Hello, using ICS V5 under D2007 I'm having OnDataAvailable reetrancy issues once again. (and nobody explained yet to me why the message triggering OnDataAvailable is still sticking in the queue until OnDataAvailable is fully processed)
My setup is a bit complex: 1. a GUI which also is a COM client 2. a COM server with event support so the GUI get's notified about certain things and the COM server is the embedded DLL type with single threaded appartment model 3. the COM server has a TWSocket with a OnDataAvailable handler. So in the case causing me trouble and headaches the TWSocket has successfully received some data and hands it to a callback function inside the COM server for further processing. The COM server adds the data (most important part is a string) to a queue and raises a COM event. The GUI gets the COM event and calls a method of the COM server to fetch the first item of that queue. I had thought to have decoupled the OnDataAvailable with the rest of the app by this sheme, but it's not the case. Now the data gets processed by the GUI (in this part written in MVP fashion) and if a certain situation arises the GUI has to ask the user via MessageDlg if he likes the system to do a certain ting automatically or not. And this is the culprit! Since GUI and COM server act as "one big space" for the windows messages and the decoupling didn't work out as I intended the MessageDlg's own message loop causes reetrancy inside the OnDataAvailable and bad things happen. One can prove this by replacing the MessageDlg with a if true then construct, simulating the user clicked on yes in the MessageDlg. What can I do to decouple this? My first try now (mostly successfull) was to add the received data to a queue in my TWSocket descendant and instead of directly calling the callback to call a Timer which did this. Now a normal TTimer causes a delay of about 15ms minimum so it got replaced by a MultimediaTimer now, but that's also not the ultimate solution as MMTimer is not available on W2K and is being considered as deprecated by MS already (MSDN states this). Another suggestion from a newsgroup now is to have a separate thread instead of the timer which has its own message loop and would be notified via PostThreadMessage from the OnDataAvailable event of my TWSocket descendant. I couldn't yet try this but would try it the next time possible. But I'm also open for any other suggestions. What else could I do, as threads can get messy if not really properly coded. And: wouldn't it be good to have another OnDataAvailable event available within TWSocket which is not prone to reetrancy? (it would have to signal windows somehow that the message used to trigger this has already been processed. Would such a thing be possible? Greetings Markus -- To unsubscribe or change your settings for TWSocket mailing list please goto http://lists.elists.org/cgi-bin/mailman/listinfo/twsocket Visit our website at http://www.overbyte.be
