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
   37:- use_module(library(lists)).   38:- use_module(library(neck)).   39:- use_module(library(codegen)).   40:- use_module(library(change_alias)).   41:- reexport(library(compound_expand)).   42:- reexport(library(interface)).   43:- init_expansors.

WebSocket broker

WebSocket broker that allows to execute predicates remotely.

fallback(local)
timeout
timereset

balancing roundrobin leastconec

*/

   59alias_file(RelTo, Alias, File) :-
   60    absolute_file_name(Alias, File, [file_type(prolog), relative_to(RelTo)]).
   61
   62generate_server(File, Alias, Module, AliasTo) -->
   63    { prolog_load_context(source, RelTo),
   64      atom_concat(Module, '_intf', Interface),
   65      atom_concat(Module, '_remt', ImplRemote),
   66      atom_concat(Module, '_locl', ImplLocal),
   67      generate_intf(File, RelTo, Module, Interface,  AliasTo, AliasIntf),
   68      generate_locl(File, RelTo, Alias,  ImplLocal,  AliasTo, AliasIntf),
   69      generate_remt('_remt', File, RelTo, Module, ImplRemote, AliasTo, AliasIntf),
   70      generate_serv(File, RelTo, Module, AliasTo, AliasServ)
   71    },
   72    [(:- use_module(AliasServ, []))].
   73
   74generate_proxy(ImplProxy, File, Module, AliasIntf, AliasTo) -->
   75    { prolog_load_context(source, RelTo),
   76      generate_remt('', File, RelTo, Module, ImplProxy, AliasTo, AliasIntf),
   77      generate_prxy(File, RelTo, Module, ImplProxy, AliasTo, AliasSuff)
   78    },
   79    [(:- use_module(AliasSuff, []))].
   80
   81generate_intf(File, RelTo, Module, Interface, AliasTo, AliasIntf) :-
   82    generate_file('_intf', File, RelTo, AliasTo, AliasIntf, dump_interface(Module, Interface)).
   83
   84generate_locl(File, RelTo, Alias, ImplLocal, AliasTo, AliasIntf) :-
   85    generate_file('_locl', File, RelTo, AliasTo, _, dump_local(Alias, ImplLocal, AliasIntf)).
   86
   87generate_remt(Suff, File, RelTo, Module, ImplRemote, AliasTo, AliasIntf) :-
   88    generate_file(Suff, File, RelTo, AliasTo, _, dump_remote(Module, ImplRemote, AliasIntf)).
   89
   90generate_prxy(File, RelTo, Module, ImplRemote, AliasTo, AliasSuff) :-
   91    atom_concat(ImplRemote, '_serv', ModuleServ),
   92    generate_file('_serv', File, RelTo, AliasTo, AliasSuff, dump_server(Module, ModuleServ)).
   93
   94generate_serv(File, RelTo, Module, AliasTo, AliasSuff) :-
   95    atom_concat(Module, '_serv', ModuleServ),
   96    generate_file('_serv', File, RelTo, AliasTo, AliasSuff, dump_server(Module, ModuleServ)).
   97
   98:- meta_predicate
   99    generate_file(+,+,+,+,+,2).  100
  101generate_file(Suffix, File, RelTo, AliasIntf, AliasSuff, Dump) :-
  102    change_alias(add_suffix(Suffix), AliasIntf, AliasSuff),
  103    alias_file(RelTo, AliasSuff, FileSuff),
  104    ( is_newer(FileSuff, File)
  105    ->true
  106    ; term_to_file(FileSuff, Dump)
  107    ).
  108
  109dump_interface(Module, Interface) -->
  110    {module_property(Module, exports(PIL))},
  111    [ (:- module(Interface, PIL)),
  112      (:- use_module(library(interface))),
  113      (:- init_expansors)
  114    ],
  115    end_interface(Interface, PIL).
  116
  117dump_local(Alias, ImplLocal, AliasIntf) -->
  118    [ (:- module(ImplLocal, [])),
  119      (:- use_module(library(interface))),
  120      (:- reexport(Alias)),
  121      (:- init_expansors),
  122      (:- implements(AliasIntf))
  123    ].
  124
  125dump_remote(Module, ImplRemote, AliasIntf) -->
  126    [ (:- module(ImplRemote, [])),
  127      (:- use_module(library(interface))),
  128      (:- use_module(library(broker_rt))),
  129      (:- init_expansors),
  130      (:- implements(AliasIntf)),
  131      broker_rt:'$broker'(Module)
  132    ],
  133    findall((H :- remote_call(H, Module)),
  134            ( module_property(Module, exports(PIL)),
  135              member(F/A, PIL),
  136              functor(H, F, A)
  137            )).
  138
  139dump_server(Module, ImplService) -->
  140    [ (:- module(ImplService, [])),
  141      (:- use_module(library(http/http_dispatch))),
  142      (:- use_module(library(http/websocket))),
  143      (:- use_module(library(broker_ws))),
  144      (:- init_expansors),
  145      (:- http_handler(root(broker/Module),
  146                       http_upgrade_to_websocket(broker_ws(Module), []),
  147                       [spawn([])]))
  148    ].
  149
  150term_expansion_proxy(ImplRemote, AliasIntf, AliasImpl, AliasPrxy) -->
  151    { prolog_load_context(source, RelTo),
  152      absolute_file_name(AliasImpl, File, [file_type(prolog), access(read), relative_to(RelTo)]),
  153      use_module(AliasImpl, []), % Ensure that the module is loaded
  154      module_property(Module, file(File))
  155    },
  156    generate_proxy(ImplRemote, File, Module, AliasIntf, AliasPrxy).
  157
  158term_expansion_server(Alias, AliasIntf) -->
  159    { prolog_load_context(source, RelTo),
  160      absolute_file_name(Alias, File, [file_type(prolog), access(read), relative_to(RelTo)]),
  161      use_module(Alias, []), % Ensure that the module is loaded
  162      module_property(Module, file(File))
  163    },
  164    generate_server(File, Alias, Module, AliasIntf).
  165
  166term_expansion((:- broker_server(Alias, AliasIntf)), Clauses) :-
  167    phrase(term_expansion_server(Alias, AliasIntf), Clauses).
  168term_expansion((:- broker_proxy(ImplRemote, AliasIntf, AliasImpl, AliasPrxy)), Clauses) :-
  169    phrase(term_expansion_proxy(ImplRemote, AliasIntf, AliasImpl, AliasPrxy), Clauses)