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HTTP the Date header line indicates the time

HTTP RESPONSEBasically, response message is a message which is sent in response to request message. Below picture shows general format of HTTP request message.?Let us take one example to understand it more deeply.HTTP/1.1 200 OKConnection: closeDate: Sat,07 Jul 2010 12:00:15 GMTServer: Apache/1.3.0(Unix)Last modified: Sun,6 May 2010 09:23:24 GMTContent-length: 5428Content-type: text/html(data data data data……)Response message  has three sections:(i) an initial status line(ii)six header lines(iii)entity bodyStatus Line:the start line of HTTP response is called status line.It has three fields:The protocol version fieldA status code which indicates failure of the requestA corresponding status messageIn above example, status line indicates that server is using HTTP/1.1 which is protocol version .200 is the status code and OK is corresponding status message which indicates that everything is OK.Header lines: It follows the same structure as any other header for example,a case-insensitive string followed by a colon (:) and a value whose structure depends upon the type of the header. The whole header with  its value presents as a single line.In above example, server uses Connection : close  header line and tell the client that it is going to close TCP connection after sending message.In above example, the Date header line indicates the time and date when HTTP response message was created and sent by server.Here note that it is not the when the object was created or last modified, it is the time when server retrieves the objects from its file system and inserts the object into the HTTP response and sends it.In above example the server header line indicates that the message is served (generated) by apache web server .In above example,  User-agent which is analogous by server is a response header line.In above example,Last-Modified header line indicates the date and time when the object was created and last modified.It is critical for object caching.In above example, Content-Length header line indicates that the object in the entity body is HTML text.  There are so many response headers are available. We can divide it in some several groups: General headers, e.g., Via,  which applies to the whole message.Response headers, e.g., Vary and Accept-Ranges,  which gives additional information about the server which doesn’t fit in the status line.Entity headers, e.g., Content-Length, which applies to the body of the request. Obviously no such headers are transmitted when there is no body in the request.?Entity Body: The last part of a response message is the body. Not all responses have one: responses with a status code, like 201 or 204, usually don’t.Bodies can be divided into three categories:Single-resource bodies : it contains sa single file of known length.  It is defined by the two headers: Content-Type and Content-Length.Single-resource bodies: it contains a single file of unknown length.It is encoded by chunks with Transfer-Encoding set to chunked.Multiple-resource bodies: it constains a multipart body in which each part contains a different section of information. These are relatively rare

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