kind of polling software that connects to each client machine in turn to look for new transactions, then you may find that the default keep_awake=1 setting prevents your CE devices from suspending. In this case you must either disable the keep_awake setting for [TCPMGR], or modify your polling software so that the delay between succesive polls of CE devices is long enough for them to be allowed to suspend when there is no activity. The latter solution is preferable as it will enable [TCPMGR] to stay awake when more significant network activity is taking place.

• [progname]

  The keep_awake setting also applies to programs run using the DP4 thin client.

  Unless you specify keep_awake=0 in the [progname] section for an application, then calls received by the DP4 thin client on behalf of that application will reset the inactivity timeout. Please note the following important points about this use of the keep_awake setting:

  • This setting must be specified in the DP4 configuration file on the application server and not on the client Windows CE device.
  • An application will not be able to keep a CE device awake when it is awaiting a response from the user. If the application is waiting for a response, but the user does not provide one in time to prevent the inactivity timer from suspending the machine, then Windows CE will suspend the device. This will cause the network connection to break, and the application to terminate. For this reason it is a good idea to build logic into your application that will allow it to remember its state and resume later on.
  • The keep_awake setting for applications is not a true [TRMW] type setting. It can only be specified in a named program section, and can only be specified at the executable file level - for example you cannot specify this setting for individual QAB programs.