ππ» If you want to enjoy the full experience exploring this pdf, check it out here Chapter 2
Principles of the Application Layer
- When building new applications, all you have to worry about is two things:
- The services provided by the transport layer
- How the API (application layer interface) look like to these services
- So, we have to write applications that:
- run on different end systems
- communicate over network
- The are two styles of interaction that describe how the pieces of the network application are going to interact with each other:
- Client-Server model
- Peer-To-Peer (P2P) model
The Client-Server Paradigm
- On the server side:
- An always-on host
- Generally has a permanent IP address so that the clients will know where to contact it
- may be hosted in home, company, university or commercial data centers
- On the client side:
- Clients are going to operate by contacting and communicating with a server
- Clients will typically be intermittently (Ψ¨Ψ΄ΩΩ Ω
ΨͺΩΨ·ΨΉ) connected to the internet β wonβt have a permanent IP address
- Clients do NOT connect with each others, they interact with servers
- Ex. HTTP, IMAP, FTP
Peer-Peer architecture
- The is NO server
- We have peers -end systems- that are going to directly communicate with each other
- They request service from other peers
- They provide service in return to other peers