22 releases

0.0.22 Apr 19, 2024
0.0.21 Apr 16, 2024
0.0.16 Mar 30, 2024
0.0.7 Feb 23, 2024

#314 in WebAssembly

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645 downloads per month
Used in 6 crates (5 directly)




Defines data types for Golem's remote function invocation and conversions between them.

  • WitValue is the WIT-defined generic data type capable of representing an arbitrary value, generated by wit-bindgen
  • A builder and an extractor API for WitValue
  • Value is a recursive Rust type which is more convenient to work with than WitValue. Conversion between WitValue and Value is implemented in both directions.
  • Protobuf message types for describing values and types, and a protobuf version of WitValue itself and conversion from and to Value and WitValue
  • JSON representation of WIT values, as defined in the Golem docs.
  • Conversion of Value to and from wasmtime values

The JSON representation requires additional type information which can be extracted using the golem-wasm-ast crate.

Host and stub mode

The golem-wasm-rpc crate can be both used in host and guest environments:

To compile the host version:

cargo build -p wasm-rpc --no-default-features --features host

To compile the guest version, has minimal dependencies and feature set to be used in generated stubs:

cargo component build -p wasm-rpc --no-default-features --features stub

Feature flags

  • arbitrary adds an Arbitrary instance for Value
  • json adds conversion functions for mapping of a WIT value and type definition to/from JSON
  • protobuf adds the protobuf message types
  • wasmtime adds conversion to wasmtime Val values
  • host enables all features: arbitrary, json, protobuf, typeinfo, and wasmtime
  • stub is to be used in generated WASM stubs and disables all features, and generates guest bindings instead of host bindings


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