Software Engineering 3156

1
Software Engineering 3156

• Fall 2001 Section 1
• 24-Sep-01
• 5 Project, OOA, UML
• Phil Gross

2
Administrivia

• Recitation looking like Friday 10am
• Anyone planning to use C?
• Project is here

3
Project Stuff

• Going over it in class
• Will be mutating during the next week
• Have three weeks to do specification

4
TCP

• One of the protocols on top of IP
• Quite popular, but not popular enough to call the
  whole shebang TCP/IP
• Packets will be delivered reliably, once, in
  order
• Will request retransmissions if packets are
  dropped
• Supports multiple recipients per machine with
  idea of port

5
UDP

• Alias datagrams
• Adds ports to IP, but nothing else
• I.e. totally unreliable, packets may be delivered
  out of order, not at all, multiply, etc.
• Used for real-time data

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Services Listening On Ports

• Servers have programs running in the background,
  waiting for connections on a particluar port
• Telnet on 23
• FTP on 21
• Mail (SMTP) on 25
• HTTP on 80
• Many more

7
RFCs

• Define entire structure of Internet
• Collection of publicly available documents
• www.faqs.org/rfcs

8
DNS / nslookup

• IP only understands 4-byte address
• Has no understanding of www.columbia.edu
• DNS (Domain Name System) is an amazing
  distributed database
• Translates names to numbers, globally

9
Socket Programming

• Basic client (java.net.)
• http//java.sun.com/docs/books/tutorial/networking
  /sockets/readingWriting.html
• Open a socket to destination machine
• Get Input and Output streams from socket
• Read and write
• Close streams, then sockets

10
Socket Programming II

• Basic Server
• Listen on a port
• Call accept
• You will sleep until a connection happens
• Then you will have a socket
• http//java.sun.com/docs/books/tutorial/networking
  /sockets/clientServer.html

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Java Network Programming

• Makes networking extremely easy
• One of the reasons why Java was hyped so hard in
  the early days
• Turn that stream into an ObjectOutputStream and
  send objects across the network
• C much trickier
• ACE Framework helps

12
Specifications

• UML diagrams
• Use case diagrams
• Class diagrams
• Sequence diagrams
• For AI teams, state diagrams.

13
Use Case Diagrams

• Neither Janak nor I like these much
• The idea is necessary
• Silly little stick-figure diagrams less so

14
Class Diagram

• The gutsof UML
• Show static class relationships
• Generalization inheritance
• Classes, Attributes, and Operations

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Other Attributes

• Association has a
• Have multiplicities
• And, by extension, mandatory/optional
• Can also have role name
• Navigability
• Constraints/contracts
• Composition

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Sequence Diagrams

• Show lifetime of objects
• And their interaction
• lifelines arranged vertically
• Same info as collaboration diagram
• Has numeric annotations on static diagram

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State Diagrams

• Sloppy FSMs
• States, transitions between them
• Formal FSM set of states, set of transitions,
  transition functions from (state, transition) to
  new state, set of initial states, set of final or
  accepting states

18
OOA 1

• Noun extraction
• Stepwise refinement of description
• Extract nouns
• Abstract nouns are often attributes
• Rest of nouns are candidates to be classes
• Verbs usually become events or actions

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Event Model

• Publishers and Subscribers
• Usually implies asynchronous
• synchronous is RPC
• Reliable or unreliable
• Broadcast or multicast