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Welcome to the .NET nanoFramework Protobuf repository

This repository contains the Protobuf library for the .NET nanoFramework. It provides high-performance serialization and deserialization with the smallest possible payload, making it ideal for embedded systems with limited resources.

Build status

Component	Build Status	NuGet Package
nanoFramework.Protobuf

.NET nanoFramework.Protobuf

This library is useful for projects looking to transfer data to or from embedded systems using the .NET nanoFramework. It provides assemblies compiled with .NET nanoFramework and netstandard 2.0, making it usable in both .NET nanoFramework projects and other .NET flavors.

While JSON is a viable option for data transfer, the goal of this library is to provide high-performance serialization and deserialization with the smallest possible payload. This is beneficial given the limited RAM and storage capacity of embedded systems.

The library mimics the principles of Protobuf-net. Many features of protobuf-net are not needed (so far) or do not make sense in the context of .NET nanoFramework. Hence, some features are lacking or shortcuts have been taken. A noteworthy choice in this regard is the format of the binary data, which is stored in accordance with the MessagePack spec instead of the less concise .NET nanoFramework format.

Due to current limitations of the .NET nanoFramework API, there are some restrictions in the current implementation:

1. Only fields can be decorated with ProtoMember. .NET nanoFramework lacks Type.GetProperties at the moment. All code to support properties is present in the codebase, so this can be easily added when GetProperties is implemented.
2. The ProtoInclude attribute allows describing inherited types on the base type so that they are properly serialized. The typeof() syntax does compile in .NET nanoFramework but yields an empty Type at runtime.
3. The current implementation of Type.GetElementType returns null at runtime which prevents from detecting the array element type. An additional attribute ProtoArrayElementAttribute is provided to get around this.
4. There is no Enum.ToObject implementation in .NET nanoFramework which means enums are not currently supported. This can be solved by casting an enum to an integer in a wrapper class.
5. Conversions from unsigned types to signed types with the same or less byte size are not supported in .NET nanoFramework (ushort to int for instance). While this has no consequences on a functional level, it does on the performance side since it is currently solved with string parsing.
6. Lastly, the .NET nanoFramework MemoryStream is limited to 65kB. Since the payload may be bigger an interface IStream is implemented in either a wrapper around MemoryStream (the preferred approach) or, when in need of (de)serializing a bigger payload, an alternative ProtobufStream implementation is available. See also the BigString unit test. The Serializer class defaults to the MemoryStream wrapper.

With these limitations in mind, the library requires specific contracts, which means existing DTOs can probably not be reused as such. This is easily circumvented by creating wrapper classes, though.

The first five limitations mentioned are denoted in the code with a comment (look for //NanoTODO).

Acknowledgements

The initial version of the protobuf library was coded by Klaus Vancamelbeke, who has kindly handed over the library to the .NET nanoFramework project.

Feedback and documentation

For documentation, providing feedback, issues, and finding out how to contribute, please refer to the Home repo.

Join our Discord community here.

Credits

The list of contributors to this project can be found at CONTRIBUTORS.

License

The nanoFramework WebServer library is licensed under the MIT license.

Code of Conduct

This project has adopted the code of conduct defined by the Contributor Covenant to clarify expected behaviour in our community. For more information see the .NET Foundation Code of Conduct.

.NET Foundation

This project is supported by the .NET Foundation.