CORE: Putting Things Together

1
CORE Putting Things Together

• Larry Rudolph

2
CORE Communication Oriented Routing Environment

• Part of ORG (Oxygen Research Group)
• Assumptions
• Actuators / Sensors (I/O) in the environment
• Many are shared by apps users
• Many are flaky / faulty
• User does not know much about them
• Environment, application, users desires change
  over time

3
An Oxygen Application

• Interconnected Collection of Stuff
• Who specifies the stuff?
• I dont know, but its mostly virtual stuff
• Many layers of abstraction
• Dont ask, its turtles all the way down
• Two main layers of programming
• Professionals
• Users, e.g. grandmother

4
Communications-Oriented Programs

• Connecting the (virtual) stuff done by user
• Home stereo / theater analogy
• Plug Stuff together unplug it if doesnt work
• Dont like it, unplug it
• Device drivers, services, clients, dont know to
  whom or to what they connect
• In client/server model,
• server knows a lot about the client,
• the client knows even more about the server
• Extend Unix Pipes

5
CORE
Larry Bear
6
Message Flow

• Messages flow between nodes core
• Core is both language and router
• Within Core Router, some messages
• are interpreted and may trigger actions
• other messages get routed to other nodes
• Request-Reply message strategy
• Even number of messages
• No reply within time period, means error

7
CORE Language Elements

• Interpreted Language
• Statement is a message request with 3 parts
• ( ACTION, param1, param2 )
• Reply indicated success or failure
• Each language element has an inverse
• Four elements
• Nodes, Links, Messages, Rules

8
Nodehandler (nickname, specifier)
Nodes Specify via INS
Cam deviceweb-cam location518
PTRvision deviceprocess OSLinuxFileLaser
Vision, ..
CORE
Laser Vision
9
Node Statement Handler

• When node message arrives
• Verified for correctness (statements allowed)
• Routed to Node Manager (just another node)
• Node Manager
• INS lookup, verifies if allowed, creates if
  needed
• Creates core thread to manage communication with
  node
• Bookkeeping reply message with handle/error

10
CORE Essentials
Links specify with nicknames
Lcamera,vision (Cam,PTRvision)
Slide Speech
Presentation Speech
Command Speech
CORE
Laser Vision
11
Link Statement Handler

• Message routed to link manager
• Two queries to node mng for thread cntl
• Message to thread controller of source node
• Specifying destination thread controller
• Message to thread controller of dest node
• Specifying source thread controller
• Bookkeeping reply message handler/error

12
CORE Essentials
Messages flow over the links
Next Slide!
Slide Speech
Presentation Speech
Command Speech
CORE
Laser Vision
13
CORE Essentials
Messages flow over the links
Slide Speech
Presentation Speech
Command Speech
CORE
Next Slide!
Next Slide!
Laser Vision
14
CORE Essentials
Messages flow over the links
Slide Speech
Presentation Speech
ADVANCE
Command Speech
CORE
ADVANCE
ADVANCE
Laser Vision
15
Message Handling

• Messages can be encrypted
• Core statement messages have fixed format
• Everything else is data message
• Each node thread has two unbounded buffers
• Core to node Node to core
• Logging, rollback, fault-tolerance

16
CORE Essentials
How do we change output for questions?
Questions?
Slide Speech
Presentation Speech
Command Speech
CORE
Laser Vision
17
CORE Essentials
Slide Speech
Presentation Speech
Command Speech
Question?
CORE
Question?
Laser Vision
18
CORE Essentials
RULES (trigger,action)
( MESSQuestion , Lslide,lcd -- Lslide,qlcd )
Slide Speech
Presentation Speech
Questions
Command Speech
CORE
Questions
Questions
Laser Vision
19
Rule Statement Handler

• ( trigger , consequence )
• Both are event sets
• Eight basic events
• Node, -Node, Link, -Link
• Message, -Message, Rule, -Rule
• Event set is a set of events
• Trigger is true when events are true
• Consequence makes events true

20
Rules II

• A message event is of form
• (node, message specifier)
• ( message specifier , node )
• Message came from or going to node
• A link (x,y) is just shorthand for the rule
• ( x , m ) ? ( - (x, m) , (m , y) )
• If a message m arrives at node x, then make that
  event false (remove the message) and make the
  event of m arriving at y from core true.

21
Rules III

• Rule statement gets sent to rule manager
• Event set is just another shorthand for rules
• Rule manager sends command to trigger node thread
  that tells it about the consequence
• Rules are reversable