Finegrained Middleware Composition for the Boeing NEST OEP

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Fine-grained Middleware Composition for the
Boeing NEST OEP

• Venkita Subramonian,Chris Gill,
• Jeff Parsons, Huang-Ming Huang, Stephen Torri
• Washington University, St. Louis
• venkita,cdgill,hh1,storri
• _at_cs.wustl.edu

Jeanna Gossett, Tom Corcoran, Douglas Stuart The
Boeing Company, St. Louis jeanna.m.gossett,
tom.corcoran,douglas.a.stuart _at_boeing.com
Research Supported under the NEST program DARPA
contract F33615-01-C-1898 with AFRL
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Topics

• NEST overview
• Boeing OEP overview and architecture
• Motivation for nORB
• Relationship of CORBA to nORB
• nORB components
• Future work

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NEST overview

• Networked Embedded Software Technology
• Distributed Real-Time system with 100 to 100,000
  networked sensor-actuator nodes
• Resource constrained hardware components
• Requires fine-grained fusion of hardware and
  software components
• Applications in advanced avionics and space
  systems, weapon systems, wireless devices

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NEST middleware services

• Real-time Coordination Services
• Fault tolerance
• Data exchange
• Synchronization
• Self-stabilizing protocols
• Replication
• Automated synthesis of services
• Services should address three orthogonal
  dimensions
• Scalability, Resource Constraints, Real-time
• OEPs to create challenge problems

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Boeing NEST OEP
Acoustic and Structural Damping
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Boeing OEP architecture
Application Components
Configuration
System Identification
Group Control
Low Level Control
Domain Services
Clock Synchronization
Scheduling
Group Communication
Constraint Satisfaction
Group Management
System Services
Dispatch
Time Service
Discovery
Naming
NEST ORB
NEST subset of ACE
Operating System
ACE Adaptive Communication Environment
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Why Not a Full CORBA ORB?

• Mis-match with the NEST Domain
• Most CORBA features not necessary in NEST
• Application specificity is a key issue
• Limited number of objects in NEST
• Scalability in terms of number of nodes
• not number of objects per node
• Footprint constraints

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Motivation for nORB

• Provide primitives for NEST middleware and
  services
• Limit communication middleware features to
  application requirements
• Reduce footprint
• Assure Timeliness, Support Adaptation
• Top-down approach very difficult, prolonged, and
  error-prone to achieve
• More minimal than minimum-CORBA

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Related work

• Ubicore
• Framework to hide different middleware protocols
  like IIOP, COM, Java RMI
• Generic request broker for hand-held devices
• Vertel eORB
• Uses well known patterns embodied by ACE
• MicroQoSCORBA
• CASE-tool based approach to middleware
  customization/composition
• Prototyped in Java

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CORBA-ness of nORB

• GIOP messages
• Request, Reply, Locate request, Locate reply
• Object Adapter, albeit a very simple one
• Remote Object References
• IDL compiler generated stubs and skeletons
• Limited form of Exception support

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nORB interface

• registerObject()
• resolveReference()
• objectToString()
• stringToObject()
• init()
• run()
• shutdown()

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nORB - Under the hood

• ACE - Adapative Communication Environment
• Highly efficient, portable primitive components
• ACE components used in NEST
• Reactor, Timer, Threads, Acceptor, Connector,
  CDRStream
• Further decomposition of ACE primitives on an
  as-needed basis.

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Towards a Fine-Grained Substrate

• Decoupling concerns
• Reactor
• Acceptor
• Connector
• Event Handler
• Svc Handler
• Task

ACE_Event_Handler
ACE_Event_Handler
ACE_Service_Object
ACE_Task_Base
PS_Event_Handler
ACE_Task
Peer stream
ACE_Svc_Handler
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nORB Dispatcher

• Based on Kokyu Scheduling Framework
• Adaptive Scheduling in NEST
• Scheduler as a middleware service in NEST
• Dispatching infrastructure to support the
  scheduler
• Support for FIFO (RMS)
• Future support for different scheduling
  strategies EDF, MLF

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Dispatcher interface

• initQueues()
• clearQueues()
• registerDispatchable()
• mergeSchedule()
• clearSchedule()
• dispatch()
• start()
• stop()

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Future work

• Infrastructure Composition techniques for
  scheduling/dispatching
• Further decomposition of ACE classes to achieve
  additional footprint reductions
• Apply Generative/Generic/AOP techniques for
  customizable middleware composition
• nORB performance metrics/optimizations