Overview of Prism-MW
CS 795 / SWE 699
Sam Malek
Spring 2010
Prism-MW
A simple and extensible architectural
middleware, i.e., a framework of abstract
classes for architectural concepts such as
(sub)systems, components, connectors,
and events. The middleware supports
composition of arbitrarily complex
components and connectors.
Objectives
•
“Programming”
•
Architectural abstractions directly
reified in the implementation
•
“Small”
•
Efficiency demanded by resource
constraints
•
“Many”
•
Scalability in the numbers of
devices, threads, components,
connectors, events
Extensibility to support
awareness, mobility,
•
reconfigurability, security, delivery
guarantees
2
Prism: Programming-in-the-Small-and-Many
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
From architecture to implementation

Architectures provide high-level concepts


Programming languages provide low-level constructs


Components, connectors, ports, events, configurations
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”
Prism-MW

An architectural middleware for embedded systems

Supports architecture-based software development




Efficient
Scalable
Flexible and Extensible


Architecture-based software development is the implementation
of a software system in terms of its architectural elements
Allows us to cope with heterogeneity
Supports arbitrary complex architectural styles
Architectural Middleware


Natively support architectural concepts as middleware
constructs
Include system design support


Support round-trip development


From architecture to implementation and back
Support automated transformation of architectural models
to implementations


Typically via an accompanying ADL and analysis tools
i.e., dependable implementation
Examples




ArchJava
Aura
c2.fw
Prism-MW
Prism-MW
Round Robin
Dispatcher
Fifo
Scheduler
Abstract
Dispatcher
Abstract
Monitor
Scaffold
Serializable
Abstract
Scheduler
Extensible
Event
Event
Brick
Architecture
Port
Abstract Event
Extensions
Connector
Extensible
Port
...
Extensible
Architecture
IPort
#mutualPort
IComponent
Abstract
Implementation
Extensible
Component
Abstract
Awareness
...
Awareness
Extensions
Component
Extensible
Connector
Abstract Port
Extensions
...
Application
Specific Impl.
IConnector
IArchitecture
...
Abstract
Topology
Abstract Comp
Behavior
Abstract
Handler
Abstract Conn
Behavior
Prism-MW
Serializable
Fifo
Scheduler
Abstract
Scheduler
Round Robin
Dispatcher
Abstract
Dispatcher
Brick
Scaffold
Event
IPort #mutualPort
Architecture
Port
IComponent
IConnector
Component
IArchitecture
Connector
Extensible
Component
Using Prism-MW
Component A
Component B
Connector C
C
Component D
class DemoArch {
static public void main(String argv[]) {
Architecture arch = new Architecture ("DEMO");
// create components
ComponentA a = new ComponentA ("A");
ComponentB b = new ComponentB ("B");
ComponentD d = new ComponentD ("D");
// create connectors
Connector conn = new Connector("C");
// add components and connectors
arch.addComponent(a);
arch.addComponent(b);
arch.addComponent(d);
arch.addConnector(conn);
Architecture - DEMO
Component A
Component B
Component D
}
}
// establish the interconnections
arch.weld(a, conn);
arch.weld(b, conn);
Connector C
C
arch.weld(conn, d)
Using Prism-MW
Component A
Component B
Send (e1)
Component D sends an event
Event e = new Event ("Event_D");
e.addParameter("param_1", p1);
send (e);
Component B handles the event and sends a response
Connector C
C
Send (e)
Component D
Architecture - DEMO
public void handle(Event e)
{
if (e.equals("Event_D")) {
...
Event e1= new Event("Response_to_D");
e1.addParameter("response", resp);
send(e1);
}...
}
Event Dispatching
Thread Pool
Scaffold
Adaptation of an existing
worker
Component
B B thread pool technique
Component
handle Event
E2
Component A

E 2Network

Connector C

send Event
Topology based routing
Single event queue for both
locally and remotely generated
events
Easy redeployment
and
E E
X
X E E E E
3 4 5
redistribution 1of2 applications
onto different hardware
configurations
Component D
E
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 events
not limited by Prism-MW
• Numbers of components and connectors
available_memory – middleware_size
average_element_size
…
100 001 components
100 000 connectors
Total event roundtrip time 2.7
sec
Prism-MW Benchmarks on a PC
3000
2500
2000
1500
T i me ( ms )
1000
500
0
N u mb e r o f
c o mp o n e n t s
100
50
10
1
1
100
1000
10000
100000
N u mb e r o f e v e n t s
1E +05
10000
1000
100
1
100
2674
300
50
20
20
50
1843
211
40
20
10
10
1222
150
30
11
10
1
1081
131
30
10
1
Prism-MW has been adopted by several
industry partners
Troops Deployment Simulation
US Army
MIDAS
Bosch Research and Technology Center
Architecture of MIDAS
PDA
Architecture
Gateway Architecture
Service-Oriented
Sub-Architecture
FileInput
Svc
Trouble
LogSvc
Topology
Calculator
EventNotificat
ionSvc
Hub
Operator
Pub-Sub Conn
To other PDAs
Unicast
Conn
Admin
Pub-Sub Conn
Admin
To other gateways
Peer-to-Peer
Sub-Architecture
EventDisplay
To other gateways
GwToGw
Processor
SDEngine
Pub-Sub Conn
To sensors
Sensor
Processor
Pub-Sub Conn
Session
Administrator
SDEngine
SDEngine
Pub-Sub Conn
GwToHub
Processor
Session
Operator
Publish-Subscribe
Sub-Architecture
NodeInfo
Svc
Hub Architecture
Deployer
Legend:
Prism-MW
Architecture
Component
Meta-level Comp
Request Port
Reply Port
Distribution
Request Port
Service
Distribution
Reply Port
Connector
Pointer
Recent Progress