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| ~-<<SeeSaw(section="table-of-contents", show="true", seesaw="false", toshow="<<(Show>> table-of-contents)", tohide="<<(Hide>> table-of-contents)", speed="Slow")>>-~ <<TableOfContents>> `ServiceState` is part of the CategoryAplTree project. == Overview == {{{ServiceState}}} is a namespace script that offers an interface between the Windows SCM (Service Control Manager) and a Dyalog APL application running as a service. In you application workspace you need to have a function on `⎕LX` similar to this: {{{ Start;ps [1] ps←#.ServiceState.CreateParmSpace [2] ps.ride←1 [3] #.ServiceState.Init ps [4] :If #.ServiceState.IsRunningAsService [5] {#.TestService.Run ⍵}&⍬ [6] ⎕DQ'.' [7] #.TestService.Off [8] :Else [9] #.TestService.Run ⍬ [10] :EndIf }}} Note that this example focuses on getting the application running as a service. For the purpose of demonstrating how to overwrite defaults (no RIDE) it shows how to create a parameter space with default settings (line [1]) and then overwrite a setting (line [2]). If you are happy with the defaults (which you can check by executing `#.ServiceState.CreateParmSpace.∆List`) then you can specify `⍬` as the right argument of `#.ServiceState.Init` in line [3]. Remarks: '''[4]''': Checks whether the application is actually running as a Windows Service. This allows to execute the application in its own thread in case its running as a service but not otherwise - that makes debugging the application significantly easier. '''[5]''': Here we start the real application. Note that this '''must''' run in its own thread because otherwise the application might well become unresponsive. '''[6]''': We need to execute `⎕DQ '.'` in order to make sure that the interpreter processes all events. '''[7]''': At this stage we need to execute `⎕OFF`; that's what `#.TestService.Off` is doing. == The application == The application must make sure in its main loop that it checks for state changes, and act accordingly. This is all done by the Operator `#.ServiceState.CheckServiceMessages` which takes the name of a logging function as operand: {{{ MainLoop dummmy;buffer;data;event;obj;rc;r;msg;cs [1] :Repeat [2] ⎕DL 1 ⍝ What is reasonable here depends on the application [3] :If (Log #.ServiceState.CheckServiceMessages)#.ServiceState.IsRunningAsService [4] Log'The service is in the process of shutting down...' [5] :Leave [6] :EndIf [7] :Until 0 }}} Remarks: Line '''[3]''' checks for any changes signalled from the Service Control Manager (SCM). If a "Pause" is detected, then the function loops until either a "Continue" or a "Stop" is detected. The explicit result is 1 in case a "Stop" is detected and 0 otherwise. <<Include(APLTreeDownloads)>> ---- CategoryAplTree |
The project has been relocated to [[https://github.com/aplteam/ServiceState]] on 2018-03-03. |
ServiceState: interface between SCM and APL
The project has been relocated to https://github.com/aplteam/ServiceState on 2018-03-03.