Hey Richard, Before you go and spend time on Request Transaction Manager (RTM) - please note that it does impact sending of requests, also for subscriptions, but does not block incoming packets. This is an coordination mechanism for plc4x to control data link access. Since I haven't looked nor compared ADS driver logic between releases you did mention I suppose that we simply missed a handling of subscriptions in this or other way. This logic should be portable with little effort. My suggestion towards you is to compare these parts of drivers to see how 0.8 or 0.9 evolved.
The only case when RTM comes into the play is when you do want to send another request once you receive answer for previous one. In such cases you need to do everything inside transaction runnable which accquired the 'lock'. Also make sure that you release it both for success and failure scenarios. If you fail to release transaction then your subsequent requests will get stuck. It is fairly easy to spot if you do smaller changes. Kind regards, Łukasz śr., 4 sie 2021 o 17:41 Richard Meister <richard.meis...@ascon-systems.de> napisał(a): > Hi Christofer, > > thank you for the quick response and good to hear there is no specific > technical reason. I will give it a go and come back with a PR and > (probably) more questions :) > > > Regards, > Richard > > -----Ursprüngliche Nachricht----- > Von: Christofer Dutz [mailto:christofer.d...@c-ware.de] > Gesendet: Mittwoch, 4. August 2021 17:05 > An: dev@plc4x.apache.org > Betreff: AW: ADS Subscriptions for >0.8 > > Hi Richard, > > first of all, welcome and happy you like our little project :-) > > There is no technical reason for us not supporting subscriptions. In > general the only reason is that when I re-wrote the driver from 0.6 to 0.8 > I switched from single-item requests to multi-item requests. There was some > semi-documentation on this for read and write. However not for > subscriptions. So this would require some reverse-engineering work and I > simply didn't have the time for that. > > I think this would definitely be something we'll be providing in the > future ... I just can't say when I'll have the time for it. > > If this however is something you and your company need, feel free to work > on this ... I'd be willing to be of assistance as long as the results go > back into the open-source project. > > Or if you're willing to put a few bucks on the table this definitely can > help shift some priorities ;-) > > Chris > > > -----Ursprüngliche Nachricht----- > Von: Richard Meister <richard.meis...@ascon-systems.de> > Gesendet: Mittwoch, 4. August 2021 16:30 > An: dev@plc4x.apache.org > Betreff: ADS Subscriptions for >0.8 > > Hi everyone, > > first of all, thank you for creating and maintaining this project! PLC4X > helped us to get started with ADS in Java quickly and painlessly. > > The matter of my writing is that we use subscriptions as the primary > communication mode for ADS, so to the best of my knowledge we're bound to > v0.6(.1). We've applied a patch to set the cycleTime in AdsTcpPlcConnection > to zero, because otherwise we would miss changes that occur more frequently > than once per 400ms. > Probably there are some good reasons that subscriptions do not work with > the generated driver. I have poked a bit into the code of v0.8 and presume > it is a restriction of the RequestTransactionManager. But before taking a > deep dive into the code I thought I'd hear your thoughts on this first. > Maybe someone can point me into the right direction and enable me to > contribute. I'm willing to spend time on this and I have access to a > Beckhoff iPC with TwinCat 2 for testing. > > > Cheers, > Richard > > > >
