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Class type Netcgi.cgi

class type cgi = object .. end
Object symbolizing a CGI-like request/response cycle.

This is the minimal set of services a connector must provide. Additional methods may be defined for specific connectors.

Arguments -- data sent to the script

method argument : string -> cgi_argument
#argument name returns the value of the argument named name. If the argument appears several times, only one of its instances is used.
Raises Not_found if no such argument exists.
method argument_value : ?default:string -> string -> string
#argument_value returns the value of the argument as a string. If the argument does not exist, the default is returned.
default : defaults to "".
method argument_exists : string -> bool
#argument_exists returns false if the named parameter is missing and true otherwise.
method multiple_argument : string -> cgi_argument list
#multiple_argument name returns all the values of the argument named name.
method arguments : cgi_argument list
The complete list of arguments.
method environment : cgi_environment
The environment object. This object is the "outer layer" of the activation object that connects it with real I/O channels.
method request_method : [ `DELETE | `GET | `HEAD | `POST | `PUT of cgi_argument ]
The HTTP method used to make the request.
method finalize : unit -> unit
This method calls #finalize for every CGI argument (including the possible one of PUT) to ensure that all files are deleted. It also executes all functions registered with #at_exit. It does not close the in/out channels, however. This method is not registered in the garbage collector, and it is a bad idea to do so. However, all connectors offered in Netcgi automatically call #finalize at the end of the request cycle (even when its terminated by an uncaught exception when #config.default_exn_handler is true) so you do not have to worry much about calling it yourself.

Self-referencing URL

method url : ?protocol:Nethttp.protocol ->
?with_authority:other_url_spec ->
?with_script_name:other_url_spec ->
?with_path_info:other_url_spec ->
?with_query_string:query_string_spec -> unit -> string
Returns the URL of the current CGI-like script. (Note that it may differ from the actual URL that requested the script if, for example, rewriting rules were specified in the web server configuration.)
protocol : The URL scheme. By default, the URL scheme is used that is described in the environment
with_authority : Whether to include authority part (e.g. http or https) of the URL, and if yes, from which source. Default: `Env.
with_script_name : Whether to include the part of the URL path identifying the CGI script, and if yes, from which source. Default: `Env.
with_path_info : Whether to include the rest of the URL path exceeding the script name, and if yes, from which source. Default: `Env.
with_query_string : Whether to include a query string, and if yes, which one. Only arguments with #store being `Memory will be added. Default: `None, i.e. no query string.


method set_header : ?status:Nethttp.http_status ->
?content_type:string ->
?content_length:int ->
?set_cookie:Nethttp.cookie list ->
?set_cookies:Cookie.t list ->
?cache:cache_control ->
?filename:string ->
?language:string ->
?script_type:string ->
?style_type:string -> ?fields:(string * string list) list -> unit -> unit
Sets the header (removing any previous one). When the output channel supports transactions, it is possible to set the header (possibly several times) until the #out_channel is commited for the first time or #env#send_output_header() is called. When there is no support for transactions, the header must be set before the first byte of output is written.

If #set_header is called a second time, it will overwrite all the header fields.

status : Sets the HTTP status of the reply according to RFC 2616. Defaults to "no status", but the server normally complements an `Ok status in this case.
content_type : Sets the content type. Defaults to "text/html".
content_length : Sets the content length (in bytes). Default: No such field.
set_cookie : Deprecated, use set_cookies.
set_cookies : Sets a number of cookies. Default: []. Remember that the browser may not support more than 20 cookies per web server. You can query the cookies using env#cookies and env#cookie. If you set cookies, you want to think about an appropriate cache setting. You may also want to add a P3P header (Platform for Privacy Preferences) -- otherwise your cookies may be discarded by some browsers.
cache : Sets the cache behavior for replies to GET requests. The default is `Unspecified. It is strongly recommended to specify the caching behaviour!!! You are on the safe side with `No_cache, forcing every page to be regenerated. If your data do not change frequently, `Max_age n tells the caches to store the data at most n seconds.
filename : Sets the filename associated with the page. This filename is taken for the "save as..." dialog. Default: "", i.e. no filename. Note: It is bad practice if the filename contains problematic characters (backslash, double quote, space), or the names of directories. It is recommended that you set content_type to "application/octet-stream" for this feture to work with most browsers and, if possible, to set content_length because that usually improves the download dialog.)
script_type : Sets the language of the script tag (for HTML replies). It is recommended to use this field if there are ONXXX attributes containing scripts before the first <SCRIPT> element, because you cannot specify the script language for the ONXXX attributes otherwise. script_type must be a media type, e.g. "text/javascript". Default: no language is specified.
style_type : Sets the language of the style tag (for HTML replies). It is recommended to use this field if there are STYLE attributes containing scripts before the first <STYLE> element, because you cannot specify the style language for the STYLE attributes otherwise. style_type must be a media type, e.g. "text/css". Default: no language is specified.
fields : Sets additional fields of the header. Default: [].
method set_redirection_header : ?set_cookies:Cookie.t list ->
?fields:(string * string list) list -> string -> unit
Sets the header such that a redirection to the specified URL is performed. If the URL begins with "http:" the redirection directive is passed back to the client, and the client will repeat the request for the new location (with a GET method). If the URL begins with "/", the server performs the redirection, and it is invisible for the client.
method output : Netchannels.trans_out_obj_channel
Deprecated.Use #out_channel instead.
method out_channel : Netchannels.trans_out_obj_channel
The output channel to which the generated content is intended to be written. The header is not stored in this channel, so #pos_out returns the size of the DATA in bytes (useful to set Content-Length). Note that HEAD requests must not send back a message body so, in this case, all data sent to this channel is discarded. This allows your scripts to work unmodified for GET, POST and HEAD requests.

The output channel may have transactional semantics, and because of this, it is an trans_out_obj_channel. Implementations are free to support transactions or not.

After all data have been written, the method #commit_work() must be called, even if there is no support for transactions.

Simple Example:

        cgi # out_channel # output_string "Hello world!\n";
        cgi # out_channel # commit_work()

Example for an error handler and a transaction buffer: If an error happens, it is possible to roll the channel back, and to write the error message.

          cgi # set_header ... ();
          cgi # out_channel # output_string "Hello World!"; ...
          cgi # out_channel # commit_work();
        with err ->
          cgi # out_channel # rollback_work();
          cgi # set_header ... ();
          cgi # out_channel # output_string "Software error!"; ...
          cgi # out_channel # commit_work();

method at_exit : (unit -> unit) -> unit
#at_exit f registers the function f to be executed when #finalize is called (which is done automatically when the request finishes). The functions are executed in the reverse order in which they were registered.
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