Swish Concurrency Engine

The Swish Concurrency Engine is a framework used to write fault-tolerant programs with message-passing concurrency. It uses the Chez Scheme programming language and embeds concepts from the Erlang programming language. Swish also provides a web server.

Design

The latest design document can be found here.

Swish uses libuv for cross-platform asynchronous I/O.

Although Swish can be run in threaded Chez Scheme for convenience, it is not thread safe and should be used from the main thread only.

Versioning

Swish follows the semantic versioning scheme, starting with 2.0.0 to avoid confusion with internal projects.

Notes

1. install the prerequisites (see Build System Requirements)
2. ./configure (see ./configure --help for options)
3. make
4. make test

• After ./configure; you can also cd src; ./go to build and run the engine.

• We disable the expression editor with --eedisable because Chez Scheme's expression editor does not use asynchronous console I/O. We would have to modify the places where s/expeditor.ss calls $ee-read-char in blocking mode to use libuv's asynchronous read function instead of the one in c/expeditor.c.

• If you get a "symbol(s) not found" error, you may need to use CPPFLAGS and LDFLAGS to supply the header and library path. If the C compiler refuses unused arguments, you may need CFLAGS="-Qunused-arguments". e.g.,

  ./configure CPPFLAGS="-I/usr/local/opt/libiconv/include" \
    CFLAGS="-Qunused-arguments" LDFLAGS="-L/usr/local/opt/libiconv/lib"
  

Build System Requirements

Linux

• Chez Scheme 9.5.4 or 9.5.5
• GCC, the GNU Compiler Collection
• GNU make
• GNU C++ compiler for libuv
• cmake for libuv
• libsystemd-dev and uuid-dev packages
• graphviz, texlive, texlive-latex-recommended, and texlive-latex-extra packages for building the documentation

Mac

• Chez Scheme 9.5.4 or 9.5.5
• ginstall and realpath (can be installed through homebrew using brew install coreutils)
• cmake for libuv (can be installed through homebrew using brew install cmake)
• XCode Command Line Tools
• dot (can be installed through homebrew using brew install graphviz)
• pdflatex (can be installed through homebrew using brew cask install mactex)
• Latin Modern fonts from LaTeX (can be installed with Font Book from a location like /usr/local/texlive/2020/texmf-dist/fonts/opentype/public/lm)

Windows

• Chez Scheme 9.5.4 or 9.5.5
• Cygwin or MinGW/MSYS with bash, git, graphviz, grep, perl, texlive, GNU make, etc.
• Microsoft Visual Studio 2019 or 2017 with Visual C++
• Put scheme in PATH.

Stand-alone Swish Applications

Swish can be used to build, test, and deploy stand-alone applications. A given application might load foreign code for image processing or USB access. Code that may block should use the API described in the "Operating System Interface" chapter of the documentation to integrate with Swish's I/O loop.

Build

For details about building a Swish application, see: swish-build --help

Test

For details about testing a Swish application, see: swish-test --help

Deploying a Stand-alone Application

On Linux and macOS, you can deploy your application's executable and boot file.

On Windows, your install should include the application's executable and boot file, osi.dll, uv.dll, sqlite3.dll, Chez Scheme's csv954.dll, and Microsoft's C Runtime Library vcruntime140.dll.

Developers writing stand-alone applications should clone the Swish repository and run configure. Swish's source repository provides swish.h to define callable exports for osi.dll. Mf-config can be used in makefiles to define variables for system-specific paths.