====== PHP HTTP Response Handling Summary ======

See [[java:HttpServletResponse]] for more information on how Java handles HTTP Responses.

See [[HTTP Request Handling]] for more information on how PHP handles HTTP requests.

===== HTTP Response Content =====

PHP has a fairly simple output mechanism compared to Java Servlets.

  * [[phpfn>print]] - Output one or more strings
  * [[phpfn>printf]] - Output formated strings
  * [[phpfn>echo]] - Output one or more strings (as a function)

The [[http://us2.php.net/manual/en/ref.outcontrol.php|Output Control Functions]] provide control over the buffering of the content output of the request.  They also provide a simple mechanism to stack output filters.  See InterceptingFilter.

  * [[phpfn>flush]] - Flush the output buffer ( useful to give end users the impression of realtime updates - see [[http://ben.milleare.com/archives/000210.html|The Joy of Flush]] for details and PEAR::HTML_Progress [[http://pear.laurent-laville.org/HTML/Progress/examples/index.html|examples]])
  * [[phpfn>ob_clean]] -  Clean (erase) the output buffer
  * [[phpfn>ob_end_clean]] -  Clean (erase) the output buffer and turn off output buffering
  * [[phpfn>ob_end_flush]] -  Flush (send) the output buffer and turn off output buffering
  * [[phpfn>ob_flush]] -  Flush (send) the output buffer
  * [[phpfn>ob_get_clean]] -  Get current buffer contents and delete current output buffer
  * [[phpfn>ob_get_contents]] -  Return the contents of the output buffer
  * [[phpfn>ob_get_length]] -  Return the length of the output buffer
  * [[phpfn>ob_get_level]] -  Return the nesting level of the output buffering mechanism
  * [[phpfn>ob_get_status]] -  Get status of output buffers
  * [[phpfn>ob_implicit_flush]] -  Turn implicit flush on/off
  * [[phpfn>ob_start]] - Turn on output buffering
  * [[phpfn>mb_output_handler]] -  Callback function converts character encoding in output buffer
output buffer configuration settings (ini)
  * ''output_buffering'' - enable buffering for all requests
  * ''output_handler'' - Register an output handling function.  Same as ob_start.
  * ''implicit_flush'' - flush output after every output block (echo, print or printf)

[[http://www.php.net/manual/en/ref.session.php|Session Handling Functions]] provide the capability to use url based session Ids in the content output.

  * ''session.use_trans_sid'' - when this option is enabled, relative URIs in the response output will be rewritten to contain a session Id.
  * ''url_rewriter.tags'' - specifies which html tags are rewritten to include session information.

The [[http://www.php.net/manual/en/ref.zlib.php|Zlib Compression Functions]] can compress output on-the-fly.

  * [[phpfn>ob_gzhandler]] -  ob_start callback function to gzip output buffer
  * [[phpfn>zlib_get_coding_type]] - Returns the coding type used for output compression

Zlib compression configuration options:
  * ''zlib.output_compression'' - Whether to transparently compress pages
  * ''zlib.output_compression_level'' - Compression level used for transparent output compression
  * ''zlib.output_handler'' - similiar to output_handler

===== HTTP Response Headers =====

Basic [[http://us2.php.net/manual/en/ref.http.php|HTTP Functions]].

  * [[phpfn>header]] - Send a raw HTTP header
  * [[phpfn>setcookie]] - Send a cookie (see [[http://www.php.net/manual/en/features.cookies.php|Cookies]])
  * [[phpfn>headers_sent]] - Checks if or where headers have been sent
  * [[phpfn>apache_response_headers]] - Fetch all HTTP response headers (see [[http://www.php.net/manual/en/ref.apache.php|Apache specific functions]])

Output compression configuration
  * ''zlib.output_compression'' - outputs ''Content-Encoding'' and ''Vary'' headers when content is compressed.

Several configuration options control how the php session handling functions output cookies for tracking sessions.

  * ''session.auto_start'' - specifies whether the session module starts a session automatically
  * ''session.name'' - Used as the cookie name
  * ''session.cookie_lifetime'' - How long should the browser store the cookie
  * ''session.cookie_path''
  * ''session.cookie_domain''
  * ''session.cookie_secure''
  * ''session.use_cookies'' - specifies whether the module will use cookies to store the session id on the client side
  * ''session.use_only_cookies'' - specifies whether the module will only use cookies to store the session id on the client side

functions controling how cookies are output during session handling.

  * [[phpfn>session_set_cookie_params]] - Set the session cookie parameters
  * [[phpfn>session_get_cookie_params]] - Get the session cookie parameters

Configuration options controlling page caching during a session:

  * ''session.cache_limiter'' - specifies cache control method to use for session page
  * ''session.cache_expire'' - specifies time-to-live for cached session pages

Functions controlling page caching during a session:

  * [[phpfn>session_cache_limiter]] - Get and/or set the current cache limiter
  * [[phpfn>session_cache_expire]] - Return current cache expire

[[http://www.php.net/manual/en/ref.apache.php|Apache specific functions]] configuration options

  * ''last_modified'' - send PHP scripts modification date as ''Last-Modified:'' header for the request.

===== HTTP Response Status =====

The [[phpfn>header]] function has special case logic to also set the response status code.  When the header paramter to the header() function begins with HTTP/, Status:, or Location:, the HTTP response status code is modified.

See [[http://www.php.net/manual/en/features.http-auth.php|HTTP authentication with PHP]] for more information about setting the response status.

===== Web Server Interface =====

[[http://www.php.net/manual/en/ref.apache.php|Apache specific functions]] for response processing

  * [[phpfn>apache_child_terminate]] - Terminate apache process after this request
  * [[phpfn>apache_lookup_uri]] -  Perform a partial request for the specified URI and return all info about it
  * [[phpfn>apache_setenv]] - Set an Apache subprocess_env variable
  * [[phpfn>virtual]] - Perform an Apache sub-request

===== HTTP Response Header / PHP Cross Reference =====

==== Content-Encoding ====

The ''zlib.output_compression'' configuration option or [[phpfn>ob_gzhandler]] output handler can output Content-Encoding: gzip or Content-Encoding: deflate headers.

==== Content-Length ====

The ''zlib.output_compression'' configuration option or [[phpfn>ob_gzhandler]] output handler can output ''Content-Length'' headers.

==== Content-Type ====

The [[phpfn>mb_output_handler]] function and the configuration option ''mbstring.http_output'' can add charset information to the ''Content-Type'' headers.

==== Last-Modified ====

The ''last_modified'' configuration option send PHP scripts modification date as ''Last-Modified:'' header for the request.  See [[http://www.php.net/manual/en/ref.apache.php|Apache specific functions]].

==== Set-Cookie ====

The [[phpfn>setcookie]] function is the standard API for developers to output this header.
PHP [[http://www.php.net/manual/en/ref.session.php|Session Handling Functions]] Will also set a cookie for tracking session Ids.

==== Vary ====

The ''zlib.output_compression'' configuration option or [[phpfn>ob_gzhandler]] output handler can output ''Vary: Accept-Encoding'' headers.