Examples, Lecture 4

1
Examples, Lecture 4
Lecturer H. Muccini http//www.ics.uci.edu/
muccini/ics123
2
Connector

• A connector is a building block that enables
  interaction among components
• A connector exists if there is connection between
  components
• It coordinates the interaction between components
• Its main purpose is to receive information, make
  some changes to the data, ship the data to the
  final component
• Its main purpose is not doing computation but
  connect different components. Some computations
  can be done, but only to transfer information
  from one component to another
• A component is (or should be) independent of the
  context in which it is used to provide
  functionality
• A connector is (or should be) completely
  dependent on the context in which it is used to
  connect components

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Connector
Comp 2
m1
m1
Comp 1
Connector
Comp 3
Comp 4

• The Connector
• can decide who is going to receive m1
• based on a selected policy
• More reliable component, closer component, faster
  component,
• can compress the data
• Using different algorithms
• can encrypt the data
• Using different encryption algorithms

4
Connectors and Styles

• Pipe and filter
• Pipe that receives and forward outputs
• Layered
• A protocol
• Blackboard
• Blackboard
• Implicit invocation
• Event broadcast and registration infrastructure

5
A C2 Chat

• Chat Client
• A Chat Client is used by users to chat with other
  users in a Chat Room.
• A user must first register with a particular Chat
  Room before chatting with other users in that
  room.
• A User may start different Chat Clients to chat
  in multiple Chat Rooms
• Chat Room
• It queries the Registration Database to ensure
  that the user associated with a message is
  currently registered to chat in the room.
• If the user is registered, the message is
  delivered to all other users registered in the
  room, and a copy of the message is filed in a
  Chat Log associated with the Room.
• There are multiple Chat Room components
  available, each devoted to a different chat
  topic.
• Registration Database
• The Registration Database stores the set of
  currently registered users for each Chat Room and
  is able to remember which users are registered
  with which Chat Room.
• There is one Registration Database in the system.
  
• Chat Log 
• The Chat Log stores a record of all messages sent
  in a Chat Room.
• There is one Chat Log associated with each Chat
  Room.

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Chat in C2
User Registration
User in Chat
Registration Dbase
Chat Log
Chat Log
Chat Client
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First Example
F
G
D
C
E
B
D
B
F
A

• There is a choice between using or not component D

• A.B.D.F.B.A
• A.B.F.B.A.

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First Example
F
G
D
C
E
B
A

• There could be a very direct computation

• A.C.G.C.A
• A.C.G.E

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First Example
F
G
D
C
E
B
A

• We may have two different clients

• A and E

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Second Example
H
D
G
F
B
C
A
E

• Two subsystems
• They can work independently

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Second Example
H
D
G
F
B
C
A
E

• Two subsystems
• They can work together
• If A requires a service, and B or C cannot
  provide that service, H may provide it

• I A requires a service, if B or C cannot provide
  it, if G is the only component that can provide
  the service, what happen?