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cyber physical by Koyal sharma.pptx
1.
2.
3.
4. • Cyber – computation, communication, and control that are discrete,
logical, and switched
• Physical – natural and human-made systems governed by the laws of
physics and operating in continuous time
• Cyber-Physical Systems – systems in which the cyber and
physical systems are tightly integrated at all scales and levelsChange from
cyber merely appliquéd on physical
• Change from physical with off-the-shelf commodity “computing as parts”
mindset
• Change from ad hoc to grounded, assured development
11. The embedded systems problem:
• Embedded software is software on small
computers. The technical problem is one of
optimization (coping with limited resources).
The CPS problem:
• Computation and networking integrated with
physical processes. The technical problem is
managing time and concurrency in networked
computational systems.
12. package org.apache.tomcat.session;
import org.apache.tomcat.core.*;
import org.apache.tomcat.util.StringManager;
import java.io.*;
import java.net.*;
import java.util.*;
import javax.servlet.*;
import javax.servlet.http.*;
/
*
*
* Core implementation of a server session
*
* @author James Duncan Davidson [duncan@eng.sun.com]
* @author James Todd [gonzo@eng.sun.com]
*
/
public class ServerSession {
private StringManager sm =
StringManager.getManager("org.apache.tomcat.session");
private Hashtable values = new Hashtable();
private Hashtable appSessions = new Hashtable();
private String i
d
;
private long creationTime = System.currentTimeMillis();;
private long thisAccessTime = creationTime;
private long lastAccessed = creationTime;
private int inactiveInterval = -1
;
ServerSession(String id) {
this.id = i
d
;
}
public String getId() {
return i
d
;
}
public long getCreationTime() {
return creationTime;
}
public long getLastAccessedTime() {
return lastAccessed;
}
public ApplicationSession getApplicationSession(Context
context, boolean create) {
ApplicationSession appSession =
(ApplicationSession)appSessions.get(context);
if (appSession == null && create) {
// X
X
X
// sync to ensure valid?
appSession = new ApplicationSession(id, this, context);
appSessions.put(context, appSession);
}
// X
X
X
// make sure that we haven't gone over the end of o
u
r
// inactive interval -- if so, invalidate and create
// a new appSession
return appSession;
}
void removeApplicationSession(Context context)
{ appSessions.remove(context);
}
/
*
*
* Called by context when request comes in so that accesses an
d
* inactivities can be dealt with accordingly.
*
/
void accessed() {
// set last accessed to thisAccessTime as it will be left o
v
e
r
// from the previous access
lastAccessed = thisAccessTime;
thisAccessTime = System.currentTimeMillis();
}
void validate()
Software Control
Crosses Interdisciplinary Boundaries
• Disciplinary boundaries need to be realigned
• New fundamentals need to be created
• New technologies and tools need to be developed
• Education need to be restructured
14. • Transform how we interact with the physical world just like the
internet transformed how we interact with one another.
– Transcend space
– Control the physical environment remotely
• Building CPSs that integrate computational and physical objects
requires new systems science foundations.
– Fusion of physical and computational
sciences
15. •
•
•
•
•
Rich time models instead
of sequencing
Behavioral invariants
instead of end results
Functionality through
interactions of ongoing
behaviors instead of
sequence of actions
Component architectures
instead of procedural
abstraction
Concurrency models with
partially ordered instead of
linearly ordered event sets
Precise interaction and
coordination protocols
Hugely increased system
size with controllable,
stable behavior
Dynamic system
architectures (nature and
extent of interaction can
be modified)
Adaptive, autonomic
behavior
Self-descriptive, self
monitoring system
architecture for safety
guarantees.
