Software Communications Architecture - Reference Implementation

The SCA is defined only as a set of specifications subject to numerous interpretations that can easily limit interoperability between various implementations. Thus, it became necessary to develop a reference implementation (RI) to define the behavior of the specifications and codify the technical aspects.

In 2001, CRC has been contracted a first time by the SDRF to develop a reference implementation (RI) of the SCA and to make it available open source on its web site. The aim of this RI was to:

• Reduce the level of ambiguity of the SCA specification documents
• Increase the potential for interoperability by allowing implementers to customize the RI instead of rewriting the whole architecture
• Increase understanding of the architecture through an example
• Accelerate the emergence of SDRs through the availability of an implementation
• Reduce the cost and time-to-market for SDRs

In collaboration with DRDC-O, CRC produced a RI of the Software Communications Architecture (SCA) version 2.1. Nearly 60,000 lines of codes, extensively documented and cross-referenced with the SCA specification documents, over 300 pages of technical documentation, including 30 example programs each modeled using UML sequence diagrams have been produced and made freely available for download. Since the beginning of the project, the SCARI Web site has received over 22,000 visits and more than 6,000 software downloads.

This project allowed CRC to identify and submit over 20 SCA specification change proposals to the Joint Tactical Radio System (JTRS) Joint Program Office (JPO). These change proposals identified sources of ambiguities and address problems with the SCA core framework specification and many have been adopted.

In 2004, the SDR Forum has again contracted CRC to upgrade its initial SCARI-Open implementation to SCA v2.2 and to have it certified by the JTRS-JPO. For this project, CRC assembled a team of distinguished international partners composed of SDRF members from industry, government, and academia. The following companies or organization have joined CRC in this project:

• ISR Technologies
• Joint Tactical Radio System
• Mercury Computer Systems
• Nasa Glenn Research Centre
• Rohde and Schwarz

Similar to the initial release of SCARI-Open, this upgrade is implemented in Java, an ideal language to simplify the understanding and promote the acceptance of the SCA worldwide :

• Java source code of JTeL certified SCAv2.2 Core Framework
• Demonstration Applications: source code of two SCA applications
• Human Computer Interface (HCI) Tools: set of basic graphical tools that simplifies the installation and control of SCA applications
• Design and Development Documentation: design documentation, user guides, JTeL certification documents

SCARI-Open Features

The open source implementation, available for free download, is written in Java, giving it a number of advantages over more conventional C or C++ languages. Java is a platform-independent language, which is an important factor for the diffusion and adoption of the implementation. It also offers a high level of abstraction in programming, which simplifies the implementation allowing quicker code release and minimizing the proliferation of multiple independent implementations.

The RI provides the mandatory components of the SCA core framework, along with support for the most used features, including Service Interfaces, Core Framework with the XML Domain Profile, related tools to operate the radio and simple waveform applications to demonstrate the operation of the radio. The SCARI provides the following:

• Full-featured nodebooter
  
  
  • Supports the launch of any type of component including logical Devices and Services
  • Supports the launch of aggregated device hierarchies
  • Automatically selects a valid implementation for each component
  • Supports dependencies between components
  • Supports host-collocation
  • Can deploy Devices onto other Devices
  • Supports "naming service findby" type of connections between any two component
• A generic implementation of a Device, an ExecutableDevice and an AggregateDevice
• Generic implementation of a Resource and examples of pushports
• Framework which facilitates the implementation of Devices and Resources
• Full-featured ApplicationFactory
  
  
  • Automatically selects a valid implementation for each component
  • Supports the specification of dependencies between different components
  • Supports host-collocation
  • Supports "naming service findby" type of connections between any two components
  • Supports the definition of properties at all level (SCD, SPD level, SPD implementation, SAD component properties, SAD factory properties) and implements the precedence order rules
  • Supports the use of application external ports
• Logging of messages even before a connection is established with a Log component
• Many code examples (well documented through UML diagrams)
• Basic Component Inspector GUI for introspections of all SCA components
• Basic Application Manager GUI to install, load and control waveform applications

SCARI-Open Downloads

Follow this link to gain access to the SCARI-Open free download site