My initial thoughts: Although it is kind of discussed very broadly, I did struggle a bit to properly grasp the value add this adds over the alternative approaches that are available today (or need a little work to accomplish) in specific use cases. I feel its better to take specific common use cases and show why this will do better to make it clear. For example data flow starting from a pool of web server and finally end up in HDFS or Hive while providing At-least one guarantees.
Below are more specific points that occurred to me: - Import: Today we can create data flows to pick up data from a variety of source and push data into Kafka using Flume. Not clear how this system can do better in this specific case. - Export: For pulling data out of Kakfa there is Camus (which limits destination to HDFS), Flume (which can deliver to many places) and also Sqoop (which could be extended to support Kafka). Camus and Sqoop don't have the problem of "requires defining many tasks" issue for parallelism. - YARN support – Letting YARN manage things is actually good thing (not a bad thing as indicated), since its easier for the scaling in/out as needed and not worry too much about hardware allocation. - Exactly-Once: It is clear that on the import side you won't support that for now. Not clear how you will support that on export side for destination like HDFS or some other. Exactly once only make sense when we can have that guarantee on the entire data flow (not just portions of the flow). - Connector Variety: Flume and Sqoop already have out of the box- support for multiple destinations and sources. -roshan On 6/19/15 2:47 PM, "Jay Kreps" <j...@confluent.io<mailto:j...@confluent.io>> wrote: I think we want the connectors to be federated just because trying to maintain all the connectors centrally would be really painful. I think if we really do this well we would want to have >100 of these connectors so it really won't make sense to maintain them with the project. I think the thought was just to include the framework and maybe one simple connector as an example. Thoughts? -Jay On Fri, Jun 19, 2015 at 2:38 PM, Gwen Shapira <gshap...@cloudera.com<mailto:gshap...@cloudera.com>> wrote: I think BikeShed will be a great name. Can you clarify the scope? The KIP discusses a framework and also few examples for connectors. Does the addition include just the framework (and perhaps an example or two), or do we plan to start accepting connectors to Apache Kafka project? Gwen On Thu, Jun 18, 2015 at 3:09 PM, Jay Kreps <j...@confluent.io<mailto:j...@confluent.io>> wrote: > I think the only problem we came up with was that Kafka KopyKat abbreviates > as KKK which is not ideal in the US. Copykat would still be googlable > without that issue. :-) > > -Jay > > On Thu, Jun 18, 2015 at 1:20 PM, Otis Gospodnetic < > otis.gospodne...@gmail.com<mailto:otis.gospodne...@gmail.com>> wrote: > >> Just a comment on the name. KopyKat? More unique, easy to write, >> pronounce, remember... >> >> Otis >> >> >> >> > On Jun 18, 2015, at 13:36, Jay Kreps >> > <j...@confluent.io<mailto:j...@confluent.io>> wrote: >> > >> > 1. We were calling the plugins connectors (which is kind of a generic way >> > to say either source or sink) and the framework copycat. The pro of >> copycat >> > is it is kind of fun. The con is that it doesn't really say what it does. >> > The Kafka Connector Framework would be a duller but more intuitive name, >> > but I suspect people would then just shorten it to KCF which again has no >> > intuitive meaning. >> > >> > 2. Potentially. One alternative we had thought of wrt the consumer was to >> > have the protocol just handle the group management part and have the >> > partition assignment be purely driven by the client. At the time copycat >> > wasn't even a twinkle in our eyes so we weren't really thinking about >> that. >> > There were pros and cons to this and we decided it was better to do >> > partition assignment on the broker side. We could revisit this, it might >> > not be a massive change in the consumer, but it would definitely add work >> > there. I do agree that if we have learned one thing it is to keep clients >> > away from zk. This zk usage is more limited though, in that there is no >> > intention of having copycat in different languages as the clients are. >> > >> > 4. I think the idea is to include the structural schema information you >> > have available so it can be taken advantage of. Obviously the easiest >> > approach would just be to have a static schema for the messages like >> > timestamp + string/byte[]. However this means that i the source has >> schema >> > information there is no real official way to propagate that. Having a >> real >> > built-in schema mechanism gives you a little more power to make the data >> > usable. So if you were publishing apache logs the low-touch generic way >> > would just be to have the schema be "string" since that is what apache >> log >> > entries are. However if you had the actual format string used for the log >> > you could use that to have a richer schema and parse out the individual >> > fields, which is significantly more usable. The advantage of this is that >> > systems like databases, Hadoop, and so on that have some notion of >> schemas >> > can take advantage of this information that is captured with the source >> > data. So, e.g. the JDBC plugin can map the individual fields to columns >> > automatically, and you can support features like projecting out >> particular >> > fields and renaming fields easily without having to write custom >> > source-specific code. >> > >> > -Jay >> > >> >> On Tue, Jun 16, 2015 at 5:00 PM, Joe Stein >> >> <joe.st...@stealth.ly<mailto:joe.st...@stealth.ly>> >> wrote: >> >> >> >> Hey Ewen, very interesting! >> >> >> >> I like the idea of the connector and making one side always being Kafka >> for >> >> all the reasons you mentioned. It makes having to build consumers (over >> and >> >> over and over (and over)) again for these type of tasks much more >> >> consistent for everyone. >> >> >> >> Some initial comments (will read a few more times and think more through >> >> it). >> >> >> >> 1) Copycat, it might be weird/hard to talk about producers, consumers, >> >> brokers and copycat for what and how "kafka" runs. I think the other >> naming >> >> makes sense but maybe we can call it something else? "Sinks" or whatever >> >> (don't really care just bringing up it might be something to consider). >> We >> >> could also just call it "connectors"...dunno.... producers, consumers, >> >> brokers and connectors... >> >> >> >> 2) Can we do copycat-workers without having to rely on Zookeeper? So >> much >> >> work has been done to remove this dependency if we can do something >> without >> >> ZK lets try (or at least abstract it so it is easier later to make it >> >> pluggable). >> >> >> >> 3) Even though connectors being managed in project has already been >> >> rejected... maybe we want to have a few (or one) that are in the project >> >> and maintained. This makes out of the box really out of the box (if only >> >> file or hdfs or something). >> >> >> >> 4) "all records include schemas which describe the format of their >> data" I >> >> don't totally get this... a lot of data doesn't have the schema with >> it, we >> >> have to plug that in... so would the plugin you are talking about for >> >> serializer would inject the schema to use with the record when it sees >> the >> >> data? >> >> >> >> >> >> ~ Joe Stein >> >> - - - - - - - - - - - - - - - - - >> >> >> >> http://www.stealth.ly >> >> - - - - - - - - - - - - - - - - - >> >> >> >> On Tue, Jun 16, 2015 at 4:33 PM, Ewen Cheslack-Postava < >> e...@confluent.io<mailto:e...@confluent.io>> >> >> wrote: >> >> >> >>> Oops, linked the wrong thing. Here's the correct one: >> >> >> https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=58851767 >> >>> >> >>> -Ewen >> >>> >> >>> On Tue, Jun 16, 2015 at 4:32 PM, Ewen Cheslack-Postava < >> >> e...@confluent.io<mailto:e...@confluent.io>> >> >>> wrote: >> >>> >> >>>> Hi all, >> >>>> >> >>>> I just posted KIP-26 - Add Copycat, a connector framework for data >> >>>> import/export here: >> >> >> https://cwiki.apache.org/confluence/display/KAFKA/Kafka+Improvement+Proposals >> >>>> >> >>>> This is a large KIP compared to what we've had so far, and is a bit >> >>>> different from most. We're proposing the addition of a fairly big new >> >>>> component to Kafka because we think including it as part of Kafka >> >> rather >> >>>> than as an external project is in the best interest of both Copycat >> and >> >>>> Kafka itself. >> >>>> >> >>>> The goal with this KIP is to decide whether such a tool would make >> >> sense >> >>>> in Kafka, give a high level sense of what it would entail, and scope >> >> what >> >>>> would be included vs what would be left to third-parties. I'm hoping >> to >> >>>> leave discussion of specific design and implementation details, as >> well >> >>>> logistics like how best to include it in the Kafka repository & >> >> project, >> >>> to >> >>>> the subsequent JIRAs or follow up KIPs. >> >>>> >> >>>> Looking forward to your feedback! >> >>>> >> >>>> -Ewen >> >>>> >> >>>> P.S. Preemptive relevant XKCD: https://xkcd.com/927/ >> >>> >> >>> >> >>> -- >> >>> Thanks, >> >>> Ewen >> >> >>
