COMP 310 Fall 2011	Lec35: Design Post-Mortem

HW08 is due tomorrow, Tues. Nov. 15, 2011 @ 10 AM.

Outstanding design issues:

• Return type of IChatRoom.relayMsg()

Implemenation Issues:

• Adding yourself to a chat room safely -- don't want to receive your own IAddUser packet!
• How to insure that the processing of a datapacket has completed for all users.

Let's spend today's lecture hour dissecting the ChatApp design for both its strengths and weaknesses:

The Hardest Parts:

• Hardest to design?
• Hardest to understand?
• Hardest to code?
• Hardest to debug?

Issues to consider

• How did the design decision affect the program as a whole?  
  • Was it a positive or negative impact?
  • Did it make the system simpler or more complex?
  • Did it make coding easier or harder?
  • Were you coding with or against the paradigm, i.e. did it help or hinder your ability to express your ideas?
  • Did it make the system more/less
    • flexible
    • extensible
    • robust
    • correct
• What were the alternatives?
• Overall, was it the right decision?
  • What were the compromises?

Starting Points for Discussion:

• Use of extended visitors
  • Overall effect on system
    • For datapackets
    • For status
  • ICmd2ModelAdapter interface
    • Available services
• IConnection
  • alternatives?
• IChatRoom
  • No Add/RemoveAllUsers?
  • Returned type of sendMsg was an array, vs. an Iterable.
  • Lack of model access.
• IUser
  • getMsg return type, e.g. IStatus vs. ADataPacket
• IStatus
  • Inclusion of IUser sender.
• Threading issues

Class Discussion Synopsis:

© 2011 by Stephen Wong and Scott Rixner