Basics of Network

HTTP Keywords

1. Hyper Text Transfer Protocal: deliver hyper text from server to local browser etc.
2. Based on TCP/IP
3. Current version: HTTP/2
4. Server - Client
5. Client can request through GET, HEAD, POST, PUT, DELETE, TRACE, OPTIONS, CONNECT, PATCH.
6. Transfer anything defined by Content-Type
7. Connectionless Protocol: doesn’t maintain the connection all the time
8. Stateless protocal: A very nice explanation

URL Keywords

1. Uniform Resource Locator
2. Interpret each part of this URL: http://abc.com:8000/folder/file.html#title1location?param1=123&param2=234
3. No limits on length of URL by HTTP itself. However, some servers or clients do set limits.

Difference between URI and URL and URN: The Difference Between URLs and URIs checkout the Venn diagram.

From The Difference Between URLs and URIs

How HTTP Works

HTTP Request: use Chrome Dev Tool -> Network to find out the requests, including GET and Response.

How to Request

1. GET: request for the page
2. HEAD: similar to GET but only for the head
3. POST: post data to the uri; data is in the body; might replace existing data
4. PUT:
5. DELETE: request a deletion of the page
6. CONNECT: HTTP/1.1
7. OPTIONS: allow the user to request for info about the server
8. TRACE: mostly used for diagnostic purpose

GET will attach data on the URL, while POST will attach data in the package. Thus POST is safer.

Models

The OSI Model

Refer to The Open Systems Interconnection Model on Wikipedia.

A nice visualization of the seven layers.

The Internet Procotcal Suite

About TCP/IP

This is the Link Layer.

IP Address and Domain

Some key concepts:

• Address
• Subnet: a sub network that shares the same subnet address
• Subnet mask: 32-bit, mask the address to specify the subnet and host
• Interface

What is the slash 28 (/28) in the notation 255.255.255.240 (/28)? It means 28 bits. See the illustration bellow ¹.

204.17.5.0 -      11001100.00010001.00000101.00000000
255.255.255.240 - 11111111.11111111.11111111.11110000
                  --------------------------|sub |---

IaaS, Paas, Saas

• Infrastructure as a Service
• Platform as a Service
• Software as a Service