CS 241 Section(11/18/2010)

In Section Today…

• MP7

• Networking

• File System Intro

MP7

• MP7 is due tonight is 11:59:59pm.– Contest results based on due-date– Usual late submission policy applies for grading

purposes (30% off for up to 1 day late)

• Contest results announced in-lecture on Friday (at beginning of lecture)– Must be in attendance to claim prize– Some nice prizes by Intel

MP7

Networking Review

• Major TCP Benefits– Connect via a 3-way handshake– Reliable, ordered delivery– Single endpoint per connection

• TCP:– Extremely useful protocol features– High Overhead

Networking Review

• Major UDP Benefits– Stateless protocol• No connection, no pre-defined endpoint

– Low overhead• No reliable delivery• No ordered delivery• Generally faster round trip time than TCP

Networking Review

• TCP and UDP BOTH Provide:– IP Routing– Port-based delivery

• The address “192.168.1.1:80” could refer to TCP or UDP.– Q: How do we know that address is likely TCP?

Networking Review

• Would TCP or UDP be best to be used for…– Streaming Audio/Video?

Networking Review

• Would TCP or UDP be best to be used for…– Streaming Audio/Video? UDP– Instant Messaging?

Networking Review

• Would TCP or UDP be best to be used for…– Streaming Audio/Video? UDP– Instant Messaging? TCP– Simple File Transfer?

Networking Review

• Would TCP or UDP be best to be used for…– Streaming Audio/Video? UDP– Instant Messaging? TCP– Simple File Transfer? TCP– Short, infrequent status updates of non-essential

information?• BitTorrent Peer Updates• DNS, DHCP, etc

Networking Review

• Would TCP or UDP be best to be used for…– Streaming Audio/Video? UDP– Instant Messaging? TCP– Simple File Transfer? TCP– Short, infrequent status updates of non-essential

information? UDP• BitTorrent Peer Updates• DNS, DHCP, etc

MP8

• MP8 is scheduled to be released on Monday over break (Nov. 22nd)– The MP is designed as a one-week MP.– However, you have 2.5 weeks to work on it.• One week during break• One full week after break, and until Wednesday of the

next week.

MP8

• Broad Topic:– Make a web server!

• Programming Concepts Used:– Socket Programming– Multi-threaded Programming

• More on it in section in two weeks…

UNIX File Systems Introduction

• Nearly every modern file system is based on a directory structure:– /– /usr/– /usr/kingst/– /usr/kingst/svn/– /usr/kingst/svn/mp7/– /usr/kingst/svn/mp7/alloc.c

UNIX File Systems Introduction

• Each and every directory contains at least two links to files:– /. A reference to itself.– /.. A reference to its parent.

• Every other reference will be some form of a file or link.

UNIX File Systems Introduction

• Information about the contents of a directory is stored in a directory file.

• A directory file is simply a table containing two pieces of information:– The i-node ID of the file– The name of the file

UNIX File Systems Introduction

• Information about the contents of a directory is stored in a directory file.

• A directory file is simply a table containing two pieces of information:– The i-node ID of the file– The name of the file

UNIX File Systems Introduction

• Much like many MP7 implementations, an i-node simply contains data about a file.– File size– Location (on disk) of the file’s contents– Modification date, creation date, etc.– File’s owner– File’s permissions– …– NOT THE NAME OF THE FILE (directory file)

UNIX File Systems Introduction

UNIX File Systems Introduction

• Main lecture will discuss more on i-nodes and file systems over the next week...– We’ll discuss i-node details next week