1. Space Plug-and-Play Architecture (SPA) and SSM
Add appropriate AFRL Logo.

2. Introduction
SPA implements a self-configuration Publish/Subscribe methodology
Computer-negotiated interfaces permit the elements of a complex system to interoperate without the need of traditional interface control documents
SPA processing sequence:
Network discovery and configuration
Component registration (Publish)
Component queries
Component subscriptions (Subscribe)

3. Introduction
Accelerates the development and integration process by reducing or eliminating error-prone human interpretation
Standards based
SPA standards submitted to AIAA
Provides a contract between component providers that if their component is SPA compliant they can expect full interoperability on a SPA system

4. Software Architecture
Non-SPA
Applications
Board Support Package
Operating System and System Services
Libraries
Platform Abstraction Library
SPA Middleware
Core Libraries
Core Services
Subnet Management
SPA API
SPA Applications

5. Software Architecture
SPA Middleware
Software required in order to support SPA infrastructure and functionality
Open source SPA middleware reference implementation provided by AFRL - SPA Services Manager (SSM)
SSM Target Architectures
VxWorks 6.x using Real Time Processes (RTPs), Linux 2.6.x, and Windows XP and 7
Design uses a Platform Abstraction Layer (PAL) to ease port to other platforms

6. Software Architecture
SPA Middleware Core Services
Discovery and addressing service
Network topology discovery, component discovery, and component addressing methodology
Publication service
Component registration, re-registration, deregistration
Query service
Query methodology in order to identify components that provide required data consumption and/or functionality
Subscription service
Methodology to subscribe and unsubscribe to required data and/or functionality

7. Software Architecture
SPA Middleware Core Services cont.
System status monitoring service
Methodology to monitor overall SPA system status and provide appropriate response to SPA system anomalies
SPA Middleware Core Libraries
A Collection of commonly used SPA functions, constants, classes, utilities, etc that provide basic functionality to perform several SPA tasks
Dynamically or statically linkable

8. Software Architecture
SPA Middleware Subnet Management
Subnet management for multiple heterogeneous subnets. For example, SpaceWire (SM-S), USB (SM-U), I2C (SM-1), etc.
Provides interoperability between different types of SPA subnets

9. Example SPA System SPA PR1 SPA PR3 SPA PR2 SPA NetworkLS
SPA PR3
SPA PR2 A3
SM-S
SM-S
CAS
SM-L A3 A4
SM-L A1 A2
SM-L
SM-S
SM-S
SM-U
SM-1 R1 R2 R3
SPA Network is an addressable and routable physically connected infrastructure composed of standard SPA transports for transporting SPA messages between SPA endpoints and SPA gateways.
SPA Processor Resource (SPA PR) are discoverable shared resources for executing SPA applications.
SPA Core Components are SPA components which provide one or more SPA services.
SPA Services are SPA-specific capabilities and functionality available to SPA components by SPA core components through a standard interface
The SSM consists of all SPA core components that provide SPA services to the system.
SPA Network
SPA Processor Resource
SPA Core Component
SPA Application
SPA Router
SPA-S Device
SPA-U Device
SPA-1 Device

10. Software Architecture
OSI Model
SPA Model
Application
Data, application-to-application communication
Applications & Devices
Transport
End-to-end connection and reliability
SPA Messaging Interface
Network
Path determination and logical addressing
SPA Subnet Managers
Data Link
Physical addressing
SPA-X Protocols
SPA-S, SPA-U, etc
Physical
Media, signal and binary transmission
I2C, USB, SpaceWire, Sockets

11. Software Architecture
Platform Abstraction Library
Abstracts OS and architecture differences
Threading, semaphores, file I/O, timing, XML parsing, etc
Code modifications needed to port to a specific OS should only happen inside this platform specific library
SPA Application Programming Interface (API)
Defines a standard programming interface which allows a software application to interoperate with other software applications or devices
Could be used to abstract different PnP middleware implantations

12. SPA Services Manager

13. Computer-negotiated Interfaces
Extended Transducer Electronic Data Sheet (xTEDS)
Contains a complete interface description of a SPA component
Component-specific service request
Component-specific service request replies
Commands
Data messages
eXtensible Markup Language (XML) based
Schema controlled

14. Common Data Dictionary
A universal dictionary of terms, names, definitions, qualifiers, units, scales, formats, interfaces, etc.
Available as a standard reference
A living document

15. Appliqué Sensor Interface Module (ASIM)
Provides SPA interface to a legacy or simple device
Pre-programmed to support SPA messaging, xTEDS registration, and Subscription/Publishing.
SM-S (SpaceWire) ASIMs are currently available
SM_U (USB), SM-1 (I^2C), and SM-C (CAN) ASIMs are currently being developed

16. Validation - Component
Components to test as UUT
SPATS
Java GUI and core code
Suite of SpatsTests
Match SpatsTests to UUT Component Type
Each SpatsTest exercises set of protocols
SPATS verifies protocol content, sequence, and messages are correct
SM-S ASIM / Component
CAS
SM-S
SM-L
SM-U ASIM / Component LS
SM-U
SPA Application
SM-1 ASIM / Component
SM-1
On System w IP
With Hardware Support
Use SPA Test Suite (SPATS) to validate SPA core components against Standards documents.
SPATS will test each component in isolation (the Unit-Under-Test or UUT), simulating the non-UUT components in a protocol exchange
Verifies protocols and message formats are followed
Hardware support required for SM-X and SPA Device SPATS testing

17. CubeFlow Tools
Creating SPA software can be more complicated than creating traditional software.
xTEDS – Not many people are used to handcrafting XML
ASIM – ASIM protocol is a different way of thinking about embedded software
PnP Flight Software using standard interface and data centric publish/subscribe paradigm
CubeFlow tools automate many common SPA software development requirements
Open source web based tool suite

18. CubeFlow Tools xTEDS Developer
Assists a user in creating and maintaining xTEDS through a UI without requiring full XML knowledge

19. CubeFlow Tools ASIM Wizard
Aids creation of ASIM code for supported platforms by generating the code templates that match the selected xTEDS

20. CubeFlow Tools App Wizard
Aids creation of SPA application templates that will utilize a given device kind, as specified through the selected xTEDS

21. Common Data Dictionary Tool
Common Data Dictionary (CDD) Tool
Used to manage and define the Common Data Dictionary

22. CubeFlow Training Courses & Development Kits
SDL and COSMIAC have developed a training course including hardware / software to introduce SPA concepts
Development kit contains all the items needed to develop xTEDs, ASIMs, and applications, and test their functionality

23. CubeFlow Training Courses & Development Kits
As of Dec 2010 there are 343 registered users on the CubeFlow site
Over 500 individuals trained from 100+ organizations including:
NASA
Lockheed
Boeing
NRO
ORS
Universities