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preface
In this article you will gain
๐ a picture to understand the difference between HTTP and HTTPS
๐ About HTTP caching process diagram (recommended)
๐ Some common HTTP request headers and response headers explain
๐ Common HTTP status codes and explanations
๐ Protocols and explanations for the use of live video broadcasting
๐ Various parameters and explanations of cookies
๐ This HTTP memo will be updated continuously at……
The difference between HTTP and HTTPS
HTTPS has one more layer of encryption than HTTP
HTTP cache
HTTP cache processing flow
Strong cache
Expires: Indicates an Expires
The values of cache-control are
- Max-age: the unit is second. The cache time is calculated in seconds from the time when the cache is initiated. If the interval exceeds the number of seconds, the cache is invalid
- No-cache: no strong cache is used. Check whether the cache is fresh with the server
- No-store: Disables the use of caches (including negotiated caches) to request the latest resources from the server each time
- Must -revalidate: This parameter is valid before the cache expires, after which it must be verified with the server
Negotiate the cache
ETag/ LF-none-match, : hash code, which represents the identifier of a resource
Last-modified/lf-modified-since: indicates the time when the file was Last Modified
Common HTTP status code
200: OK, the client request is successful
301: Resources (web pages, etc.) are permanently transferred to another URL
302: Temporary jump
401: Unauthorized – The request is not authorized
404: Requested resource does not exist, possibly the wrong URL was entered
500: An unexpected error occurred inside the server
504: Gateway Timeout- The Gateway or proxy server cannot get the desired response within the specified time.
Request Headers
Accept: The received Type, indicating the MIME Type supported by the browser (content-type returned by the benchmarking server)
Content-type: indicates the Type of entity Content sent by the client
Cache-control: Specifies the caching mechanism followed by requests and responses, such as no-cache
If-modified-since: last-modified on the server to see If the file has changed, accurate to less than 1s
Expires: Cache-controlled. No request is made for this time
Max-age: indicates the number of seconds for resources to be cached locally. Within the validity period, no request is made but the cache is used
If-none-match: ETag of the server to Match whether the file content has changed (very accurate)
Cookie: Cookies exist and are automatically carried when the domain is accessed
Referer: Source URL of the page (applies to all types of requests, will be accurate to the detailed page address, CSRF interception commonly used for this field)
Origin: Where does the original request originate from (only down to port)), is Origin more respectful of privacy than Referer
User-agent: information about the User client, such as the UA header
HTTP Response Headers
Content-type: Specifies the Type of entity Content returned by the server
Cache-control: Specifies the caching mechanism followed by requests and responses, such as no-cache
Last-modified:
The last modification time of the requested resource
Expires: When should a document be considered expired so that it is no longer cached
Max-age: specifies the number of seconds that the client should Cache local resources. This parameter is valid only after cache-control is enabled
ETag: Identifiers for a specific version of a resource. Etags are like fingerprints
Set-cookie: Sets the Cookie associated with the page. The server passes the Cookie to the client through this header
Server: Information about a Server
Access-control-allow-origin: specifies the Origin header allowed by the server (e.g. *).
HTTP request methods
The GET:
Requests a representation of the specified resource. Requests using GET should only be used to GET data
POST:
Used to commit entities to a specified resource, often resulting in state changes or side effects on the server
PUT:
Replace all current representations of the target resource with the request payload
DELETE:
Deletes the specified resource
The HEAD:
Request a response that is identical to the response of the GET request, but without the response body
CONNECT:
Establishes a tunnel to the server identified by the target resource.
The OPTIONS:
Communication options used to describe the target resource.
TRACE:
Perform a message loopback test along the path to the target resource.
PATCH:
Used to apply partial modifications to a resource.
Live video protocol
| agreement | describe | advantages |
|---|---|---|
| HLS | HTTP Live Streaming, Apple 2. Based on HTTP protocol 3. Divide a video stream into small HTTP-based files for download |
cross-platform |
| RTMP | Real Time Messaging Protocol 2. Adobe 3. Based on TCP |
Low latency |
| HTTP – FLV | 1. Based on HTTP 2. HTTP + FLV: Encapsulate audio and video data into FLV format and then transmit it to the client through HTTP protocol |
Low latency |
Cookie
Set-Cookie – response
| Name=value | The names and values of the various cookies |
|---|---|
| Expires=Date | Cookie validity period. By default, cookies are valid only before the browser is closed. |
| Path= Path | The file directory that limits the range to which the specified Cookie can be sent. Default is current |
| Domain=domain | The default domain name is the domain name of the service that created the cookie |
| secure | Cookies can be sent only during HTTPS secure connections |
| HttpOnly | JavaScript scripts cannot get cookies |
SameSite=[None/Strict/Lax] |
– None Indicates that both same-site and cross-site requests can be sent Strict Indicates that it is sent only in the same station – Allows to be sent with top-level navigation and will be sent with GET requests initiated by third party websites |
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