Chapter 2: Application Layer
Applications and application-layer protocols
Network applications: some jargon
Client-server paradigm
Application-layer protocols (cont).
What transport service does an app need?
Transport service requirements of common apps
Services provided by Internet transport protocols
Internet apps: their protocols and transport protocols
The Web: some jargon
The Web: the http protocol
The http protocol: more
http example
http example (cont.)
Non-persistent and persistent connections
http message format: request
http request message: general format
http message format: respone
http response status codes
Trying out http (client side) for yourself
User-server interaction: authentication
User-server interaction: cookies
User-server interaction: conditional GET
Web Caches (proxy server)
Why Web Caching?
ftp: the file transfer protocol
ftp: separate control, data connections
ftp commands, responses
Electronic Mail
Electronic Mail: mail servers
Electronic Mail: smtp [RFC 821]
Sample smtp interaction
try smtp interaction for yourself:
smtp: final words
Mail message format
Message format: multimedia extensions
MIME types Content-Type: type/subtype; parameters
Multipart Type
Mail access protocols
POP3 protocol
Email: shankar@cs.umd.edu