License

LmcpGen is developed by the Air Force Research Laboratory, Aerospace System Directorate, Power and Control Division. The LMCP specification and all source code for LmcpGen is publicaly released under the Air Force Open Source Agreement Version 1.0. See LICENSE.md for complete details. The Air Force Open Source Agreement closely follows the NASA Open Source Agreement Verion 1.3. NOTE the terms of the license include registering use of the software by emailing afrl.rq.opensource@us.af.mil.

Introduction

The Lightweight Message Construction Protocol (LMCP) is a standard that serves two purposes. First, it defines a structure for common structured data and a process for serializing objects based on those types. Secondly, it defines a method for encapsulating objects for transmission between applications. This specification describes the structure of data, without specifying how applications implement the handling instantiations of those data types. Applications that implement this specification can send and receive objects regardless of the operating system, platform, or programming language used. LMCP is a simple and extensible specification, so it can be implemented without central runtime, proprietary libraries, or the complexity of other protocols such as HLA and DIS. This system offers several advantages to the end-user, including:

• A design independent of language, platform, and transport protocol.
• Object-oriented approach through structured data types, including support for null objects.
• A high level of customizability through user-defined data models.
• Support for variable length arrays and nested objects.
• Simple and open design, free of proprietary code and requiring no runtime infrastructure or special libraries.

LMCP also defines the structure of a message. A message is an LMCP object that is encapsulated with header and footer items to enable communication of LMCP objects between applications. LMCP allows developers to create custom data types (structs) easily through a message data model (MDM). Custom classes can be created for a given MDM through automatic code generation or other means to recognize and handle messages.

LMCP was created at the Air Force Research Library as a way to ease communications between applications written in a variety of computing languages and running on different computing platforms. For more information on LMCP and its precise specification, see the doc directory in the LmcpGen git repository.

Using LmcpGen

The LmcpGen tool autogenerates source-code libraries in several languages that conform to the serialization specification of LMCP. Currently, LmcpGen creates libraries for the following languages:

• Java
• C++
• C#
• Python

Additionally, LmcpGen can create HTML documentation in the form of an easy-to-navigate webpage for viewing the messages described in source MDMs.

Requirements

To use LmcpGen, a Java JRE version 1.8 or higher is required. To modify LmcpGen, the Java JDK 1.8 or higher is required. LmcpGen does not rely on any external libraries and is completely stand-alone. For convenience, Netbeans project files are included to allow developers a quick way to change and re-build LmcpGen.

Installation

LmcpGen is a simple Java program that will run on any system with Java installed.

Running LmcpGen

LmcpGen can be run both in a user-interactive mode or silently as a command line tool. To run in user-interactive mode, double-click LmcpGen.jar or use the command

java -jar LmcpGen.jar

If LmcpGen is run with any additional command-line arguments, then it will run silently until completion. The command line options are as follows:

• -mdm <filename> path to the MDM XML file. Multiple MDMs can be specified by repeating the -mdm tag.
• -mdmdir <directory path> to directory containing multiple MDM XML files. Can be used multiple times to specify multiple directories.
• -java Adds proper template and method name for Java output.
• -cpp Adds proper template and method name for C++ output. Note: creates c++11 compatible code.
• -cs Adds proper template and method name for C# output.
• -py Adds proper template and method name for Python output.
• -xsd Adds proper template and method name for XML schema output.
• -doc Adds proper template and method name for documentation output.
• -dir <directory path> path to the directory where files are to be written.
• -checkMDM <mdm file> Checks the MDM file for errors and exits.

For example, with a set of proper LMCP MDMs in the directory mdms, the command to create documentation would be:

java -jar LmcpGen.jar -mdmdir "mdms" -doc -dir "doc/LMCP"