# httpreq.h | documentation

    #charset "us-ascii"
    #pragma once

    /*
     *   Copyright 2010 Michael J. Roberts.
     *
     *   This file is part of TADS 3.
     *
     *   This module defines the HTTPRequest intrinsic class.  This class
     *   represents a request sent from a network client to the byte-code program
     *   via the program's HTTP server object.
     *
     *   See the HTTPServer object for details on setting up an HTTP server
     *   within the program.
     *
     *   HTTPRequest objects are not created with 'new'.  Instead, the system
     *   creates them when HTTP requests arrive, and returns them to the
     *   byte-code program via the netEvent() built-in function.
     */

    /*
     *   HTTP Request object.  This object represents an HTTP protocol request
     *   from a client to one of our servers.  HTTPRequest objects are created by
     *   the HTTPServer object as requests arrive, and are passed to the byte
     *   code program as network events, via the getNetEvent() function.  The
     *   program uses the object to get information on the request and to send
     *   back the reply.
     */
    intrinsic class HTTPRequest 'http-request/030001': Object
    {
        /*
         *   Get the HTTPServer object.  This is the server that received the
         *   network request that 'self' represents.
         */
        getServer();

        /*
         *   Get the verb.  This is the HTTP verb that the client sent with the
         *   request to indicate what action to perform.  The standard HTTP verbs
         *   are GET (this is the most common request type; it simply retrieves a
         *   resource from the server), POST (used to submit form data), OPTIONS,
         *   HEAD, PUT, DELETE, TRACE, CONNECT, and PATCH.  If the client sends a
         *   non-standard verb, the system simply passes it through to the
         *   request, allowing you to write a custom server for a custom client;
         *   however, this isn't recommended, since proxies and firewalls often
         *   block what they consider ill-formed requests.
         */
        getVerb();

        /*
         *   Get the query string.  This is the portion of the URL after the
         *   server address.  For example, if the client web browser navigated to
         *   the URL "http://www.tads.org:1234/path/resource?a=1&b=2" would
         *   return "/path/resource?a=1&b=2".
         *
         *   This is the raw query string, exactly as the client sent it.  Any
         *   '%xx' character sequences are still present in this version of the
         *   string.
         */
        getQuery();

        /*
         *   Parse the query string.  This returns a LookupTable containing the
         *   parsed elements of the query.  The element table[1] is the base
         *   resource name: this is the part of the query string up to the first
         *   '?', if any, or the entire query string if there are no parameters.
         *   If there are any parameters, they're entered in the table under the
         *   parameter names as keys.  For example, for this query string:
         *
         *.     http://www.tads.org:1234/path/resource?a=one&b=two&c=three&d
         *
         *   we'd generate this table:
         *
         *.     table[1] = '/path/resource'
         *.     table['a'] = 'one'
         *.     table['b'] = 'two'
         *.     table['c'] = 'three'
         *.     table['d'] = ''
         *
         *   For all of the strings (including the base resource name, the
         *   parameter names, and the parameter values), any '%xx' sequences are
         *   converted into the corresponding character values.  For example, if
         *   the base resource name is '/C%C3%A1fe', the resource name will be
         *   parsed to 'C�fe' (%C3%A1 is the percent-encoded representation of
         *   the UTF-8 character small A with acute accent).
         */
        parseQuery();

        /*
         *   Get a parameter from the query string.  This parses the query string
         *   and returns the parameter with the specified name, if present, or
         *   nil if not.  This does the same parsing as parseQuery(), but it
         *   returns just the specified parameter value rather than building a
         *   lookup table with all of the parameters.  This is more efficient
         *   than parseQuery() if you're just looking up one or two parameters,
         *   since it avoids building the whole table, but it's less efficient if
         *   you're looking up many parameters because this routine has to
         *   re-parse the query string on each call.
         */
        getQueryParam(name);

        /*
         *   Get the headers sent with the request by the client.  This returns a
         *   LookupTable object: the keys are the header names, and the values
         *   are the corresponding header values.  For example, for a POST, there
         *   might be a 'Content-type' key with the corresponding value
         *   'application/x-www-form-urlencoded'.
         *
         *   The element table[1] contains the HTTP request line - the first line
         *   of the request, which isn't technically a header.  This line
         *   contains the verb, the query string, and (optionally) the HTTP
         *   version string (in that order, with spaces separating the elements).
         *   The method includes this so that you can inspect the unparsed
         *   request line, if desired.
         */
        getHeaders();

        /*
         *   Look up a cookie.  This looks for the given cookie name in the
         *   cookies sent by the client, and returns a string containing the
         *   cookie's text if found.  If the cookie isn't found, returns nil.
         */
        getCookie(name);

        /*
         *   Get the cookies sent with the request by the client.  This returns a
         *   LookupTable of the cookies, with each key set to a cookie name and
         *   the corresponding value set to the cookie's text.  Cookies are
         *   assumed to contain only plan ASCII characters; any 8-bit characters
         *   in a cookie's name or value will be replaced by '?' characters.
         */
        getCookies();

        /*
         *   Get the form data-entry field values.  This returns a LookupTable
         *   containing the field values sent with the request.  Each key in the
         *   table is a field name (given by the NAME property of the HTML
         *   <INPUT> tag for the field), and each corresponding value is a string
         *   giving the value of the field as entered by the user.
         *
         *   If the form includes uploaded files (via <INPUT TYPE=FILE>), the
         *   value of each file field will be a FileUpload object instead of a
         *   string.  The 'file' property of this object contains a File object,
         *   opened in read-only mode, that can be used to retrieve the contents
         *   of the uploaded file.  Other properties of object provide the
         *   client-side name of the file and the MIME type specified by the
         *   browser.
         *
         *   This method is a convenience function that parses the message body
         *   information.  You can obtain the raw information on the posted data
         *   via the getHeader() method.
         *
         *   This method recognizes form data as a message body with content-type
         *   application/x-www-form-urlencoded or multipart/form-data.  If the
         *   request doesn't have a message body at all, or has a message body
         *   with a different content-type, this method assumes that the request
         *   has no posted form data and returns nil.  We return nil rather than
         *   an empty lookup table so that the caller can tell that this doesn't
         *   appear to be a form submission request at all.
         */
        getFormFields();

        /*
         *   Get the body of the request, if any.  Some types of HTTP requests,
         *   such as POST and PUT, contain a message body.  This returns the raw,
         *   unparsed message body.  Returns a File object, open with read-only
         *   access. If there's no message body at all, this returns nil.
         *
         *   If the body is a text type, the file will be open in text mode, with
         *   the character mapping set according to the content type passed from
         *   the client; otherwise it's open in raw binary mode.
         *
         *   The message body retrieved here is the raw request payload, without
         *   any processing.  There are two standard structured body types that
         *   are frequently used with POSTs, both of which require further
         *   parsing.  First is MIME type application/x-www-form-urlencoded,
         *   which is used to represent a basic HTML form, and encodes the data
         *   entry fields in a form; this type can be parsed via the
         *   getFormFields() method.  Second is multipart/form-data, which is
         *   used to POST forms that include uploaded files; this can be parsed
         *   with getFormFields() to retrieve the data fields, and getUploads()
         *   to get the uploaded file data.
         */
        getBody();

        /*
         *   Get the network address of the client.  This returns a list:
         *   ['ip-address', port], where 'ip-address' is a string with the IP
         *   address of the client, in decimal notation ('192.168.1.15', for
         *   example), and 'port' is an integer giving the network port number on
         *   the client side.
         */
        getClientAddress();

        /*
         *   Set a cookie in the reply.  This sets a cookie with the given name
         *   and value, both given as strings.  The value string starts with the
         *   text to set for the cookie, and can be followed by additional
         *   parameters, delimited by semicolons:
         *
         *.   expires=Fri, 31-Dec-2010 23:59:59 GMT  - set expiration date
         *.   domain=.tads.org                       - scope cookie to domain
         *.   path=/                                 - scope cookie within site
         *.   httponly                               - hide cookie from Javascript
         *.   secure                                 - only send via https://
         *
         *   (These are all defined by the HTTP protocol, not by TADS.  For
         *   details, refer to any HTTP reference book or web site.)
         *
         *   A cookie without an expiration date is a session cookie: it
         *   implicitly expires as soon as the browser application terminates.
         *   The presence of an expiration date makes the cookie persistent,
         *   meaning it's to be stored on disk until the given expiration date
         *   and should survive even after the browser is closed.
         *
         *   To send a cookie, you must call this BEFORE sending the reply or
         *   starting to send a chunked reply.  This is a limitation of the
         *   protocol, since the cookies must be sent at the start of the reply
         *   with the headers.  Calling this routine doesn't actually send
         *   anything immediately to the client, but simply stores the cookie
         *   with the pending request, to be sent with the reply.
         */
        setCookie(name, value);

        /*
         *   Send the reply to the request.
         *
         *   'body' is the content of the reply.  For example, for a request for
         *   an HTML page, this would contain the HTML text of the page.  This
         *   can be a string or StringBuffer, in which case the string is sent as
         *   UTF-8 data; a ByteArray, in which case the raw bytes of the byte
         *   array are sent exactly as given; an integer, in which case the body
         *   will be a default HTML page automatically generated for the
         *   corresponding HTML status code; a File object opened with read
         *   access, in which case the contents of the file will be sent; or nil,
         *   in which case no message body is sent at all (just the status code
         *   and the headers).  A file open in text mode will be sent as text,
         *   and raw mode will be sent as binary.  "Data" mode isn't allowed.
         *   Note that if a file is used, this will send the entire contents of
         *   the file, regardless of the current seek position, and the routine
         *   will have the side effect of setting the file's seek position to end
         *   of file upon return.
         *
         *   'contentType' is an optional string giving the MIME type of the
         *   reply body.  This is used to generate a Content-type header in the
         *   reply.  If this is omitted, the server generates a default MIME type
         *   according to the type of the 'body' argument.  If 'body' is given as
         *   a string, and the string starts with <HTML (ignoring any initial
         *   whitespace), the default content type is "text/html"; if the string
         *   starts with <?XML, the default type is "text/xml"; otherwise the
         *   default type is "text/plain".  If 'body' is a ByteArray, the server
         *   checks the first few bytes for signature strings for a few known
         *   types (JPEG, PNG, MP3, Ogg, MIDI), and uses the corresponding MIME
         *   type if matched; otherwise the MIME type is set to
         *   "application/octet-stream".  'contentType' is ignored when the
         *   'body' argument is an integer (because in this case the body is
         *   known to be HTML), or hwen it's nil (since there's no body at all in
         *   this case).
         *
         *   When the 'body' is a string, the server automatically adds the
         *   "charset" parameter to the Content-type header with value "utf-8".
         *
         *   'status' is an optional HTTP status code.  This can be a string, in
         *   which case it must have the standard format for an HTTP status code,
         *   which consists of a decimal status code number followed by the text
         *   description of the code: for example, "404 Not Found.  This argument
         *   can alternatively be a simple integer giving one of the standard
         *   HTTP status code numbers, in which case we'll automatically add the
         *   corresponding status code text.  If this argument is omitted, AND
         *   the 'body' is given as an integer, the 'body' value will be used as
         *   the status code.  If this is omitted and there's a non-integer
         *   'body' argument, we use "200 OK" as the default status code.
         *
         *   'headers' is an optional list of header strings.  Each element of
         *   the list is a string giving one header, in the standard format
         *   "Name: Value".  If this is omitted, the reply will contain only the
         *   standard headers synthesized by the server.
         *
         *   The server automatically generates certain headers with each reply.
         *   These should not be specified in the 'headers' argument.  The
         *   standard headers are:
         *
         *.     Content-type: per the 'contentType' argument
         *.     Content-length: length in bytes of 'body'
         *
         *   After sending the reply, the request is completed, and no further
         *   reply can be sent.
         */
        sendReply(body, contentType?, status?, headers?);

        /*
         *   Start a chunked reply.  This sends the initial headers of a reply
         *   that will be generated in pieces.  This is an alternative to sending
         *   the entire reply as a single string via sendReply(), for situations
         *   where you're generating the reply algorithmically and want to send a
         *   little bit at a time, rather than buffering up the entire reply in a
         *   string or StringBuffer to send all at once.  This is particularly
         *   useful for cases where the reply will take a while to generate,
         *   since it allows the client to interpret partial data before the
         *   entire reply is completed; and for very large reply bodies, where it
         *   would consume a lot of memory to buffer the whole reply.
         *
         *   This routine doesn't send any initial data, but simply begins the
         *   reply process.  For this reason, the content type must be specified:
         *   there's no way for the routine to infer the content type here since
         *   we don't have any body data to look at.  The content type, result
         *   code, and headers arguments work as they do with sendReply().
         *
         *   After calling this routine, call sendReplyChunk() as many times as
         *   needed to send the pieces of the reply.  After sending all of the
         *   pieces, call endChunkedReply() to finish the reply.
         */
        startChunkedReply(contentType, resultCode?, headers?);

        /*
         *   Send a piece of a chunked reply.  This can be called any number of
         *   times after calling startChunkedReply() to send the pieces of a
         *   chunked reply.
         *
         *   'body' can be a string or StringBuffer, in which case the string
         *   data are sent as UTF-8 text; or a ByteArray, in which case the raw
         *   bytes are sent.
         */
        sendReplyChunk(body);

        /*
         *   Finish a chunked reply.  This completes a chunked reply started with
         *   startChunkedReply().  After calling this routine, the request is
         *   completed, and no further reply can be sent.
         *
         *   'headers' is an optional list of additional headers to send with the
         *   end of the reply.  The HTTP chunked reply mechanism allows a server
         *   to send headers at the beginning of the reply (which corresponds to
         *   the startChunkedReply() call), at the end of the reply (in this
         *   routine), or both.  This accommodates situations where the server
         *   might not be able to determine the final value for a header until
         *   after generating full reply.  If this argument is included, it works
         *   just like the 'headers' argument to sendReply().
         */
        endChunkedReply(headers?);

        /*
         *   Send the reply to the request asynchronously.  This works like
         *   sendReply(), except that this method starts a new background thread
         *   to handle the data transfer and then immediately returns.  This
         *   allows the caller to continue servicing other requests while the
         *   data transfer proceeds, which is important when sending a large file
         *   (such as a large image or audio file) as the reply body.  Most
         *   browsers allow the user to continue interacting with the displayed
         *   page while images and audio files are transfered in the background,
         *   so it's likely that the browser will generate new requests during
         *   the time it takes to send a single large reply body.  When you use
         *   sendReply(), the server won't be able to service any of those new
         *   requests until the reply is fully sent, so the browser will appear
         *   unresponsive for the duration of the reply data transfer.  Using
         *   sendReplyAsync() allows you to service new requests immediately,
         *   without waiting for the data transfer to complete.
         *
         *   The parameters are the same as for sendReply().  If 'body' is a
         *   File, this function opens its own separate handle to the file, so
         *   you're free to close the File object immediately, or to continue to
         *   use it for other operations.  Note that if you continue writing to
         *   the file after calling this method, it's unpredictable whether the
         *   reply data will contain the original or updated data (or a mix of
         *   new and old data), since the reply data transfer is handled in a
         *   separate thread that runs in parallel with the main program.
         *
         *   When the reply data transfer is completed, or if it fails, the
         *   system posts a NetEvent of type NetEvReplyDone to the network
         *   message queue.  The event contains the original HTTPRequest object,
         *   to allow you to relate the event back to the request that generated
         *   the reply, and status information indicating whether or not the
         *   transfer was successful.
         */
        sendReplyAsync(body, contentType?, status?, headers?);
    }

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