Thông điệp trả lời đã thiết lập riêng của họ tiêu đề phản ứng. Những tiêu đề này cung cấp cho khách hàng với thông tin về yêu cầu cụ thể. Những tiêu đề này có thể cung cấp thông tin có thể giúp khách hàng có những yêu cầu tốt hơn trong tương lai. Bảng 1-9 cho thấy tiêu đề phản ứng thông thường HTTP. | The server is not guaranteed to respond to any request headers. If it does it does so out of the goodness of its administrator s heart for none of them are required. Response headers Response messages have their own set of response headers. These headers provide the client with information regarding this particular request. These headers can provide information that might help the client make better requests in the future. Table 1-9 shows common HTTP response headers. Table 1-9. HTTP response headers Header Description Age Public How old the response is A list of request methods the server supports Retry-After Server A date or time to try back if unavailable The name and version of the server s application software Title For HTML documents the title as given in the HTML Warning Accept-Ranges Vary Proxy-Authenticate Set-Cookie A more detailed warning message than what is in the reason phrase of the HTTP response The type of ranges that a server will accept A list of other headers that the server looks at that may cause the response to vary A list of challenges for the client from the proxy Used to set a token on the client Set-Cookie2 Similar to Set-Cookie WWW-Authenticate A list of challenges for the client from the server Entity headers Entity headers provide more detailed information about the requested entity. Table 1-10 lists some typical HTTP entity headers. Table 1-10. HTTP entity headers Header Description Allow Lists the request methods that can be performed Location Tells the client where the entity really is located Content headers Content headers describe useful metadata about the content in the HTTP message. Most servers will include data about the content type length of content encoding and other useful information. Table 1-11 is a list of HTTP content headers. The Rise of the Web 11 Download at Table 1-11. HTTP content headers Header Description Content-Base The base URL for resolving relative URLs Content-Encoding Content-Language .
