% ---------------------------------------------------------------------- % System: ECLiPSe Constraint Logic Programming System % Copyright (C) Imperial College London and ICL 1995-1999 % Version: $Id: http_client.pl,v 1.9 2001/09/13 17:48:56 js10 Exp $ % ---------------------------------------------------------------------- /* RPC using HTTP/1.0 (request status line) and MIME-Version:1.0 (request general header) CLIENT http document used is HTTP/1.0 from the Network Working Group - internet draft - expiring in june, 19 1995. */ :- module(http_client). :- comment(summary, "HTTP client library"). :- comment(author, "Ph. Bonnet, S. Bressan and M. Meier, ECRC Munich"). :- comment(copyright, "Imperial College London and ICL"). :- comment(date, "$Date: 2001/09/13 17:48:56 $"). :- comment(http_client/7, [ template:"http_client(+Method, +Uri, +ObjectBody, +HttpParams, -RespError, -RespParam, -RespObjectBody)", summary:"Used to access HTML pages, given their URI (the method GET is applied)", args:["Method":"A string","Uri":"A string","ObjectBody":"A string", "HttpParams":"A list of terms as defined in the DCG grammar", "RespError":"Outputs a term error(ErrorCode, ErrorPhrase), where ErrorCode is he error code contained in the response and ErrorPhrase is the error phrase contained in the response", "RespParam":"Outputs a list of terms as defined in the DCG grammar", "RespObjectBody":"Outputs the object body of the response"], eg:" [eclipse 1]: use_module(http). http_grammar.pl compiled traceable 25048 bytes in 0.38 seconds http_client.pl compiled traceable 5916 bytes in 0.47 seconds http_server.pl compiled traceable 5304 bytes in 0.07 seconds http.pl compiled traceable 0 bytes in 0.57 seconds yes. [eclipse 2]: http_client(\"GET\", \"http://www.ecrc.de/staff/\", \"\", [], Status, Param, Resp). Status = error(200, \"Document follows \") Param = [date, server, contentType(mt(text, html))] Resp = \"...\" yes. "]). :- export http_compile/1, http_compile/2, http_open/2, http_client/7. :- tool(http_compile/1). :- use_module(http_grammar). /* http_client(+Method, +Uri, +ObjectBody, +HttpParams, -RespError, -RespParams, -RespObjectBody): Metod and Uri and ObjectBody and String are strings HttpParams is a list of terms defined in the DCG (http_grammar.pl) Error is a term error(ErrorCode, ErrorPhrase) ErrorCode: the error code contained in the response ErrorCode: the error phrase contained in the response RespParams is a list of terms defined in DCG (http_grammar.pl) RespObjectBody is a string containing the object body of the response The client does: - encoding of a request - sending of a request - reception of the response - decoding of the response (nothing) HttpParams are the parameteres used to constitute the header. */ http_client(Method, Uri, ObjectBody, HttpParams, RespError, RespParams, RespObjectBody):- request_enco(Method, Uri, ObjectBody, HttpParams, HostName, Request), request_send(HostName, Request, Soc), respons_recp(Soc, RespError, RespParams, RespObjectBody), close(Soc),!. /* The request encoding composes a full request. The host name and the port are obtained from the uri http document p.15 */ request_enco(Method, Uri, ObjectBody, HttpParams, HostName, Request):- hostname(Uri, HostName, PartialURL), status_line(Method, PartialURL , SL), resp_header(HttpParams, ObjectBody, H), concat_strings(SL, H, St1), concat_strings(St1, "\r\n", St2), concat_strings(St2, ObjectBody, Request). /* url decoding for http */ hostname(Uri, HostName, PartialURL):- append_strings("http://", S, Uri), open(S, string, St), read_string(St, "/", _, HostName), close(St), append_strings(HostName, PartialURL, S), !. /* Constitution of The header starting from the http parameters and the length of the object body */ status_line(Method, URL, SL):- concat_strings(Method, " ", St1), concat_strings(St1, URL, St2), concat_strings(St2, " ", St3), concat_strings(St3, "HTTP/1.0\r\n", SL). resp_header(HttpParams, ObjectBody, H):- params_format(HttpParams, P), string_length(ObjectBody, L), (L == 0 -> H = P ; params_format([contentLength(L)], CL), % could become a pb concat_strings is better concat_string([P, CL], H) ). params_format(HttpParams, P):- params_format(HttpParams, "", P). params_format([], S, S). params_format([H|T], S0, S):- phrase(header(H), L, _), open(_, string, St), list_to_token(L, St), current_stream(S1, string, St), close(St), concat_string([S0, S1, "\r\n"], S2), params_format(T, S2, S). /* sending of a request: - a socket is created and connected to hostName - the encoded request is sent */ request_send(HostName, Request, Soc):- host_and_port(HostName, HN, P), socket(internet, stream, Soc), connect(Soc, HN / P), concat_strings(Request, "\r\n", R), write(Soc, R), flush(Soc). host_and_port(HostName, HH, 80):- open(HostName, string, St), read_string(St, ":", L, H), close(St), string_length(HostName, L),!, atom_string(HH, H). host_and_port(HostName, HHH, PPP):- open(HostName, string, St), read_string(St, ":", _, H), close(St), concat_strings(H, ":", HH), append_strings(HH, P, HostName), atom_string(HHH, H), atom_string(PP, P), integer_atom(PPP, PP), !. /* reception of a response: - read a message until a CRLF is found -> response status line % status error management - analyse the response header -> length, type, encoding of the object body - read the object body */ respons_recp(S, Error, HttpParams, ObjectBody):- read_Error(S, Error),!, (Error = error(200,_) -> read_ParamsClient(S, Params), parse_Params(Params, HttpParams), read_objectBody(S, HttpParams, ObjectBody) ; true ). read_Error(S, error(ErrorCode, ErrorPhrase)):- read_string(S, end_of_line, _, SL), open(SL, string, St), token_to_list(St, L), phrase(status(_, ErrorCode, ErrorPhrase), L, _), close(St). /* general header* request header* object header* */ read_ParamsClient(S, List):- % \n instead of \r\n as in the http document read_string(S, end_of_line, _Length, Elem0), ( Elem0 \= "", Elem0 \= "\r" -> append_strings(Elem0, "\n", Elem), List = [Elem|Tail], read_ParamsClient(S, Tail) ; List = [] ). /* parsing using the DCG grammar */ parse_Params([], []). parse_Params([H|T], [P|TT]):- open(H, string, St), token_to_list(St, L), close(St), phrase(header(P), L, _), !, parse_Params(T, TT). /* read object body according to the content length in the http params */ read_objectBody(S, HttpParams, ObjectBody):- member(contentLength(L), HttpParams),!, read_string(S, "", L, ObjectBody). read_objectBody(S, HttpParams, ObjectBody):- member(contentType(_), HttpParams),!, read_string(S, "", _, ObjectBody). read_objectBody(_, _, ""). /* No response decoding. */ :- comment(http_open/2, [ template:"http_open(+Url, -Stream)", summary:"Download a web document given its URL and open a Stream to read it", args:["Url":"A string","Stream":"A variable or atom"], desc:html("This utility downloads a web document (given its URL) into a string stream and returns that string stream's identifier for reading."), eg:" [eclipse 1]: lib(http_client). yes. [eclipse 2]: http_open(\"http://icparc.ic.ac.uk/index.html\",S), read_string(S, end_of_line, _, L). S = 19 L = \"\" yes. "]). http_open(URL, Stream) :- http_client("GET", URL, "", [], Error, _Params, Response), ( Error = error(200, _OK) -> open(Response, string, Stream) ; fail ). :- comment(http_compile/1, [ template:"http_compile(+Url)", summary:"Compile an ECLiPSe source file, given its URL", args:["Url":"A string"], desc:html("This utility downloads an eclipse source file (given its URL) and compiles it. Note that this represents a security risk: the downloaded code may contain Eclipse commands that are executed on your computer. Make sure you trust the code that you download!"), eg:" [eclipse 1]: lib(http_client). yes. [eclipse 2]: http_compile(\"http://icparc.ic.ac.uk/eclipse/examples/sendmore.pl\"). yes. [eclipse 8]: sendmore1(X). X = [9, 5, 6, 7, 1, 0, 8, 2] More? (;) no (more) solution. "]). :- tool(http_compile/1, http_compile/2). http_compile(URL, Module) :- http_open(URL, Stream), compile_stream(Stream)@Module, close(Stream).