Hi All, The KIP wiki page is now up-to-date with the scope we have agreed on: Producer and Consumer Interceptors with a minimal set of mutable API that are not dependent on producer and consumer internal implementation.
I have few more API details that I would like to bring attention to or/and discuss: 1. Handling exceptions Exceptions can provide an additional level of control. For example, we can filter messages on consumer side or stop messages on producer if they don’t have the right field. I see two options: 1.1. For callbacks that can mutate records (onSend and onConsume), propagate exceptions through the original calls (KafkaProducer.send() and KafkaConsumer.poll() respectively). For other callbacks, catch exception, log, and ignore. 1.2. Catch exceptions from all the interceptor callbacks and ignore. The issue with 1.1. is that it effectively changes KafkaProducer.send() and KafkaConsumer.poll() API, since now they may throw exceptions that are not documented in KafkaProducer/Consumer API. Another option is to allow to propagate some exceptions, and ignore others. I think our use-cases do not require propagating exceptions. So, I propose option 1.2. Unless someone has suggestion/use-cases for propagating exceptions. Please let me know. 2. Intercepting record CRC and record size Since we decided not to add any intermediate callbacks (such as onEnqueue or onReceive) to interceptors, I think it is still valuable to intercept record CRC and record size in bytes for monitoring and audit use-cases. I propose to add checksum and size fields to RecordMetadata and ConsumerRecord. Another option would be to add them as parameters in onAcknowledgement() and onConsume() callbacks. 3. Callbacks that allow to modify records look as follows: ProducerRecord<K, V> onSend(ProducerRecord<K, V> record); ConsumerRecords<K, V> onConsume(ConsumerRecords<K, V> records); This means that interceptors can potentially modify topic/partition in ProducerRecord and topic/partition/offset in ConsumerRecord. I propose that it is up to the interceptor implementation to ensure that topic/partition, etc is correct. KafkaProducer.send() will use topic, partition, key, and value from ProducerRecord returned from the onSend(). Similarly, ConsumerRecords returned from KafkaConsumer.poll() would be the ones returned from the interceptor. Please let me know if you have any suggestions or objections to the above. Thanks, Anna On Wed, Jan 27, 2016 at 2:56 PM, Anna Povzner <a...@confluent.io> wrote: > Hi Mayuresh, > > I see why you would want to check for messages left in the > RecordAccumulator. However, I don't think this will completely solve the > problem. Messages could be in-flight somewhere else, like in the socket, or > there maybe in-flight messages on the consumer side of the MirrorMaker. So, > if we go the route of checking whether there are any in-flight messages for > topic deletion use-case, maybe it is better count them with onSend() and > onAcknowledge() -- whether all messages sent were acknowledged. I also > think that it would be better to solve this without interceptors, such as > fix error handling in this scenario. However, I do not have any good > proposal right now, so these are just general thoughts. > > Thanks, > Anna > > > > On Wed, Jan 27, 2016 at 11:18 AM, Mayuresh Gharat < > gharatmayures...@gmail.com> wrote: > >> Calling producer.flush(), flushes all the data. So this is OK. But when >> you >> are running Mirror maker, I am not sure there is a way to flush() from >> outside. >> >> >> Thanks, >> >> Mayuresh >> >> On Wed, Jan 27, 2016 at 11:08 AM, Becket Qin <becket....@gmail.com> >> wrote: >> >> > Mayuresh, >> > >> > Regarding your use case about mirror maker. Is it good enough as long >> as we >> > know there is no message for the topic in the producer anymore? If that >> is >> > the case, call producer.flush() is sufficient. >> > >> > Thanks, >> > >> > Jiangjie (Becket) Qin >> > >> > On Tue, Jan 26, 2016 at 6:18 PM, Mayuresh Gharat < >> > gharatmayures...@gmail.com >> > > wrote: >> > >> > > Hi Anna, >> > > >> > > Thanks a lot for summarizing the discussion on this kip. >> > > >> > > It LGTM. >> > > This is really nice : >> > > We decided not to add any callbacks to producer and consumer >> > > interceptors that will depend on internal implementation as part of >> this >> > > KIP. >> > > *However, it is possible to add them later as part of another KIP if >> > there >> > > are good use-cases.* >> > > >> > > Do you agree with the use case I explained earlier for knowing the >> number >> > > of records left in the RecordAccumulator for a particular topic. It >> might >> > > be orthogonal to this KIP, but will be helpful. What do you think? >> > > >> > > Thanks, >> > > >> > > Mayuresh >> > > >> > > >> > > On Tue, Jan 26, 2016 at 2:46 PM, Todd Palino <tpal...@gmail.com> >> wrote: >> > > >> > > > This looks good. As noted, having one mutable interceptor on each >> side >> > > > allows for the use cases we can envision right now, and I think >> that’s >> > > > going to provide a great deal of opportunity for implementing things >> > like >> > > > audit, especially within a multi-tenant environment. Looking >> forward to >> > > > getting this available in the clients. >> > > > >> > > > Thanks! >> > > > >> > > > -Todd >> > > > >> > > > >> > > > On Tue, Jan 26, 2016 at 2:36 PM, Anna Povzner <a...@confluent.io> >> > wrote: >> > > > >> > > > > Hi All, >> > > > > >> > > > > Here is meeting notes from today’s KIP meeting: >> > > > > >> > > > > 1. We agreed to keep the scope of this KIP to be producer and >> > consumer >> > > > > interceptors only. Broker-side interceptor will be added later as >> a >> > > > > separate KIP. The reasons were already mentioned in this thread, >> but >> > > the >> > > > > summary is: >> > > > > * Broker interceptor is riskier and requires careful >> consideration >> > > about >> > > > > overheads, whether to intercept leaders vs. leaders/replicas, >> what to >> > > do >> > > > on >> > > > > leader failover and so on. >> > > > > * Broker interceptors increase monitoring resolution, but not >> > > including >> > > > it >> > > > > in this KIP does not reduce usefulness of producer and consumer >> > > > > interceptors that enable end-to-end monitoring >> > > > > >> > > > > 2. We agreed to scope ProducerInterceptor and ConsumerInterceptor >> > > > callbacks >> > > > > to minimal set of mutable API that are not dependent on producer >> and >> > > > > consumer internal implementation. >> > > > > >> > > > > ProducerInterceptor: >> > > > > *ProducerRecord<K, V> onSend(ProducerRecord<K, V> record);* >> > > > > *void onAcknowledgement(RecordMetadata metadata, Exception >> > exception);* >> > > > > >> > > > > ConsumerInterceptor: >> > > > > *ConsumerRecords<K, V> onConsume(ConsumerRecords<K, V> records);* >> > > > > *void onCommit(Map<TopicPartition, OffsetAndMetadata> offsets);* >> > > > > >> > > > > We will allow interceptors to modify ProducerRecord on producer >> side, >> > > and >> > > > > modify ConsumerRecords on consumer side. This will support >> end-to-end >> > > > > monitoring and auditing and support the ability to add metadata >> for a >> > > > > message. This will support Todd’s Auditing and Routing use-cases. >> > > > > >> > > > > We did not find any use-case for modifying records in onConsume() >> > > > callback, >> > > > > but decided to enable modification of consumer records for >> symmetry >> > > with >> > > > > onSend(). >> > > > > >> > > > > 3. We agreed to ensure compatibility when/if we add new methods to >> > > > > ProducerInterceptor and ConsumerInterceptor by using default >> methods >> > > with >> > > > > an empty implementation. Ok to assume Java 8. (This is Ismael’s >> > method >> > > > #2). >> > > > > >> > > > > 4. We decided not to add any callbacks to producer and consumer >> > > > > interceptors that will depend on internal implementation as part >> of >> > > this >> > > > > KIP. However, it is possible to add them later as part of another >> KIP >> > > if >> > > > > there are good use-cases. >> > > > > >> > > > > *Reasoning.* We did not have concrete use-cases that justified >> more >> > > > methods >> > > > > at this point. Some of the use-cases were for more fine-grain >> latency >> > > > > collection, which could be done with Kafka Metrics. Another >> use-case >> > > was >> > > > > encryption. However, there are several design options for >> encryption. >> > > One >> > > > > is to do per-record encryption which would require adding >> > > > > ProducerInterceptor.onEnqueued() and >> ConsumerInterceptor.onReceive(). >> > > One >> > > > > could argue that in that case encryption could be done by adding a >> > > custom >> > > > > serializer/deserializer. Another option is to do encryption after >> > > message >> > > > > gets compressed, but there are issues that arise regarding broker >> > doing >> > > > > re-compression. We decided that it is better to have that >> discussion >> > > in a >> > > > > separate KIP and decide that this is something we want to do with >> > > > > interceptors or by other means. >> > > > > >> > > > > >> > > > > Todd, Mayuresh and others who missed the KIP meeting, please let >> me >> > > know >> > > > > your thoughts on the scope we agreed on during the meeting. >> > > > > >> > > > > I will update the KIP proposal with the current decision by end of >> > > today. >> > > > > >> > > > > Thanks, >> > > > > Anna >> > > > > >> > > > > >> > > > > On Tue, Jan 26, 2016 at 11:41 AM, Mayuresh Gharat < >> > > > > gharatmayures...@gmail.com> wrote: >> > > > > >> > > > > > Hi, >> > > > > > >> > > > > > I won't be able to make it to KIP hangout due to conflict. >> > > > > > >> > > > > > Anna, here is the use case where knowing if there are messages >> in >> > the >> > > > > > RecordAccumulator left to be sent to the kafka cluster for a >> topic >> > is >> > > > > > useful. >> > > > > > >> > > > > > 1) Consider a pipeline : >> > > > > > A ---> Mirror-maker -----> B >> > > > > > >> > > > > > 2) We have a topic T in cluster A mirrored to cluster B. >> > > > > > >> > > > > > 3) Now if we delete topic T in A and immediately proceed to >> delete >> > > the >> > > > > > topic in cluster B, some of the the Mirror-maker machines die >> > because >> > > > > > atleast one of the batches in RecordAccumulator for topic T >> fail to >> > > be >> > > > > > produced to cluster B. We have seen this happening in our >> clusters. >> > > > > > >> > > > > > >> > > > > > If we know that there are no more messages left in the >> > > > RecordAccumulator >> > > > > to >> > > > > > be produced to cluster B, we can safely delete the topic in >> > cluster B >> > > > > > without disturbing the pipeline. >> > > > > > >> > > > > > Thanks, >> > > > > > >> > > > > > Mayuresh >> > > > > > >> > > > > > On Tue, Jan 26, 2016 at 10:31 AM, Anna Povzner < >> a...@confluent.io> >> > > > > wrote: >> > > > > > >> > > > > > > Thanks Ismael and Todd for your feedback! >> > > > > > > >> > > > > > > I agree about coming up with lean, but useful interfaces that >> > will >> > > be >> > > > > > easy >> > > > > > > to extend later. >> > > > > > > >> > > > > > > When we discuss the minimal set of producer and consumer >> > > interceptor >> > > > > API >> > > > > > in >> > > > > > > today’s KIP meeting (discussion item #2 in my previous email), >> > lets >> > > > > > compare >> > > > > > > two options: >> > > > > > > >> > > > > > > *1. Minimal set of immutable API for producer and consumer >> > > > > interceptors* >> > > > > > > >> > > > > > > ProducerInterceptor: >> > > > > > > public void onSend(ProducerRecord<K, V> record); >> > > > > > > public void onAcknowledgement(RecordMetadata metadata, >> Exception >> > > > > > > exception); >> > > > > > > >> > > > > > > ConsumerInterceptor: >> > > > > > > public void onConsume(ConsumerRecords<K, V> records); >> > > > > > > public void onCommit(Map<TopicPartition, OffsetAndMetadata> >> > > offsets); >> > > > > > > >> > > > > > > Use-cases: >> > > > > > > — end-to-end monitoring; custom tracing and logging >> > > > > > > >> > > > > > > >> > > > > > > *2. Minimal set of mutable API for producer and consumer >> > > > interceptors* >> > > > > > > >> > > > > > > ProducerInterceptor: >> > > > > > > ProducerRecord<K, V> onSend(ProducerRecord<K, V> record); >> > > > > > > void onAcknowledgement(RecordMetadata metadata, Exception >> > > exception); >> > > > > > > >> > > > > > > ConsumerInterceptor: >> > > > > > > void onConsume(ConsumerRecords<K, V> records); >> > > > > > > void onCommit(Map<TopicPartition, OffsetAndMetadata> offsets); >> > > > > > > >> > > > > > > Additional use-cases to #1: >> > > > > > > — Ability to add metadata to a message or fill in standard >> fields >> > > for >> > > > > > audit >> > > > > > > and routing. >> > > > > > > >> > > > > > > Implications >> > > > > > > — Partition assignment will be done based on modified >> key/value >> > > > instead >> > > > > > of >> > > > > > > original key/value. If key/value transformation is not >> consistent >> > > > (same >> > > > > > key >> > > > > > > and value does not mutate to the same, but modified, >> key/value), >> > > then >> > > > > log >> > > > > > > compaction would not work. However, audit and routing >> use-cases >> > > from >> > > > > Todd >> > > > > > > will likely do consistent transformation. >> > > > > > > >> > > > > > > >> > > > > > > *Additional callbacks (discussion item #3 in my previous >> email):* >> > > > > > > >> > > > > > > If we want to support encryption, we would want to be able to >> > > modify >> > > > > > > serialized key/value, rather than key and value objects. This >> > will >> > > > add >> > > > > > the >> > > > > > > following API to producer and consumer interceptors: >> > > > > > > >> > > > > > > ProducerInterceptor: >> > > > > > > SerializedKeyValue onEnqueued(TopicPartition tp, >> > ProducerRecord<K, >> > > V> >> > > > > > > record, SerializedKeyValue serializedKeyValue); >> > > > > > > >> > > > > > > ConsumerInterceptor: >> > > > > > > SerializedKeyValue onReceive(TopicPartition tp, >> > SerializedKeyValue >> > > > > > > serializedKeyValue); >> > > > > > > >> > > > > > > >> > > > > > > I am leaning towards implementing the minimal set of >> immutable or >> > > > > mutable >> > > > > > > interfaces, making sure that we have a compatibility plan that >> > > allows >> > > > > us >> > > > > > to >> > > > > > > add more callbacks in the future (per Ismael comment), and add >> > more >> > > > > APIs >> > > > > > > later. E.g., for encryption use-case, there could be an >> argument >> > in >> > > > > doing >> > > > > > > encryption after message compression vs. per-record encryption >> > that >> > > > > could >> > > > > > > be done using the above additional API. There is also more >> > > > implications >> > > > > > for >> > > > > > > every API that modifies records: modifying serialized >> key/value >> > > will >> > > > > > again >> > > > > > > impact partition assignment (we will likely do that after >> > partition >> > > > > > > assignment), which may impact log compaction and mirror maker >> > > > > > partitioning. >> > > > > > > >> > > > > > > >> > > > > > > Thanks, >> > > > > > > Anna >> > > > > > > >> > > > > > > On Tue, Jan 26, 2016 at 7:26 AM, Todd Palino < >> tpal...@gmail.com> >> > > > > wrote: >> > > > > > > >> > > > > > > > Finally got a chance to take a look at this. I won’t be >> able to >> > > > make >> > > > > > the >> > > > > > > > KIP meeting due to a conflict. >> > > > > > > > >> > > > > > > > I’m somewhat disappointed in this proposal. I think that the >> > > > explicit >> > > > > > > > exclusion of modification of the messages is short-sighted, >> and >> > > not >> > > > > > > > accounting for it now is going to bite us later. Jay, aren’t >> > you >> > > > the >> > > > > > one >> > > > > > > > railing against public interfaces and how difficult they >> are to >> > > > work >> > > > > > with >> > > > > > > > when you don’t get them right? The “simple” change to one of >> > > these >> > > > > > > > interfaces to make it able to return a record is going to >> be a >> > > > > > > significant >> > > > > > > > change and is going to require all clients to rewrite their >> > > > > > interceptors. >> > > > > > > > If we’re not willing to put the time to think through >> > > manipulation >> > > > > now, >> > > > > > > > then this KIP should be shelved until we are. Implementing >> > > > something >> > > > > > > > halfway is going to be worse than taking a little longer. In >> > > > > addition, >> > > > > > I >> > > > > > > > don’t believe that manipulation requires anything more than >> > > > > > interceptors >> > > > > > > to >> > > > > > > > receive the full record, and then to return it. >> > > > > > > > >> > > > > > > > There are 3 use case I can think of right now without any >> deep >> > > > > > discussion >> > > > > > > > that can make use of interceptors with modification: >> > > > > > > > >> > > > > > > > 1. Auditing. The ability to add metadata to a message for >> > > auditing >> > > > is >> > > > > > > > critical. Hostname, service name, timestamps, etc. are all >> > pieces >> > > > of >> > > > > > data >> > > > > > > > that can be used on the other side of the pipeline to >> > categorize >> > > > > > > messages, >> > > > > > > > determine loss and transport time, and pin down issues. You >> may >> > > say >> > > > > > that >> > > > > > > > these things can just be part of the message schema, but >> anyone >> > > who >> > > > > has >> > > > > > > > worked with a multi-user data system (especially those who >> have >> > > > been >> > > > > > > > involved with LinkedIn) know how difficult it is to maintain >> > > > > consistent >> > > > > > > > message schemas and to get other people to put in fields for >> > your >> > > > > use. >> > > > > > > > >> > > > > > > > 2. Encryption. This is probably the most obvious case for >> > record >> > > > > > > > manipulation on both sides. The ability to tie in end to end >> > > > > encryption >> > > > > > > is >> > > > > > > > important for data that requires external compliance (PCI, >> > HIPAA, >> > > > > > etc.). >> > > > > > > > >> > > > > > > > 3. Routing. By being able to add a bit of information about >> the >> > > > > source >> > > > > > or >> > > > > > > > destination of a message to the metadata, you can easily >> > > construct >> > > > an >> > > > > > > > intelligent mirror maker that can prevent loops. This has >> the >> > > > > > opportunity >> > > > > > > > to result in significant operational savings, as you can get >> > rid >> > > of >> > > > > the >> > > > > > > > need for tiered clusters in order to prevent loops in >> mirroring >> > > > > > messages. >> > > > > > > > >> > > > > > > > All three of these share the feature that they add metadata >> to >> > > > > > messages. >> > > > > > > > With the pushback on having arbitrary metadata as an >> “envelope” >> > > to >> > > > > the >> > > > > > > > message, this is a way to provide it and make it the >> > > responsibility >> > > > > of >> > > > > > > the >> > > > > > > > client, and not the Kafka broker and system itself. >> > > > > > > > >> > > > > > > > -Todd >> > > > > > > > >> > > > > > > > >> > > > > > > > >> > > > > > > > On Tue, Jan 26, 2016 at 2:30 AM, Ismael Juma < >> > ism...@juma.me.uk> >> > > > > > wrote: >> > > > > > > > >> > > > > > > > > Hi Anna and Neha, >> > > > > > > > > >> > > > > > > > > I think it makes a lot of sense to try and keep the >> interface >> > > > lean >> > > > > > and >> > > > > > > to >> > > > > > > > > add more methods later when/if there is a need. What is >> the >> > > > current >> > > > > > > > > thinking with regards to compatibility when/if we add new >> > > > methods? >> > > > > A >> > > > > > > few >> > > > > > > > > options come to mind: >> > > > > > > > > >> > > > > > > > > 1. Change the interface to an abstract class with empty >> > > > > > implementations >> > > > > > > > for >> > > > > > > > > all the methods. This means that the path to adding new >> > methods >> > > > is >> > > > > > > clear. >> > > > > > > > > 2. Hope we have moved to Java 8 by the time we need to add >> > new >> > > > > > methods >> > > > > > > > and >> > > > > > > > > use default methods with an empty implementation for any >> new >> > > > method >> > > > > > > (and >> > > > > > > > > potentially make existing methods default methods too at >> that >> > > > point >> > > > > > for >> > > > > > > > > consistency) >> > > > > > > > > 3. Introduce a new interface that inherits from the >> existing >> > > > > > > Interceptor >> > > > > > > > > interface when we need to add new methods. >> > > > > > > > > >> > > > > > > > > Option 1 is the easiest and it also means that interceptor >> > > users >> > > > > only >> > > > > > > > need >> > > > > > > > > to override the methods that they are interested (more >> useful >> > > if >> > > > > the >> > > > > > > > number >> > > > > > > > > of methods grows). The downside is that interceptor >> > > > implementations >> > > > > > > > cannot >> > > > > > > > > inherit from another class (a straightforward workaround >> is >> > to >> > > > make >> > > > > > the >> > > > > > > > > interceptor a forwarder that calls another class). Also, >> our >> > > > > existing >> > > > > > > > > callbacks are interfaces, so seems a bit inconsistent. >> > > > > > > > > >> > > > > > > > > Option 2 may be the most appealing one as both users and >> > > > ourselves >> > > > > > > retain >> > > > > > > > > flexibility. The main downside is that it relies on us >> moving >> > > to >> > > > > Java >> > > > > > > 8, >> > > > > > > > > which may be more than a year away potentially (if we >> support >> > > the >> > > > > > last >> > > > > > > 2 >> > > > > > > > > Java releases). >> > > > > > > > > >> > > > > > > > > Thoughts? >> > > > > > > > > >> > > > > > > > > Ismael >> > > > > > > > > >> > > > > > > > > On Tue, Jan 26, 2016 at 4:59 AM, Neha Narkhede < >> > > > n...@confluent.io> >> > > > > > > > wrote: >> > > > > > > > > >> > > > > > > > > > Anna, >> > > > > > > > > > >> > > > > > > > > > I'm also in favor of including just the APIs for which >> we >> > > have >> > > > a >> > > > > > > clear >> > > > > > > > > use >> > > > > > > > > > case. If more use cases for finer monitoring show up in >> the >> > > > > future, >> > > > > > > we >> > > > > > > > > can >> > > > > > > > > > always update the interface. Would you please highlight >> in >> > > the >> > > > > KIP >> > > > > > > the >> > > > > > > > > APIs >> > > > > > > > > > that you think we have an immediate use for? >> > > > > > > > > > >> > > > > > > > > > Joel, >> > > > > > > > > > >> > > > > > > > > > Broker-side monitoring makes a lot of sense in the long >> > term >> > > > > > though I >> > > > > > > > > don't >> > > > > > > > > > think it is a requirement for end-to-end monitoring. >> With >> > the >> > > > > > > producer >> > > > > > > > > and >> > > > > > > > > > consumer interceptors, you have the ability to get full >> > > > > > > > > > publish-to-subscribe end-to-end monitoring. The broker >> > > > > interceptor >> > > > > > > > > > certainly improves the resolution of monitoring but it >> is >> > > also >> > > > a >> > > > > > > > riskier >> > > > > > > > > > change. I prefer an incremental approach over a big-bang >> > and >> > > > > > > recommend >> > > > > > > > > > taking baby-steps. Let's first make sure the >> > > producer/consumer >> > > > > > > > > interceptors >> > > > > > > > > > are successful. And then come back and add the broker >> > > > interceptor >> > > > > > > > > > carefully. >> > > > > > > > > > >> > > > > > > > > > Having said that, it would be great to understand your >> > > proposal >> > > > > for >> > > > > > > the >> > > > > > > > > > broker interceptor independently. We can either add an >> > > > > interceptor >> > > > > > > > > > on-append or on-commit. If people want to use this for >> > > > > monitoring, >> > > > > > > then >> > > > > > > > > > possibly on-commit might be more useful? >> > > > > > > > > > >> > > > > > > > > > Thanks, >> > > > > > > > > > Neha >> > > > > > > > > > >> > > > > > > > > > On Mon, Jan 25, 2016 at 6:47 PM, Jay Kreps < >> > j...@confluent.io >> > > > >> > > > > > wrote: >> > > > > > > > > > >> > > > > > > > > > > Hey Joel, >> > > > > > > > > > > >> > > > > > > > > > > What is the interface you are thinking of? Something >> like >> > > > this: >> > > > > > > > > > > onAppend(String topic, int partition, Records >> > records, >> > > > long >> > > > > > > time) >> > > > > > > > > > > ? >> > > > > > > > > > > >> > > > > > > > > > > One challenge right now is that we are still using the >> > old >> > > > > > > > > > > Message/MessageSet classes on the broker which I'm not >> > sure >> > > > if >> > > > > > we'd >> > > > > > > > > want >> > > > > > > > > > to >> > > > > > > > > > > support over the long haul but it might be okay just >> to >> > > > create >> > > > > > the >> > > > > > > > > > records >> > > > > > > > > > > instance for this interface. >> > > > > > > > > > > >> > > > > > > > > > > -Jay >> > > > > > > > > > > >> > > > > > > > > > > On Mon, Jan 25, 2016 at 12:37 PM, Joel Koshy < >> > > > > > jjkosh...@gmail.com> >> > > > > > > > > > wrote: >> > > > > > > > > > > >> > > > > > > > > > > > I'm definitely in favor of having such hooks in the >> > > > > > > produce/consume >> > > > > > > > > > > > life-cycle. Not sure if people remember this but in >> > Kafka >> > > > 0.7 >> > > > > > > this >> > > > > > > > > was >> > > > > > > > > > > > pretty much how it was: >> > > > > > > > > > > > >> > > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > > >> > > > > > > > > >> > > > > > > > >> > > > > > > >> > > > > > >> > > > > >> > > > >> > > >> > >> https://github.com/apache/kafka/blob/0.7/core/src/main/scala/kafka/producer/async/CallbackHandler.scala >> > > > > > > > > > > > i.e., we had something similar to the interceptor >> > > proposal >> > > > > for >> > > > > > > > > various >> > > > > > > > > > > > stages of the producer request. The producer >> provided >> > > > > > call-backs >> > > > > > > > for >> > > > > > > > > > > > beforeEnqueue, afterEnqueue, afterDequeuing, >> > > beforeSending, >> > > > > > etc. >> > > > > > > So >> > > > > > > > > at >> > > > > > > > > > > > LinkedIn we in fact did auditing within these >> > call-backs >> > > > (and >> > > > > > not >> > > > > > > > > > > > explicitly in the wrapper). Over time and with 0.8 >> we >> > > moved >> > > > > > that >> > > > > > > > out >> > > > > > > > > to >> > > > > > > > > > > the >> > > > > > > > > > > > wrapper libraries. >> > > > > > > > > > > > >> > > > > > > > > > > > On a side-note while audit and other monitoring can >> be >> > > done >> > > > > > > > > internally >> > > > > > > > > > > in a >> > > > > > > > > > > > convenient way I think it should be clarified that >> > > having a >> > > > > > > wrapper >> > > > > > > > > is >> > > > > > > > > > in >> > > > > > > > > > > > general not a bad idea and I would even consider it >> to >> > > be a >> > > > > > > > > > > best-practice. >> > > > > > > > > > > > Even with 0.7 we still had a wrapper library and >> that >> > API >> > > > has >> > > > > > > > largely >> > > > > > > > > > > > stayed the same and has helped protect against >> > (sometimes >> > > > > > > backwards >> > > > > > > > > > > > incompatible) changes in open source. >> > > > > > > > > > > > >> > > > > > > > > > > > While we are on this topic I have one comment and >> Anna, >> > > you >> > > > > may >> > > > > > > > have >> > > > > > > > > > > > already considered this but I don't see mention of >> it >> > in >> > > > the >> > > > > > KIP: >> > > > > > > > > > > > >> > > > > > > > > > > > Add a custom message interceptor/validator on the >> > broker >> > > on >> > > > > > > message >> > > > > > > > > > > > arrival. >> > > > > > > > > > > > >> > > > > > > > > > > > We decompress and do basic validation of messages on >> > > > > arrival. I >> > > > > > > > think >> > > > > > > > > > > there >> > > > > > > > > > > > is value in supporting custom validation and expand >> it >> > to >> > > > > > support >> > > > > > > > > > custom >> > > > > > > > > > > > on-arrival processing. Here is a specific use-case I >> > have >> > > > in >> > > > > > > mind. >> > > > > > > > > The >> > > > > > > > > > > blog >> > > > > > > > > > > > that James referenced describes our auditing >> > > > infrastructure. >> > > > > In >> > > > > > > > order >> > > > > > > > > > to >> > > > > > > > > > > > audit the Kafka cluster itself we need to run a >> > "console >> > > > > > auditor" >> > > > > > > > > > service >> > > > > > > > > > > > that consumes everything and spits out audit events >> > back >> > > to >> > > > > the >> > > > > > > > > > cluster. >> > > > > > > > > > > I >> > > > > > > > > > > > would prefer not having to run this service because: >> > > > > > > > > > > > >> > > > > > > > > > > > - Well, it is one more service that we have to >> run >> > and >> > > > > > monitor >> > > > > > > > > > > > - Consuming everything takes up bandwidth which >> can >> > be >> > > > > > avoided >> > > > > > > > > > > > - The console auditor consumer itself can lag and >> > > cause >> > > > > > > > temporary >> > > > > > > > > > > audit >> > > > > > > > > > > > discrepancies >> > > > > > > > > > > > >> > > > > > > > > > > > One way we can mitigate this is by having >> mirror-makers >> > > in >> > > > > > > between >> > > > > > > > > > > clusters >> > > > > > > > > > > > emit audit events. The problem is that the very last >> > > > cluster >> > > > > in >> > > > > > > the >> > > > > > > > > > > > pipeline will not have any audit which is why we >> need >> > to >> > > > have >> > > > > > > > > something >> > > > > > > > > > > to >> > > > > > > > > > > > audit the cluster. >> > > > > > > > > > > > >> > > > > > > > > > > > If we had a custom message validator then the audit >> can >> > > be >> > > > > done >> > > > > > > > > > > on-arrival >> > > > > > > > > > > > and we won't need a console auditor. >> > > > > > > > > > > > >> > > > > > > > > > > > One potential issue in this approach and any >> elaborate >> > > > > > on-arrival >> > > > > > > > > > > > processing for that matter is that you may need to >> > > > > deserialize >> > > > > > > the >> > > > > > > > > > > message >> > > > > > > > > > > > as well which can drive up produce request handling >> > > times. >> > > > > > > However >> > > > > > > > > I'm >> > > > > > > > > > > not >> > > > > > > > > > > > terribly concerned about that especially if the >> audit >> > > > header >> > > > > > can >> > > > > > > be >> > > > > > > > > > > > separated out easily or even deserialized partially >> as >> > > this >> > > > > > Avro >> > > > > > > > > thread >> > > > > > > > > > > > touches on >> > > > > > > > > > > > >> > > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > > >> > > > > > > > > >> > > > > > > > >> > > > > > > >> > > > > > >> > > > > >> > > > >> > > >> > >> http://search-hadoop.com/m/F2svI1HDLY12W8tnH1&subj=Re+any+optimization+in+reading+a+partial+schema+in+the+decoder+ >> > > > > > > > > > > > >> > > > > > > > > > > > Thanks, >> > > > > > > > > > > > >> > > > > > > > > > > > Joel >> > > > > > > > > > > > >> > > > > > > > > > > > On Mon, Jan 25, 2016 at 12:02 PM, Mayuresh Gharat < >> > > > > > > > > > > > gharatmayures...@gmail.com> wrote: >> > > > > > > > > > > > >> > > > > > > > > > > > > Nice KIP. Excellent idea. >> > > > > > > > > > > > > Was just thinking if we can add onDequed() to the >> > > > > > > > > ProducerIterceptor >> > > > > > > > > > > > > interface. Since we have the onEnqueued(), it will >> > help >> > > > the >> > > > > > > > client >> > > > > > > > > or >> > > > > > > > > > > the >> > > > > > > > > > > > > tools to know how much time the message spent in >> the >> > > > > > > > > > RecordAccumulator. >> > > > > > > > > > > > > Also an API to check if there are any messages >> left >> > > for a >> > > > > > > > > particular >> > > > > > > > > > > > topic >> > > > > > > > > > > > > in the RecordAccumulator would help. >> > > > > > > > > > > > > >> > > > > > > > > > > > > Thanks, >> > > > > > > > > > > > > >> > > > > > > > > > > > > Mayuresh >> > > > > > > > > > > > > >> > > > > > > > > > > > > On Mon, Jan 25, 2016 at 11:29 AM, Todd Palino < >> > > > > > > tpal...@gmail.com >> > > > > > > > > >> > > > > > > > > > > wrote: >> > > > > > > > > > > > > >> > > > > > > > > > > > > > Great idea. I’ve been talking about this for 2 >> > years, >> > > > and >> > > > > > I’m >> > > > > > > > > glad >> > > > > > > > > > > > > someone >> > > > > > > > > > > > > > is finally picking it up. Will take a look at >> the >> > KIP >> > > > at >> > > > > > some >> > > > > > > > > point >> > > > > > > > > > > > > > shortly. >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > -Todd >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > On Mon, Jan 25, 2016 at 11:24 AM, Jay Kreps < >> > > > > > > j...@confluent.io> >> > > > > > > > > > > wrote: >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > > Hey Becket, >> > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > Yeah this is really similar to the callback. >> The >> > > > > > difference >> > > > > > > > is >> > > > > > > > > > > really >> > > > > > > > > > > > > in >> > > > > > > > > > > > > > > who sets the behavior. The idea of the >> > interceptor >> > > is >> > > > > > that >> > > > > > > it >> > > > > > > > > > > doesn't >> > > > > > > > > > > > > > > require any code change in apps so you can >> > globally >> > > > add >> > > > > > > > > behavior >> > > > > > > > > > to >> > > > > > > > > > > > > your >> > > > > > > > > > > > > > > Kafka usage without changing app code. Whereas >> > the >> > > > > > callback >> > > > > > > > is >> > > > > > > > > > > added >> > > > > > > > > > > > by >> > > > > > > > > > > > > > the >> > > > > > > > > > > > > > > app. The idea is to kind of obviate the need >> for >> > > the >> > > > > > > wrapper >> > > > > > > > > code >> > > > > > > > > > > > that >> > > > > > > > > > > > > > e.g. >> > > > > > > > > > > > > > > LinkedIn maintains to hold this kind of stuff. >> > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > -Jay >> > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > On Sun, Jan 24, 2016 at 4:21 PM, Becket Qin < >> > > > > > > > > > becket....@gmail.com> >> > > > > > > > > > > > > > wrote: >> > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > This could be a useful feature. And I think >> > there >> > > > are >> > > > > > > some >> > > > > > > > > use >> > > > > > > > > > > > cases >> > > > > > > > > > > > > to >> > > > > > > > > > > > > > > > mutate the data like rejected alternative >> one >> > > > > > mentioned. >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > I am wondering if there is functional >> > overlapping >> > > > > > between >> > > > > > > > > > > > > > > > ProducerInterceptor.onAcknowledgement() and >> the >> > > > > > producer >> > > > > > > > > > > callback? >> > > > > > > > > > > > I >> > > > > > > > > > > > > > can >> > > > > > > > > > > > > > > > see that the Callback could be a per record >> > > setting >> > > > > > while >> > > > > > > > > > > > > > > > onAcknowledgement() is a producer level >> > setting. >> > > > > Other >> > > > > > > than >> > > > > > > > > > that, >> > > > > > > > > > > > is >> > > > > > > > > > > > > > > there >> > > > > > > > > > > > > > > > any difference between them? >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > Thanks, >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > Jiangjie (Becket) Qin >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > On Fri, Jan 22, 2016 at 6:21 PM, Neha >> Narkhede >> > < >> > > > > > > > > > > n...@confluent.io> >> > > > > > > > > > > > > > > wrote: >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > James, >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > That is one of the many monitoring use >> cases >> > > for >> > > > > the >> > > > > > > > > > > interceptor >> > > > > > > > > > > > > > > > interface. >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > Thanks, >> > > > > > > > > > > > > > > > > Neha >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > On Fri, Jan 22, 2016 at 6:18 PM, James >> Cheng >> > < >> > > > > > > > > > jch...@tivo.com> >> > > > > > > > > > > > > > wrote: >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > Anna, >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > I'm trying to understand a concrete use >> > case. >> > > > It >> > > > > > > sounds >> > > > > > > > > > like >> > > > > > > > > > > > > > producer >> > > > > > > > > > > > > > > > > > interceptors could be used to implement >> > part >> > > of >> > > > > > > > > LinkedIn's >> > > > > > > > > > > > Kafak >> > > > > > > > > > > > > > > Audit >> > > > > > > > > > > > > > > > > > tool? >> > > > > > > > > > > > >> > > https://engineering.linkedin.com/kafka/running-kafka-scale >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > Part of that is done by a wrapper >> library >> > > > around >> > > > > > the >> > > > > > > > > kafka >> > > > > > > > > > > > > producer >> > > > > > > > > > > > > > > > that >> > > > > > > > > > > > > > > > > > keeps a count of the number of messages >> > > > produced, >> > > > > > and >> > > > > > > > > then >> > > > > > > > > > > > sends >> > > > > > > > > > > > > > that >> > > > > > > > > > > > > > > > > count >> > > > > > > > > > > > > > > > > > to a side-topic. It sounds like the >> > producer >> > > > > > > > interceptors >> > > > > > > > > > > could >> > > > > > > > > > > > > > > > possibly >> > > > > > > > > > > > > > > > > be >> > > > > > > > > > > > > > > > > > used to implement that? >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > -James >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > On Jan 22, 2016, at 4:33 PM, Anna >> > Povzner < >> > > > > > > > > > > a...@confluent.io >> > > > > > > > > > > > > >> > > > > > > > > > > > > > > wrote: >> > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > Hi, >> > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > I just created a KIP-42 for adding >> > producer >> > > > and >> > > > > > > > > consumer >> > > > > > > > > > > > > > > interceptors >> > > > > > > > > > > > > > > > > for >> > > > > > > > > > > > > > > > > > > intercepting messages at different >> points >> > > on >> > > > > > > producer >> > > > > > > > > and >> > > > > > > > > > > > > > consumer. >> > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > >> > > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > > >> > > > > > > > > >> > > > > > > > >> > > > > > > >> > > > > > >> > > > > >> > > > >> > > >> > >> https://cwiki.apache.org/confluence/display/KAFKA/KIP-42%3A+Add+Producer+and+Consumer+Interceptors >> > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > Comments and suggestions are welcome! >> > > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > > Thanks, >> > > > > > > > > > > > > > > > > > > Anna >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > ________________________________ >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > > This email and any attachments may >> contain >> > > > > > > confidential >> > > > > > > > > and >> > > > > > > > > > > > > > > privileged >> > > > > > > > > > > > > > > > > > material for the sole use of the >> intended >> > > > > > recipient. >> > > > > > > > Any >> > > > > > > > > > > > review, >> > > > > > > > > > > > > > > > copying, >> > > > > > > > > > > > > > > > > > or distribution of this email (or any >> > > > > attachments) >> > > > > > by >> > > > > > > > > > others >> > > > > > > > > > > is >> > > > > > > > > > > > > > > > > prohibited. >> > > > > > > > > > > > > > > > > > If you are not the intended recipient, >> > please >> > > > > > contact >> > > > > > > > the >> > > > > > > > > > > > sender >> > > > > > > > > > > > > > > > > > immediately and permanently delete this >> > email >> > > > and >> > > > > > any >> > > > > > > > > > > > > attachments. >> > > > > > > > > > > > > > No >> > > > > > > > > > > > > > > > > > employee or agent of TiVo Inc. is >> > authorized >> > > to >> > > > > > > > conclude >> > > > > > > > > > any >> > > > > > > > > > > > > > binding >> > > > > > > > > > > > > > > > > > agreement on behalf of TiVo Inc. by >> email. >> > > > > Binding >> > > > > > > > > > agreements >> > > > > > > > > > > > > with >> > > > > > > > > > > > > > > TiVo >> > > > > > > > > > > > > > > > > > Inc. may only be made by a signed >> written >> > > > > > agreement. >> > > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > > -- >> > > > > > > > > > > > > > > > > Thanks, >> > > > > > > > > > > > > > > > > Neha >> > > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > > >> > > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > -- >> > > > > > > > > > > > > > *—-* >> > > > > > > > > > > > > > *Todd Palino* >> > > > > > > > > > > > > > Staff Site Reliability Engineer >> > > > > > > > > > > > > > Data Infrastructure Streaming >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > >> > > > > > > > > > > > > > linkedin.com/in/toddpalino >> > > > > > > > > > > > > > >> > > > > > > > > > > > > >> > > > > > > > > > > > > >> > > > > > > > > > > > > >> > > > > > > > > > > > > -- >> > > > > > > > > > > > > -Regards, >> > > > > > > > > > > > > Mayuresh R. Gharat >> > > > > > > > > > > > > (862) 250-7125 >> > > > > > > > > > > > > >> > > > > > > > > > > > >> > > > > > > > > > > >> > > > > > > > > > >> > > > > > > > > > >> > > > > > > > > > >> > > > > > > > > > -- >> > > > > > > > > > Thanks, >> > > > > > > > > > Neha >> > > > > > > > > > >> > > > > > > > > >> > > > > > > > >> > > > > > > > >> > > > > > > > >> > > > > > > > -- >> > > > > > > > *—-* >> > > > > > > > *Todd Palino* >> > > > > > > > Staff Site Reliability Engineer >> > > > > > > > Data Infrastructure Streaming >> > > > > > > > >> > > > > > > > >> > > > > > > > >> > > > > > > > linkedin.com/in/toddpalino >> > > > > > > > >> > > > > > > >> > > > > > >> > > > > > >> > > > > > >> > > > > > -- >> > > > > > -Regards, >> > > > > > Mayuresh R. Gharat >> > > > > > (862) 250-7125 >> > > > > > >> > > > > >> > > > >> > > > >> > > > >> > > > -- >> > > > *—-* >> > > > *Todd Palino* >> > > > Staff Site Reliability Engineer >> > > > Data Infrastructure Streaming >> > > > >> > > > >> > > > >> > > > linkedin.com/in/toddpalino >> > > > >> > > >> > > >> > > >> > > -- >> > > -Regards, >> > > Mayuresh R. Gharat >> > > (862) 250-7125 >> > > >> > >> >> >> >> -- >> -Regards, >> Mayuresh R. Gharat >> (862) 250-7125 >> > >
