1/*  Part of Extended Libraries for SWI-Prolog
    2
    3    Author:        Edison Mera
    4    E-mail:        efmera@gmail.com
    5    WWW:           https://github.com/edisonm/xlibrary
    6    Copyright (C): 2021, Process Design Center, Breda, The Netherlands.
    7    All rights reserved.
    8
    9    Redistribution and use in source and binary forms, with or without
   10    modification, are permitted provided that the following conditions
   11    are met:
   12
   13    1. Redistributions of source code must retain the above copyright
   14       notice, this list of conditions and the following disclaimer.
   15
   16    2. Redistributions in binary form must reproduce the above copyright
   17       notice, this list of conditions and the following disclaimer in
   18       the documentation and/or other materials provided with the
   19       distribution.
   20
   21    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   22    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   23    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   24    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   25    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   26    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   27    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   28    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   29    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   30    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   31    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   32    POSSIBILITY OF SUCH DAMAGE.
   33*/
   34
   35:- module(broker,
   36          [ add_server/2,
   37            del_server/1,
   38            module_server/2
   39          ]).   40
   41:- use_module(library(lists)).   42:- use_module(library(neck)).   43:- use_module(library(codegen)).   44:- reexport(library(compound_expand)).   45:- use_module(library(change_alias)).   46:- reexport(library(interface)).

fallback(local)
timeout
timereset

   62:- dynamic
   63    module_server/2.   64
   65:- multifile
   66    '$broker'/1.   67
   68:- discontiguous
   69    '$broker'/1.   70
   71alias_file(RelTo, Alias, File) :-
   72    absolute_file_name(Alias, File, [file_type(prolog), relative_to(RelTo)]).
   73
   74add_server(Module, URL) :-
   75    '$broker'(Module),
   76    assertz(module_server(Module, URL)).
   77
   78del_server(Module) :-
   79    '$broker'(Module),
   80    retractall(module_server(Module, _)).
   81
   82generate_broker(Target, File, Module, AliasTo) -->
   83    { prolog_load_context(source, RelTo),
   84      atom_concat(Module, '_intf', Interface),
   85      atom_concat(Module, '_remt', ImplRemote),
   86      atom_concat(Module, '_locl', ImplLocal)
   87    },
   88    [broker:'$broker'(Module)],
   89    generate_interface(     File, RelTo, Module, Interface,  AliasTo, AliasIntf),
   90    generate_local( Target, File, RelTo, Module, ImplLocal,  AliasTo, AliasIntf),
   91    generate_remote(Target, File, RelTo, Module, ImplRemote, AliasTo, AliasIntf),
   92    generate_server(Target, File, RelTo, Module, Interface,  AliasTo),
   93    {bind_implementation(Target, ImplLocal, ImplRemote, BindModule)},
   94    [(:- initialization(bind_interface(Interface, BindModule)))].
   95
   96bind_implementation(client, _, M, M).
   97bind_implementation(server, M, _, M).
   98bind_implementation(proxy,  _, M, M).
   99bind_implementation(A,B,C,D) :- writeln(user_error, bind_implementation(A,B,C,D)),fail.
  100
  101generate_interface(File, RelTo, Module, Interface, AliasTo, AliasIntf) -->
  102    {generate_file('_intf', File, RelTo, AliasTo, AliasIntf, dump_interface(Module, Interface))},
  103    [(:- use_module(AliasIntf))].
  104
  105generate_local(Target, _, _, _, _, _, _) -->
  106    {member(Target, [client, proxy])},
  107    neck.
  108generate_local(server, File, RelTo, Module, ImplLocal, AliasTo, AliasIntf) -->
  109    generate_file('_locl', File, RelTo, AliasTo, _, dump_local(Module, ImplLocal, AliasIntf)).
  110
  111generate_remote(server, _, _, _, _, _, _) --> [].
  112generate_remote(Target, File, RelTo, Module, ImplRemote, AliasTo, AliasIntf) -->
  113    {member(Target, [client, proxy])},
  114    neck,
  115    generate_file('_remt', File, RelTo, AliasTo, _, dump_remote(Module, ImplRemote, AliasIntf)).
  116
  117generate_server(client, _, _, _, _, _) --> [].
  118generate_server(Target, File, RelTo, Module, Interface, AliasTo) -->
  119    {member(Target, [server, proxy])},
  120    neck,
  121    generate_file('_serv', File, RelTo, AliasTo, _, dump_server(Module, Interface)).
  122
  123:- meta_predicate
  124    generate_file(+,+,+,+,+,2),
  125    generate_file(+,+,+,+,+,2,?,?).  126
  127generate_file(Suffix, File, RelTo, AliasIntf, AliasSuff, Dump) :-
  128    change_alias(add_suffix(Suffix), AliasIntf, AliasSuff),
  129    alias_file(RelTo, AliasSuff, FileSuff),
  130    ( is_newer(FileSuff, File)
  131    ->true
  132    ; save_to_file(FileSuff, Dump)
  133    ).
  134
  135generate_file(Suffix, File, RelTo, AliasIntf, AliasSuff, Dump) -->
  136    {generate_file(Suffix, File, RelTo, AliasIntf, AliasSuff, Dump)},
  137    [(:- use_module(AliasSuff, []))].
  138
  139dump_interface(Module, Interface) -->
  140    [(:- module(Interface, [])),
  141     (:- use_module(library(interface))),
  142     (:- interfaces_mod(Module))].
  143
  144dump_local(Module, ImplLocal, AliasIntf) -->
  145    [(:- module(ImplLocal, [])),
  146     (:- use_module(library(interface))),
  147     (:- implements(AliasIntf)),
  148     (:- module_property(Module, file(File)),
  149         reexport(File))].
  150
  151dump_remote(Module, ImplRemote, AliasIntf) -->
  152    [(:- module(ImplRemote, [])),
  153     (:- use_module(library(interface))),
  154     (:- use_module(library(broker_rt))),
  155     (:- implements(AliasIntf))
  156    ],
  157    findall((H :- remote_call(H, Module)),
  158            ( module_property(Module, exports(PIL)),
  159              member(F/A, PIL),
  160              functor(H, F, A)
  161            )).
  162
  163dump_server(Module, Interface) -->
  164    {atom_concat(Module, '_serv', ImplService)},
  165    [(:- module(ImplService, [])),
  166     (:- use_module(library(http/http_dispatch))),
  167     (:- use_module(library(http/websocket))),
  168     (:- use_module(library(interface))),
  169     (:- use_module(library(broker_ws))),
  170     (:- http_handler(root(broker/Module),
  171                      http_upgrade_to_websocket(broker_ws(Interface), []),
  172                      [spawn([])]))].
  173
  174term_expansion_broker(Target, Alias, AliasIntf) -->
  175    { use_module(Alias, []), % Ensure that the module is loaded
  176      absolute_file_name(Alias, File, [file_type(prolog), access(read)]),
  177      module_property(Module, file(File))
  178    },
  179    generate_broker(Target, File, Module, AliasIntf).
  180
  181term_expansion((:- broker_client(Alias, AliasIntf)), Clauses) :-
  182    phrase(term_expansion_broker(client, Alias, AliasIntf), Clauses).
  183term_expansion((:- broker_server(Alias, AliasIntf)), Clauses) :-
  184    phrase(term_expansion_broker(server, Alias, AliasIntf), Clauses).
  185term_expansion((:- broker_proxy( Alias, AliasIntf)), Clauses) :-
  186    phrase(term_expansion_broker(proxy,  Alias, AliasIntf), Clauses)