#!/usr/bin/env swipl % -*- mode: Prolog -*- % adapted from: https://github.com/kamahen/swipl-server-js-client % Start this with: % swipl simple_server.pl --port 9999 --staticdir static % TODO: if using daemon: % swipl simple_server.pl --port=.... --pidfile=/var/run/simple_server.pid % and kill $(cat /var/run/simple_server.pid) % TODO: Support HTTPS: https://www.swi-prolog.org/pldoc/man?section=ssl-https-server % See README.md for an overview of how the code works. % Access this from a browser with % http://localhost:9999 % which does a redirect to: % http://localhost:9999/static/simple_client.html % See also: % http://www.pathwayslms.com/swipltuts/html/index.html % https://swi-prolog.discourse.group/t/yet-another-web-applications-tutorial/566 % https://www.swi-prolog.org/howto/http/ % TODO: add a simple example of generating source with headers. % and use reply_html_page/3 % See also: https://swi-prolog.discourse.group/t/additional-http-headers-with-reply-html-page-2-3/3624/3 :- module(simple_server, [simple_server_main/0, simple_server_impl/1]). :- use_module(library(http/thread_httpd)). :- use_module(library(http/http_dispatch)). :- use_module(library(http/http_json)). :- use_module(library(http/http_server), [http_server/2, http_redirect/3, http_stop_server/2, http_read_json_dict/3, reply_json_dict/2]). :- use_module(library(http/http_path), [http_absolute_location/3]). :- use_module(library(http/http_files), [http_reply_from_files/3]). :- use_module(library(uri), [uri_components/2, uri_data/4, uri_edit/3]). :- use_module(library(debug)). :- use_module(library(optparse), [opt_arguments/3]). :- use_module('../../api.pl', [start_api_server/0, set_le_program_module/1, le_program_module/1, hack_module_for_taxlog/1, handle_api/1]). :- thread_pool_create(compute, 8, [ local(20000), global(100000), trail(50000), backlog(0) ]). % The most useful debug flags are here. A complete set of debug % flags can be found by % find /usr/lib/swi-prolog/library/http/ -type f | xargs -0 fgrep -nH 'debug(' :- debug(log). % enable log messages with debug(log, '...', [...]). :- debug(http(request)). :- debug(http(error)). :- debug(redirect_log). % :- debug(request_json_log). % :- debug(http(post_request)) % :- debug(http_session). % :- debug(http_path). % :- debug(http(header)). % :- debug(http(hook)). :- multifile prolog:message//1. prolog:message(S-Args) --> {atomic(S),is_list(Args)},[S-Args]. % Start with simple_server_main. :- initialization(simple_server_main, main). :- multifile http:location/3. :- multifile user:file_search_path/2. :- dynamic http:location/3. % assert_server_locations/3 dynamically set user:file_search_path/2 % using comnmand-line options. This is used by absolute_file_name/3 % to locate the directory for serving the files. :- dynamic user:file_search_path/2. % See https://www.swi-prolog.org/howto/http/HTTPFile.html % and library(http/mimetype). % e.g.: file_content_type('foo.js', text/javascript, 'text/javascript; charset=UTF-8'). %! http:location(+Alias, -Expansion, -Options) is nondet. % See https://www.swi-prolog.org/pldoc/doc_for?object=http%3Alocation/3 % This is called by http_absolute_location(+Spec, -Path, +Options), e.g.: % http_absolute_location(static('simple_client.js'), Path, []), Path='/static/simple_client.js'. % http_absolute_location(json(.), Path, []), Path='/json/'. http:location(build, root(build), []). % to use the build dir of my-app in LE http:location(static, root(static), []). http:location(json, root(json), []). %! simple_server_main/0 is det. % Start the server, then start a top-level REPL. % TODO: start the server as a daemon (see library(http/http_unix_daemon)), % which means not starting the REPL. % See also library(main):main/0 % % Note: If you run simple_server_impl/1, it exits immediately. % Instead of running prolog/0, you can do something like % thread_get_message(x), which will wait forever, or you can do % thread_join('http@9999', _Status) -- this convention is not % documented but can be found by using % thread_httpd:current_server(Port, _Goal, Thread, _Queue, _Scheme, _StartTime). % See also: https://www.swi-prolog.org/pldoc/man?section=httpunixdaemon simple_server_main :- simple_server_impl(Opts), debug(log, 'Options: ~q', [Opts]), debug(log, 'Starting REPL ...', []), prolog. % REPL - terminated with exit. % TODO: use at_halt/1 to schedule http_stop_server(Opts.port, []) % after a short time-out. %! simple_server_impl(-Opts) is det. % Process the options, start the http server. % Opts gets a dict of the options simple_server_impl(Opts) :- server_opts(Opts), % set_prolog_flag(verbose_file_search, true), % for debugging assert_server_locations(Opts), http_server(http_dispatch, % LE using dispatch to expand a new thread [port(Opts.port) % TODO: enable ssl (https): % ssl([certificate_file('cacert.pem'), % or cert.csr? % key_file('privkey.pem')]), ]). %! server_opts(-Opts:dict) is det. % Process the command-line options into a dict. server_opts(Opts) :- MinPrologVersion = 80307, current_prolog_flag(version, PrologVersion), ( PrologVersion >= MinPrologVersion -> true ; throw(error(prolog_version >= MinPrologVersion, context(current_prolog_flag(version,PrologVersion), 'SWI-Prolog version is too old'))) ), OptsSpec = [[opt(port), type(integer), default(9999), longflags([port]), help('Server port')], [opt(staticdir), type(atom), default('static'), longflags([staticdir]), help('Directory for the static files (for "static" URL)')]], opt_arguments(OptsSpec, Opts0, PositionalArgs), dict_create(Opts, opts, Opts0), ( PositionalArgs == [] -> true ; throw(error(extra_args, context(PositionalArgs), 'Unknown positional arg(s)')) ). %! assert_server_locations(+Opts:dict) is det. % Assert user:file_search_path/2 facts for the static files that can % then be accessed (using absolute_file_name/3) by % static(FileName). This is asserted dynamically because the value is % taken from the command line. assert_server_locations(Opts) :- debug(log, 'static dir: ~q', [Opts.staticdir]), asserta(user:file_search_path(static_dir, Opts.staticdir)). % http://localhost:9999/ ... redirects to /static/simple_client.html % - for debugging, 'moved' can be cleared by chrome://settings/clearBrowserData % (Cached images and files) % % This simple situation can be handled by http_redirect/2, but % for debugging, it uses http_handler_/3. :- http_handler(root(.), http_redirect_( moved, % or 'moved_temporary', for easier debugging static('simple_client.html')), []). :- http_handler(root('index.html'), http_redirect_( moved, % or 'moved_temporary', for easier debugging static('simple_client.html')), []). % Serve localhost:9999/static/ from 'static' directory (See also facts for http:location/3) % See also https://swi-prolog.discourse.group/t/how-to-debug-if-modified-since-with-http-reply-from-files/1892/3 :- http_handler(static(.), http_reply_from_files(static_dir(.), % disable cache for debugging [cache(false)]), [prefix, spawn(compute)]). :- http_handler(root(json), % localhost:9999/json reply_with_json, [priority(0)]). %! http_redirect_(+How:atom, +To, +Request) is det. % This is used to output some debug information before % calling http_redirect/3. http_redirect_(How, To, Request) :- memberchk(path(Base), Request), memberchk(request_uri(RequestURI), Request), http_absolute_location(To, ToURL, [relative_to(Base)]), uri_components(RequestURI, URI), uri_data(path, URI, ToURL, ToURI), uri_components(NewTo, ToURI), debug(redirect_log, 'Redirect: ~q', [[how:How, to:To, toURL:ToURL, requestURI:RequestURI, uri:URI, toURI:ToURI, newTo: NewTo]]), http_redirect(How, NewTo, Request). %! reply_with_json(+Request) is det. % HTTP handler for "/json" request. % This gets handed off to json_response/2. reply_with_json(Request) :- ( memberchk(method(post), Request) -> true ; throw(error(invalid_request_type, context(Request), 'Invalid request type')) ), http_read_json_dict(Request, JsonIn, % [content_type("application/json")]), [value_string_as(atom), end_of_file(@(end)), default_tag(json), true(#(true)), false(#(false)), null(#(null))]), debug(request_json_log, 'Request(json): ~q', [JsonIn]), ( json_response(JsonIn, JsonOut) -> true ; throw(error(failed_json_response, context(JsonIn, 'json_response/2 failed'))) ), reply_json_dict(JsonOut, [width(0)]). % TODO: consider Options=[status(201)] %! json_response(+Request, -Result) is det. % Process a request from the client. The Request is a "JSON" dict % (as produced by json_read_dict/3) and the Results is a "JSON" dict % that can be serialized with json_write_dict/2. % For more details, see https://www.swi-prolog.org/pldoc/man?section=jsonsupport % % If you want to debug json_response/2 (to see what's sent to the client), % you can use json_write_dict/2, which is in library(http/json: % ?- json_response(json{query: "... GoalString ..."}, Result), % json_write(user_output, Result). json_response(json{query: GoalString}, json{success: TrueFalseError, error: ErrorString, query: GoalString, query_after_call: GoalStringAfterCall, printed_output: PrintedOutput, vars: VarsResult}) :- catch(do_query(GoalString, TrueFalseError, GoalStringAfterCall, VarsResult, PrintedOutput, ErrorString), Error, handle_error(GoalString, TrueFalseError, GoalStringAfterCall, VarsResult, PrintedOutput, Error, ErrorString) ). %! do_query(+GoalString:string, -TrueFalseError:atom, -GoalStringAfterCall:string, % -VarsResult:list, -PrintedOutput:string, -ErrorString:string) :- % Parse the GoalString and call it, capturing the results, including success/error, % variable bindings, output. do_query(GoalString, TrueFalseError, GoalStringAfterCall, VarsResult, PrintedOutput, ErrorString) :- ( read_term_from_atom(GoalString, Goal, [syntax_errors(error), variable_names(Vars)]), with_output_to(string(PrintedOutput), Goal) -> maplist(format_var, Vars, VarsResult), TrueFalseError = true, format(string(GoalStringAfterCall), '~q', [Goal]) ; VarsResult = [], TrueFalseError = false, PrintedOutput = "", GoalStringAfterCall = GoalString ), ErrorString = ''. %! format_var(+VarEqualsValue, -JsonDict) is det. % Format a Var=Value into a JSON structure. format_var(Var=Value, json{var: Var, value: ValueStr}) :- format(string(ValueStr), '~q', [Value]). %! handle_error(+GoalString:string, -TrueFalseError:atom, -GoalStringAfterCall:string, % -VarsResult:list, -PrintedOutput:string, +Error, -ErrorString:string) is det. % Catch handler for json_response/2 - sets the output variables and also % processes the error term. handle_error(GoalString, TrueFalseError, GoalStringAfterCall, VarsResult, PrintedOutput, Error, ErrorString) :- TrueFalseError = error, GoalStringAfterCall = GoalString, VarsResult = [], PrintedOutput = "", format(string(ErrorString), '~q', [Error]).