/* Part of XPCE --- The SWI-Prolog GUI toolkit Author: Jan Wielemaker and Anjo Anjewierden E-mail: jan@swi.psy.uva.nl WWW: http://www.swi.psy.uva.nl/projects/xpce/ Copyright (c) 2000-2011, University of Amsterdam All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ :- module(pce_http_client, []). :- use_module(library(pce)). :- use_module(library(url)). :- use_module(library(option)). /* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - This module defines the clas http_client, a subclass of class socket for fetching data from HTTP servers (aka `web-servers'). It can deal with two HTTP operations # GET Get data from an URL # HEAD Get only the header from an URL. The GET operation is implemented by ->fetch_data: http_client ->fetch_data: Into:object, Confirm:[code]*, Location:[string] Fetches data from the server. Data is stored into `Into' in chunks using `->append: string' to this object. If confirm is not @nil, ->fetch_data returns after connecting and sending the request to the server. On completion, the Confirm message is executed with @arg1 The http_client object @arg2 The `Into' object If `Confirm' is @nil, ->fetch_data blocks until all data has been received. In addition to returning the data, the header of the HTTP reply is attached to the data in a sheet using the attribute `http_header'. Field-names are in lowercase. The date and last-modified fields appear as XPCE date objects and the content-length as an XPCE integer. http_client <-data --> String Simple interface to get data. Returns a string with http_header attribute sheet (see above). Blocks until all data has been received. http_client <-header --> Sheet Yield a sheet containing the header only the header data for the URL. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */ :- pce_begin_class(http_client, socket, "Client socket for HTTP Protocol"). :- pce_global(@nl_regex, new(regex('\n'))). :- pce_global(@http_reply_regex, new(regex('HTTP/([0-9]\\.[0-9])\\s*(\\d+)\\s*(\\w*)'))). :- pce_global(@http_field_regex, new(regex('([a-zA-Z0-9-]+):\\s*(.*)$'))). :- pce_global(@http_empty_line_regex, new(regex('\\s*\r?$'))). :- initialization new(_, error(http_bad_header, '%O: Bad header line: %s', warning)), new(_, error(url_bad_protocol, '%O: Can only handle %s URLs', error)), new(_, error(url_bad_syntax, '%O: Not a legal URL: %s')). variable(host, name, get, "Host-name of URL"). variable(location, string, get, "Location on server"). variable(message, code*, both, "Message send on completion"). variable(data_object, object*, get, "Object holding data"). variable(received, int*, get, "Data received"). variable(remaining, int*, get, "Remaining data"). variable(request, {header,data}*, get, "Last request"). variable(req_status, name*, get, "Progress"). variable(http_version, name, both, "Used version (1.0/1.1)"). variable(user_agent, name, both, "Provided User-Agent"). variable(verbose, {silent,connect,transfer} := connect, both, "Verbosity"). initialise(S, URL:prolog) :-> "Create from URL or parsed URL":: ( atomic(URL) -> ( parse_url(URL, Parts) -> true ; send(S, error, url_bad_syntax, URL), fail ) ; Parts = URL ), ( memberchk(protocol(http), Parts) -> true ; send(S, error, url_bad_protocol, 'HTTP'), fail ), option(host(Host), Parts), option(port(Port), Parts, 80), http_location(Parts, Location), send(S, slot, host, Host), send(S, slot, location, Location), send(S, slot, http_version, '1.0'), send(S, slot, user_agent, 'XPCE/SWI-Prolog'), send_super(S, initialise, tuple(Host, Port)). :- pce_group(feedback). req_status(S, Status:{connecting,connected,header,data,complete}) :-> "Indicate status changes":: send(S, slot, req_status, Status), ( get(S, verbose, silent) -> true ; message(Status, S, Message), ignore(send(S, Message)) ). message(connecting, S, report(progress, 'Connecting %s', Host)) :- get(S, host, Host). message(connected, _, report(progress, 'Connected')). message(header, _, report(progress, 'Receiving header')). message(data, _, report(progress, 'Receiving data')). message(complete, _, report(done)). progress(S, Progress:int, What:{percent,bytes}) :-> "Indicate progress":: ( get(S, verbose, transfer), send(S, report, progress, 'Received %d %s', Progress, What) -> true ; true ). :- pce_group(connect). connect(S) :-> "Connect to <-host":: ( get(S, status, connected) -> true ; send(S, req_status, connecting), send_super(S, connect), send(S, req_status, connected) ). :- pce_group(fetch). fetch_data(S, Object:into=object, Confirm:confirm=[code]*, Location:location=[string]) :-> "Fetch data from location into Object":: send(S, slot, data_object, Object), ( Confirm == @default -> true ; send(S, slot, message, Confirm) ), ( Location == @default -> true ; send(S, slot, location, Location) ), send(S, slot, request, data), send(S, send_header, 'GET'), ( get(S, message, Msg), Msg \== @nil -> true ; send(S, wait) ). header(S, Location:[string], Header:sheet) :<- "Fetch header data from location as a sheet":: new(Object, object), send(S, slot, data_object, Object), ( Location == @default -> true ; send(S, slot, location, Location) ), send(S, slot, request, header), send(S, send_header, 'HEAD'), send(S, wait), get(Object, http_header, Header), send(Header, lock_object, @on), send(Object, delete_attribute, http_header), get(Header, unlock, _). data(S, Data:string) :<- "Fetch data from location as string":: new(TB, text_buffer), send(TB, undo_buffer_size, 0), send(S, fetch_data, TB), get(TB, contents, Data), get(TB, http_header, Header), send(Data, attribute, http_header, Header), free(TB). :- pce_group(internal). send_header(S, Action:name) :-> "Send request header to HTTP server":: get(S, host, Host), send(S, slot, received, 0), send(S, prepare_header), send(S, slot, req_status, @nil), send(S, connect), get(S, http_version, Version), get(S, user_agent, Agent), get(S, location, Location), send(S, format, '%s %s HTTP/%s\r\n', Action, Location, Version), send(S, format, 'Host: %s\r\n', Host), send(S, format, 'User-Agent: %s\r\n', Agent), send(S, format, '\r\n'). wait(S) :-> "Wait for completion":: repeat, ( get(S, req_status, complete) -> ! ; send(@display, dispatch), fail ). prepare_header(S) :-> "Prepare for receiving header info":: send(S, record_separator, @nl_regex), send(S, input_message, message(S, header_line, @arg1)), send(S?data_object, attribute, http_header, new(sheet)). header_line(S, Line:string) :-> "Handle the header lines as they come in":: ( send(@http_field_regex, match, Line) -> get(@http_field_regex, register_value, Line, 1, name, FieldName0), get(FieldName0, downcase, FieldName), get(@http_field_regex, register_value, Line, 2, string, Value), send(Value, strip), field_type(FieldName, Type), get(@pce, convert, Value, Type, FieldValue), get(S, data_object, DataObject), send(DataObject?http_header, value, FieldName, FieldValue) ; send(@http_reply_regex, match, Line) -> get(S, data_object, DataObject), get(@http_reply_regex, register_value, Line, 2, int, ReplyStatus), send(DataObject?http_header, value, status, ReplyStatus), send(S, req_status, header) ; send(@http_empty_line_regex, match, Line) -> send(S, prepare_data) ; send(S, error, http_bad_header, Line) ). field_type('content-length', int). field_type('date', date). field_type('last-modified', date). field_type(_, name). prepare_data(S) :-> "Header has been received, prepare for content":: ( get(S, request, header) -> send(S, req_status, complete) ; ( get(S, data_object, Object), get(Object?http_header, value, 'content-length', Length) -> send(S, slot, remaining, Length) ; send(S, slot, remaining, @nil) ), send(S, input_message, message(S, data_record, @arg1)), send(S, record_separator, @nil) ). data_record(S, Record:string) :-> "Receive a data record":: get(S, data_object, Data), ( get(S, remaining, Rem), Rem \== @nil -> get(Record, size, Read), NewRem is Rem - Read, get(Data?http_header, value, 'content-length', Len), Percent is ((Len-NewRem)*100)//Len, send(S, progress, Percent, percent), ( NewRem >= 0 -> send(Data, append, Record), send(S, slot, remaining, NewRem), ( NewRem == 0 -> send(S, complete) ; true ) ; send(Record, truncate, Rem), send(Data, append, Record), send(S, complete) ) ; send(Data, append, Record), get(Record, size, Bytes), get(S, received, Rec0), Rec is Rec0 + Bytes, send(S, slot, received, Rec), send(S, progress, Rec, bytes) ). end_of_file(S) :-> "Implicit completion":: send(S, close), ( get(S, req_status, complete) -> true ; send(S, complete) ). complete(S) :-> "We received all data":: send(S, req_status, complete), ( get(S, message, Message), Message \== @nil -> get(S, data_object, Data), send(Message, forward, S, Data) ; send(S, req_status, complete) ). :- pce_end_class.