Request message
- Start line: defines the method, access address, protocol version, CRL carriage return and line feed
- Header line: There are multiple lines, that is, various states of the header, followed by a blank line.
- Entity body: usually not used, usually only used when uploading files
Response message
- Status line: that is, the response code and protocol version
- Header line: also various header fields, for example: cookie, time, etc.
- Entity subject: generally not available
method method
- GET: Get a resource from the server
- HEAD: Only get the response header of the document from the server
- POST: Input data to the server, usually processed by the gateway program
- PUT: Store the body of the request in the server, such as uploading a file
- DELETE: request to delete the specified document on the server
- TRACE: Trace the proxy server through which the request reaches the server
- OPTIONS: request the server to return a request to support the use of the specified resource
First explanation
General header
Date: the creation time of the message
Connection: connection status, such as keepalive, close
Via: display the intermediate node (that is, the proxy server) the message passes through
Cache-control: control the cache
Request header
Accept: Media types acceptable by the server itself (eg: text/html, application/xml...)
Accept-encoding: Receive encoding format, generally refers to compression mechanisms, such as: gzip, deflate, sdch, etc.
Accept-language: Accept The language of
Host: the requested server name and port
Referer: refers to which resource the current resource is transferred from
User-agent: client agent
Conditional request header
if-modified-since: Whether the requested resource has been modified since the specified time
if-none-match: Whether the ETag tag of the document stored in the local cache does not match the Etag of the server document;
Security request header
Authorization: send authentication information to the server, such as account and password
Cookie: the client sends a cookie to the server
Proxy request header
Proxy-Authorization: Authenticate to the proxy server
Response header
age: response duration
Server: server program software name and version; generally this item should be removed on the server side
Negotiation header
accept-ranges: the type of request range acceptable to the
server Vary: the server views other header lists
Security response header
set-cookie: set cookie to the client
WWW-Authenticate: challenge authentication form from the server to the client
Entity header
Allow: List the request methods available for this entity.
Location: Tell the client where the real entity is located.
Content-Length: the length of the body.
Content-Location: the real location of the entity;
Content-Type: the object type of the body.
status code
- 100-101 information prompt, generally rarely appears
- 200-206 success, indicating that all the requested data has been successfully returned
- 300-305 redirect
- 400-415 error, client error
- 500-505 error, server-side error
Common types
200: Indicates that the server successfully processed the request. Return to the web page
301 that the client wants to access : The resource pointed to by the requested URL has been deleted, but the location of the header in the response message indicates the new location of the resource.
302: Similar to 301, but the temporary location of the resource is specified in the location of the header of the response message.
304: If the client sends a conditional method for access, and the content of the document has not changed, the server will respond with this status code
401: The authentication method of the account and password is required to access the resource 403: The request is forbidden 404 : The server cannot find the resource requested by the client 500: Internal error
502 of the server: The proxy server received a false response from the backend server