NAD-chapter3.pdf

Chapter 3: Client Software Design
Chapter goal:
„ Algorithm and issues
„ Concurrency in client
„ Client examples
哈工大计算机学院 work Application Development Client Software Design 1
Chapter 3: Client Software Design
Chapter goal:
„ Algorithm and issues
„ Concurrency in client
„ Client examples
哈工大计算机学院 work Application Development Client Software Design 2
Learning algorithm instead of
details
„ An application that uses TCP/IP must specify many
details about the munication.
„ Knowing the low-level details of all possible socket
functions and their exact parameters does not provide
programmers with an understanding of how to build
well-designed, distributed program.
„ General understanding of the functions used for
munication is important.
„ If the programmer knows what the program should do,
finding out how to do it is straightforward.
„ Although programmers need to understand the
conceptual capabilities of the protocol interface, they
should concentrate on learning about ways to structure
communicating programs instead of memorizing the
details of a particular interface.
哈工大计算机学院 work Application Development Client Software Design 3
Client architecture
„ Clients are conceptually simpler than
servers.
„ Most client does not explicitly handle
concurrent interaction with multiple servers.
„ Most client executes as a conventional app
program.
„ Most client does not need to enforce
protections.
哈工大计算机学院 work Application Development Client Software Design 4
Identify a server
„ Several methods to find a server’s IP address and
protocol port number:
„ Domain name or IP address as a constant in program;
„ Requiring user to identify;
„ From stable storage;
„ Using a separate protocol to find;
„ Allowing the user to specify a server address when
invoking client software makes the client program
more general and makes it possible to change server
locations.
„ Building