Advances in Large-scale Advances in Large-scale
Distributed, Distributed,
Real-time, & Embedded Systems Real-time, & Embedded Systems Douglas C. Schmidt
Professor of EECS Vanderbilt University Nashville, Tennessee
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The Evolution of DRE Systems
• Stringent quality of service (QoS) demands• e.g., latency, jitter, footprint
• Resource constrained
• Stringent quality of service (QoS) demands• e.g., latency, jitter, footprint
• Resource constrained
The Past
• Network-centric & larger-scale• Stringent simultaneous quality of service (QoS) demands• e.g., availability, security, throughput, scalability
• Part of larger systems• Dynamic context
• Network-centric & larger-scale• Stringent simultaneous quality of service (QoS) demands• e.g., availability, security, throughput, scalability
• Part of larger systems• Dynamic context
The Future
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Evolution of DRE System Development
Technology ProblemsDRE systems have
historically tended to be:StovepipedProprietary
Brittle & non-adaptiveExpensiveVulnerable
Historically, mission-critical DRE applications were built directly atop hardware
• Tedious• Error-prone• Costly over lifecycles
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
BSE
BSE
BSE
BSE
BSE
BSE
BSEBSE
BSE
AirFrame
AP
Nav HUD
GPS IFF
FLIR
Cyclic Exec
CLI
SS7
SM CM
RX TX
IP
RTOS
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Technology ProblemsDRE systems have
historically tended to be:StovepipedProprietary
Brittle & non-adaptiveExpensiveVulnerable
Historically, mission-critical apps were built directly atop hardware
• Tedious• Error-prone• Costly over lifecycles
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
IOM
BSE
BSE
BSE
BSE
BSE
BSE
BSEBSE
BSE
Middleware
MiddlewareServices
DRE Applications
Operating Sys& Protocols
Hardware & Networks
Middleware
MiddlewareServices
DRE Applications
Operating Sys& Protocols
Hardware & Networks
•Middleware has effectively factored out many reusable mechanisms & services from what was traditionally DRE application responsibility
•Middleware is no longer primary DRE system performance bottleneck
Evolution of DRE System Development
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Middleware
MiddlewareServices
DRE Applications
Operating Sys& Protocols
Hardware & Networks
DRE Systems: The Challenges Ahead
•There is a limit to how much application functionality can be factored into broadly reusable COTS middleware
•System infrastructure has become extremely complicated to use, configure, & provision statically & dynamically
•There are now multiple middleware technologies to choose from
IntServ + Diffserv
RTOS + RT Java
RT/DP CORBA + DRTSJ
Load BalancerFT CORBA
Network latency & bandwidth
Workload & Replicas
CPU & memory
Connections & priority bands
CORBA
CORBAServices
CORBAApps
J2EE
J2EEServices
J2EEApps
.NET
.NETServices
.NETApps
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•e.g., standard technologies are emerging that can:1. Model2. Analyze3. Synthesize & optimize4. Provision & deploy
multiple layers of QoS-enabled middleware & applications
•These technologies are guided by patterns & implemented by component frameworks
•Partial specialization is essential for inter-/intra-layer optimization
Promising Approach: Model Driven Middleware
Middleware
MiddlewareServices
DRE Applications
Operating Sys& Protocols
Hardware & Networks
<CONFIGURATION_PASS> <HOME> <…> <COMPONENT> <ID> <…></ID> <EVENT_SUPPLIER> <…events this component supplies…> </EVENT_SUPPLIER> </COMPONENT> </HOME></CONFIGURATION_PASS>
<CONFIGURATION_PASS> <HOME> <…> <COMPONENT> <ID> <…></ID> <EVENT_SUPPLIER> <…events this component supplies…> </EVENT_SUPPLIER> </COMPONENT> </HOME></CONFIGURATION_PASS>
Distributedsystem
Goal is not to replace programmers per se – it is to provide higher-level domain-specific languages for middleware developers & users
Solution approach: Integrate model-based software technologies with QoS-enabled component middleware
