Hi, Michael, Thanks for the reply. I find it very helpful.
Data lineage: 100. I'd like to understand the APM use case a bit more. It sounds like that those APM plugins can generate a transaction id that we could potentially put in the header of every message. How would you typically make use of such transaction ids? Are there other metadata associated with the transaction id and if so, how are they propagated downstream? 101. For the finance use case, if the concept of transaction is important, wouldn't it be typically included in the message payload instead of as an optional header field? 102. The data lineage that Altas and Navigator support seems to be at the dataset level, not per record level? So, not sure if per message headers are relevant there. Mirroring: 103. The benefit of using separate partitions is that it potentially makes it easy to preserve offsets during mirroring. This will make it easier for consumer to switch clusters. Currently, the consumers can switch clusters by using the timestampToOffset() api, but it has to deal with duplicates. Good point on the issue with log compact and I am not sure how to address this. However, even if we mirror into the existing partitions, the ordering for messages generated from different clusters seems non-deterministic anyway. So, it seems that the consumers already have to deal with that? If a topic is compacted, does that mean which messages are preserved is also non-deterministic across clusters? 104. Good point on partition key. End-to-end encryption: 105. So, it seems end-to-end encryption is useful. Are headers useful there? Auditing: 106. It seems other than the UUID, all other metadata are per producer? EOS: 107. How are those UUIDs generated? I am not sure if they can be generated in the producer library. An application may send messages through a load balancer and on retry, the same message could be routed to a different producer instance. So, it seems that the application has to generate the UUIDs. In that case, shouldn't the application just put the UUID in the payload? Thanks, Jun On Fri, Dec 2, 2016 at 4:57 PM, Michael Pearce <michael.pea...@ig.com> wrote: > Hi Jun. > > Per Transaction Tracing / Data Lineage. > > As Stated in the KIP this has the first use case of how many APM tools now > work. > I would find it impossible for any one to argue this is not important or a > niche market as it has its own gartner report for this space. Such > companies as Appdynamics, NewRelic, Dynatrace, Hawqular are but a few. > > Likewise these APM tools can help very rapidly track down issues and > automatically capture metrics, perform actions based on unexpected behavior > to auto recover services. > > Before mentioning looking at aggregated stats, in these cases where > actually on critical flows we cannot afford to have aggregated rolled up > stats only. > > With the APM tool we use its actually able to detect a single transaction > failure and capture the thread traces in the JVM where it failed and > everything for us, to the point it sends us alerts where we have this > giving the line number of the code that caused it, the transaction trace > through all the services and endpoints (supported) upto the point of > failure, it can also capture the data in and out (so we can replay). > Because atm Kafka doesn’t support us being able to stich in these tracing > transaction ids natively, we cannot get these benefits as such is limiting > our ability support apps and monitor them to the same standards we come to > expect when on a kafka flow. > > This actually ties in with Data Lineage, as the same tracing can be used > to back stich this. Essentially many times due to the sums of money > involved there are disputes, and typically as a financial institute the > easiest and cleanest way to prove when disputes arise is to present the > actual flow and processes involved in a transaction. > > Likewise as Hadoop matures its evident this case is important, as tools > such as Atlas (Hortonworks led) and Navigator (cloudera led) are evident > also I believe the importance here is very much NOT just a financial issue. > > From a MDM point of view any company wanting to care about Data Quality > and Data Governance - Data Lineage is a key piece in this puzzle. > > > > RE Mirroring, > > As per the KIP in-fact this is exactly what we do re cluster id, to mirror > a network of clusters between AZ’s / Regions. We know a transaction for a > key will be done within a AZ/Region, as such we know the write to kafka > would be ordered per key. But we need eventual view of that across in our > other regions/az’s. When we have complete AZ or Region failure we know > there will be a brief interruption whilst those transactions are moved to > another region but we expect after it to continue. > > As mentioned having separate Partions to do this starts to get > ugly/complicated for us: > how would I do compaction where a key is in two partitions? > How do we balance consumers so where multiple partitions with the same key > goto the same consumer > What do you do if cluster 1 has 5 partitions but cluster 20 has 10 because > its larger kit in our more core DC’s, as such key to partition mappings for > consumers get even more complicated. > What do you do if we add or remove a complete region > > Where as simple mirror will work we just need to ensure we don’t have a > cycle which we can do with clusterId. > > We even have started to look at shortest path mirror routing based on > clusterId, if we also had the region and az info on the originating > message, this we have not implemented but some ideas come from network > routing, and also the dispatcher router in apache qpid. > > Also we need to have data perimeters e.g. certain data cannot leave > certain countries borders. We want this all automated so that at the > platform level without having to touch or look at the business data inside > we can have headers we can put tags into so that we can ensure this doesn’t > occur when we mirror. (actually links in to data lineage / tracing as again > we need to tag messages at a platform level) Examples are we are not > allowed Private customer details to leave Switzerland, yet we need those > systems integrated. > > Lastly around mirroring we have a partionKey field, as the key used for > portioning logic != compaction key all the time but we want to preserve it > for when we mirror so that if source cluster partition count != destination > cluster partition count we can honour the same partitioning logic. > > > > RE End 2 End encryption > > As I believe mentioned just before, the solution you mention just doesn’t > cut the mustard these days with many regulators. An operations person with > access to the box should not be able to have access to the data. Many now > actually impose quite literally the implementation expected being end2end > encryption for certain data (Singapore for us is one that I am most aware > of). In fact we’re even now needing encrypt the data and store the keys in > HSM modules. > > Likewise the performance penalty on encrypting decrypting as you produce > over wire, then again encrypt decrypt as the data is stored on the brokers > disks and back again, then again encrypted and decrypted back over the wire > each time for each consumer all adds up, ignoring this doubling with mirror > makers etc. simply encrypting the value once on write by the client and > again decrypting on consume by the consumer is far more performant, but > then the routing and platform meta data needs to be separate (thus headers) > > > > RE Auditing: > > Our Auditing needs are: > Producer Id, > Origin Cluster Id that message first produced into > Origin AZ – agreed we can derive this if we have cluster id, but it makes > resolving this for audit reporting a lot easier. > Origin Region – agreed we can derive this if we have cluster id, but it > makes resolving this for audit reporting a lot easier. > Unique Message Identification (this is not the same as transaction > tracing) – note offset and partition are not the same, as when we mirror or > have for what ever system failure duplicate send, > Custom Client wrapper version (where organizations have to wrap the kafka > client for added features) so we know what version of the wrapper is used > Producer IP address (in case of clients being in our vm/open stack infra > where they can move around, producer id will stay the same but this would > change) > > > > RE Once and only once delivery case > > Using the same Message UUID for auditing we can achieve this quite simply. > > As per how some other brokers do this (cough qpid, artemis) message uuid > are used to dedupe where message is sent and produced but the client didn’t > receive the ack, and there for replays the send, by having a unique message > id per message, this can be filtered out, on consumers where message > delivery may occur twice for what ever reasons a message uuid can be used > to remove duplicates being deliverd , like wise we can do this in the > mirrormakers so if we detect a dupe message we can avoid replicating it. > > > > > Cheers > Mike > > > > On 02/12/2016, 22:09, "Jun Rao" <j...@confluent.io> wrote: > > Since this KIP affects message format, wire protocol, apis, I think > it's > worth spending a bit more time to nail down the concrete use cases. It > would be bad if we add this feature, but when start implementing it > for say > mirroring, we then realize that header is not the best approach. > Initially, > I thought I was convinced of the use cases of headers and was trying to > write down a few use cases to convince others. That's when I became > less > certain. For me to be convinced, I just want to see two strong use > cases > (instead of 10 maybe use cases) in the third-party space. The reason is > that when we discussed the use cases within a company, often it ends > with > "we can't force everyone to use this standard since we may have to > integrate with third-party tools". > > At present, I am not sure why headers are useful for things like > schemaId > or encryption. In order to do anything useful to the value, one needs > to > know the schemaId or how data is encrypted, but header is optional. > But, I > can be convinced if someone (Radai, Sean, Todd?) provides more details > on > the argument. > > I am not very sure header is the best approach for mirroring either. If > someone has thought about this more, I'd be happy to hear. > > I can see the data lineage use case. I am just not sure how widely > applicable this is. If someone familiar with this space can justify > this is > a significant use case, say in the finance industry, this would be a > strong > use case. > > I can see the auditing use case. I am just not sure if a native > producer id > solves that problem. If there are additional metadata that's worth > collecting but not covered by the producer id, that would make this a > strong use case. > > Thanks, > > Jun > > > On Fri, Dec 2, 2016 at 1:41 PM, radai <radai.rosenbl...@gmail.com> > wrote: > > > this KIP is about enabling headers, nothing more nothing less - so > no, > > broker-side use of headers is not in the KIP scope. > > > > obviously though, once you have headers potential use cases could > include > > broker-side header-aware interceptors (which would be the topic of > other > > future KIPs). > > > > a trivially clear use case (to me) would be using such broker-side > > interceptors to enforce compliance with organizational policies - it > would > > make our SREs lives much easier if instead of retroactively > discovering > > "rogue" topics/users those messages would have been rejected > up-front. > > > > the kafka broker code is lacking any such extensibility support > (beyond > > maybe authorizer) which is why these use cases were left out of the > "case > > for headers" doc - broker extensibility is a separate discussion. > > > > On Fri, Dec 2, 2016 at 12:59 PM, Gwen Shapira <g...@confluent.io> > wrote: > > > > > Woah, I wasn't aware this is something we'll do. It wasn't in the > KIP, > > > right? > > > > > > I guess we could do it the same way ACLs currently work. > > > I had in mind something that will allow admins to apply rules to > the > > > new create/delete/config topic APIs. So Todd can decide to reject > > > "create topic" requests that ask for more than 40 partitions, or > > > require exactly 3 replicas, or no more than 50GB partition size, > etc. > > > > > > ACLs were added a bit ad-hoc, if we are planning to apply more > rules > > > to requests (and I think we should), we may want a bit more generic > > > design around that. > > > > > > On Fri, Dec 2, 2016 at 7:16 AM, radai <radai.rosenbl...@gmail.com> > > wrote: > > > > "wouldn't you be in the business of making sure everyone uses > them > > > > properly?" > > > > > > > > thats where a broker-side plugin would come handy - any incoming > > message > > > > that does not conform to org policy (read - does not have the > proper > > > > headers) gets thrown out (with an error returned to user) > > > > > > > > On Thu, Dec 1, 2016 at 8:44 PM, Todd Palino <tpal...@gmail.com> > wrote: > > > > > > > >> Come on, I’ve done at least 2 talks on this one :) > > > >> > > > >> Producing counts to a topic is part of it, but that’s only > part. So > > you > > > >> count you have 100 messages in topic A. When you mirror topic A > to > > > another > > > >> cluster, you have 99 messages. Where was your problem? Or > worse, you > > > have > > > >> 100 messages, but one producer duplicated messages and another > one > > lost > > > >> messages. You need details about where the message came from in > order > > to > > > >> pinpoint problems when they happen. Source producer info, where > it was > > > >> produced into your infrastructure, and when it was produced. > This > > > requires > > > >> you to add the information to the message. > > > >> > > > >> And yes, you still need to maintain your clients. So maybe my > original > > > >> example was not the best. My thoughts on not wanting to be > responsible > > > for > > > >> message formats stands, because that’s very much separate from > the > > > client. > > > >> As you know, we have our own internal client library that can > insert > > the > > > >> right headers, and right now inserts the right audit > information into > > > the > > > >> message fields. If they exist, and assuming the message is Avro > > encoded. > > > >> What if someone wants to use JSON instead for a good reason? > What if > > > user X > > > >> wants to encrypt messages, but user Y does not? Maintaining the > client > > > >> library is still much easier than maintaining the message > formats. > > > >> > > > >> -Todd > > > >> > > > >> > > > >> On Thu, Dec 1, 2016 at 6:21 PM, Gwen Shapira <g...@confluent.io > > > > wrote: > > > >> > > > >> > Based on your last sentence, consider me convinced :) > > > >> > > > > >> > I get why headers are critical for Mirroring (you need tags to > > prevent > > > >> > loops and sometimes to route messages to the correct > destination). > > > >> > But why do you need headers to audit? We are auditing by > producing > > > >> > counts to a side topic (and I was under the impression you do > the > > > >> > same), so we never need to modify the message. > > > >> > > > > >> > Another thing - after we added headers, wouldn't you be in the > > > >> > business of making sure everyone uses them properly? Making > sure > > > >> > everyone includes the right headers you need, not using the > header > > > >> > names you intend to use, etc. I don't think the "policing" > business > > > >> > will ever go away. > > > >> > > > > >> > On Thu, Dec 1, 2016 at 5:25 PM, Todd Palino < > tpal...@gmail.com> > > > wrote: > > > >> > > Got it. As an ops guy, I'm not very happy with the > workaround. > > Avro > > > >> means > > > >> > > that I have to be concerned with the format of the messages > in > > > order to > > > >> > run > > > >> > > the infrastructure (audit, mirroring, etc.). That means > that I > > have > > > to > > > >> > > handle the schemas, and I have to enforce rules about good > > formats. > > > >> This > > > >> > is > > > >> > > not something I want to be in the business of, because I > should be > > > able > > > >> > to > > > >> > > run a service infrastructure without needing to be in the > weeds of > > > >> > dealing > > > >> > > with customer data formats. > > > >> > > > > > >> > > Trust me, a sizable portion of my support time is spent > dealing > > with > > > >> > schema > > > >> > > issues. I really would like to get away from that. Maybe > I'd have > > > more > > > >> > time > > > >> > > for other hobbies. Like writing. ;) > > > >> > > > > > >> > > -Todd > > > >> > > > > > >> > > On Thu, Dec 1, 2016 at 4:04 PM Gwen Shapira < > g...@confluent.io> > > > wrote: > > > >> > > > > > >> > >> I'm pretty satisfied with the current workarounds (Avro > container > > > >> > >> format), so I'm not too excited about the extra work > required to > > do > > > >> > >> headers in Kafka. I absolutely don't mind it if you do > it... > > > >> > >> I think the Apache convention for "good idea, but not > willing to > > > put > > > >> > >> any work toward it" is +0.5? anyway, that's what I was > trying to > > > >> > >> convey :) > > > >> > >> > > > >> > >> On Thu, Dec 1, 2016 at 3:05 PM, Todd Palino < > tpal...@gmail.com> > > > >> wrote: > > > >> > >> > Well I guess my question for you, then, is what is > holding you > > > back > > > >> > from > > > >> > >> > full support for headers? What’s the bit that you’re > missing > > that > > > >> has > > > >> > you > > > >> > >> > under a full +1? > > > >> > >> > > > > >> > >> > -Todd > > > >> > >> > > > > >> > >> > > > > >> > >> > On Thu, Dec 1, 2016 at 1:59 PM, Gwen Shapira < > > g...@confluent.io> > > > >> > wrote: > > > >> > >> > > > > >> > >> >> I know why people who support headers support them, and > I've > > > seen > > > >> > what > > > >> > >> >> the discussion is like. > > > >> > >> >> > > > >> > >> >> This is why I'm asking people who are against headers > > > (especially > > > >> > >> >> committers) what will make them change their mind - so > we can > > > get > > > >> > this > > > >> > >> >> part over one way or another. > > > >> > >> >> > > > >> > >> >> If I sound frustrated it is not at Radai, Jun or you > (Todd)... > > > I am > > > >> > >> >> just looking for something concrete we can do to move > the > > > >> discussion > > > >> > >> >> along to the yummy design details (which is the > argument I > > > really > > > >> am > > > >> > >> >> looking forward to). > > > >> > >> >> > > > >> > >> >> On Thu, Dec 1, 2016 at 1:53 PM, Todd Palino < > > tpal...@gmail.com> > > > >> > wrote: > > > >> > >> >> > So, Gwen, to your question (even though I’m not a > > > committer)... > > > >> > >> >> > > > > >> > >> >> > I have always been a strong supporter of introducing > the > > > concept > > > >> > of an > > > >> > >> >> > envelope to messages, which headers accomplishes. The > > message > > > key > > > >> > is > > > >> > >> >> > already an example of a piece of envelope > information. By > > > >> > providing a > > > >> > >> >> means > > > >> > >> >> > to do this within Kafka itself, and not relying on > use-case > > > >> > specific > > > >> > >> >> > implementations, you make it much easier for > components to > > > >> > >> interoperate. > > > >> > >> >> It > > > >> > >> >> > simplifies development of all these things (message > routing, > > > >> > auditing, > > > >> > >> >> > encryption, etc.) because each one does not have to > reinvent > > > the > > > >> > >> wheel. > > > >> > >> >> > > > > >> > >> >> > It also makes it much easier from a client point of > view if > > > the > > > >> > >> headers > > > >> > >> >> are > > > >> > >> >> > defined as part of the protocol and/or message format > in > > > general > > > >> > >> because > > > >> > >> >> > you can easily produce and consume messages without > having > > to > > > >> take > > > >> > >> into > > > >> > >> >> > account specific cases. For example, I want to route > > messages, > > > >> but > > > >> > >> >> client A > > > >> > >> >> > doesn’t support the way audit implemented headers, and > > client > > > B > > > >> > >> doesn’t > > > >> > >> >> > support the way encryption or routing implemented > headers, > > so > > > now > > > >> > my > > > >> > >> >> > application has to create some really fragile (my > > autocorrect > > > >> just > > > >> > >> tried > > > >> > >> >> to > > > >> > >> >> > make that “tragic”, which is probably appropriate > too) code > > to > > > >> > strip > > > >> > >> >> > everything off, rather than just consuming the > messages, > > > picking > > > >> > out > > > >> > >> the > > > >> > >> >> 1 > > > >> > >> >> > or 2 headers it’s interested in, and performing its > > function. > > > >> > >> >> > > > > >> > >> >> > Honestly, this discussion has been going on for a > long time, > > > and > > > >> > it’s > > > >> > >> >> > always “Oh, you came up with 2 use cases, and yeah, > those > > use > > > >> cases > > > >> > >> are > > > >> > >> >> > real things that someone would want to do. Here’s an > > alternate > > > >> way > > > >> > to > > > >> > >> >> > implement them so let’s not do headers.” If we have a > few > > use > > > >> cases > > > >> > >> that > > > >> > >> >> we > > > >> > >> >> > actually came up with, you can be sure that over the > next > > year > > > >> > >> there’s a > > > >> > >> >> > dozen others that we didn’t think of that someone > would like > > > to > > > >> > do. I > > > >> > >> >> > really think it’s time to stop rehashing this > discussion and > > > >> > instead > > > >> > >> >> focus > > > >> > >> >> > on a workable standard that we can adopt. > > > >> > >> >> > > > > >> > >> >> > -Todd > > > >> > >> >> > > > > >> > >> >> > > > > >> > >> >> > On Thu, Dec 1, 2016 at 1:39 PM, Todd Palino < > > > tpal...@gmail.com> > > > >> > >> wrote: > > > >> > >> >> > > > > >> > >> >> >> C. per message encryption > > > >> > >> >> >>> One drawback of this approach is that this > significantly > > > reduce > > > >> > the > > > >> > >> >> >>> effectiveness of compression, which happens on a > set of > > > >> > serialized > > > >> > >> >> >>> messages. An alternative is to enable SSL for wire > > > encryption > > > >> and > > > >> > >> rely > > > >> > >> >> on > > > >> > >> >> >>> the storage system (e.g. LUKS) for at rest > encryption. > > > >> > >> >> >> > > > >> > >> >> >> > > > >> > >> >> >> Jun, this is not sufficient. While this does cover > the case > > > of > > > >> > >> removing > > > >> > >> >> a > > > >> > >> >> >> drive from the system, it will not satisfy most > compliance > > > >> > >> requirements > > > >> > >> >> for > > > >> > >> >> >> encryption of data as whoever has access to the > broker > > itself > > > >> > still > > > >> > >> has > > > >> > >> >> >> access to the unencrypted data. For end-to-end > encryption > > you > > > >> > need to > > > >> > >> >> >> encrypt at the producer, before it enters the > system, and > > > >> decrypt > > > >> > at > > > >> > >> the > > > >> > >> >> >> consumer, after it exits the system. > > > >> > >> >> >> > > > >> > >> >> >> -Todd > > > >> > >> >> >> > > > >> > >> >> >> > > > >> > >> >> >> On Thu, Dec 1, 2016 at 1:03 PM, radai < > > > >> radai.rosenbl...@gmail.com > > > >> > > > > > >> > >> >> wrote: > > > >> > >> >> >> > > > >> > >> >> >>> another big plus of headers in the protocol is that > it > > would > > > >> > enable > > > >> > >> >> rapid > > > >> > >> >> >>> iteration on ideas outside of core kafka and would > reduce > > > the > > > >> > >> number of > > > >> > >> >> >>> future wire format changes required. > > > >> > >> >> >>> > > > >> > >> >> >>> a lot of what is currently a KIP represents use > cases that > > > are > > > >> > not > > > >> > >> 100% > > > >> > >> >> >>> relevant to all users, and some of them require > rather > > > invasive > > > >> > wire > > > >> > >> >> >>> protocol changes. a thing a good recent example of > this is > > > >> > kip-98. > > > >> > >> >> >>> tx-utilizing traffic is expected to be a very small > > > fraction of > > > >> > >> total > > > >> > >> >> >>> traffic and yet the changes are invasive. > > > >> > >> >> >>> > > > >> > >> >> >>> every such wire format change translates into > painful and > > > slow > > > >> > >> >> adoption of > > > >> > >> >> >>> new versions. > > > >> > >> >> >>> > > > >> > >> >> >>> i think a lot of functionality currently in KIPs > could be > > > "spun > > > >> > out" > > > >> > >> >> and > > > >> > >> >> >>> implemented as opt-in plugins transmitting data over > > > headers. > > > >> > this > > > >> > >> >> would > > > >> > >> >> >>> keep the core wire format stable(r), core codebase > > smaller, > > > and > > > >> > >> avoid > > > >> > >> >> the > > > >> > >> >> >>> "burden of proof" thats sometimes required to prove > a > > > certain > > > >> > >> feature > > > >> > >> >> is > > > >> > >> >> >>> useful enough for a wide-enough audience to warrant > a wire > > > >> format > > > >> > >> >> change > > > >> > >> >> >>> and code complexity additions. > > > >> > >> >> >>> > > > >> > >> >> >>> (to be clear - kip-98 goes beyond "mere" wire format > > changes > > > >> and > > > >> > im > > > >> > >> not > > > >> > >> >> >>> saying it could have been completely done with > headers, > > but > > > >> > >> >> exactly-once > > > >> > >> >> >>> delivery certainly could) > > > >> > >> >> >>> > > > >> > >> >> >>> On Thu, Dec 1, 2016 at 11:20 AM, Gwen Shapira < > > > >> g...@confluent.io > > > >> > > > > > >> > >> >> wrote: > > > >> > >> >> >>> > > > >> > >> >> >>> > On Thu, Dec 1, 2016 at 10:24 AM, radai < > > > >> > >> radai.rosenbl...@gmail.com> > > > >> > >> >> >>> wrote: > > > >> > >> >> >>> > > "For use cases within an organization, one could > > always > > > use > > > >> > >> other > > > >> > >> >> >>> > > approaches such as company-wise containers" > > > >> > >> >> >>> > > this is what linkedin has traditionally done > but there > > > are > > > >> > now > > > >> > >> >> cases > > > >> > >> >> >>> > (read > > > >> > >> >> >>> > > - topics) where this is not acceptable. this > makes > > > headers > > > >> > >> useful > > > >> > >> >> even > > > >> > >> >> >>> > > within single orgs for cases where > > > one-container-fits-all > > > >> > cannot > > > >> > >> >> >>> apply. > > > >> > >> >> >>> > > > > > >> > >> >> >>> > > as for the particular use cases listed, i dont > want > > > this to > > > >> > >> devolve > > > >> > >> >> >>> to a > > > >> > >> >> >>> > > discussion of particular use cases - i think its > > enough > > > >> that > > > >> > >> some > > > >> > >> >> of > > > >> > >> >> >>> them > > > >> > >> >> >>> > > > > >> > >> >> >>> > I think a main point of contention is that: We > > identified > > > few > > > >> > >> >> >>> > use-cases where headers are useful, do we want > Kafka to > > > be a > > > >> > >> system > > > >> > >> >> >>> > that supports those use-cases? > > > >> > >> >> >>> > > > > >> > >> >> >>> > For example, Jun said: > > > >> > >> >> >>> > "Not sure how widely useful record-level lineage > is > > though > > > >> > since > > > >> > >> the > > > >> > >> >> >>> > overhead could > > > >> > >> >> >>> > be significant." > > > >> > >> >> >>> > > > > >> > >> >> >>> > We know NiFi supports record level lineage. I > don't > > think > > > it > > > >> > was > > > >> > >> >> >>> > developed for lols, I think it is safe to assume > that > > the > > > NSA > > > >> > >> needed > > > >> > >> >> >>> > that functionality. We also know that certain > financial > > > >> > institutes > > > >> > >> >> >>> > need to track tampering with records at a record > level > > and > > > >> > there > > > >> > >> are > > > >> > >> >> >>> > federal regulations that absolutely require > this. They > > > also > > > >> > need > > > >> > >> to > > > >> > >> >> >>> > prove that routing apps that "touches" the > messages and > > > >> either > > > >> > >> reads > > > >> > >> >> >>> > or updates headers couldn't have possibly > modified the > > > >> payload > > > >> > >> >> itself. > > > >> > >> >> >>> > They use record level encryption to do that - > apps can > > > read > > > >> and > > > >> > >> >> >>> > (sometimes) modify headers but can't touch the > payload. > > > >> > >> >> >>> > > > > >> > >> >> >>> > We can totally say "those are corner cases and > not worth > > > >> adding > > > >> > >> >> >>> > headers to Kafka for", they should use a different > > pubsub > > > >> > message > > > >> > >> for > > > >> > >> >> >>> > that (Nifi or one of the other 1000 that cater > > > specifically > > > >> to > > > >> > the > > > >> > >> >> >>> > financial industry). > > > >> > >> >> >>> > > > > >> > >> >> >>> > But this gets us into a catch 22: > > > >> > >> >> >>> > If we discuss a specific use-case, someone can > always > > say > > > it > > > >> > isn't > > > >> > >> >> >>> > interesting enough for Kafka. If we discuss more > general > > > >> > trends, > > > >> > >> >> >>> > others can say "well, we are not sure any of them > really > > > >> needs > > > >> > >> >> headers > > > >> > >> >> >>> > specifically. This is just hand waving and not > > > interesting.". > > > >> > >> >> >>> > > > > >> > >> >> >>> > I think discussing use-cases in specifics is super > > > important > > > >> to > > > >> > >> >> decide > > > >> > >> >> >>> > implementation details for headers (my use-cases > lean > > > toward > > > >> > >> >> numerical > > > >> > >> >> >>> > keys with namespaces and object values, others > differ), > > > but I > > > >> > >> think > > > >> > >> >> we > > > >> > >> >> >>> > need to answer the general "Are we going to have > > headers" > > > >> > question > > > >> > >> >> >>> > first. > > > >> > >> >> >>> > > > > >> > >> >> >>> > I'd love to hear from the other committers in the > > > discussion: > > > >> > >> >> >>> > What would it take to convince you that headers > in Kafka > > > are > > > >> a > > > >> > >> good > > > >> > >> >> >>> > idea in general, so we can move ahead and try to > agree > > on > > > the > > > >> > >> >> details? > > > >> > >> >> >>> > > > > >> > >> >> >>> > I feel like we keep moving the goal posts and > this is > > > truly > > > >> > >> >> exhausting. > > > >> > >> >> >>> > > > > >> > >> >> >>> > For the record, I mildly support adding headers > to Kafka > > > >> > (+0.5?). > > > >> > >> >> >>> > The community can continue to find workarounds to > the > > > issue > > > >> and > > > >> > >> there > > > >> > >> >> >>> > are some benefits to keeping the message format > and > > > clients > > > >> > >> simpler. > > > >> > >> >> >>> > But I see the usefulness of headers to many > use-cases > > and > > > if > > > >> we > > > >> > >> can > > > >> > >> >> >>> > find a good and generally useful way to add it to > Kafka, > > > it > > > >> > will > > > >> > >> make > > > >> > >> >> >>> > Kafka easier to use for many - worthy goal in my > eyes. > > > >> > >> >> >>> > > > > >> > >> >> >>> > > are interesting/feasible, but: > > > >> > >> >> >>> > > A+B. i think there are use cases for polyglot > topics. > > > >> > >> especially if > > > >> > >> >> >>> kafka > > > >> > >> >> >>> > > is being used to "trunk" something else. > > > >> > >> >> >>> > > D. multiple topics would make it harder to write > > > portable > > > >> > >> consumer > > > >> > >> >> >>> code. > > > >> > >> >> >>> > > partition remapping would mess with locality of > > > consumption > > > >> > >> >> >>> guarantees. > > > >> > >> >> >>> > > E+F. a use case I see for lineage/metadata is > > > >> > >> billing/chargeback. > > > >> > >> >> for > > > >> > >> >> >>> > that > > > >> > >> >> >>> > > use case it is not enough to simply record the > point > > of > > > >> > origin, > > > >> > >> but > > > >> > >> >> >>> every > > > >> > >> >> >>> > > replication stop (think mirror maker) must also > add a > > > >> record > > > >> > to > > > >> > >> >> form a > > > >> > >> >> >>> > > "transit log". > > > >> > >> >> >>> > > > > > >> > >> >> >>> > > as for stream processing on top of kafka - i > know > > samza > > > >> has a > > > >> > >> >> metadata > > > >> > >> >> >>> > map > > > >> > >> >> >>> > > which they carry around in addition to user > values. > > > headers > > > >> > are > > > >> > >> the > > > >> > >> >> >>> > perfect > > > >> > >> >> >>> > > fit for these things. > > > >> > >> >> >>> > > > > > >> > >> >> >>> > > > > > >> > >> >> >>> > > > > > >> > >> >> >>> > > On Wed, Nov 30, 2016 at 6:50 PM, Jun Rao < > > > j...@confluent.io > > > >> > > > > >> > >> wrote: > > > >> > >> >> >>> > > > > > >> > >> >> >>> > >> Hi, Michael, > > > >> > >> >> >>> > >> > > > >> > >> >> >>> > >> In order to answer the first two questions, it > would > > be > > > >> > helpful > > > >> > >> >> if we > > > >> > >> >> >>> > could > > > >> > >> >> >>> > >> identify 1 or 2 strong use cases for headers > in the > > > space > > > >> > for > > > >> > >> >> >>> > third-party > > > >> > >> >> >>> > >> vendors. For use cases within an organization, > one > > > could > > > >> > always > > > >> > >> >> use > > > >> > >> >> >>> > other > > > >> > >> >> >>> > >> approaches such as company-wise containers to > get > > > around > > > >> w/o > > > >> > >> >> >>> headers. I > > > >> > >> >> >>> > >> went through the use cases in the KIP and in > Radai's > > > wiki > > > >> ( > > > >> > >> >> >>> > >> https://cwiki.apache.org/confl > uence/display/KAFKA/A+ > > > >> > >> >> >>> > Case+for+Kafka+Headers > > > >> > >> >> >>> > >> ). > > > >> > >> >> >>> > >> The following are the ones that that I > understand and > > > >> could > > > >> > be > > > >> > >> in > > > >> > >> >> the > > > >> > >> >> >>> > >> third-party use case category. > > > >> > >> >> >>> > >> > > > >> > >> >> >>> > >> A. content-type > > > >> > >> >> >>> > >> It seems that in general, content-type should > be set > > at > > > >> the > > > >> > >> topic > > > >> > >> >> >>> level. > > > >> > >> >> >>> > >> Not sure if mixing messages with different > content > > > types > > > >> > >> should be > > > >> > >> >> >>> > >> encouraged. > > > >> > >> >> >>> > >> > > > >> > >> >> >>> > >> B. schema id > > > >> > >> >> >>> > >> Since the value is mostly useless without > schema id, > > it > > > >> > seems > > > >> > >> that > > > >> > >> >> >>> > storing > > > >> > >> >> >>> > >> the schema id together with serialized bytes > in the > > > value > > > >> is > > > >> > >> >> better? > > > >> > >> >> >>> > >> > > > >> > >> >> >>> > >> C. per message encryption > > > >> > >> >> >>> > >> One drawback of this approach is that this > > > significantly > > > >> > reduce > > > >> > >> >> the > > > >> > >> >> >>> > >> effectiveness of compression, which happens on > a set > > of > > > >> > >> serialized > > > >> > >> >> >>> > >> messages. An alternative is to enable SSL for > wire > > > >> > encryption > > > >> > >> and > > > >> > >> >> >>> rely > > > >> > >> >> >>> > on > > > >> > >> >> >>> > >> the storage system (e.g. LUKS) for at rest > > encryption. > > > >> > >> >> >>> > >> > > > >> > >> >> >>> > >> D. cluster ID for mirroring across Kafka > clusters > > > >> > >> >> >>> > >> This is actually interesting. Today, to avoid > > > introducing > > > >> > >> cycles > > > >> > >> >> when > > > >> > >> >> >>> > doing > > > >> > >> >> >>> > >> mirroring across data centers, one would > either have > > to > > > >> set > > > >> > up > > > >> > >> two > > > >> > >> >> >>> Kafka > > > >> > >> >> >>> > >> clusters (a local and an aggregate) per data > center > > or > > > >> > rename > > > >> > >> >> topics. > > > >> > >> >> >>> > >> Neither is ideal. With headers, the producer > could > > tag > > > >> each > > > >> > >> >> message > > > >> > >> >> >>> with > > > >> > >> >> >>> > >> the producing cluster ID in the header. > MirrorMaker > > > could > > > >> > then > > > >> > >> >> avoid > > > >> > >> >> >>> > >> mirroring messages to a cluster if they are > tagged > > with > > > >> the > > > >> > >> same > > > >> > >> >> >>> cluster > > > >> > >> >> >>> > >> id. > > > >> > >> >> >>> > >> > > > >> > >> >> >>> > >> However, an alternative approach is to > introduce sth > > > like > > > >> > >> >> >>> hierarchical > > > >> > >> >> >>> > >> topic and store messages from different > clusters in > > > >> > different > > > >> > >> >> >>> partitions > > > >> > >> >> >>> > >> under the same topic. This approach avoids > filtering > > > out > > > >> > >> unneeded > > > >> > >> >> >>> data > > > >> > >> >> >>> > and > > > >> > >> >> >>> > >> makes offset preserving easier to support. It > may > > make > > > >> > >> compaction > > > >> > >> >> >>> > trickier > > > >> > >> >> >>> > >> though since the same key may show up in > different > > > >> > partitions. > > > >> > >> >> >>> > >> > > > >> > >> >> >>> > >> E. record-level lineage > > > >> > >> >> >>> > >> For example, a source connector could store in > the > > > message > > > >> > the > > > >> > >> >> >>> metadata > > > >> > >> >> >>> > >> (e.g. UUID) of the source record. Similarly, > if a > > > stream > > > >> job > > > >> > >> >> >>> transforms > > > >> > >> >> >>> > >> messages from topic A to topic B, the library > could > > > >> include > > > >> > the > > > >> > >> >> >>> source > > > >> > >> >> >>> > >> message offset in each of the transformed > message in > > > the > > > >> > >> header. > > > >> > >> >> Not > > > >> > >> >> >>> > sure > > > >> > >> >> >>> > >> how widely useful record-level lineage is > though > > since > > > the > > > >> > >> >> overhead > > > >> > >> >> >>> > could > > > >> > >> >> >>> > >> be significant. > > > >> > >> >> >>> > >> > > > >> > >> >> >>> > >> F. auditing metadata > > > >> > >> >> >>> > >> We could put things like clientId/host/user in > the > > > header > > > >> in > > > >> > >> each > > > >> > >> >> >>> > message > > > >> > >> >> >>> > >> for auditing. These metadata are really at the > > producer > > > >> > level > > > >> > >> >> though. > > > >> > >> >> >>> > So, a > > > >> > >> >> >>> > >> more efficient way is to only include a > "producerId" > > > per > > > >> > >> message > > > >> > >> >> and > > > >> > >> >> >>> > send > > > >> > >> >> >>> > >> the producerId -> metadata mapping > independently. > > > KIP-98 > > > >> is > > > >> > >> >> actually > > > >> > >> >> >>> > >> proposing including such a producerId natively > in the > > > >> > message. > > > >> > >> >> >>> > >> > > > >> > >> >> >>> > >> So, overall, I not sure that I am fully > convinced of > > > the > > > >> > strong > > > >> > >> >> >>> > third-party > > > >> > >> >> >>> > >> use cases of headers yet. Perhaps we could > discuss a > > > bit > > > >> > more > > > >> > >> to > > > >> > >> >> make > > > >> > >> >> >>> > one > > > >> > >> >> >>> > >> or two really convincing use cases. > > > >> > >> >> >>> > >> > > > >> > >> >> >>> > >> Another orthogonal question is whether header > should > > > be > > > >> > >> exposed > > > >> > >> >> in > > > >> > >> >> >>> > stream > > > >> > >> >> >>> > >> processing systems such Kafka stream, Samza, > and > > Spark > > > >> > >> streaming. > > > >> > >> >> >>> > >> Currently, those systems just deal with > key/value > > > pairs. > > > >> > >> Should we > > > >> > >> >> >>> > expose a > > > >> > >> >> >>> > >> third thing header there too or somehow map > header to > > > key > > > >> or > > > >> > >> >> value? > > > >> > >> >> >>> > >> > > > >> > >> >> >>> > >> Thanks, > > > >> > >> >> >>> > >> > > > >> > >> >> >>> > >> Jun > > > >> > >> >> >>> > >> > > > >> > >> >> >>> > >> > > > >> > >> >> >>> > >> On Tue, Nov 29, 2016 at 3:35 AM, Michael > Pearce < > > > >> > >> >> >>> michael.pea...@ig.com> > > > >> > >> >> >>> > >> wrote: > > > >> > >> >> >>> > >> > > > >> > >> >> >>> > >> > I assume, that after a period of a week, > that there > > > is > > > >> no > > > >> > >> >> concerns > > > >> > >> >> >>> now > > > >> > >> >> >>> > >> > with points 1, and 2 and now we have > agreement that > > > >> > headers > > > >> > >> are > > > >> > >> >> >>> useful > > > >> > >> >> >>> > >> and > > > >> > >> >> >>> > >> > needed in Kafka. As such if put to a KIP > vote, this > > > >> > wouldn’t > > > >> > >> be > > > >> > >> >> a > > > >> > >> >> >>> > reason > > > >> > >> >> >>> > >> to > > > >> > >> >> >>> > >> > reject. > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > @ > > > >> > >> >> >>> > >> > Ignacio on point 4). > > > >> > >> >> >>> > >> > I think for purpose of getting this KIP > moving past > > > >> this, > > > >> > we > > > >> > >> can > > > >> > >> >> >>> state > > > >> > >> >> >>> > >> the > > > >> > >> >> >>> > >> > key will be a 4 bytes space that can will be > > > naturally > > > >> > >> >> interpreted > > > >> > >> >> >>> as > > > >> > >> >> >>> > an > > > >> > >> >> >>> > >> > Int32 (if namespacing is later wanted you can > > easily > > > >> split > > > >> > >> this > > > >> > >> >> >>> into > > > >> > >> >> >>> > two > > > >> > >> >> >>> > >> > int16 spaces), from the wire protocol > > implementation > > > >> this > > > >> > >> makes > > > >> > >> >> no > > > >> > >> >> >>> > >> > difference I don’t believe. Is this > reasonable to > > > all? > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > On 5) as per point 4 therefor happy we keep > with 32 > > > >> bits. > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > On 18/11/2016, 20:34, " > ignacio.so...@gmail.com on > > > >> behalf > > > >> > of > > > >> > >> >> >>> Ignacio > > > >> > >> >> >>> > >> > Solis" <ignacio.so...@gmail.com on behalf of > > > >> > iso...@igso.net > > > >> > >> > > > > >> > >> >> >>> wrote: > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > Summary: > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > 3) Yes - Header value as byte[] > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > 4a) Int,Int - No > > > >> > >> >> >>> > >> > 4b) Int - Yes > > > >> > >> >> >>> > >> > 4c) String - Reluctant maybe > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > 5) I believe the header system should > take a > > > single > > > >> > >> int. I > > > >> > >> >> >>> think > > > >> > >> >> >>> > >> > 32bits is > > > >> > >> >> >>> > >> > a good size, if you want to interpret > this as > > to > > > >> 16bit > > > >> > >> >> numbers > > > >> > >> >> >>> in > > > >> > >> >> >>> > the > > > >> > >> >> >>> > >> > layer > > > >> > >> >> >>> > >> > above go right ahead. If somebody wants > to > > argue > > > >> for > > > >> > 16 > > > >> > >> >> bits > > > >> > >> >> >>> or > > > >> > >> >> >>> > 64 > > > >> > >> >> >>> > >> > bits of > > > >> > >> >> >>> > >> > header key space I would listen. > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > Discussion: > > > >> > >> >> >>> > >> > Dividing the key space into sub_key_1 and > > > sub_key_2 > > > >> > >> makes no > > > >> > >> >> >>> > sense to > > > >> > >> >> >>> > >> > me at > > > >> > >> >> >>> > >> > this layer. Are we going to start > providing > > > APIs to > > > >> > get > > > >> > >> all > > > >> > >> >> >>> the > > > >> > >> >> >>> > >> > sub_key_1s? or all the sub_key_2s? If > there is > > > no > > > >> > >> >> >>> distinguishing > > > >> > >> >> >>> > >> > functions > > > >> > >> >> >>> > >> > that are applied to each one then they > should > > be > > > a > > > >> > single > > > >> > >> >> >>> value. > > > >> > >> >> >>> > At > > > >> > >> >> >>> > >> > this > > > >> > >> >> >>> > >> > layer all we're doing is equality. > > > >> > >> >> >>> > >> > If the above layer wants to interpret > this as > > 2, > > > 3 > > > >> or > > > >> > >> more > > > >> > >> >> >>> values > > > >> > >> >> >>> > >> > that's a > > > >> > >> >> >>> > >> > different question. I personally think > it's > > all > > > one > > > >> > >> >> keyspace > > > >> > >> >> >>> > that is > > > >> > >> >> >>> > >> > getting assigned using some structure, > but if > > you > > > >> > want to > > > >> > >> >> >>> > sub-assign > > > >> > >> >> >>> > >> > parts > > > >> > >> >> >>> > >> > of it then that's fine. > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > The same discussion applies to strings. > If > > > somebody > > > >> > >> argued > > > >> > >> >> for > > > >> > >> >> >>> > >> > strings, > > > >> > >> >> >>> > >> > would we be arguing to divide the > strings with > > > dots > > > >> > ('.') > > > >> > >> >> as a > > > >> > >> >> >>> > >> > requirement? > > > >> > >> >> >>> > >> > Would we want them to give us the > different > > name > > > >> > segments > > > >> > >> >> >>> > separately? > > > >> > >> >> >>> > >> > Would we be performing any actions on > this key > > > other > > > >> > than > > > >> > >> >> >>> > matching? > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > Nacho > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > On Fri, Nov 18, 2016 at 9:30 AM, Michael > > Pearce < > > > >> > >> >> >>> > >> michael.pea...@ig.com > > > >> > >> >> >>> > >> > > > > > >> > >> >> >>> > >> > wrote: > > > >> > >> >> >>> > >> > > > > >> > >> >> >>> > >> > > #jay #jun any concerns on 1 and 2 > still? > > > >> > >> >> >>> > >> > > > > > >> > >> >> >>> > >> > > @all > > > >> > >> >> >>> > >> > > To get this moving along a bit more > I'd also > > > like > > > >> to > > > >> > >> ask > > > >> > >> >> to > > > >> > >> >> >>> get > > > >> > >> >> >>> > >> > clarity on > > > >> > >> >> >>> > >> > > the below last points: > > > >> > >> >> >>> > >> > > > > > >> > >> >> >>> > >> > > 3) I believe we're all roughly happy > with the > > > >> header > > > >> > >> value > > > >> > >> >> >>> > being a > > > >> > >> >> >>> > >> > byte[]? > > > >> > >> >> >>> > >> > > > > > >> > >> >> >>> > >> > > 4) I believe consensus has been for an > > > namespace > > > >> > based > > > >> > >> int > > > >> > >> >> >>> > approach > > > >> > >> >> >>> > >> > > {int,int} for the key. Any objections > if this > > > is > > > >> > what > > > >> > >> we > > > >> > >> >> go > > > >> > >> >> >>> > with? > > > >> > >> >> >>> > >> > > > > > >> > >> >> >>> > >> > > 5) as we have if assumption in (4) is > > correct, > > > >> > >> {int,int} > > > >> > >> >> >>> keys. > > > >> > >> >> >>> > >> > > Should both int's be int16 or int32? > > > >> > >> >> >>> > >> > > I'm for them being int16(2 bytes) as > combined > > > is > > > >> > space > > > >> > >> of > > > >> > >> >> >>> > 4bytes as > > > >> > >> >> >>> > >> > per > > > >> > >> >> >>> > >> > > original and gives plenty of > combinations for > > > the > > > >> > >> >> >>> foreseeable, > > > >> > >> >> >>> > and > > > >> > >> >> >>> > >> > keeps > > > >> > >> >> >>> > >> > > the overhead small. > > > >> > >> >> >>> > >> > > > > > >> > >> >> >>> > >> > > Do we see any benefit in another kip > call to > > > >> discuss > > > >> > >> >> these at > > > >> > >> >> >>> > all? > > > >> > >> >> >>> > >> > > > > > >> > >> >> >>> > >> > > Cheers > > > >> > >> >> >>> > >> > > Mike > > > >> > >> >> >>> > >> > > ______________________________ > __________ > > > >> > >> >> >>> > >> > > From: K Burstev <k.burs...@yandex.com> > > > >> > >> >> >>> > >> > > Sent: Friday, November 18, 2016 > 7:07:07 AM > > > >> > >> >> >>> > >> > > To: dev@kafka.apache.org > > > >> > >> >> >>> > >> > > Subject: Re: [DISCUSS] KIP-82 - Add > Record > > > Headers > > > >> > >> >> >>> > >> > > > > > >> > >> >> >>> > >> > > For what it is worth also i agree. As > a user: > > > >> > >> >> >>> > >> > > > > > >> > >> >> >>> > >> > > 1) Yes - Headers are worthwhile > > > >> > >> >> >>> > >> > > 2) Yes - Headers should be a top level > > option > > > >> > >> >> >>> > >> > > > > > >> > >> >> >>> > >> > > 14.11.2016, 21:15, "Ignacio Solis" < > > > >> iso...@igso.net > > > >> > >: > > > >> > >> >> >>> > >> > > > 1) Yes - Headers are worthwhile > > > >> > >> >> >>> > >> > > > 2) Yes - Headers should be a top > level > > option > > > >> > >> >> >>> > >> > > > > > > >> > >> >> >>> > >> > > > On Mon, Nov 14, 2016 at 9:16 AM, > Michael > > > Pearce > > > >> < > > > >> > >> >> >>> > >> > michael.pea...@ig.com> > > > >> > >> >> >>> > >> > > > wrote: > > > >> > >> >> >>> > >> > > > > > > >> > >> >> >>> > >> > > >> Hi Roger, > > > >> > >> >> >>> > >> > > >> > > > >> > >> >> >>> > >> > > >> The kip details/examples the > original > > > proposal > > > >> > for > > > >> > >> key > > > >> > >> >> >>> > spacing > > > >> > >> >> >>> > >> , > > > >> > >> >> >>> > >> > not > > > >> > >> >> >>> > >> > > the > > > >> > >> >> >>> > >> > > >> new mentioned as per discussion > namespace > > > >> idea. > > > >> > >> >> >>> > >> > > >> > > > >> > >> >> >>> > >> > > >> We will need to update the kip, > when we > > get > > > >> > >> agreement > > > >> > >> >> >>> this > > > >> > >> >> >>> > is a > > > >> > >> >> >>> > >> > better > > > >> > >> >> >>> > >> > > >> approach (which seems to be the > case if I > > > have > > > >> > >> >> understood > > > >> > >> >> >>> > the > > > >> > >> >> >>> > >> > general > > > >> > >> >> >>> > >> > > >> feeling in the conversation) > > > >> > >> >> >>> > >> > > >> > > > >> > >> >> >>> > >> > > >> Re the variable ints, at very > early stage > > > we > > > >> did > > > >> > >> think > > > >> > >> >> >>> about > > > >> > >> >> >>> > >> > this. I > > > >> > >> >> >>> > >> > > think > > > >> > >> >> >>> > >> > > >> the added complexity for the > saving isn't > > > >> worth > > > >> > it. > > > >> > >> >> I'd > > > >> > >> >> >>> > rather > > > >> > >> >> >>> > >> go > > > >> > >> >> >>> > >> > > with, if > > > >> > >> >> >>> > >> > > >> we want to reduce overheads and > size > > int16 > > > >> > (2bytes) > > > >> > >> >> keys > > > >> > >> >> >>> as > > > >> > >> >> >>> > it > > > >> > >> >> >>> > >> > keeps it > > > >> > >> >> >>> > >> > > >> simple. > > > >> > >> >> >>> > >> > > >> > > > >> > >> >> >>> > >> > > >> On the note of no headers, there > is as > > per > > > the > > > >> > kip > > > >> > >> as > > > >> > >> >> we > > > >> > >> >> >>> > use an > > > >> > >> >> >>> > >> > > attribute > > > >> > >> >> >>> > >> > > >> bit to denote if headers are > present or > > > not as > > > >> > such > > > >> > >> >> >>> > provides a > > > >> > >> >> >>> > >> > zero > > > >> > >> >> >>> > >> > > >> overhead currently if headers are > not > > used. > > > >> > >> >> >>> > >> > > >> > > > >> > >> >> >>> > >> > > >> I think as radai mentions would be > good > > > first > > > >> > if we > > > >> > >> >> can > > > >> > >> >> >>> get > > > >> > >> >> >>> > >> > clarity if > > > >> > >> >> >>> > >> > > do > > > >> > >> >> >>> > >> > > >> we now have general consensus that > (1) > > > headers > > > >> > are > > > >> > >> >> >>> > worthwhile > > > >> > >> >> >>> > >> and > > > >> > >> >> >>> > >> > > useful, > > > >> > >> >> >>> > >> > > >> and (2) we want it as a top level > entity. > > > >> > >> >> >>> > >> > > >> > > > >> > >> >> >>> > >> > > >> Just to state the obvious i > believe (1) > > > >> headers > > > >> > are > > > >> > >> >> >>> > worthwhile > > > >> > >> >> >>> > >> > and (2) > > > >> > >> >> >>> > >> > > >> agree as a top level entity. > > > >> > >> >> >>> > >> > > >> > > > >> > >> >> >>> > >> > > >> Cheers > > > >> > >> >> >>> > >> > > >> Mike > > > >> > >> >> >>> > >> > > >> ______________________________ > __________ > > > >> > >> >> >>> > >> > > >> From: Roger Hoover < > > roger.hoo...@gmail.com > > > > > > > >> > >> >> >>> > >> > > >> Sent: Wednesday, November 9, 2016 > 9:10:47 > > > PM > > > >> > >> >> >>> > >> > > >> To: dev@kafka.apache.org > > > >> > >> >> >>> > >> > > >> Subject: Re: [DISCUSS] KIP-82 - Add > > Record > > > >> > Headers > > > >> > >> >> >>> > >> > > >> > > > >> > >> >> >>> > >> > > >> Sorry for going a little in the > weeds but > > > >> thanks > > > >> > >> for > > > >> > >> >> the > > > >> > >> >> >>> > >> replies > > > >> > >> >> >>> > >> > > regarding > > > >> > >> >> >>> > >> > > >> varint. > > > >> > >> >> >>> > >> > > >> > > > >> > >> >> >>> > >> > > >> Agreed that a prefix and {int, > int} can > > be > > > the > > > >> > >> same. > > > >> > >> >> It > > > >> > >> >> >>> > doesn't > > > >> > >> >> >>> > >> > look > > > >> > >> >> >>> > >> > > like > > > >> > >> >> >>> > >> > > >> that's what the KIP is saying the > "Open" > > > >> > section. > > > >> > >> The > > > >> > >> >> >>> > example > > > >> > >> >> >>> > >> > shows > > > >> > >> >> >>> > >> > > >> 2100001 > > > >> > >> >> >>> > >> > > >> for New Relic and 210002 for App > Dynamics > > > >> > implying > > > >> > >> >> that > > > >> > >> >> >>> the > > > >> > >> >> >>> > New > > > >> > >> >> >>> > >> > Relic > > > >> > >> >> >>> > >> > > >> organization will have only a > single > > > header id > > > >> > to > > > >> > >> work > > > >> > >> >> >>> > with. Or > > > >> > >> >> >>> > >> > is > > > >> > >> >> >>> > >> > > 2100001 > > > >> > >> >> >>> > >> > > >> a prefix? The main point of a > namespace > > or > > > >> > prefix > > > >> > >> is > > > >> > >> >> to > > > >> > >> >> >>> > reduce > > > >> > >> >> >>> > >> > the > > > >> > >> >> >>> > >> > > >> overhead of config mapping or > > registration > > > >> > >> depending > > > >> > >> >> on > > > >> > >> >> >>> how > > > >> > >> >> >>> > >> > > >> namespaces/prefixes are managed. > > > >> > >> >> >>> > >> > > >> > > > >> > >> >> >>> > >> > > >> Would love to hear more feedback > on the > > > >> > >> higher-level > > > >> > >> >> >>> > questions > > > >> > >> >> >>> > >> > > though... > > > >> > >> >> >>> > >> > > >> > > > >> > >> >> >>> > >> > > >> Cheers, > > > >> > >> >> >>> > >> > > >> > > > >> > >> >> >>> > >> > > >> Roger > > > >> > >> >> >>> > >> > > >> > > > >> > >> >> >>> > >> > > >> On Wed, Nov 9, 2016 at 11:38 AM, > radai < > > > >> > >> >> >>> > >> > radai.rosenbl...@gmail.com> > > > >> > >> >> >>> > >> > > wrote: > > > >> > >> >> >>> > >> > > >> > > > >> > >> >> >>> > >> > > >> > I think this discussion is > getting a > > bit > > > >> into > > > >> > the > > > >> > >> >> >>> weeds on > > > >> > >> >> >>> > >> > technical > > > >> > >> >> >>> > >> > > >> > implementation details. > > > >> > >> >> >>> > >> > > >> > I'd liek to step back a minute > and try > > > and > > > >> > >> establish > > > >> > >> >> >>> > where we > > > >> > >> >> >>> > >> > are in > > > >> > >> >> >>> > >> > > the > > > >> > >> >> >>> > >> > > >> > larger picture: > > > >> > >> >> >>> > >> > > >> > > > > >> > >> >> >>> > >> > > >> > (re-wording nacho's last > paragraph) > > > >> > >> >> >>> > >> > > >> > 1. are we all in agreement that > headers > > > are > > > >> a > > > >> > >> >> >>> worthwhile > > > >> > >> >> >>> > and > > > >> > >> >> >>> > >> > useful > > > >> > >> >> >>> > >> > > >> > addition to have? this was > contested > > > early > > > >> on > > > >> > >> >> >>> > >> > > >> > 2. are we all in agreement on > headers > > as > > > top > > > >> > >> level > > > >> > >> >> >>> entity > > > >> > >> >> >>> > vs > > > >> > >> >> >>> > >> > headers > > > >> > >> >> >>> > >> > > >> > squirreled-away in V? > > > >> > >> >> >>> > >> > > >> > > > > >> > >> >> >>> > >> > > >> > if there are still concerns > around > > these > > > #2 > > > >> > >> points > > > >> > >> >> >>> (#jay? > > > >> > >> >> >>> > >> > #jun?)? > > > >> > >> >> >>> > >> > > >> > > > > >> > >> >> >>> > >> > > >> > (and now back to our normal > programming > > > ...) > > > >> > >> >> >>> > >> > > >> > > > > >> > >> >> >>> > >> > > >> > varints are nice. having said > that, its > > > >> adding > > > >> > >> >> >>> complexity > > > >> > >> >> >>> > >> (see > > > >> > >> >> >>> > >> > > >> > https://github.com/addthis/ > > > >> > >> >> stream-lib/blob/master/src/ > > > >> > >> >> >>> > >> > > >> > main/java/com/clearspring/ > > > >> > >> >> analytics/util/Varint.java > > > >> > >> >> >>> > >> > > >> > as 1st google result) and would > require > > > >> anyone > > > >> > >> >> writing > > > >> > >> >> >>> > other > > > >> > >> >> >>> > >> > clients > > > >> > >> >> >>> > >> > > (C? > > > >> > >> >> >>> > >> > > >> > Python? Go? Bash? ;-) ) to > > get/implement > > > the > > > >> > >> same, > > > >> > >> >> and > > > >> > >> >> >>> for > > > >> > >> >> >>> > >> > relatively > > > >> > >> >> >>> > >> > > >> > little gain (int vs string is > order of > > > >> > magnitude, > > > >> > >> >> this > > > >> > >> >> >>> > isnt). > > > >> > >> >> >>> > >> > > >> > > > > >> > >> >> >>> > >> > > >> > int namespacing vs {int, int} > > namespacing > > > >> are > > > >> > >> >> basically > > > >> > >> >> >>> > the > > > >> > >> >> >>> > >> > same > > > >> > >> >> >>> > >> > > thing - > > > >> > >> >> >>> > >> > > >> > youre just namespacing an int64 > and > > > giving > > > >> > people > > > >> > >> >> while > > > >> > >> >> >>> > 2^32 > > > >> > >> >> >>> > >> > ranges > > > >> > >> >> >>> > >> > > at a > > > >> > >> >> >>> > >> > > >> > time. the part i like about this > is > > > letting > > > >> > >> people > > > >> > >> >> >>> have a > > > >> > >> >> >>> > >> large > > > >> > >> >> >>> > >> > > swath of > > > >> > >> >> >>> > >> > > >> > numbers with one registration so > they > > > dont > > > >> > have > > > >> > >> to > > > >> > >> >> come > > > >> > >> >> >>> > back > > > >> > >> >> >>> > >> > for > > > >> > >> >> >>> > >> > > every > > > >> > >> >> >>> > >> > > >> > single plugin/header they want to > > > "reserve". > > > >> > >> >> >>> > >> > > >> > > > > >> > >> >> >>> > >> > > >> > > > > >> > >> >> >>> > >> > > >> > On Wed, Nov 9, 2016 at 11:01 AM, > Roger > > > >> Hoover > > > >> > < > > > >> > >> >> >>> > >> > > roger.hoo...@gmail.com> > > > >> > >> >> >>> > >> > > >> > wrote: > > > >> > >> >> >>> > >> > > >> > > > > >> > >> >> >>> > >> > > >> > > Since some of the debate has > been > > about > > > >> > >> overhead + > > > >> > >> >> >>> > >> > performance, I'm > > > >> > >> >> >>> > >> > > >> > > wondering if we have > considered a > > > varint > > > >> > >> encoding > > > >> > >> >> ( > > > >> > >> >> >>> > >> > > >> > > https://developers.google.com/ > > > >> > >> >> protocol-buffers/docs/ > > > >> > >> >> >>> > >> > > encoding#varints) > > > >> > >> >> >>> > >> > > >> > for > > > >> > >> >> >>> > >> > > >> > > the header length field (int32 > in the > > > >> > proposal) > > > >> > >> >> and > > > >> > >> >> >>> for > > > >> > >> >> >>> > >> > header > > > >> > >> >> >>> > >> > > ids? If > > > >> > >> >> >>> > >> > > >> > you > > > >> > >> >> >>> > >> > > >> > > don't use headers, the > overhead would > > > be a > > > >> > >> single > > > >> > >> >> >>> byte > > > >> > >> >> >>> > and > > > >> > >> >> >>> > >> > for each > > > >> > >> >> >>> > >> > > >> > header > > > >> > >> >> >>> > >> > > >> > > id < 128 would also need only a > > single > > > >> byte? > > > >> > >> >> >>> > >> > > >> > > > > > >> > >> >> >>> > >> > > >> > > > > > >> > >> >> >>> > >> > > >> > > > > > >> > >> >> >>> > >> > > >> > > On Wed, Nov 9, 2016 at 6:43 AM, > > radai < > > > >> > >> >> >>> > >> > radai.rosenbl...@gmail.com> > > > >> > >> >> >>> > >> > > >> > wrote: > > > >> > >> >> >>> > >> > > >> > > > > > >> > >> >> >>> > >> > > >> > > > @magnus - and very dangerous > (youre > > > >> > >> essentially > > > >> > >> >> >>> > >> > downloading and > > > >> > >> >> >>> > >> > > >> > executing > > > >> > >> >> >>> > >> > > >> > > > arbitrary code off the > internet on > > > your > > > >> > >> servers > > > >> > >> >> ... > > > >> > >> >> >>> > bad > > > >> > >> >> >>> > >> > idea > > > >> > >> >> >>> > >> > > without > > > >> > >> >> >>> > >> > > >> a > > > >> > >> >> >>> > >> > > >> > > > sandbox, even with) > > > >> > >> >> >>> > >> > > >> > > > > > > >> > >> >> >>> > >> > > >> > > > as for it being a purely > > > administrative > > > >> > task > > > >> > >> - i > > > >> > >> >> >>> > >> disagree. > > > >> > >> >> >>> > >> > > >> > > > > > > >> > >> >> >>> > >> > > >> > > > i wish it would, really, > because > > > then my > > > >> > >> earlier > > > >> > >> >> >>> > point on > > > >> > >> >> >>> > >> > the > > > >> > >> >> >>> > >> > > >> > complexity > > > >> > >> >> >>> > >> > > >> > > of > > > >> > >> >> >>> > >> > > >> > > > the remapping process would > be > > > invalid, > > > >> > but > > > >> > >> at > > > >> > >> >> >>> > linkedin, > > > >> > >> >> >>> > >> > for > > > >> > >> >> >>> > >> > > example, > > > >> > >> >> >>> > >> > > >> > we > > > >> > >> >> >>> > >> > > >> > > > (the team im in) run kafka > as a > > > service. > > > >> > we > > > >> > >> dont > > > >> > >> >> >>> > really > > > >> > >> >> >>> > >> > know > > > >> > >> >> >>> > >> > > what our > > > >> > >> >> >>> > >> > > >> > > users > > > >> > >> >> >>> > >> > > >> > > > (developing applications > that use > > > kafka) > > > >> > are > > > >> > >> up > > > >> > >> >> to > > > >> > >> >> >>> at > > > >> > >> >> >>> > any > > > >> > >> >> >>> > >> > given > > > >> > >> >> >>> > >> > > >> moment. > > > >> > >> >> >>> > >> > > >> > > it > > > >> > >> >> >>> > >> > > >> > > > is very possible (given the > > > existance of > > > >> > >> headers > > > >> > >> >> >>> and a > > > >> > >> >> >>> > >> > > corresponding > > > >> > >> >> >>> > >> > > >> > > plugin > > > >> > >> >> >>> > >> > > >> > > > ecosystem) for some > application to > > > >> "equip" > > > >> > >> their > > > >> > >> >> >>> > >> producers > > > >> > >> >> >>> > >> > and > > > >> > >> >> >>> > >> > > >> > consumers > > > >> > >> >> >>> > >> > > >> > > > with the required plugin > without us > > > >> > knowing. > > > >> > >> i > > > >> > >> >> dont > > > >> > >> >> >>> > mean > > > >> > >> >> >>> > >> > to imply > > > >> > >> >> >>> > >> > > >> thats > > > >> > >> >> >>> > >> > > >> > > > bad, i just want to make the > point > > > that > > > >> > its > > > >> > >> not > > > >> > >> >> as > > > >> > >> >> >>> > simple > > > >> > >> >> >>> > >> > > keeping it > > > >> > >> >> >>> > >> > > >> in > > > >> > >> >> >>> > >> > > >> > > > sync across a large-enough > > > organization. > > > >> > >> >> >>> > >> > > >> > > > > > > >> > >> >> >>> > >> > > >> > > > > > > >> > >> >> >>> > >> > > >> > > > On Wed, Nov 9, 2016 at 6:17 > AM, > > > Magnus > > > >> > >> Edenhill > > > >> > >> >> < > > > >> > >> >> >>> > >> > > mag...@edenhill.se> > > > >> > >> >> >>> > >> > > >> > > > wrote: > > > >> > >> >> >>> > >> > > >> > > > > > > >> > >> >> >>> > >> > > >> > > > > I think there is a piece > missing > > in > > > >> the > > > >> > >> >> Strings > > > >> > >> >> >>> > >> > discussion, > > > >> > >> >> >>> > >> > > where > > > >> > >> >> >>> > >> > > >> > > > > pro-Stringers > > > >> > >> >> >>> > >> > > >> > > > > reason that by providing > unique > > > string > > > >> > >> >> >>> identifiers > > > >> > >> >> >>> > for > > > >> > >> >> >>> > >> > each > > > >> > >> >> >>> > >> > > header > > > >> > >> >> >>> > >> > > >> > > > > everything will just > > > >> > >> >> >>> > >> > > >> > > > > magically work for all > parts of > > the > > > >> > stream > > > >> > >> >> >>> pipeline. > > > >> > >> >> >>> > >> > > >> > > > > > > > >> > >> >> >>> > >> > > >> > > > > But the strings dont mean > > anything > > > by > > > >> > >> >> themselves, > > > >> > >> >> >>> > and > > > >> > >> >> >>> > >> > while we > > > >> > >> >> >>> > >> > > >> could > > > >> > >> >> >>> > >> > > >> > > > > probably envision > > > >> > >> >> >>> > >> > > >> > > > > some auto plugin loader > that > > > >> downloads, > > > >> > >> >> compiles, > > > >> > >> >> >>> > links > > > >> > >> >> >>> > >> > and > > > >> > >> >> >>> > >> > > runs > > > >> > >> >> >>> > >> > > >> > > plugins > > > >> > >> >> >>> > >> > > >> > > > > on-demand > > > >> > >> >> >>> > >> > > >> > > > > as soon as they're seen by > a > > > >> consumer, I > > > >> > >> dont > > > >> > >> >> >>> really > > > >> > >> >> >>> > >> see > > > >> > >> >> >>> > >> > a > > > >> > >> >> >>> > >> > > use-case > > > >> > >> >> >>> > >> > > >> > for > > > >> > >> >> >>> > >> > > >> > > > > something > > > >> > >> >> >>> > >> > > >> > > > > so dynamic (and fragile) in > > > practice. > > > >> > >> >> >>> > >> > > >> > > > > > > > >> > >> >> >>> > >> > > >> > > > > In the real world an > application > > > will > > > >> be > > > >> > >> >> >>> configured > > > >> > >> >> >>> > >> with > > > >> > >> >> >>> > >> > a set > > > >> > >> >> >>> > >> > > of > > > >> > >> >> >>> > >> > > >> > > plugins > > > >> > >> >> >>> > >> > > >> > > > > to either add (producer) > > > >> > >> >> >>> > >> > > >> > > > > or read (consumer) headers. > > > >> > >> >> >>> > >> > > >> > > > > This is an administrative > task > > > based > > > >> on > > > >> > >> what > > > >> > >> >> >>> > features a > > > >> > >> >> >>> > >> > client > > > >> > >> >> >>> > >> > > >> > > > > needs/provides and results > in > > > >> > >> >> >>> > >> > > >> > > > > some sort of configuration > to > > > enable > > > >> and > > > >> > >> >> >>> configure > > > >> > >> >> >>> > the > > > >> > >> >> >>> > >> > desired > > > >> > >> >> >>> > >> > > >> > plugins. > > > >> > >> >> >>> > >> > > >> > > > > > > > >> > >> >> >>> > >> > > >> > > > > Since this needs to be kept > > > somewhat > > > >> in > > > >> > >> sync > > > >> > >> >> >>> across > > > >> > >> >> >>> > an > > > >> > >> >> >>> > >> > > organisation > > > >> > >> >> >>> > >> > > >> > > > (there > > > >> > >> >> >>> > >> > > >> > > > > is no point in having > producers > > > >> > >> >> >>> > >> > > >> > > > > add headers no consumers > will > > read, > > > >> and > > > >> > >> vice > > > >> > >> >> >>> versa), > > > >> > >> >> >>> > >> the > > > >> > >> >> >>> > >> > added > > > >> > >> >> >>> > >> > > >> > > complexity > > > >> > >> >> >>> > >> > > >> > > > > of assigning an id > namespace > > > >> > >> >> >>> > >> > > >> > > > > for each plugin as it is > being > > > >> > configured > > > >> > >> >> should > > > >> > >> >> >>> be > > > >> > >> >> >>> > >> > tolerable. > > > >> > >> >> >>> > >> > > >> > > > > > > > >> > >> >> >>> > >> > > >> > > > > > > > >> > >> >> >>> > >> > > >> > > > > /Magnus > > > >> > >> >> >>> > >> > > >> > > > > > > > >> > >> >> >>> > >> > > >> > > > > 2016-11-09 13:06 GMT+01:00 > > Michael > > > >> > Pearce < > > > >> > >> >> >>> > >> > > michael.pea...@ig.com>: > > > >> > >> >> >>> > >> > > >> > > > > > > > >> > >> >> >>> > >> > > >> > > > > > Just following/catching > up on > > > what > > > >> > seems > > > >> > >> to > > > >> > >> >> be > > > >> > >> >> >>> an > > > >> > >> >> >>> > >> > active > > > >> > >> >> >>> > >> > > night :) > > > >> > >> >> >>> > >> > > >> > > > > > > > > >> > >> >> >>> > >> > > >> > > > > > @Radai sorry if it may > seem > > > obvious > > > >> > but > > > >> > >> what > > > >> > >> >> >>> does > > > >> > >> >> >>> > MD > > > >> > >> >> >>> > >> > stand > > > >> > >> >> >>> > >> > > for? > > > >> > >> >> >>> > >> > > >> > > > > > > > > >> > >> >> >>> > >> > > >> > > > > > My take on String vs Int: > > > >> > >> >> >>> > >> > > >> > > > > > > > > >> > >> >> >>> > >> > > >> > > > > > I will state first I am > pro Int > > > (16 > > > >> or > > > >> > >> 32). > > > >> > >> >> >>> > >> > > >> > > > > > > > > >> > >> >> >>> > >> > > >> > > > > > I do though playing > devils > > > advocate > > > >> > see a > > > >> > >> >> big > > > >> > >> >> >>> plus > > > >> > >> >> >>> > >> > with the > > > >> > >> >> >>> > >> > > >> > argument > > > >> > >> >> >>> > >> > > >> > > of > > > >> > >> >> >>> > >> > > >> > > > > > String keys, this is > around > > > >> > integrating > > > >> > >> >> into an > > > >> > >> >> >>> > >> > existing > > > >> > >> >> >>> > >> > > >> > eco-system. > > > >> > >> >> >>> > >> > > >> > > > > > > > > >> > >> >> >>> > >> > > >> > > > > > As many other systems use > > String > > > >> based > > > >> > >> >> headers > > > >> > >> >> >>> > >> (Flume, > > > >> > >> >> >>> > >> > JMS) > > > >> > >> >> >>> > >> > > it > > > >> > >> >> >>> > >> > > >> > makes > > > >> > >> >> >>> > >> > > >> > > > it > > > >> > >> >> >>> > >> > > >> > > > > > much easier for these to > be > > > >> > >> >> >>> > incorporated/integrated > > > >> > >> >> >>> > >> > into. > > > >> > >> >> >>> > >> > > >> > > > > > > > > >> > >> >> >>> > >> > > >> > > > > > How with Int based > headers > > could > > > we > > > >> > >> provide > > > >> > >> >> a > > > >> > >> >> >>> > >> > way/guidence to > > > >> > >> >> >>> > >> > > >> make > > > >> > >> >> >>> > >> > > >> > > this > > > >> > >> >> >>> > >> > > >> > > > > > integration simple / > easy with > > > >> > transition > > > >> > >> >> flows > > > >> > >> >> >>> > over > > > >> > >> >> >>> > >> to > > > >> > >> >> >>> > >> > > kafka? > > > >> > >> >> >>> > >> > > >> > > > > > > > > >> > >> >> >>> > >> > > >> > > > > > * tough luck buddy > you're on > > your > > > >> own > > > >> > >> >> >>> > >> > > >> > > > > > * simply hash the string > into > > int > > > >> code > > > >> > >> and > > > >> > >> >> hope > > > >> > >> >> >>> > for > > > >> > >> >> >>> > >> no > > > >> > >> >> >>> > >> > > collisions > > > >> > >> >> >>> > >> > > >> > > (how > > > >> > >> >> >>> > >> > > >> > > > to > > > >> > >> >> >>> > >> > > >> > > > > > convert back though?) > > > >> > >> >> >>> > >> > > >> > > > > > * http2 style as > mentioned by > > > nacho. > > > >> > >> >> >>> > >> > > >> > > > > > > > > >> > >> >> >>> > >> > > >> > > > > > cheers, > > > >> > >> >> >>> > >> > > >> > > > > > Mike > > > >> > >> >> >>> > >> > > >> > > > > > > > > >> > >> >> >>> > >> > > >> > > > > > > > > >> > >> >> >>> > >> > > >> > > > > > > ______________________________ > > > >> > __________ > > > >> > >> >> >>> > >> > > >> > > > > > From: radai < > > > >> > radai.rosenbl...@gmail.com> > > > >> > >> >> >>> > >> > > >> > > > > > Sent: Wednesday, > November 9, > > 2016 > > > >> > 8:12 AM > > > >> > >> >> >>> > >> > > >> > > > > > To: dev@kafka.apache.org > > > >> > >> >> >>> > >> > > >> > > > > > Subject: Re: [DISCUSS] > KIP-82 - > > > Add > > > >> > >> Record > > > >> > >> >> >>> Headers > > > >> > >> >> >>> > >> > > >> > > > > > > > > >> > >> >> >>> > >> > > >> > > > > > thinking about it some > more, > > the > > > >> best > > > >> > >> way to > > > >> > >> >> >>> > transmit > > > >> > >> >> >>> > >> > the > > > >> > >> >> >>> > >> > > header > > > >> > >> >> >>> > >> > > >> > > > > remapping > > > >> > >> >> >>> > >> > > >> > > > > > data to consumers would > be to > > > put it > > > >> > in > > > >> > >> the > > > >> > >> >> MD > > > >> > >> >> >>> > >> response > > > >> > >> >> >>> > >> > > payload, > > > >> > >> >> >>> > >> > > >> so > > > >> > >> >> >>> > >> > > >> > > > maybe > > > >> > >> >> >>> > >> > > >> > > > > > it should be discussed > now. > > > >> > >> >> >>> > >> > > >> > > > > > > > > >> > >> >> >>> > >> > > >> > > > > > > > > >> > >> >> >>> > >> > > >> > > > > > On Wed, Nov 9, 2016 at > 12:09 > > AM, > > > >> > radai < > > > >> > >> >> >>> > >> > > >> radai.rosenbl...@gmail.com > > > >> > >> >> >>> > >> > > >> > > > > > >> > >> >> >>> > >> > > >> > > > > wrote: > > > >> > >> >> >>> > >> > > >> > > > > > > > > >> > >> >> >>> > >> > > >> > > > > > > im not opposed to the > idea of > > > >> > namespace > > > >> > >> >> >>> mapping. > > > >> > >> >> >>> > >> all > > > >> > >> >> >>> > >> > im > > > >> > >> >> >>> > >> > > saying > > > >> > >> >> >>> > >> > > >> is > > > >> > >> >> >>> > >> > > >> > > > that > > > >> > >> >> >>> > >> > > >> > > > > > its > > > >> > >> >> >>> > >> > > >> > > > > > > not part of the "mvp" > and, > > > since > > > >> it > > > >> > >> >> requires > > > >> > >> >> >>> no > > > >> > >> >> >>> > >> wire > > > >> > >> >> >>> > >> > format > > > >> > >> >> >>> > >> > > >> > change, > > > >> > >> >> >>> > >> > > >> > > > can > > > >> > >> >> >>> > >> > > >> > > > > > > always be added later. > > > >> > >> >> >>> > >> > > >> > > > > > > also, its not as > simple as > > just > > > >> > >> >> configuring > > > >> > >> >> >>> MM > > > >> > >> >> >>> > to > > > >> > >> >> >>> > >> do > > > >> > >> >> >>> > >> > the > > > >> > >> >> >>> > >> > > >> > transform: > > > >> > >> >> >>> > >> > > >> > > > > lets > > > >> > >> >> >>> > >> > > >> > > > > > > say i've implemented > large > > > message > > > >> > >> >> support as > > > >> > >> >> >>> > >> > {666,1} and > > > >> > >> >> >>> > >> > > on > > > >> > >> >> >>> > >> > > >> some > > > >> > >> >> >>> > >> > > >> > > > > mirror > > > >> > >> >> >>> > >> > > >> > > > > > > target cluster its been > > > remapped > > > >> to > > > >> > >> >> {999,1}. > > > >> > >> >> >>> the > > > >> > >> >> >>> > >> > consumer > > > >> > >> >> >>> > >> > > >> plugin > > > >> > >> >> >>> > >> > > >> > > code > > > >> > >> >> >>> > >> > > >> > > > > > would > > > >> > >> >> >>> > >> > > >> > > > > > > also need to be told > to look > > > for > > > >> the > > > >> > >> large > > > >> > >> >> >>> > message > > > >> > >> >> >>> > >> > "part X > > > >> > >> >> >>> > >> > > of > > > >> > >> >> >>> > >> > > >> Y" > > > >> > >> >> >>> > >> > > >> > > > header > > > >> > >> >> >>> > >> > > >> > > > > > > under {999,1}. doable, > but > > > tricky. > > > >> > >> >> >>> > >> > > >> > > > > > > > > > >> > >> >> >>> > >> > > >> > > > > > > On Tue, Nov 8, 2016 at > 10:29 > > > PM, > > > >> > Gwen > > > >> > >> >> >>> Shapira < > > > >> > >> >> >>> > >> > > >> g...@confluent.io > > > >> > >> >> >>> > >> > > >> > > > > > >> > >> >> >>> > >> > > >> > > > > wrote: > > > >> > >> >> >>> > >> > > >> > > > > > > > > > >> > >> >> >>> > >> > > >> > > > > > >> While you can do > whatever > > you > > > >> want > > > >> > >> with a > > > >> > >> >> >>> > >> namespace > > > >> > >> >> >>> > >> > and > > > >> > >> >> >>> > >> > > your > > > >> > >> >> >>> > >> > > >> > code, > > > >> > >> >> >>> > >> > > >> > > > > > >> what I'd expect is > for each > > > app > > > >> to > > > >> > >> >> >>> namespaces > > > >> > >> >> >>> > >> > > configurable... > > > >> > >> >> >>> > >> > > >> > > > > > >> > > > >> > >> >> >>> > >> > > >> > > > > > >> So if I accidentally > used > > 666 > > > for > > > >> > my > > > >> > >> HR > > > >> > >> >> >>> > >> department, > > > >> > >> >> >>> > >> > and > > > >> > >> >> >>> > >> > > still > > > >> > >> >> >>> > >> > > >> > want > > > >> > >> >> >>> > >> > > >> > > > to > > > >> > >> >> >>> > >> > > >> > > > > > >> run RadaiApp, I can > config > > > >> > >> "namespace=42" > > > >> > >> >> >>> for > > > >> > >> >> >>> > >> > RadaiApp and > > > >> > >> >> >>> > >> > > >> > > > everything > > > >> > >> >> >>> > >> > > >> > > > > > >> will look normal. > > > >> > >> >> >>> > >> > > >> > > > > > >> > > > >> > >> >> >>> > >> > > >> > > > > > >> This means you only > need to > > > sync > > > >> > usage > > > >> > >> >> >>> inside > > > >> > >> >> >>> > your > > > >> > >> >> >>> > >> > own > > > >> > >> >> >>> > >> > > >> > > organization. > > > >> > >> >> >>> > >> > > >> > > > > > >> Still hard, but > somewhat > > > easier > > > >> > than > > > >> > >> >> syncing > > > >> > >> >> >>> > with > > > >> > >> >> >>> > >> > the > > > >> > >> >> >>> > >> > > entire > > > >> > >> >> >>> > >> > > >> > > world. > > > >> > >> >> >>> > >> > > >> > > > > > >> > > > >> > >> >> >>> > >> > > >> > > > > > >> On Tue, Nov 8, 2016 > at 10:07 > > > PM, > > > >> > >> radai < > > > >> > >> >> >>> > >> > > >> > > radai.rosenbl...@gmail.com> > > > >> > >> >> >>> > >> > > >> > > > > > >> wrote: > > > >> > >> >> >>> > >> > > >> > > > > > >> > and we can start > with > > > >> {namespace, > > > >> > >> id} > > > >> > >> >> and > > > >> > >> >> >>> no > > > >> > >> >> >>> > >> > re-mapping > > > >> > >> >> >>> > >> > > >> > support > > > >> > >> >> >>> > >> > > >> > > > and > > > >> > >> >> >>> > >> > > >> > > > > > >> always > > > >> > >> >> >>> > >> > > >> > > > > > >> > add it later on > if/when > > > >> > collisions > > > >> > >> >> >>> actually > > > >> > >> >> >>> > >> > happen (i > > > >> > >> >> >>> > >> > > dont > > > >> > >> >> >>> > >> > > >> > think > > > >> > >> >> >>> > >> > > >> > > > > > they'd > > > >> > >> >> >>> > >> > > >> > > > > > >> be > > > >> > >> >> >>> > >> > > >> > > > > > >> > a problem). > > > >> > >> >> >>> > >> > > >> > > > > > >> > > > > >> > >> >> >>> > >> > > >> > > > > > >> > every interested > party (so > > > orgs > > > >> > or > > > >> > >> >> >>> > individuals) > > > >> > >> >> >>> > >> > could > > > >> > >> >> >>> > >> > > then > > > >> > >> >> >>> > >> > > >> > > > register > > > >> > >> >> >>> > >> > > >> > > > > a > > > >> > >> >> >>> > >> > > >> > > > > > >> > prefix (0 = > reserved, 1 = > > > >> > confluent > > > >> > >> ... > > > >> > >> >> >>> 666 > > > >> > >> >> >>> > = me > > > >> > >> >> >>> > >> > :-) ) > > > >> > >> >> >>> > >> > > and > > > >> > >> >> >>> > >> > > >> do > > > >> > >> >> >>> > >> > > >> > > > > whatever > > > >> > >> >> >>> > >> > > >> > > > > > >> with > > > >> > >> >> >>> > >> > > >> > > > > > >> > the 2nd ID - so once > > > linkedin > > > >> > >> >> registers, > > > >> > >> >> >>> say > > > >> > >> >> >>> > 3, > > > >> > >> >> >>> > >> > then > > > >> > >> >> >>> > >> > > >> linkedin > > > >> > >> >> >>> > >> > > >> > > devs > > > >> > >> >> >>> > >> > > >> > > > > are > > > >> > >> >> >>> > >> > > >> > > > > > >> free > > > >> > >> >> >>> > >> > > >> > > > > > >> > to use {3, *} with a > > > reasonable > > > >> > >> >> >>> expectation > > > >> > >> >> >>> > to > > > >> > >> >> >>> > >> to > > > >> > >> >> >>> > >> > > collide > > > >> > >> >> >>> > >> > > >> with > > > >> > >> >> >>> > >> > > >> > > > > > anything > > > >> > >> >> >>> > >> > > >> > > > > > >> > else. further > partitioning > > > of > > > >> > that * > > > >> > >> >> >>> becomes > > > >> > >> >> >>> > >> > linkedin's > > > >> > >> >> >>> > >> > > >> > problem, > > > >> > >> >> >>> > >> > > >> > > > but > > > >> > >> >> >>> > >> > > >> > > > > > the > > > >> > >> >> >>> > >> > > >> > > > > > >> > "upstream > registration" > > of a > > > >> > >> namespace > > > >> > >> >> >>> only > > > >> > >> >> >>> > has > > > >> > >> >> >>> > >> to > > > >> > >> >> >>> > >> > > happen > > > >> > >> >> >>> > >> > > >> > once. > > > >> > >> >> >>> > >> > > >> > > > > > >> > > > > >> > >> >> >>> > >> > > >> > > > > > >> > On Tue, Nov 8, 2016 > at > > 9:03 > > > PM, > > > >> > >> James > > > >> > >> >> >>> Cheng < > > > >> > >> >> >>> > >> > > >> > > wushuja...@gmail.com > > > >> > >> >> >>> > >> > > >> > > > > > > > >> > >> >> >>> > >> > > >> > > > > > >> wrote: > > > >> > >> >> >>> > >> > > >> > > > > > >> > > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > On Nov 8, 2016, > at 5:54 > > > PM, > > > >> > Gwen > > > >> > >> >> >>> Shapira < > > > >> > >> >> >>> > >> > > >> > g...@confluent.io> > > > >> > >> >> >>> > >> > > >> > > > > > wrote: > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > Thank you so > much for > > > this > > > >> > clear > > > >> > >> and > > > >> > >> >> >>> fair > > > >> > >> >> >>> > >> > summary of > > > >> > >> >> >>> > >> > > the > > > >> > >> >> >>> > >> > > >> > > > > arguments. > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > I'm in favor of > ints. > > > Not a > > > >> > >> >> >>> deal-breaker, > > > >> > >> >> >>> > but > > > >> > >> >> >>> > >> > in > > > >> > >> >> >>> > >> > > favor. > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > Even more in > favor of > > > >> Magnus's > > > >> > >> >> >>> > decentralized > > > >> > >> >> >>> > >> > > suggestion > > > >> > >> >> >>> > >> > > >> > with > > > >> > >> >> >>> > >> > > >> > > > > > Roger's > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > tweak: add a > namespace > > > for > > > >> > >> headers. > > > >> > >> >> >>> This > > > >> > >> >> >>> > will > > > >> > >> >> >>> > >> > allow > > > >> > >> >> >>> > >> > > each > > > >> > >> >> >>> > >> > > >> > app > > > >> > >> >> >>> > >> > > >> > > to > > > >> > >> >> >>> > >> > > >> > > > > > just > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > use whatever IDs > it > > wants > > > >> > >> >> internally, > > > >> > >> >> >>> and > > > >> > >> >> >>> > >> then > > > >> > >> >> >>> > >> > let > > > >> > >> >> >>> > >> > > the > > > >> > >> >> >>> > >> > > >> > admin > > > >> > >> >> >>> > >> > > >> > > > > > >> deploying > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > the app figure > out an > > > >> > available > > > >> > >> >> >>> namespace > > > >> > >> >> >>> > ID > > > >> > >> >> >>> > >> > for the > > > >> > >> >> >>> > >> > > app > > > >> > >> >> >>> > >> > > >> to > > > >> > >> >> >>> > >> > > >> > > > live > > > >> > >> >> >>> > >> > > >> > > > > > in. > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > So > > > >> > io.confluent.schema-registry > > > >> > >> can > > > >> > >> >> be > > > >> > >> >> >>> > >> > namespace > > > >> > >> >> >>> > >> > > 0x01 on > > > >> > >> >> >>> > >> > > >> my > > > >> > >> >> >>> > >> > > >> > > > > > >> deployment > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > and 0x57 on > yours, and > > > the > > > >> > poor > > > >> > >> guys > > > >> > >> >> >>> > >> > developing the > > > >> > >> >> >>> > >> > > app > > > >> > >> >> >>> > >> > > >> > don't > > > >> > >> >> >>> > >> > > >> > > > > need > > > >> > >> >> >>> > >> > > >> > > > > > to > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > worry about that. > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > > > >> > >> >> >>> > >> > > >> > > > > > >> >> Gwen, if I > understand > > your > > > >> > example > > > >> > >> >> >>> right, an > > > >> > >> >> >>> > >> > > application > > > >> > >> >> >>> > >> > > >> > > deployer > > > >> > >> >> >>> > >> > > >> > > > > > might > > > >> > >> >> >>> > >> > > >> > > > > > >> >> decide to use 0x01 > in one > > > >> > >> deployment, > > > >> > >> >> and > > > >> > >> >> >>> > that > > > >> > >> >> >>> > >> > means > > > >> > >> >> >>> > >> > > that > > > >> > >> >> >>> > >> > > >> > once > > > >> > >> >> >>> > >> > > >> > > > the > > > >> > >> >> >>> > >> > > >> > > > > > >> message > > > >> > >> >> >>> > >> > > >> > > > > > >> >> is written into the > > > broker, it > > > >> > >> will be > > > >> > >> >> >>> > saved on > > > >> > >> >> >>> > >> > the > > > >> > >> >> >>> > >> > > broker > > > >> > >> >> >>> > >> > > >> > with > > > >> > >> >> >>> > >> > > >> > > > > that > > > >> > >> >> >>> > >> > > >> > > > > > >> >> specific namespace > > (0x01). > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > > > >> > >> >> >>> > >> > > >> > > > > > >> >> If you were to > mirror > > that > > > >> > message > > > >> > >> >> into > > > >> > >> >> >>> > another > > > >> > >> >> >>> > >> > > cluster, > > > >> > >> >> >>> > >> > > >> the > > > >> > >> >> >>> > >> > > >> > > 0x01 > > > >> > >> >> >>> > >> > > >> > > > > > would > > > >> > >> >> >>> > >> > > >> > > > > > >> >> accompany the > message, > > > right? > > > >> > What > > > >> > >> if > > > >> > >> >> the > > > >> > >> >> >>> > >> > deployers of > > > >> > >> >> >>> > >> > > the > > > >> > >> >> >>> > >> > > >> > same > > > >> > >> >> >>> > >> > > >> > > > app > > > >> > >> >> >>> > >> > > >> > > > > > in > > > >> > >> >> >>> > >> > > >> > > > > > >> the > > > >> > >> >> >>> > >> > > >> > > > > > >> >> other cluster uses > 0x57? > > > They > > > >> > won't > > > >> > >> >> >>> > understand > > > >> > >> >> >>> > >> > each > > > >> > >> >> >>> > >> > > other? > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > > > >> > >> >> >>> > >> > > >> > > > > > >> >> I'm not sure > that's an > > > >> avoidable > > > >> > >> >> >>> problem. I > > > >> > >> >> >>> > >> > think it > > > >> > >> >> >>> > >> > > simply > > > >> > >> >> >>> > >> > > >> > > means > > > >> > >> >> >>> > >> > > >> > > > > > that > > > >> > >> >> >>> > >> > > >> > > > > > >> in > > > >> > >> >> >>> > >> > > >> > > > > > >> >> order to share > data, you > > > have > > > >> to > > > >> > >> also > > > >> > >> >> >>> have a > > > >> > >> >> >>> > >> > shared > > > >> > >> >> >>> > >> > > (agreed > > > >> > >> >> >>> > >> > > >> > > upon) > > > >> > >> >> >>> > >> > > >> > > > > > >> >> understanding of > what the > > > >> > >> namespaces > > > >> > >> >> >>> mean. > > > >> > >> >> >>> > >> Which > > > >> > >> >> >>> > >> > I > > > >> > >> >> >>> > >> > > think > > > >> > >> >> >>> > >> > > >> > makes > > > >> > >> >> >>> > >> > > >> > > > > sense, > > > >> > >> >> >>> > >> > > >> > > > > > >> >> because the > alternate > > > (sharing > > > >> > >> >> *nothing* > > > >> > >> >> >>> at > > > >> > >> >> >>> > >> all) > > > >> > >> >> >>> > >> > would > > > >> > >> >> >>> > >> > > mean > > > >> > >> >> >>> > >> > > >> > > that > > > >> > >> >> >>> > >> > > >> > > > > > there > > > >> > >> >> >>> > >> > > >> > > > > > >> >> would be no way to > > > understand > > > >> > each > > > >> > >> >> other. > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > > > >> > >> >> >>> > >> > > >> > > > > > >> >> -James > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > Gwen > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > > > > >> > >> >> >>> > >> > > >> > > > > > >> >> > On Tue, Nov 8, > 2016 at > > > 4:23 > > > >> > PM, > > > >> > >> >> radai < > > > >> > >> >> >>> > >> > > >> > > > > radai.rosenbl...@gmail.com > > > > > >> > >> >> >>> > >> > > >> > > > > > >> >> wrote: > > > >> > >> >> >>> > >> > > >> > > > > > >> >> >> +1 for sean's > > document. > > > it > > > >> > >> covers > > > >> > >> >> >>> pretty > > > >> > >> >> >>> > >> much > > > >> > >> >> >>> > >> > all > > > >> > >> >> >>> > >> > > the > > > >> > >> >> >>> > >> > > >> > > > trade-offs > > > >> > >> >> >>> > >> > > >> > > > > > and > > > >> > >> >> >>> > >> > > >> > > > > > >> >> >> provides > concrete > > > figures > > > >> to > > > >> > >> argue > > > >> > >> >> >>> about > > > >> > >> >> >>> > :-) > > > >> > >> >> >>> > >> > > >> > > > > > >> >> >> (nit-picking - > used > > the > > > >> same > > > >> > >> xkcd > > > >> > >> >> >>> twice, > > > >> > >> >> >>> > >> also > > > >> > >> >> >>> > >> > trove > > > >> > >> >> >>> > >> > > has > > > >> > >> >> >>> > >> > > >> > been > > > >> > >> >> >>> > >> > > >> > > > > > >> superceded > > > >> > >> > > > > >> > > > > >> > > > > >> > > > > >> > -- > > > >> > Gwen Shapira > > > >> > Product Manager | Confluent > > > >> > 650.450.2760 | @gwenshap > > > >> > Follow us: Twitter | blog > > > >> > > > > >> > > > >> > > > >> > > > >> -- > > > >> *Todd Palino* > > > >> Staff Site Reliability Engineer > > > >> Data Infrastructure Streaming > > > >> > > > >> > > > >> > > > >> linkedin.com/in/toddpalino > > > >> > > > > > > > > > > > > -- > > > Gwen Shapira > > > Product Manager | Confluent > > > 650.450.2760 | @gwenshap > > > Follow us: Twitter | blog > > > > > > > > The information contained in this email is strictly confidential and for > the use of the addressee only, unless otherwise indicated. If you are not > the intended recipient, please do not read, copy, use or disclose to others > this message or any attachment. Please also notify the sender by replying > to this email or by telephone (+44(020 7896 0011) and then delete the email > and any copies of it. Opinions, conclusion (etc) that do not relate to the > official business of this company shall be understood as neither given nor > endorsed by it. IG is a trading name of IG Markets Limited (a company > registered in England and Wales, company number 04008957) and IG Index > Limited (a company registered in England and Wales, company number > 01190902). Registered address at Cannon Bridge House, 25 Dowgate Hill, > London EC4R 2YA. Both IG Markets Limited (register number 195355) and IG > Index Limited (register number 114059) are authorised and regulated by the > Financial Conduct Authority. >
