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GS1 Syntax Engine

The GS1 Syntax Engine is a library that supports the processing of GS1 syntax data, including Application Identifier element strings and GS1 Digital Link URIs. It includes a native C library together with bindings for C# .NET, Java and Swift, that is intended to be integrated into a wide variety of platforms.

The project also serves as a reference implementation of a framework for processing the GS1 Syntax Dictionary and Linters.

This project includes:

  • A C library that can be:
    • Vendored into third-party code.
    • Compiled to native code for use as a shared library (Linux / MacOS / BSD) or dynamic-link library (Windows).
    • Compiled to WebAssembly or pure JavaScript for use in a browser-based web application or Node.js application.
  • A C# .NET wrapper class that provides an object interface to the native library from managed code, using Platform Invoke (P/Invoke).
  • A Java wrapper class that provides an object interface to the native library from managed code, using Java Native Interface.
  • Several example applications:
    • A console application whose C code shows how to use the native library.
    • A console application whose Java code shows how to use the Java Native Interface wrapper.
    • A desktop application using Windows Presentation Foundation (WPF) whose code shows how to use the C# .NET wrapper.
    • A browser-based web application that shows how to use the WebAssembly or pure JavaScript build of the library.
    • A Node.js console application that shows how to use the WebAssembly or pure JavaScript build of the library.
    • An Android Studio project that shows how to use the Java wrapper from Kotlin to create an Android app that includes support for decoding GS1 data in barcodes scanned using ML Kit.
    • An Xcode project that shows how to use the native library from Swift to create an iOS app that includes support for decoding GS1 data in barcodes scanned using ML Kit.

Documentation

The C library API is fully documented in the docs/ directory and is available online here: https://gs1.github.io/gs1-syntax-engine/

Instructions for getting started with the console application are provided in the Console Application User Guide.

Instructions for getting started with the desktop application are provided in the Desktop Application User Guide.

Using the library

The library is provided with full source and also in the form of a pre-built library (portable DLL) along with associated development headers (.h) and linker (.lib) files.

Pre-built assets are available here:

https://github.com/gs1/gs1-syntax-engine/releases/latest

The license is permissive allowing for the source code to be vendored into an application codebase (Open Source or proprietary) or for the pre-built shared library to be redistributed with an application.

This repository contains:

Directory Purpose
src/c-lib Source for the native C library ("The library"), unit tests, fuzzers and demo console application
docs Documentation for the public API of the native C library
src/dotnet-lib C# .NET wrappers that provide a managed code interface to the native library using P/Invoke
src/dotnet-app A demo C# .NET desktop application (WPF) that uses the wrappers and native library
src/js-wasm A JavaScript wrapper that provides an developer-friendly interface to the WASM or pure JavaScript build, with demo web and console applications
src/java A Java wrapper that provides a managed code interface to the native library using Java Native interface
src/android An Android Studio project that demonstrates how to use the Java wrapper from Kotlin to create an Android app
src/ios An Xcode project that demonstrates how to use the native library from Swift to create an iOS app

Building on Windows

The library, wrappers, demonstration console application and demonstration desktop application can be rebuilt on Windows using MSVC.

The project contains a solution file (.sln) compatible with recent versions of Microsoft Visual Studio. In the Visual Studio Installer you will need to ensure that MSVC is installed by selecting the "C++ workload" and that a recent .NET Core SDK is available. You must build using the "x86" solution platform.

Alternatively, all components can be built from the command line by opening a Developer Command Prompt, cloning this repository, changing to the src directory and building the solution using:

msbuild /p:Configuration=release gs1encoders.sln

Building on Linux or MacOS

The library and demonstration console application can be rebuilt on any Linux or macOS system that has a C compiler (such as GCC or Clang).

To build using the default compiler change into the src/c-lib directory and run:

make

A specific compiler can be chosen by setting the CC argument for example:

make CC=gcc

make CC=clang

Development targets

There are a number of other targets that are useful for library development purposes:

make test [SANITIZE=yes]  # Run the unit test suite, optionally building using LLVM sanitizers.
make fuzzer               # Build fuzzers for exercising the individual encoders. Requires LLVM libfuzzer.

JavaScript / WASM build

The WASM build artifacts can be generated by first installing and activating the Emscripten SDK and then running:

make wasm [JSONLY=yes]    # Set JSONLY=yes to create a JS-only build that does not use WebAssembly.

Alternatively, on a Docker-enabled system a WASM / JS-only build can be launched from the project home directory with:

docker run --rm -v $(pwd):/src -u $(id -u):$(id -g) emscripten/emsdk  make -C src/c-lib wasm [JSONLY=yes]

Java wrapper

The Java wrapper for the Syntax Engine can be built by first compiling the Syntax Engine C library as a static library, and then building the wrapper itself:

make -C src/c-lib -j `nproc` libstatic
ant -f src/java/build.xml test

To use the wrapper in a Java project it is sufficient to place the generated src/java/libgs1encoders.{jar,so} files into accessible locations, then:

  • At compile time and runtime, add the .jar file into the project's classpath.
  • At runtime, add the directory containing the .so file into java.library.path.

Installing the Pre-built Demo Console Application

A demonstration console application is provided in the form of an .EXE file compatible with modern 64-bit Windows operating systems and as a .bin file compatible with 64-bit Linux operating systems. There are no installation dependencies and the file can be run from any location on the file system.

The most recent version of the console application can be downloaded from here.

For Windows systems download the asset named gs1encoders-windows-console-app.zip. For Linux systems download the asset named gs1encoders-linux-app.zip. In the event of issues with antivirus software consult the note in the User Guide.

The pre-built application requires that the Visual C++ Redistributable 2019 (32 bit) is installed: https://visualstudio.microsoft.com/downloads/#microsoft-visual-c-redistributable-for-visual-studio-2019

Installing the Pre-built Demo Desktop Application

A demonstration desktop application is provided in the form of an .EXE file compatible with modern 64-bit Windows operating systems and a recent .NET Framework.

The most recent version of the desktop application can be downloaded from here.

For Windows systems download the asset named gs1encoders-windows-gui-app.zip. In the event of issues with antivirus software consult the note in the User Guide.

The pre-built application requires that the .NET Core 3.1 Desktop Runtime - Windows x86 is installed: https://dotnet.microsoft.com/download/dotnet/3.1/runtime

Installing the Pre-built Demo Web Browser Application and Node.js Application

A demonstration build, that can be run as either a web browser application or a Node.js console application, is provided in two flavours:

  1. A compilation to a WebAssembly executable with supporting JavaScript loader
  2. A transpilation to pure JavaScript ("asm.js") with associated mem file

Each of these flavours includes the JavaScript wrapper (providing the user API) and HTML / JS / Node.js implementation files. They are compatible with all modern web browsers and Node.js 17 or later.

The most recent version can be downloaded from here.

Download the asset named gs1encoders-wasm-app.zip or gs1encoders-jsonly-app.zip based on the required flavour (WASM or pure JavaScript, respectively).

To use the demo web application, extract the ZIP file and place the resulting files in a single directory to be served by a web server as static content. Simply point a WebAssembly-enabled browser at the HTTP location of the .html file and the web application will load.

Note: For the WASM build, ensure that the web server is configured to serve the .wasm file with the MIME type application/wasm.

To use the demo Node.js console application, extract the ZIP file into a single directory and start it by running the following from within the same directory:

node example.node.mjs