Re: [protobuf] Re: Streaming Serialization - Suggestion

[Yoav H]

I saw the start\end group but I couldn't find any information on those and 
how to use them.

Your point about skipping fields makes sense.
I think it is also solvable with applying the same idea of chunked 
encoding, even on sub fields.
So instead of writing the full length of the child field, you allow the 
serializer to write it in smaller chunks.
The deserializer can then just read the chunk markings and skip them.
A very basic serializer can put just one chunk (which will be equivalent to 
the current implementation, plus one more zero marking at the end), but it 
allows a more efficient serializer to stream data.

Regarding adding something to the encoding spec, are you allowing proto2 
serializers to call into proto3 deserializers and vice versa?
I thought that if you have a protoX server, you expect clients to take the 
protoX file and generate a client out of it, which will match that proto 
version encoding. Isn't it the case?

Thanks,
Yoav.

On Tuesday, March 29, 2016 at 5:06:46 PM UTC-7, Feng Xiao wrote:
>
>
>
> On Mon, Mar 28, 2016 at 10:53 PM, Yoav H  > wrote:
>
>> They say on their website: "When evaluating new features, we look for 
>> additions that are very widely useful or very simple".
>> What I'm suggesting here is both very useful (speeding up serialization 
>> and eliminating memory duplication) and very simple (simple additions to 
>> the encoding, no need to change the language).
>> So far, no response from the Google guys...
>>
> Actually there are already a "start embedding" tag and a "end embedding" 
> tag in protobuf:
> https://developers.google.com/protocol-buffers/docs/encoding#structure
>
> 3 Start group groups (deprecated)
> 4 End group groups (deprecated)
>
> They are deprecated though.
>
> You mentioned it will be a performance gain, but what we experienced in 
> google says otherwise. For example, in a lot places we are only interested 
> in a few fields and want to skip through all other fields (if we are 
> building a proxy, or the field is simply an unknown field). The start 
> group/end group tag pair forces the parser to decode every single field in 
> the a whole group even the whole group is to be ignored after parsing, and 
> that's a very significant drawback.
>
> And adding a new wire tag type to protobuf is not a simple thing. Actually 
> I don't think we have added any new wire type to protobuf before. There are 
> a lot issues to consider. For example, isn't all code that switch on 
> protobuf wire types now suddenly broken? if a new serializer uses the new 
> wire type in its output, what will happen if the parsers can't understand 
> it?
>
> Proto3 is already finalized and we will not add new wire types in proto3. 
> Whether to add it in proto4 depends on whether we have a good use for it 
> and whether we can mitigate the risks of rolling out a new wire type.
>  
>
>>
>>
>> On Monday, March 28, 2016 at 10:24:17 AM UTC-7, Peter Hultqvist wrote:
>>>
>>> This exact suggestion has been up for discussion long time ago(years?, 
>>> before proto2?)
>>>
>>> When it comes to taking suggestions I'm only a 3rd party implementer but 
>>> my understanding is that the design process of protocol buffers and its 
>>> goals are internal to Google and they usually publish new versions of their 
>>> code implementing new features before you can read about them in the 
>>> documents.
>>> On Mar 27, 2016 5:31 AM, "Yoav H"  wrote:
>>>
 Any comment on this?
 Will you consider this for proto3?

 On Wednesday, March 23, 2016 at 11:50:36 AM UTC-7, Yoav H wrote:
>
> Hi,
>
> I have a suggestion fr improving the protobuf encoding.
> Is proto3 final?
>
> I like the simplicity of the encoding of protobuf.
> But I think it has one issue with serialization, using streams.
> The problem is with length delimited fields and the fact that they 
> require knowing the length ahead of time.
> If we have a very long string, we need to encode the entire string 
> before we know its length, so we basically duplicate the data in memory.
> Same is true for embedded messages, where we need to encode the entire 
> embedded message before we can append it to the stream.
>
> I think there is a simple solution for both issues.
>
> For strings and byte arrays, a simple solution is to use "chunked 
> encoding".
> Which means that the byte array is split into chunks and every chunk 
> starts with the chunk length. End of array is indicated by length zero.
>
> For embedded messages, the solution is to have an "start embedding" 
> tag and an "end embedding tag".
> Everything in between is the embedded message.
>
> By adding these two new features, serialization can be fully 
> streamable and there is no need to pre-serialize big chunks in memory 
> before writing them to the stream.
>
> Hope you'll find this suggestion useful 

[protobuf] Re: Getting the full (on disk) path to an input .proto from plugin

[Horst Noreick]

>
> Hm, I think you may have misunderstood me. GOPATH seems to be some 
> variable to control the paths searched by the Go language compiler
>
> Yes, it's true. I was in  golang context, I looked in the source at 
github. Im not familar with this but i think that rel paths from the file 
descriptor are not useful to detec the fullpath exactly, I have seen that 
you did not handle main()  arguments at first. Dont you get anything you 
need through the args of the main()?. arg[0] should be the command to exec 
your program. and you can get info from getcwd. I havn't wrote a plugin for 
protoc, but i think protoc should pass all arguments to the plugins.  

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[protobuf] Re: Getting the full (on disk) path to an input .proto from plugin

[Elvis Stansvik]

On Wednesday, March 30, 2016 at 2:12:46 AM UTC+2, Horst Noreick wrote:
>
> the compiler uses GOPATH from environment
>

Hm, I think you may have misunderstood me. GOPATH seems to be some variable 
to control the paths searched by the Go language compiler.

What I'm looking for is a way to determine (from the 
google::protobuf::FileDescriptor, or some other API accessible to protobuf 
compiler plugins) the full on-disk path to the directory that is considered 
the "source tree" of the currently processed file, so that I can construct 
the full on-disk path to it. The reason I need this is that my plugin needs 
to open the file to do some ad-hoc parsing of the file.

I don't think GOPATH will give me any of this.

Cheers,
Elvis


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[protobuf] Re: Default Values vs Missing Values

[Zellyn]

protos are also gaining "Well-known Types", some of which are "boxed" 
(Message) versions of the primitive 
types: 
https://developers.google.com/protocol-buffers/docs/reference/google.protobuf

I believe the actual docs on well-known types are currently Google-internal 
:-(

Zellyn


On Saturday, March 26, 2016 at 2:43:00 PM UTC-4, Yoav H wrote:
>
> Hi,
>
> I wanted ask regarding the decision to populate fields with default 
> values, even if they do not appear in the encoded message.
> If I want to send a "patch" message, where I want to update just the 
> provided fields, how can I do that with protobuf (without adding IsXXXSet 
> for every field)?
>
> Why not add another type, representing a default value? 
> So the schematics would be, if the field is missing, it is null, and if 
> the field exists, but with this "missing value" type, it will get the 
> default value?
>
> Thanks,
> Yoav. 
>

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[protobuf] Re: Protobuf - How to create a FileDescriptor object from a Descriptor file

[Jon Skeet]

Currently this isn't supported by the C# protobuf library. There's a Github 
issue for supporting DynamicMessage - which is basically what you'd want - 
here: https://github.com/google/protobuf/issues/658

It's unlikely that we'll be supporting this for the initial GA release, but 
the more we know about your use case, the better our support is likely to 
be when it comes, so please add more context to the issue.

I note that you sent another message suggesting you'd already created an 
Example.cs file - you could compile that dynamically using Roslyn, but 
that's going in a pretty different direction than dynamic messages within 
protobuf.

Jon


On Wednesday, 30 March 2016 06:29:45 UTC+1, Raghu wrote:
>
>
> I created a Descriptor file from Example.proto file using the below 
> command.
>
> .\protoc.exe --proto_path=D:\ExampleProject\ --include_imports 
> D:\ExampleProject\Example.Proto 
> --descriptor_set_out=D:\ExampleProject\Example.pb
>
> We want to read this file and create FileDescriptorSet object in C#. But 
> both FileDescriptorSet and FileDescriptorProto are internal classes.
>
> Please let me know how to create FileDescriptor object from 
> this Example.pb file. 
>
> Note: We want to use C#.
>
> Thanks & Regards
> Raghu
>

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