PCES PI Meeting

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Aspects In Real-time Embedded Systems(AIRES)
Joe Loyall
BBN Technologies
Contract No. F33615-00-C-1694
Rick Schantz, Gary Duzan, Craig Rodrigues
Northeastern University
OOMWorks
Irfan Pyarali Yamuna Krishnamurthy Pradeep Gore
Karl Lieberherr Johan Ovlinger Pengcheng Wu
Mitchell Wand Doug Orleans Ed McCormick

• PCES PI Meeting
• 3-5 April 2002

2
2 Problem Description

• Aspect Oriented Programming is limited in its
  support for distributed real-time embedded (DRE)
  systems because
• DRE applications need control over systemic
  aspects, such as timing and quality of service,
  in addition to functional aspects.
• Most AOP RD has concentrated on one or the other
• DRE applications often require composition of
  aspects that may not be complementary.
• For example, embedded shipboard applications have
  dependability and security aspects that conflict
  with their real-time performance aspects
• DRE applications need to consider composing
  aspects at several time epochs.
• The environments in which many DRE applications
  are fielded are dynamic and unpredictable, making
  it difficult to determine exactly the nature of
  the interaction between composed aspects at
  design time
• The AIRES project is addressing these problems to
  make AOP more applicable to DRE needs

3
3 Project Objectives

• Investigating the combination of functional and
  systemic aspects of programs
• Metrics for evaluation Reduced tangling of
  functional, QoS, and connection code Increased
  reuse of QoS aspects across functional
  applications Selection, addition, and
  replacement of QoS aspects with minimal impact on
  functional code Demonstration on small DRE Java
  applications that AspectJ with Traversals reduces
  tangling in the code.
• Investigating the composition of aspects and
  identification of conflicts
• Metrics for evaluation Identification of QoS
  composition points Identification of areas of
  conflict Enumeration of identification and
  mediation strategies.
• Applying to RT embedded concerns
• Metrics for evaluation Improved DRE
  capabilities Improvements in functionality with
  assured and managed QoS Improvements in creation
  of DRE applications by composition of reusable
  components and aspects.

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4a Technical Approach

• Designing and developing QDL systemic aspect
  languages and aspectual collaboration connection
  language, and examining extensions to functional
  aspect languages
• Combining them to describe DRE examples and
  evaluating effectiveness
• Examination of composition and conflict
  identification
• Prototyping and demonstration in the UAV, Bold
  Stroke environments

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4b Technical Approach - Functional, Systemic,
and Connection Languages

• Systemic (QoS) aspects Developing QuOs Quality
  Description Languages, part of the Open-Source
  QuO adaptive middleware toolkit
• CDL for programming QoS contracts that capture
  systemic state and implement adaptive policies
• ASL for programming adaptive behavior, delegating
  DOC object interfaces
• QuO Qosket component model for encapsulating
  adaptive behaviors

• Functional aspects Develop QDL functional
  support and DAJ
• Extend ASL to support wrappers around native code
  method calls
• Evaluate QDLs support for DRE AOP within the BBN
  UAV OEP
• Extend AspectJ with traversal declarations that
  are put into a separate .java file, forming DAJ
• Without modifying AspectJ compiler but by using
  novel software composition techniques made
  available by AspectJ and that will be useful to
  several other projects, implement the AspectJ
  extensions.

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4c Technical Approach - Functional, Systemic,
and Connection Languages

• Connection aspects Developing aspectual
  collaborations, a language for defining
  collaborations between components in a system and
  roles fulfilled by participants in the
  collaboration

• Using collaborations to specify the roles played
  by objects in a DRE application, i.e., the way
  objects are connected and interact
• Using adapters to specialize the collaborations
  to specific transport protocols (e.g., IIOP,
  TCP/IP, UDP) or connection services (e.g., AV
  Streams)
• Evaluate in the BBN UAV OEP software by
  specifying transports using reusable
  collaborations

7
4d Technical Approach - Describing DRE Examples
and Evaluating Effectiveness

• Describing functional aspects of the UAV
• Video format, sequencing, instrumentation,
  timestamping
• Demonstrate DAJ in small DRE examples
• Describe QoS aspects of the UAV
• Throughput, frame rate control, network
  reservation, RT priority, and fragmentation
• Describe connection aspects of the UAV
• Prototype UAV A/V Streams connections using AC
• Evaluate the effectiveness of the prototype
• Refactor the UAV code to allow for a smaller
  interface between collaborations making the
  collaborations more reusable
• Improve AC to reduce tangling even further

BBN UAV OEP

• Go or No-Go Decision Point for July 2002
• Demonstrated ability to separately specify
  functional and systemic aspects in the UAV OEP
• Encapsulated QoS behaviors in the UAV code
• (Connection) Refactoring leads to less tangled
  OEP code or improved AC leads to less tangled OEP
  code
• Alpha version of DAJ is demonstrated
  successfully in small DRE examples to reduce
  tangling

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4d Technical Approach - End-to-End Real-time QoS
Using RT-CORBA and DiffServ

• RT-CORBA preserves end-to-end priorities by
• Mapping importance of activities to OS priorities
• Propagating priorities across the network as
  activity spans multiple hosts
• However, RT-CORBA specification is less explicit
  about the communication transport and network

• Unless this behavior is carefully considered and
  modeled, end-to-end real-time predictability in
  the system is difficult to achieve

• Approach Use Differentiated Services (DiffServ)
  to prioritize RT-CORBA network traffic
• The DiffServ architecture provides different
  types or levels of service for network traffic
• DiffServ Code Points (DSCPs) are added to data
  packet headers to specify the expected type of
  service

• DiffServ enabled routers and network elements use
  DSCPs to differentiate the network traffic
• We are enhancing the TAO ORB's real-time
  implementation by making it DiffServ aware

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4e Technical Approach - Investigating
Composition and Conflict Identification

• Enumerate and examine the ways in which aspects
  and components can be composed
• Independent, layered, selection, intertwined
• Enumerate the components and aspects in the UAV
  application
• There are currently 10 qoskets and 15 aspects
  (specified in ASL) in the UAV application
• These are composed to get different behaviors, to
  support different QoS, and to support different
  video formats (e.g., MPEG and PPM) and mechanisms
  (e.g., RSVP)
• Composition is currently done in a controlled
  manner, through CORBA and SysCond interfaces to
  ensure they dont conflict
• Identify characteristics of their composition and
  generalize ways in which they can be composed
• Examine the conditions under which they can
  interfere
• Functional aspects access the same data or
  interfere with control flow
• QoS aspects access the same resources or
  interfere with measurement or adaptation
• Add analysis to weavers to recognize potential
  conflicts
• Seed woven code with adaptive code that can
  measure and mediate actual conflicts at runtime

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5 Contributions to PCES Goals

• Reduction in effort to program embedded
  systems...
• Languages for programming functional, systemic,
  and connection aspects separately, instead of
  intertwining systemic control and measurement
  throughout

• Reusable aspects that can be analyzed and
  composed
• QoS, timing and sequencing aspects
• Analysis of interactions affecting weave order
• While increasing confidence in the embedded
  system product

• Analysis and identification of conflicts (e.g.,
  affecting weave order)
• Technology supporting the development of
  adaptable systems that can preserve mission goals
  in the face of dynamic, unpredictable environments

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6 Contribution to Relevant Military Applications

• AIRES technology will enhance the applicability
  of DOC middleware to embedded systems
• Separate programming of functional and QoS
  concerns
• Reuse of QoS measurement, adaptation, and
  control
• Improved SW engineering/maintenance of DRE
  systems

• UAV (in NSWC HiPer-D Demo 2001)
• QuO controls adaptation to maintain mission goals
  under dynamic conditions
• AIRES untangles timing, sequencing, data format,
  instrumentation, and adaptation from functional
  code - allowing it to be separately specified and
  reused

• Boeing BoldStroke (in WSOA flight demo)
• QuO controls runtime adaptation of dynamic
  planning collaborations
• Adaptation is specified using QuO ASL, packaged
  using QuO qoskets

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7a Project Tasks/Schedule
July 01
July 02
July 03
May 00 Start
Sept 04 End
Define and prototype aspect QuO and
collaboration/adapters
Demonstrate and experiment
1st prototype of aspect QDL
Composition and analysis of conflicts
1st prototype of UAV using aspect QDL
Prototype and demon-stration of QDL, C/A, and UAV
UAV using QDL and C/A
UAV OEP rollout to PCES
Prototype of Collaboration/Adapters
Analysis and weaving of UAV aspects

• Design and develop functional and systemic aspect
  languages
• Design and develop aspect QDL languages
• Design and develop Collaborations/Adapters
• Demonstrate and experiment with aspect languages
  to program RT aspects in the UAV software
• Develop UAV OEP application
• Apply aspect QDL and C/A to UAV and evaluate
  improvements
• Design techniques for composing aspects and
  identifying conflicts
• Design and develop weaving techniques that
  incorporate different composition strategies
• Evaluate appropriateness of weaving techniques
  for different UAV requirements

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7b Technical Progress/Accomplishments - Systemic
Language Definition and Design

• AIRES systemic aspect oriented languages (aspect
  QDL) development has been reported as an
  accomplishment in previous PI meetings
• Were released as open-source in June 2001
• Have had (more or less) monthly releases since
  June 2001 with incremental improvements and bug
  fixes
• Available at http//www.dist-systems.bbn.com/tech/
  QuO
• Have just published a paper on QuOs qosket
  component model (ISORC02)
• Currently concentrating on evaluating QDLs use
  in DRE systems, primarily the UAV OEP, but also
  Boeings WSOA
• Most of the enhancements in QoS and adaptation in
  the UAV software have been done using QDL
• More qoskets and aspects to control ATR, to
  support PPMs (formerly supported MPEG only), to
  fragment/defragment, to control UAVs

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7c Technical Progress/Accomplishments -
Connection Language Definition and Design

• Aspectual Collaboration definition and
  development has been reported as an
  accomplishment in previous PI meetings
• We completed an implementation of the UAV
  connections (Sender-gtDistributor and
  Distributor-gtReceiver), specifying the
  connections using AC and generating the C
  implementation code
• Currently evaluating this specification/use of AC
  and looking for ways to improve it
• Reorganize UAV code looking for collaborations
  with low coupling and high cohesion
• Reformulate in terms of AC and improve AC if
  needed
• Develop an AspectJ-based implementation of AC to
  demonstrate approach on DRE examples

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7d Technical Plan - Functional Aspect Language,
DAJ

• Write back-end to produce class graph for base
  program
• Write front-end to generate AspectJ introductions
  for traversals
• Write middleware that processes traversal
  specifications
• Add visitor interfaces to traversal
  specifications and generate AspectJ code

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7e Technical Progress/Accomplishments - UAV
Prototype

• We have extended the UAV prototype in two
  dimensions
• Still send Video from the simulated UAV to
  Control Station Receiver, but now also send
  control signals back to the UAV
• Have added multiple simulated UAVs and
  distributors
• Have added more realistic UAV characteristics
• Live camera feed
• Wireless Ethernet from simulated UAV to
  distributor
• Simulated ATR on Control Station (Thanks to
  Lockheed Martin)
• PPM video format

• QuO middleware is pervasive
• We have contracts throughout the system
  coordinating and controlling the adaptation
• Adaptation resides on the simulated UAVs,
  distributor, and receivers
• Qoskets and QDL has facilitated reuse of
  behaviors (straightforward to move adaptation
  from distributor to sender) and the rapid
  addition of new behaviors (integrating others
  components, supporting other data formats, and
  new adaptations)

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8 Next Milestones

• Release of current UAV software to PCES program
• available at http//www.dist-systems.bbn.com/proje
  cts/AIRES/UAV
• Additional QoS behaviors for end-to-end and
  coordinated behavior, including RT-CORBA and
  DiffServ
• Examination of composition characteristics of the
  qoskets, aspects, and components that we have in
  UAV
• Apectual Collaborations (AC)
• Make our Java AC tool available to the AOP
  community
• Successfully refactor UAV code and improve AC
• DAJ (Traversal extension of AspectJ)
• Make DAJ available to the AspectJ community on
  the web A recent informal announcement generated
  a good response
• Search DRE applications for design patterns that
  can be expressed directly in DAJ (good uses for
  AC might also surface)
• Make DRE code shorter and more reusable

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9 Collaborations

• Vanderbilt
• Modeling larger scale, more complex contracts to
  improve design of QoS behaviors
• Vanderbilts AQME can design and simulate QuO
  contracts and can invoke QuOs code generator to
  compile the result (part of the UAV demo)
• Lockheed Martin
• Integrate LMs Quality Connectors and FT/RT
  Services and BBNs QuO and UAV to provide a more
  integrated, capable, flexible testbed
• Boeing/Washington University
• Maintaining an active participation in Boeing
  activities providing QuO and AIRES capabilities
  for use in Bold Stroke related activities
• Xerox/University of British Columbia
• Working to produce an alpha version of AspectJ
  traversals
• To gain experience with AspectJ and prepare us
  for the project, we have successfully used
  AspectJ as an implementation language in a
  graduate course on Aspect-Oriented Software
  Development
• Georgia Tech, MIT, OGI, Cornell - Active
  participation in BBN OEP

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10 Technology Transition/Transfer
AIRES technology is a prominent part of the BBN
OEP

• Transition of UAV software and AIRES concepts to
  NSWC HiPer-D demo 2001

Transition of AIRES research into Boeing WSOA
The EEL Compiler, part of the Secure Internet
Gateway System (SIGS) project at Verizon. After
four years, the system developed and maintained
using DemeterJ is still running 24x7, processing
large volumes of electronic orders. http//www.ccs
.neu.edu/research/demeter/evaluation/gte-labs

• QuO software and UAV is available open-source
• Available at http//www.dist-systems.bbn.com/tech/
  QuO
• http//www.dist-systems.bbn.com/projects/AIRES/UAV

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11 Program Issues

• None