HTTP Request message Header instance:

HTTP Request message Header instance:

Host:rss.sina.com.cn//client Specifies the domain/IP address and port number of the Web server that you want to access
user-agent:mozilla/5.0 (Windows; U Windows NT 5.1; ZH-CN; rv:1.8.1.14) gecko/20080404 firefox/2.0.0.14the contents of the//header domain contain the user information that made the request.
accept:text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5//Define the types of media that clients can handle, sort by priority; In a comma-delimited list, you can define multiple types and use wildcards.
accept-language:zh-cn,zh;q=0.5
Accept-encoding:gzip,deflate
accept-charset:gb2312,utf-8;q=0.7,*;q=0.7
keep-alive:300
Connection:keep-alive
COOKIE:USERID=C5BYPXRIMDMSIQMSBPNE1VN8ZQMDWSM3WRLEB3VRWTNRTW <–cookie
If-modified-since:sun, June 12:05:30 GMT
Cache-control:max-age=0
HTTP Response message Header instance:
The status:ok-200 <– response status code that represents the result of the Web server processing.
Date:sun, June 12:35:47 GMT
server:apache/2.0.61 (Unix)
Last-modified:sun, June 12:35:30 GMT
Accept-ranges:bytes
content-length:18616
cache-control:max-age=120
Expires:sun, June 12:37:47 GMT
Content-type:application/xml
Age:2
X-cache:hit HTTP headers used by the reverse proxy server from 236-41.d07071951.sina.com.cn <–
via:1.0 236-41.d07071951.sina.com.cn:80 (SQUID/2.6.STABLE13)
Connection:close
=====================================

HTTP Header Explanation

1. Accept: Tell the Web server what type of media you accept, */* represents any type, type/* represents all subtypes under that type, Type/sub-type.

2. Accept-charset: The browser affirms its own received character set
Accept-encoding: The browser declares itself to receive the encoding method, usually specifies the compression method, whether compression is supported, what compression method is supported (Gzip,deflate)
Accept-language:: The browser affirms that the language you receive differs from the character set: Chinese is language, Chinese has multiple character sets, such as BIG5,GB2312,GBK and so on.

3. The Accept-ranges:web server indicates whether it accepts requests to obtain a portion of its entity, such as a portion of a file. Bytes: Accept, none: Indicates not accepted.

4. Age: When the proxy server responds to a request with its own cached entity, the header is used to indicate how long the entity has been from the time it was produced to the present.

5. Authorization: When the client receives a www-authenticate response from the Web server, the header responds to its own authentication information to the Web server.

6. Cache-control: Request: No-cache (do not cache the entity, request now from the Web server to fetch)
Max-age: (Accept only the age value is less than the Max-age value, and there are no expired objects)
Max-stale: (Can accept past objects, but the expiration time must be less than
Max-stale value)
Min-fresh: (accepting that its freshness is greater than the sum of its current age and Min-fresh values
Cache objects)
Response: Public (can respond to any user with Cached content)
Private (only cached content can be used to respond to the user who previously requested the content)
No-cache (can be cached, but only after the Web server has verified that it is valid to be returned to the client)
Max-age: (The expiration time of the object contained in this response)
All:no-store (cache not allowed)

7. Connection: Request: Close (Tell the Web server or proxy server to complete the response to this request
, disconnect and do not wait for subsequent requests for this connection).
KeepAlive (Tell the Web server or proxy server to complete this request
After the response, remain connected, waiting for subsequent requests for this connection).
Response: Close (the connection is closed).
KeepAlive (connection is maintained, waiting for subsequent requests for this connection).
Keep-alive: If the browser requests to remain connected, the header indicates that you want the WEB server to remain
How long to connect (in seconds).
Example: keep-alive:300

8. The Content-encoding:web server indicates what compression method (Gzip,deflate) It uses to compress the objects in the response.
Example: Content-encoding:gzip
The Content-language:web server tells the browser the language of the object it responds to.
The Content-length:web server tells the browser the length of the object it responds to.
Example: content-length:26012
The Content-range:web server indicates that the response contains part of the object that is the entire object.
Example: Content-range:bytes 21010-47021/47022
The Content-type:web server tells the browser what type of object it responds to.
Example: Content-type:application/xml

9. ETag: is an object (such as a URL) of the flag value, in terms of an object, such as an HTML file,
If it is modified, its etag will not be modified, so the role of the ETag with last-modified
function, mainly for the WEB server to determine whether an object has changed.
For example, when a previous request for an HTML file, the ETAG was obtained, and when the file was requested this time,
The browser sends the previously acquired ETAG value to the Web server, and the Web server
Compares the etag to the current etag of the file and then knows that the file
There has been no change.

The Expired:web server indicates when the entity will expire, and for expired objects, only the
After the Web server has verified its validity, it can be used to respond to customer requests.
It's http/1.0 's head.
Example: Expires:sat, 10:02:12 GMT

Host: The client specifies the domain/IP address and port number of the Web server that you want to access.
Example: Host:rss.sina.com.cn

If-match: If the ETag of an object does not change, it actually means that the object has not changed before the requested action is executed.
If-none-match: If the ETag of an object changes, it also means that the object has changed to perform the requested action.

If-modified-since: If the requested object was modified after the specified time in the header, the request is executed
(For example, return object), or return code 304, telling the browser that the object
Not modified.
Example: If-modified-since:thu, APR 09:14:42 GMT
If-unmodified-since: If the requested object has not been modified since the time specified in the header, the
The requested action (such as returning an object).

If-range: The browser tells the WEB server that if the object I requested does not change, put my missing part
Give me, if the object has changed, give me the whole object. Browser by sending the request object's
The ETag or the last modification time you know to the WEB server to determine if the object
Has changed.
Always used with the Range header.

Last-modified:web server considers the last modification time of the object, such as the last modification time of the file,
The last generation time of the dynamic page, and so on.
For example: Last-modified:tue, May 02:42:43 GMT

The Location:web server tells the browser that the object you are trying to access has been moved to another location,
To the location specified in the header.
For example: Location:

Http://i0.sinaimg.cn/dy/deco/2008/0528/sinahome_0803_ws_005_text_0.gif

PRAMGA: The main use of pramga:no-cache, equivalent to Cache-control:no-cache.
Example: Pragma:no-cache

Proxy-authenticate: The proxy server responds to the browser and requires it to provide proxy authentication information.
Proxy-authorization: The browser responds to the proxy server's authentication request and provides its own identity information.

Range: A browser (such as a Flashget multi-threaded download) tells the WEB server what part of the object you want to take.
Example: range:bytes=1173546-

Referer: The browser indicates to the Web server from which page/url obtained/clicked the URL/url in the current request.
Example: referer:http://www.sina.com/

The Server:web server indicates what software and version information it is.
Example: server:apache/2.0.61 (Unix)

User-agent: The browser indicates its identity (which browser).
For example: user-agent:mozilla/5.0 (Windows; U Windows NT 5.1; ZH-CN;
rv:1.8.1.14) gecko/20080404 firefox/2.0.0.14

Transfer-encoding:web server indicates itself to the body of this response message (not the object inside the message body)
What kind of code, such as whether it is chunked (chunked).
Example: transfer-encoding:chunked

The Vary:web server uses the contents of the header to tell the Cache server under what conditions it can use this response
The returned object responds to subsequent requests.
If the source Web server receives the first request message, the header of its response message is:
Content-encoding:gzip; Vary:content-encoding then the Cache server will analyze subsequent
Request the header of the message, check its accept-encoding, and the Vary header value of the previous response
Consistent, that is, whether to use the same content encoding method, so that the Cache server can prevent the use of their own
The compressed entity in the Cache responds to browsers that do not have the ability to decompress.
Example: vary:accept-encoding

Via: Lists the proxy servers that the response from the client to the OCS or in the opposite direction
The Protocol (and version) of the request sent.
When a client request arrives at the first proxy server, the server is in a request made by itself
Add Via header and fill in your relevant information when the next proxy server receives the first proxy
Request from the server, the request from the previous proxy server will be copied via
Head, and add their relevant information to the back, and so on, when OCS receives the last proxy service
Check the Via header, you know the route through which the request was routed.
Example: via:1.0 236-81.d07071953.sina.com.cn:80 (SQUID/2.6.STABLE13)

HTTP Request message Header instance: