Overview of Embedded Software Research at USC

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Overview of Embedded Software Research at USC

• CSCI 589

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Architectural Abstraction
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Why Software Architecture?

• Early, high-level system model
• Stakeholder understanding and communication
• Focus on specific system properties
• Separation of concerns
• Early analysis and simulation
• Tool-supported implementation
• Improved processes and project management

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Architectural Style

• Recurring structural, behavioral, and interaction
  patterns
• Design vocabulary and grammar
• Envelope of allowed change
• Guarantee of desirable properties
• Generalization from specific experience
• Enables proper balance of
• Intuition
• Method
• Theft

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The C2 Architectural Style

• Event-based communication among autonomous
  components, mediated by active connectors
• Composition
• No component-component links
• Separation of computation from communication
• Asynchronous, implicit invocationvia connectors
• Substrate independence
• Concurrency
• Distribution
• Heterogeneity

User Repository
Main Window
Login Dialog
Graphics Toolkit
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Prism Programming-in-the-Small-and-Many
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Prism Challenges

• Resource constraints
• Demand highly efficient computation,
  communication, and memory footprint
• Demand unorthodox solutions
• e.g., off-loading components
• Hardware and software heterogeneity
• Proprietary operating systems
• Dialects of programming languages
• Device-specific data formats
• Lack of support for inter-device interaction
• Lack of support for code mobility

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From architecture to implementation

• Architectures provide high-level concepts
• Components, connectors, ports, events,
  configurations
• Programming languages provide low-level
  constructs
• Variables, arrays, pointers, procedures, objects
• Bridging the two often is an art-form
• Middleware can help split the difference
• Existing middleware technologies
• Support some architectural concepts (e.g.,
  components, events)
• but not others (e.g., configurations)
• Impose particular architectural styles
• End result ? architectural erosion
• Architecture does not match the implementation

• What is needed is architectural middleware

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Prism-MW

• An architectural middleware for embedded systems
• Supports architecture-based software development
• Architecture-based software development is the
  implementation of a software system in terms of
  its architectural elements
• Efficient
• Scalable
• Flexible and Extensible
• Allows us to cope with heterogeneity
• Supports arbitrary complex architectural styles

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Architectural Middleware

• Natively support architectural concepts as
  middleware constructs
• Include system design support
• Typically via an accompanying ADL and analysis
  tools
• Support round-trip development
• From architecture to implementation and back
• Support automated transformation of architectural
  models to implementations
• i.e., dependable implementation
• Examples
• ArchJava
• Aura
• c2.fw
• Prism-MW

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Architectural Middleware Architecture
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Prism-MW Design
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Using Prism-MW
class DemoArch static public void
main(String argv) Architecture arch
new Architecture ("DEMO") // create
components Component a new CompA
("A") Component b new CompB
("B") Component c new CompC (C") //
create connectors Connector d new
Connector(D") // add components and
connectors arch.addComponent(a) arch.addCompon
ent(b) arch.addComponent(c) arch.addConnector(
d) // establish the interconnections arch.attac
h(a, d) arch.attach(b, d) arch.attach(d,
c)
Architecture - DEMO

Connector D
Connector D
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Using Prism-MW
Component C sends an event Event e new Event
("Event_C, REQUEST) e.addParameter("param_1",
p1) send (e)
Architecture - DEMO
Connector D
Send (e)
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Event Dispatching
Scaffold
Thread Pool
handle Event
Connector D
E
X
X
E
E
E
E
E
1
2
5
3
4

• Topology-based routing
• Easy redeployment and redistribution of
  components onto different hardware configurations

send Event
Comp C
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Prism-MW Performance

• Efficiency
• 1750 SLOC
• 4600 B for the core
• 160 B per component
• 240 B per connector
• 70 B per weld
• 160 B per event
• 240 B per event parameter

• Scalability
• Numbers of devices, threads and eventsnot
  limited by Prism-MW
• Numbers of components and connectors
• available_memory middleware_size
• average_element_size

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Prism-MW Benchmarks on a PC
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Prism-MW has been adopted by several industry
partners
Troops Deployment Simulation US Army
MIDAS Bosch Research and Technology Center
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Partial View of MIDAS Architecture
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The big picture
Domain Expert
Model
Repopulate
Design-time Analysis
Runtime Analysis
Deployment Model
Deploy
Redeploy
QoS Pref.
Monitor
Monitoring Data
Hardware System
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Deployment and Monitoring Support
Architecture 2
Repository
DeSi Adapter Arch.
Architecture 1
DLL
DLL
DLL
Unicast Connector
Repository
Byte Array
Connector D
Repository