Create a Protocol Buffer type provider

[forki]

After reading http://blog.ctaggart.com/2012/11/parsing-protocol-buffers-proto-file-in-f.html and @dsyme's Mail about the Protocol Buffer (http://code.google.com/p/protobuf/) stuff I think we should add a Protocol Buffer type provider to FSharpx. Since we have type providers for CSV, JSON and XML I think it would fit very nicely.

Here's what I think we have to do:

• Create a Protocol Buffer serializer in FSharpx.Core
• Create a type provider on top of this parser in FSharpx.TypeProviders.Documents

I asked Cameron if he wants to contribute the parser. If he does we need to find a way to deal with the dependency on FParsec.
Alternatively we could write a new parser. Like what we did with the JSON parser.

What do you guys think?

[ovatsus]

What if we just wrapped Cameron's Froto.Parser and http://code.google.com/p/protobuf-net/ in a type provider? The two dependencies would just apply to the type provider and not to the whole of FSharpx. I don't think there's need to do both a serializer and a parser from scratch. Or at least we could start there and later on replace the two dependencies if we think there's additional benefits in that

[forki]

So we also need protobuf-net?

Maybe we could try this:

• Reference the Froto.Parser via nuget (Apache License, Version 2.0)
• Reference protobuf-net via nuget (Apache License 2.0)
• Wrap both in a type provider
• ILMerge the stuff into one dll and deploy via nuget

Anybody know if the Apache License, Version 2.0 allows this?

[ovatsus]

IANAL, but I think the only requirement of the Apache license is to include the license terms on any derivative work. As FSharpx is already Apache licensed, I don't think anything is required.

[ovatsus]

From http://www.apache.org/legal/3party.html:

Third-party works, in both source and binary form, may be included within Apache products when made available under the following licenses:

• Apache License 2.0
• ASL 1.1
• BSD
• MIT/X11
• NCSA
• W3C Software license
• X.Net
• zlib/libpng

[forki]

mhm. Froto seems to work only with .NET 4.5 and I get MissingMethod exceptions.

[forki]

I created a stub for the protocol buffer type provider in the protobuf branch. This version uses a dictionary to represent the data.

TODO:

• Implement or call a parser in ProtoParser.fs
• Implement or call a serializer/deserializer in ProtoSerializer.fs

[forki]

Here is another idea:

• We could use http://code.google.com/p/protobuf-csharp-port/wiki/GettingStarted by Jon Skeet in order to convert .proto files to C# classes (cs. files)
• Afterwards we run csc on this.

This would probably be much easier.

[ctaggart]

I just pushed code to Froto to fix parsing of that addressbook.proto file from that GettingStarted link. What .NET version do you want it to target? I believe I only used one .NET 4.5 specific call: use sw = new StreamWriter(ms, Encoding.UTF8, 4096, true) // leave stream open

[mausch]

If that's the only .NET 4.5 specific thing, it can be easily simulated in previous versions of .NET with a trivial wrapper: http://stackoverflow.com/a/6784157/21239

[ctaggart]

Thanks! I made Froto.Parser 0.0.0.3 and it now targets .NET 4 Client Profile. Changes: http://code.google.com/p/froto/source/list

Anyone on this, or should it be closed? It's not clear that FSharpx is the right project for this in any case (FSharp.Data may be better, or a new project)