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| = ServiceState = | = ServiceState: interface between SCM and APL = |
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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 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` like this: {{{ Start [1] #.WinFile.PolishCurrentDir [2] {}#.ServiceState.Init 1 3 [3] '#'⎕WS'Event'#.ServiceState.Events.QuitDQ [4] :If #.ServiceState.IsRunningAsService [5] {}#.ServiceState.EstablishServiceCallback ⍬ [6] {#.TestService.Run ⍵}&⍬ [7] ⎕DQ'.' [8] #.TestService.Off [9] :Else [10] #.TestService.Run ⍬ [11] :EndIf }}} Note that this example focuses just on getting the application running as a service. Remarks: '''[1]''': This makes sure that if the workspace carries a path the work (or current) directory is set accordingly. '''[2]''': This initializes the `ServiceState` interface. There are two arguments: 1. is a boolean that indicates whether the service shall connect to Ride (1) or not (0). 2. is a positive integer specifying the number of seconds until `ServiceState` gives up waiting for the application to confirm a state change requested by the SCM (timeout). Note that the two values are considered as constants; they are therefore established as niladic functions. For example, after having executed line [2] of the aforementioned `Start` function you can say: {{{ #.ServiceState.States.ride 1 #.ServiceState.States.timeout 3 }}} '''[3]''': `#.ServiceState.Events.QuitDQ` is a variable carrying an (any) integer. The application is supposed to send the same integer to `#` (when it wants to stop) in order to quit the `⎕DQ` on line 7. '''[4]''': Checks whether the application is actually running as a Windows Service. '''[5]''': This establishes `#.ServiceState.EstablishServiceCallback` as a callback that will handle all messages send by the Windows SCM. '''[6]''': Here we start the real application. Note that this '''must''' run in its own thread because otherwise the application might well become unresponsive. '''[7]''': We need to execute `⎕DQ '.'` in order to make sure that the interpreter processes all events. '''[8]''': At this stage we need to execute `⎕OFF`; that's what `#.TestService.Off` is doing. == The application == The application must make sure that it checks whether a state change was requested. This can be done by calling certain helpers as shown in this example: {{{ MainLoop dummmy;buffer;data;event;obj;rc;r;msg;cs [1] Log INI.CONFIG.appshortname,' server started' [2] :While 1 [3] ⎕DL 1 [4] :If #.ServiceState.ShallServicePause [5] Log'The service is pausing' [6] {}#.ServiceState.WaitForContinue ⍬ [7] Log'The service is resuming' [8] :EndIf [9] :If #.ServiceState.ShallServiceQuit [10] Log'The service is in the process of shutting down...' [11] :Leave [12] :EndIf [13] :EndWhile [14] ⎕NQ'#'#.ServiceState.Events.QuitDQ }}} Remarks: '''[14]''': This makes sure that the `⎕DQ` in `Start[7]` quits. Apart from `ShallServicePause` and `ShallServiceQuit` there is also a function `ShallServiceContinue` but this is called by this function: {{{ {r}←WaitForContinue dummy [1] ⍝ Returns always ⍬. [2] ⍝ Consider calling this in case ShallServicePause has returned a 1 and you don't _ [3] ⍝ have to do any particular gymnastics but just want to wait for a state change. [4] ⍝ It just waits until the status changes, although not necessarily to "continue". [5] r←⍬ [6] :While 0=ShallServiceContinue [7] ⎕DL 1 [8] :EndWhile }}} == Project Page == For bug reports, future enhancements and a full version history see [[ServiceState/ProjectPage]] == Version Information == ||Original author: ||KaiJaeger || ||Responsible: ||KaiJaeger || ||Email: || kai@aplteam.com || <<Include(APLTreeDownloads)>> ---- CategoryAplTree [[CategoryAPLTreeProject]] |
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.