This is a minor point Robert Burke but having access to the "stream" when decoding/encoding could mean that your reading/writing from the underlying transport channel directly and not needing to copy the bytes into/from memory.
On Wed, Apr 10, 2019 at 3:45 PM Kenneth Knowles <k...@apache.org> wrote: > On Mon, Apr 8, 2019 at 4:03 PM Robert Bradshaw <rober...@google.com> > wrote: > >> This email is already very long, but in summary I think the right >> answer is to just get rid of Outer altogether (except possibly for >> IOs, which we'd only preserve for legacy reasons until 3.0). >> >> - Robert >> > > I had forgotten that compatibility from legacy to portable pipelines is > not a concern. So, can this be made into a plan? Would it start from this > point: > > - Java classes have to exist as-is from a user's point of view, for > compatibility > - Portable pipelines should include only self-delimiting encodings (tiny > primitives do not require length prefix, large iterables get special > treatment) > - When creating a Coder from a portable proto, instantiate one that is > fixed to the Inner context > > I would skip having known relationship between a coder and a > self-delimiting variant. > > Kenn > > >> >> >> > On Fri, Apr 5, 2019 at 12:38 AM Robert Bradshaw < >> rober...@google.com> wrote: >> >> >> >> >> >> >> >> On Fri, Apr 5, 2019 at 12:50 AM Heejong Lee <heej...@google.com> >> wrote: >> >> >> >> > >> >> >> >> > Robert, does nested/unnested context work properly for Java? >> >> >> >> >> >> >> >> I believe so. It is similar to the bytes coder, that prefixes >> vs. not >> >> >> >> based on the context. >> >> >> >> >> >> >> >> > I can see that the Context is fixed to NESTED[1] and the >> encode method with the Context parameter is marked as deprecated[2]. >> >> >> >> > >> >> >> >> > [1]: >> https://github.com/apache/beam/blob/0868e7544fd1e96db67ff5b9e70a67802c0f0c8e/sdks/java/core/src/main/java/org/apache/beam/sdk/coders/StringUtf8Coder.java#L68 >> >> >> >> > [2]: >> https://github.com/apache/beam/blob/0868e7544fd1e96db67ff5b9e70a67802c0f0c8e/sdks/java/core/src/main/java/org/apache/beam/sdk/coders/Coder.java#L132 >> >> >> >> >> >> >> >> That doesn't mean it's unused, e.g. >> >> >> >> >> >> >> >> >> https://github.com/apache/beam/blob/release-2.12.0/sdks/java/core/src/main/java/org/apache/beam/sdk/util/CoderUtils.java#L160 >> >> >> >> >> https://github.com/apache/beam/blob/release-2.12.0/sdks/java/core/src/main/java/org/apache/beam/sdk/coders/LengthPrefixCoder.java#L64 >> >> >> >> >> >> >> >> (and I'm sure there's others). >> >> >> >> >> >> >> >> > On Thu, Apr 4, 2019 at 3:25 PM Robert Bradshaw < >> rober...@google.com> wrote: >> >> >> >> >> >> >> >> >> >> I don't know why there are two separate copies of >> >> >> >> >> standard_coders.yaml--originally there was just one (though >> it did >> >> >> >> >> live in the Python directory). I'm guessing a copy was made >> rather >> >> >> >> >> than just pointing both to the new location, but that >> completely >> >> >> >> >> defeats the point. I can't seem to access JIRA right now; >> could >> >> >> >> >> someone file an issue to resolve this? >> >> >> >> >> >> >> >> >> >> I also think the spec should be next to the definition of the >> URN, >> >> >> >> >> that's one of the reason the URNs were originally in a >> markdown file >> >> >> >> >> (to encourage good documentation, literate programming >> style). Many >> >> >> >> >> coders already have their specs there. >> >> >> >> >> >> >> >> >> >> Regarding backwards compatibility, we can't change existing >> coders, >> >> >> >> >> and making new coders won't help with inference ('cause >> changing that >> >> >> >> >> would also be backwards incompatible). Fortunately, I think >> we're >> >> >> >> >> already doing the consistent thing here: In both Python and >> Java the >> >> >> >> >> raw UTF-8 encoded bytes are encoded when used in an >> *unnested* context >> >> >> >> >> and the length-prefixed UTF-8 encoded bytes are used when the >> coder is >> >> >> >> >> used in a *nested* context. >> >> >> >> >> >> >> >> >> >> I'd really like to see the whole nested/unnested context go >> away, but >> >> >> >> >> that'll probably require Beam 3.0; it causes way more >> confusion than >> >> >> >> >> the couple of bytes it saves in a couple of places. >> >> >> >> >> >> >> >> >> >> - Robert >> >> >> >> >> >> >> >> >> >> On Thu, Apr 4, 2019 at 10:55 PM Robert Burke < >> rob...@frantil.com> wrote: >> >> >> >> >> > >> >> >> >> >> > My 2cents is that the "Textual description" should be part >> of the documentation of the URNs on the Proto messages, since that's the >> common place. I've added a short description for the varints for example, >> and we already have lenghthier format & protocol descriptions there for >> iterables and similar. >> >> >> >> >> > >> >> >> >> >> > The proto [1] *can be* the spec if we want it to be. >> >> >> >> >> > >> >> >> >> >> > [1]: >> https://github.com/apache/beam/blob/069fc3de95bd96f34c363308ad9ba988ab58502d/model/pipeline/src/main/proto/beam_runner_api.proto#L557 >> >> >> >> >> > >> >> >> >> >> > On Thu, 4 Apr 2019 at 13:51, Kenneth Knowles < >> k...@apache.org> wrote: >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> On Thu, Apr 4, 2019 at 1:49 PM Robert Burke < >> rob...@frantil.com> wrote: >> >> >> >> >> >>> >> >> >> >> >> >>> We should probably move the "java" version of the yaml >> file [1] to a common location rather than deep in the java hierarchy, or >> copying it for Go and Python, but that can be a separate task. It's >> probably non-trivial since it looks like it's part of a java resources >> structure. >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> Seems like /model is a good place for this if we don't >> want to invent a new language-independent hierarchy. >> >> >> >> >> >> >> >> >> >> >> >> Kenn >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >> >>> >> >> >> >> >> >>> Luke, the Go SDK doesn't currently do this validation, >> but it shouldn't be difficult, given pointers to the Java and Python >> variants of the tests to crib from [2]. Care would need to be taken so that >> Beam Go SDK users (such as they are) aren't forced to run them, and not >> have the yaml file to read. I'd suggest putting it with the integration >> tests [3]. >> >> >> >> >> >>> >> >> >> >> >> >>> I've filed a JIRA (BEAM-7009) for tracking this Go SDK >> side work. [4] >> >> >> >> >> >>> >> >> >> >> >> >>> 1: >> https://github.com/apache/beam/blob/master/model/fn-execution/src/main/resources/org/apache/beam/model/fnexecution/v1/standard_coders.yaml >> >> >> >> >> >>> 2: >> https://github.com/apache/beam/search?q=standard_coders.yaml&unscoped_q=standard_coders.yaml >> >> >> >> >> >>> 3: >> https://github.com/apache/beam/tree/master/sdks/go/test >> >> >> >> >> >>> 4: https://issues.apache.org/jira/browse/BEAM-7009 >> >> >> >> >> >>> >> >> >> >> >> >>> >> >> >> >> >> >>> On Thu, 4 Apr 2019 at 13:28, Lukasz Cwik < >> lc...@google.com> wrote: >> >> >> >> >> >>>> >> >> >> >> >> >>>> >> >> >> >> >> >>>> >> >> >> >> >> >>>> On Thu, Apr 4, 2019 at 1:15 PM Chamikara Jayalath < >> chamik...@google.com> wrote: >> >> >> >> >> >>>>> >> >> >> >> >> >>>>> >> >> >> >> >> >>>>> >> >> >> >> >> >>>>> On Thu, Apr 4, 2019 at 12:15 PM Lukasz Cwik < >> lc...@google.com> wrote: >> >> >> >> >> >>>>>> >> >> >> >> >> >>>>>> standard_coders.yaml[1] is where we are currently >> defining these formats. >> >> >> >> >> >>>>>> Unfortunately the Python SDK has its own copy[2]. >> >> >> >> >> >>>>> >> >> >> >> >> >>>>> >> >> >> >> >> >>>>> Ah great. Thanks for the pointer. Any idea why there's >> a separate copy for Python ? I didn't see a significant difference in >> definitions looking at few random coders there but I might have missed >> something. If there's no reason to maintain two, we should probably unify. >> >> >> >> >> >>>>> Also, seems like we haven't added the definition for >> UTF-8 coder yet. >> >> >> >> >> >>>>> >> >> >> >> >> >>>> >> >> >> >> >> >>>> Not certain as well. I did notice the timer coder >> definition didn't exist in the Python copy. >> >> >> >> >> >>>> >> >> >> >> >> >>>>>> >> >> >> >> >> >>>>>> >> >> >> >> >> >>>>>> Here is an example PR[3] that adds the >> "beam:coder:double:v1" as tests to the Java and Python SDKs to ensure >> interoperability. >> >> >> >> >> >>>>>> >> >> >> >> >> >>>>>> Robert Burke, does the Go SDK have a test where it >> uses standard_coders.yaml and runs compatibility tests? >> >> >> >> >> >>>>>> >> >> >> >> >> >>>>>> Chamikara, creating new coder classes is a pain since >> the type -> coder mapping per SDK language would select the non-well known >> type if we added a new one to a language. If we swapped the default >> type->coder mapping, this would still break update for pipelines forcing >> users to update their code to select the non-well known type. If we don't >> change the default type->coder mapping, the well known coder will gain >> little usage. I think we should fix the Python coder to use the same >> encoding as Java for UTF-8 strings before there are too many Python SDK >> users. >> >> >> >> >> >>>>> >> >> >> >> >> >>>>> >> >> >> >> >> >>>>> I was thinking that may be we should just change the >> default UTF-8 coder for Fn API path which is experimental. Updating Python >> to do what's done for Java is fine if we agree that encoding used for Java >> should be the standard. >> >> >> >> >> >>>>> >> >> >> >> >> >>>> >> >> >> >> >> >>>> That is a good idea to use the Fn API experiment to >> control which gets selected. >> >> >> >> >> >>>> >> >> >> >> >> >>>>>> >> >> >> >> >> >>>>>> >> >> >> >> >> >>>>>> 1: >> https://github.com/apache/beam/blob/master/model/fn-execution/src/main/resources/org/apache/beam/model/fnexecution/v1/standard_coders.yaml >> >> >> >> >> >>>>>> 2: >> https://github.com/apache/beam/blob/master/sdks/python/apache_beam/testing/data/standard_coders.yaml >> >> >> >> >> >>>>>> 3: https://github.com/apache/beam/pull/8205 >> >> >> >> >> >>>>>> >> >> >> >> >> >>>>>> On Thu, Apr 4, 2019 at 11:50 AM Chamikara Jayalath < >> chamik...@google.com> wrote: >> >> >> >> >> >>>>>>> >> >> >> >> >> >>>>>>> >> >> >> >> >> >>>>>>> >> >> >> >> >> >>>>>>> On Thu, Apr 4, 2019 at 11:29 AM Robert Bradshaw < >> rober...@google.com> wrote: >> >> >> >> >> >>>>>>>> >> >> >> >> >> >>>>>>>> A URN defines the encoding. >> >> >> >> >> >>>>>>>> >> >> >> >> >> >>>>>>>> There are (unfortunately) *two* encodings defined >> for a Coder (defined >> >> >> >> >> >>>>>>>> by a URN), the nested and the unnested one. IIRC, in >> both Java and >> >> >> >> >> >>>>>>>> Python, the nested one prefixes with a var-int >> length, and the >> >> >> >> >> >>>>>>>> unnested one does not. >> >> >> >> >> >>>>>>> >> >> >> >> >> >>>>>>> >> >> >> >> >> >>>>>>> Could you clarify where we define the exact encoding >> ? I only see a URN for UTF-8 [1] while if you look at the implementations >> Java includes length in the encoding [1] while Python [1] does not. >> >> >> >> >> >>>>>>> >> >> >> >> >> >>>>>>> [1] >> https://github.com/apache/beam/blob/069fc3de95bd96f34c363308ad9ba988ab58502d/model/pipeline/src/main/proto/beam_runner_api.proto#L563 >> >> >> >> >> >>>>>>> [2] >> https://github.com/apache/beam/blob/master/sdks/java/core/src/main/java/org/apache/beam/sdk/coders/StringUtf8Coder.java#L50 >> >> >> >> >> >>>>>>> [3] >> https://github.com/apache/beam/blob/master/sdks/python/apache_beam/coders/coders.py#L321 >> >> >> >> >> >>>>>>> >> >> >> >> >> >>>>>>> >> >> >> >> >> >>>>>>>> >> >> >> >> >> >>>>>>>> >> >> >> >> >> >>>>>>>> We should define the spec clearly and have >> cross-language tests. >> >> >> >> >> >>>>>>> >> >> >> >> >> >>>>>>> >> >> >> >> >> >>>>>>> +1 >> >> >> >> >> >>>>>>> >> >> >> >> >> >>>>>>> Regarding backwards compatibility, I agree that we >> should probably not update existing coder classes. Probably we should just >> standardize the correct encoding (may be as a comment near corresponding >> URN in the beam_runner_api.proto ?) and create new coder classes as needed. >> >> >> >> >> >>>>>>> >> >> >> >> >> >>>>>>>> >> >> >> >> >> >>>>>>>> >> >> >> >> >> >>>>>>>> On Thu, Apr 4, 2019 at 8:13 PM Pablo Estrada < >> pabl...@google.com> wrote: >> >> >> >> >> >>>>>>>> > >> >> >> >> >> >>>>>>>> > Could this be a backwards-incompatible change that >> would break pipelines from upgrading? If they have data in-flight in >> between operators, and we change the coder, they would break? >> >> >> >> >> >>>>>>>> > I know very little about coders, but since nobody >> has mentioned it, I wanted to make sure we have it in mind. >> >> >> >> >> >>>>>>>> > -P. >> >> >> >> >> >>>>>>>> > >> >> >> >> >> >>>>>>>> > On Wed, Apr 3, 2019 at 8:33 PM Kenneth Knowles < >> k...@apache.org> wrote: >> >> >> >> >> >>>>>>>> >> >> >> >> >> >> >>>>>>>> >> Agree that a coder URN defines the encoding. I >> see that string UTF-8 was added to the proto enum, but it needs a written >> spec of the encoding. Ideally some test data that different languages can >> use to drive compliance testing. >> >> >> >> >> >>>>>>>> >> >> >> >> >> >> >>>>>>>> >> Kenn >> >> >> >> >> >>>>>>>> >> >> >> >> >> >> >>>>>>>> >> On Wed, Apr 3, 2019 at 6:21 PM Robert Burke < >> rob...@frantil.com> wrote: >> >> >> >> >> >>>>>>>> >>> >> >> >> >> >> >>>>>>>> >>> String UTF8 was recently added as a "standard >> coder " URN in the protos, but I don't think that developed beyond Java, so >> adding it to Python would be reasonable in my opinion. >> >> >> >> >> >>>>>>>> >>> >> >> >> >> >> >>>>>>>> >>> The Go SDK handles Strings as "custom coders" >> presently which for Go are always length prefixed (and reported to the >> Runner as LP+CustomCoder). It would be straight forward to add the correct >> handling for strings, as Go natively treats strings as UTF8. >> >> >> >> >> >>>>>>>> >>> >> >> >> >> >> >>>>>>>> >>> >> >> >> >> >> >>>>>>>> >>> On Wed, Apr 3, 2019, 5:03 PM Heejong Lee < >> heej...@google.com> wrote: >> >> >> >> >> >>>>>>>> >>>> >> >> >> >> >> >>>>>>>> >>>> Hi all, >> >> >> >> >> >>>>>>>> >>>> >> >> >> >> >> >>>>>>>> >>>> It looks like UTF-8 String Coder in Java and >> Python SDKs uses different encoding schemes. StringUtf8Coder in Java SDK >> puts the varint length of the input string before actual data bytes however >> StrUtf8Coder in Python SDK directly encodes the input string to bytes >> value. For the last few weeks, I've been testing and fixing cross-language >> IO transforms and this discrepancy is a major blocker for me. IMO, we >> should unify the encoding schemes of UTF8 strings across the different SDKs >> and make it a standard coder. Any thoughts? >> >> >> >> >> >>>>>>>> >>>> >> >> >> >> >> >>>>>>>> >>>> Thanks, >> >
