Re: Kafka Connect Integration
Hey Sagar, hey Chris, I want to join your discussion for part b3 as this is something we usually require. We use a module we call the plc-scraper for that task (the term scraping in that content is borrowed from Prometheus where it is used extensively in this context [1]). Generally speaking the scraper takes a config containing addresses, addresses and scrape rates and runs than as daemon and pushes the scrape results downstream (usually Kafka but we also use other "Queues"). As we are currently rewriting this scraper I already considered donating it to plc4x in the form of an example or perhaps even as a standalone module. So I agree with Chris that this should not be part of the PlcDriver Level but rather on another layer "on top" and I would be more interested in the specification of a "line protocol" which describes how message are serialized for Kafka (or other sources). Can we come up with a common "schema" which fits many use cases? Our messages contain the following informations: - timestamp - source - values - additional tags Best Julian [1] https://prometheus.io/docs/prometheus/latest/getting_started/ Am 28.08.18, 22:53 schrieb "Christofer Dutz" : Hi Sagar, sorry for not responding ... your mail must have skipped my eye ... sorry for that. a) PLC4X works exactly the same way ... it consists of plc4x-core, which only contains the DriverManager and plc4x-api which contains the API clases. So with these two jars you can build a full PLC4X application. In order to connect to a PLC you need to add the jar containing the required driver to the classpath. b) Well if using something other than the connection url as partition key as partition key, it is possible that multiple kafka connect nodes would connect to the same PLC. In that case it could be a problem to control the order. I guess using the timestamp when receiving a response (Probably generated by the KC plc4x driver) could be a valid approach. b2) Regarding the infinite loop ... I think we won't need such a mechanism. If we think of a set of fields from a PLC, we can think of a PLC as a one-row database table. Producing diffs should be a lot simpler that way. b3) Regarding push events ... PLC4X has a subscription mode next to the polling. So it would be possible to also define PLC4X datasources that actively push events to kafka ... I have to admit that this would be the mode I would prefer most. But as not all protocols and PLCs support this mode, I think it would be safest to use polling and to add push support after that. Regarding different languages: Currently we are concentrating mainly on the Java implementation as it's the biggest challenge to understand and implement the protocols. Porting them to other languages (especially C and C++) shouldn't be as hard as implementing the first version. But that's currently a base uncovered as we don't have the resources to implement all of them at once. And there are no stupid questions :-) Hope I could answer all of yours. If not, just ask and I'll probably not miss that one ;-) Chris Am 23.08.18, 19:52 schrieb "Sagar" : Hi Chirstofer, Thanks for the detailed responses. I would like to ask a couple of more questions(which may be borderline naive or stupid :D ). First thing that I would like to know- ignore my lack of knowledge on PLCs- but from what I understand are devices which are small devices used to execute program instructions. These would have very small memory footprints as well I believe? Also, when you say the Siemens one can handle 20 connections, would it be from different devices connecting to it? The reason I ask these questions are these -> a) The way the kafka-connect framework is executed is by installing the whole framework with all the relevant jars needed on the classpath. So, if you talk about the JDBC connector for K-Connect, it would need the mysql driver jar(for example) and other jars needed to support the framework. If we say choose to use avro, then we would need more jars to support that. Would we be able to install all that? b) Also, if multiple devices do connect to it, then won't we have events arriving out of order from them? Does the ordering matter amongst events that are being pushed? Regarding the infinite loop question, the reason JDBC connector uses that is that it creates tasks for a given table and fires queries to find deltas. So, if the polling frequency is 2 seconds, and it last ran on 12.00.00 then it would run at 12.00.02 to figure out what changed in that time frame. So, the way PlcReaders read()
Re: Making your first release
I agree with Justin and Juliana and would suggest; Spend some time to get the release process automated and smooth, then start a 0.x release train, with no compatibility guarantees. On Sun, Aug 26, 2018 at 5:29 PM, Julian Feinauer < j.feina...@pragmaticminds.de> wrote: > Hi Justin, > > > > I like your suggestion and also wanted to suggest a first release soon as > we start to experiment with plc4j a lot in one project and I don’t like to > reference snapshots with the lot of changes going on (or are planned). > > What do the others think of this? > > > > Julian > > > > Am 26.08.18, 02:22 schrieb "Justin Mclean" : > > > > Hi, > > > > While looking through the incubator reports it’s come to my attention > that this podling hasn’t made a release yet and has been in the incubator > for 250+ days. "Release early and release often” should be the guideline > to follow. What is holding up this project making it first release? > Remember a first release doesn’t have to be perfect and each release just > needs to be better than the last. > > > > Thanks, > > Justin > > > -- Niclas Hedhman, Software Developer http://polygene.apache.org - New Energy for Java
Re: ASF Slack
I could be mistaken but I think anyone can join or be invited On Wed., 29 Aug. 2018, 8:41 am Julian Feinauer, < j.feina...@pragmaticminds.de> wrote: > Hi Benedikt, > > > > I think ist a good idea to have a slack for communication but I agree that > its a bit inelegant to require an apache email as many interested people or > (new) participants won't have one (I for example have none). > > > > Julian > > > > Am 28.08.18, 15:02 schrieb "Benedikt Ritter" : > > > > Hi! > > > > I've created #plc4x over at the-asf.slack.com You need an Apache > E-Mail to > > register, so it's probably not the best channel to discuss things. > > > > Regards, > > Benedikt > > > > >
Re: ASF Slack
Hi Benedikt, I think ist a good idea to have a slack for communication but I agree that its a bit inelegant to require an apache email as many interested people or (new) participants won't have one (I for example have none). Julian Am 28.08.18, 15:02 schrieb "Benedikt Ritter" : Hi! I've created #plc4x over at the-asf.slack.com You need an Apache E-Mail to register, so it's probably not the best channel to discuss things. Regards, Benedikt
Re: Kafka Connect Integration
Hi Sagar, sorry for not responding ... your mail must have skipped my eye ... sorry for that. a) PLC4X works exactly the same way ... it consists of plc4x-core, which only contains the DriverManager and plc4x-api which contains the API clases. So with these two jars you can build a full PLC4X application. In order to connect to a PLC you need to add the jar containing the required driver to the classpath. b) Well if using something other than the connection url as partition key as partition key, it is possible that multiple kafka connect nodes would connect to the same PLC. In that case it could be a problem to control the order. I guess using the timestamp when receiving a response (Probably generated by the KC plc4x driver) could be a valid approach. b2) Regarding the infinite loop ... I think we won't need such a mechanism. If we think of a set of fields from a PLC, we can think of a PLC as a one-row database table. Producing diffs should be a lot simpler that way. b3) Regarding push events ... PLC4X has a subscription mode next to the polling. So it would be possible to also define PLC4X datasources that actively push events to kafka ... I have to admit that this would be the mode I would prefer most. But as not all protocols and PLCs support this mode, I think it would be safest to use polling and to add push support after that. Regarding different languages: Currently we are concentrating mainly on the Java implementation as it's the biggest challenge to understand and implement the protocols. Porting them to other languages (especially C and C++) shouldn't be as hard as implementing the first version. But that's currently a base uncovered as we don't have the resources to implement all of them at once. And there are no stupid questions :-) Hope I could answer all of yours. If not, just ask and I'll probably not miss that one ;-) Chris Am 23.08.18, 19:52 schrieb "Sagar" : Hi Chirstofer, Thanks for the detailed responses. I would like to ask a couple of more questions(which may be borderline naive or stupid :D ). First thing that I would like to know- ignore my lack of knowledge on PLCs- but from what I understand are devices which are small devices used to execute program instructions. These would have very small memory footprints as well I believe? Also, when you say the Siemens one can handle 20 connections, would it be from different devices connecting to it? The reason I ask these questions are these -> a) The way the kafka-connect framework is executed is by installing the whole framework with all the relevant jars needed on the classpath. So, if you talk about the JDBC connector for K-Connect, it would need the mysql driver jar(for example) and other jars needed to support the framework. If we say choose to use avro, then we would need more jars to support that. Would we be able to install all that? b) Also, if multiple devices do connect to it, then won't we have events arriving out of order from them? Does the ordering matter amongst events that are being pushed? Regarding the infinite loop question, the reason JDBC connector uses that is that it creates tasks for a given table and fires queries to find deltas. So, if the polling frequency is 2 seconds, and it last ran on 12.00.00 then it would run at 12.00.02 to figure out what changed in that time frame. So, the way PlcReaders read() runs, would it keep returning newer data? We can skip over the rest of the parts, but looking at parts a and b above, would it make sense to have something like a kafka-connect framework for pushing data to Kafka? Also, from the github link, the drivers are to be supported in 3 languages as well. How would that play out? Again- apologies if the questions seem stupid. Thanks! Sagar. On Wed, Aug 22, 2018 at 10:39 PM Christofer Dutz wrote: > Hi Sagar, > > great that you managed to have a look ... I'll try to answer your > questions. > (I like to answer them postfix as whenever emails are sort of answered > in-line, they are extremely hard to read and follow on mobile email clients > __ ) > > First of all I created the original plugin via the archetype for > kafka-connect plugins. The next thing I did, was to have a look at the code > of the JDBC Kafka Connect plugin (as you might have guessed) as I thought > that it would have similar structure as we do. Unfortunately I think the > JDBC plugin is far more complex than the plc4x connector will have to be. I > sort of picked some of the things I liked with the archetype and some I > liked with the jdbc ... if there was a third, even cooler option ... I will > definitely have missed that. So if you think there is a thing worth > changing ... you can change anything you like. >
Re: Kafka Connect Integration
Hi Christofer, Just thought I will remind you with this one. There's no rush from my side but I see you're caught up with a lot of things so sending a reminder :) Thanks! Sagar. On Thu, Aug 23, 2018 at 11:22 PM Sagar wrote: > Hi Chirstofer, > > Thanks for the detailed responses. I would like to ask a couple of more > questions(which may be borderline naive or stupid :D ). > > First thing that I would like to know- ignore my lack of knowledge on > PLCs- but from what I understand are devices which are small devices used > to execute program instructions. These would have very small memory > footprints as well I believe? Also, when you say the Siemens one can handle > 20 connections, would it be from different devices connecting to it? The > reason I ask these questions are these -> > > a) The way the kafka-connect framework is executed is by installing the > whole framework with all the relevant jars needed on the classpath. So, if > you talk about the JDBC connector for K-Connect, it would need the mysql > driver jar(for example) and other jars needed to support the framework. If > we say choose to use avro, then we would need more jars to support that. > Would we be able to install all that? > > b) Also, if multiple devices do connect to it, then won't we have events > arriving out of order from them? Does the ordering matter amongst events > that are being pushed? > > Regarding the infinite loop question, the reason JDBC connector uses that > is that it creates tasks for a given table and fires queries to find > deltas. So, if the polling frequency is 2 seconds, and it last ran on > 12.00.00 then it would run at 12.00.02 to figure out what changed in that > time frame. So, the way PlcReaders read() runs, would it keep returning > newer data? > > We can skip over the rest of the parts, but looking at parts a and b > above, would it make sense to have something like a kafka-connect framework > for pushing data to Kafka? Also, from the github link, the drivers are to > be supported in 3 languages as well. How would that play out? > > Again- apologies if the questions seem stupid. > > Thanks! > Sagar. > > On Wed, Aug 22, 2018 at 10:39 PM Christofer Dutz < > christofer.d...@c-ware.de> wrote: > >> Hi Sagar, >> >> great that you managed to have a look ... I'll try to answer your >> questions. >> (I like to answer them postfix as whenever emails are sort of answered >> in-line, they are extremely hard to read and follow on mobile email clients >> __ ) >> >> First of all I created the original plugin via the archetype for >> kafka-connect plugins. The next thing I did, was to have a look at the code >> of the JDBC Kafka Connect plugin (as you might have guessed) as I thought >> that it would have similar structure as we do. Unfortunately I think the >> JDBC plugin is far more complex than the plc4x connector will have to be. I >> sort of picked some of the things I liked with the archetype and some I >> liked with the jdbc ... if there was a third, even cooler option ... I will >> definitely have missed that. So if you think there is a thing worth >> changing ... you can change anything you like. >> >> 1) >> The code of the jdbc plugin showed such a while(true) loop, however I >> think this was because the jdbc query could return a lot of rows and hereby >> Kafka events. In our case we have one request and get one response. The >> code in my example directly calls "get()" on the request and is hereby >> blocking. I don't know if this is good, but from reading the jdbc example, >> this should be blocking too ... >> So the PlcReaders read() method returns a completable future ... this >> could be completed asynchronously and the callback could fire the kafka >> events, but I didn't know if this was ok with kafka. If it is possible, >> please have a look at this example code: >> https://github.com/apache/incubator-plc4x/blob/master/plc4j/protocols/s7/src/test/java/org/apache/plc4x/java/s7/S7PlcReaderSample.java >> It demonstrates with comments the different usage types. >> >> While at it ... is there also an option for a Kafka connector that is >> able to push data? So if an incoming event arrives, this is automatically >> pushed without a fixed polling interval? >> >> 2) >> I have absolutely no idea as I am not quite familiar with the concepts >> inside kafka. What I do know is that probably the partition-key should be >> based upon the connection url. The problem is, that with kafka I could have >> 1000 nodes connecting to one PLC. While Kafka wouldn't have problems with >> that, the PLCs have very limited resources. So as far as I decoded the >> responses of my Siemens S7 1200 it can handle up to 20 connections (Usually >> a control-system already consuming 2-3 of them) ... I think it would be >> ideal, if on one Kafka node (or partition) there would be one PlcConnection >> ... this connection should then be shared among all requests to a PLC with >> a shared connection url (I hope I'm not writing
[GitHub] pisquaredover6 opened a new pull request #13: Basic example to connect S7 device to Google Cloud IoT Core
pisquaredover6 opened a new pull request #13: Basic example to connect S7 device to Google Cloud IoT Core URL: https://github.com/apache/incubator-plc4x/pull/13 Implement basic example of connecting a S7 device to Google Cloud IoT Core This is an automated message from the Apache Git Service. To respond to the message, please log on GitHub and use the URL above to go to the specific comment. For queries about this service, please contact Infrastructure at: us...@infra.apache.org With regards, Apache Git Services
Re: API Changes proposal
Hi all, I just pushed changes to my API refactoring branch ... so far I only adjusted the API module and added an example using the changed API. To have a look, please go to [1] ... General changes I implemented while working on the refactoring itself. I did notice, that my current proposal "chris-2" did Having to inject the type conversion code would have made it necessary to inject a converter which didn't feel right. So I changed the API to be purely interface based. In order to be able to construct these objects I also added builders for them. I asked a few people here what they think, and most liked the simplicity and didn't have any WTF experiences (Which seems to be a good thing as I did have to explain a lot with the current API) Quick Feedback highly appreciated as I will start implementing DefaultPlcReadRequest & Co (in driver-base ... together with the builders) after that I'll start migrating the drivers. Right now having a look a named example [1] would be a good start ... Second would be a deeper look into the API module [2]. Would be a shame to waste that time and effort if you think the changes suck (or are less than optimal as non-Germans would probably call them ;-) ) . Chris [1] https://github.com/apache/incubator-plc4x/blob/feature/api-redesign-chris-c/examples/hello-plc4x/src/main/java/org/apache/plc4x/java/examples/helloplc4x/HelloPlc4x.java [2] https://github.com/apache/incubator-plc4x/tree/feature/api-redesign-chris-c/plc4j/api Am 27.08.18, 09:57 schrieb "Christofer Dutz" : Ups ... after reloading .. I just saw Julians Proposal pop up ... haven't looked into that ... Will do that right away. Chris Am 25.08.18, 15:52 schrieb "Christofer Dutz" : Hi Julian, version 2 should now be quite different ... I started reworking my original proposal and decided to revert that an start a second proposal. My first did address some parts needing cleaning up, but I still wasn't quite satisfied with it. So I did another more radical refactoring. If you reload the second there should be a lot of differences. I just hit "save" a few minutes ago however ... but now I'm quite happy with it. So please have another look at the second proposal. And please, maybe add your own proposal ... my versions are just Brainstorming from my side. My favorite is currently "Chris' Proposal 2" ;-) Chris
