Ditto(Live)'s Rust SDK

Please visit https://docs.ditto.live/ for more info about Ditto, and its Rust documentation.

Note: for historical reasons, this SDK has been minimally maintained during 2022 and the first half of 2023. We have gradually been able to improve this, and especially since 2024, we take this SDK very seriously, to keep it on par with the high quality standards that our customers can expect from us, showcased in other SDKs such as Swift and Javascript.

• A main example of this has been linkage or ABI incompatibilities with certain Rust toolchains, which have since been fixed.

That being said, some technical debt from that time may still linger for a few extra months, until everything is properly cleaned up (which will come with a major bump to rename and clean up certain rougher parts of the API).

We apologize for the inconvenience.

Some notes about using a Rust-wrapped C library

Ditto's core functionality is released and packaged as a C library, which is then imported into Rust via the ::dittolive-ditto-sys crate.

Downloading the companion binary artifact

Such a crate will download —at build time— the appropriate binary artifact from https://software.ditto.live/rust/Ditto/<version>/<target>/release/[lib]dittoffi.{a,so,dylib,dll,lib}

• For instance: https://software.ditto.live/rust/Ditto/4.5.4/aarch64-apple-darwin/release/libdittoffi.so

If you wish to avoid this, you will have to do it yourself:

1. Download the proper binary artifact;

2. Instruct ::dittolive-ditto-sys' build.rs script about it by setting the DITTOFFI_SEARCH_PATH appropriately (using an absolute path is recommended).

More precisely, the library search resolution order is as follows:

1. $DITTOFFI_SEARCH_PATH (if set)
2. $OUT_DIR (e.g., ${CARGO_TARGET_DIR}/<profile>/build/dittolive-ditto-sys-.../out)
3. the current working directory ($PWD)
4. $CARGO_TARGET_DIR
5. Host built-in defaults (e.g., /usr/lib, /lib, /usr/local/lib, $HOME/lib) controlled by (system) linker setup.

If the library artifact is not found at any of these locations, the build script will attempt its own download into the $OUT_DIR (and use that path).

Linkage

C linkage is typically accompanied with some idiosyncrasies, such as symbol conflicts, or path resolution errors.

The first and foremost question is about dynamic vs. static linkage.

• Statically linking libdittoffi (default; recommended)

  This happens whenever the LIBDITTO_STATIC is explicitly set to 1, or unset.

  If you have a special path to the libdittoffi.a/dittoffi.lib file (on Unix and Windows, respectively), then you can use the DITTOFFI_SEARCH_PATH env var to point to its location (using an absolute path), at linkage time (during cargo build exclusively).

• Dynamically linking (advanced)

  You can opt into this behavior by setting the LIBDITTO_STATIC=0 environment variable.

  When opting into this, you will have to handle library path resolution to the libdittoffi.so/libdittoffi.dylib/dittoffi.dll file (on Linux, macOS, and Windows, respectively).

  That is, whilst the DITTOFFI_SEARCH_PATH is still important to help the cargo build / linkage step resolve the dynamic library, the actual usage of this file happens at runtime, when the (Rust) binary using ::dittolive_ditto is executed.

  It is thus advisable to install the C dynamic library artifact under one of the system folders, such as /usr/lib or whatnot on Unix.

  Otherwise, you would have to:

  • either meddle with link-time flags to set OS-specific loader metadata in the binary, such as the R{,UN}PATH / install_path, paying special attention to the choice of absolute paths, binary-relative paths (such as $ORIGIN/… on Linux), or even working-directory-relative paths;

  • or use env vars directives for the dynamic loader, such as DYLD_FALLBACK_LIBRARY_PATH on macOS, or LD_LIBRARY_PATH on Linux.

  (For the technically-savy, on macOS, the install_path of our .dylib artifact is set to $rpath/libdittoffi.dylib).