SWI-Prolog HTTP support library

This directory provides the SWI-Prolog libraries for accessing and providing HTTP services.

Client library

The main client library is library(http/http_open), which can open both HTTP and HTTPS connections and handle all request methods.

Server library

The main server libraris are

• library(http/thread_httpd) implements the server
• library(http/http_dispatch) implements binding locations predicates
• library(http/http_unix_daemon) implements integration in various Unix server managers and in general provides a suitable entry point for HTTP servers on Unix.
• library(http/html_write) implements generating HTML
• library(http/http_json) implements reading and writing JSON documents.

For simplicity, you can use library(http/http_server), which combines the typical HTTP libraries that most servers need. The idea of a common request handling system and three controlling libraries is outdated; the threaded server now being the only sensible controlling library.

Requirements

This library uses functionality from the ssl package to support HTTPS, the sgml package to read XML/HTML and the clib package for various extensions.

Prolog files

ax.pl  -- Attribute Exchange library
ax_alias/2	True when Alias is an alias name for the AX schema URL.
ax_form_attributes/2	True if Values is a list Alias(Value) for each exchanged attribute.
http_ax_attributes/2	True when HTTPAttributes is a list of Name=Value pairs that can be used with an HTTP request to query for the attributes Spec.
graphql.pl  -- GraphQL interface
html_head.pl  -- Automatic inclusion of CSS and scripts links
html_current_resource/1	True when About is a currently known resource.
html_insert_resource/3	Actually include HTML head resources.
html_requires/3	Include ResourceOrList and all dependencies derived from it and add them to the HTML head using html_post/2.
html_resource/2	Register an HTML head resource.
mime_include/4	Hook called to include a link to an HTML resource of type Mime into the HTML head.
html_quasiquotations.pl  -- HTML quasi quotations
html_write.pl  -- Write HTML text
html/3	Generate HTML from Content.
html_begin/3	For html_begin//1, Env is a term Env(Attributes); for html_end//1 it is the plain environment name.
html_current_option/1	True if Option is an active option for the HTML generator.
html_end/3	For html_begin//1, Env is a term Env(Attributes); for html_end//1 it is the plain environment name.
html_header_hook/1	This multifile hook is called just before the Content-type header is emitted.
html_meta/1	This directive can be used to declare that an HTML rendering rule takes HTML content as argument.
html_post/4	Reposition HTML to the receiving Id.
html_print_length/2	Determine the content length of a token list produced using html//1.
html_quoted/3	Quote the value for normal (CDATA) text.
html_quoted_attribute/3	Quote the value according to the rules for tag-attributes included in double-quotes.
html_receive/3	Receive posted HTML tokens.
html_receive/4	This extended version of html_receive//1 causes Handler to be called to process all messages posted to the channal at the time output is generated.
html_root_attribute/4	Add an attribute to the HTML root element of the page.
html_set_options/1	Set options for the HTML output.
layout/3	Define required newlines before and after tags.
page/3	Generate a page including the HTML <!DOCTYPE> header.
page/4	Generate a page including the HTML <!DOCTYPE> header.
print_html/1	Print list of atoms and layout instructions.
print_html/2	Print list of atoms and layout instructions.
reply_html_page/2	Provide the complete reply as required by http_wrapper.pl for a page constructed from Head and Body.
reply_html_page/3	Provide the complete reply as required by http_wrapper.pl for a page constructed from Head and Body.
xhtml_ns/4	Demand an xmlns:id=Value in the outer html tag.
http_authenticate.pl  -- Authenticate HTTP connections using 401 headers
http_client.pl  -- HTTP client library
http_cookie.pl  -- HTTP client cookie handling
update_cookies/3	Update the client cookie database.
write_cookies/3	Emit a cookie header for the current request.
cookie_remove_all_clients/0	Simply logout all clients.
cookie_remove_client/1	Fake user quitting a browser.
http_cors.pl  -- Enable CORS: Cross-Origin Resource Sharing
cors_enable/0	Emit the HTTP header Access-Control-Allow-Origin using domains from the setting http:cors.
cors_enable/2	CORS reply to a Preflight OPTIONS request.
http_digest.pl  -- HTTP Digest authentication
http_dirindex.pl  -- HTTP directory listings
mime_type_icon/2	Multi-file hook predicate that can be used to associate icons to files listed by http_reply_dirindex/3.
directory_index/4	Show index for a directory.
http_reply_dirindex/3	Provide a directory listing for Request, assuming it is an index for the physical directrory Dir.
http_dispatch.pl  -- Dispatch requests in the HTTP server
http_404/2	Reply using an "HTTP 404 not found" page.
http_current_handler/2	True if Location is handled by Closure.
http_current_handler/3	Resolve the current handler and options to execute it.
http_delete_handler/1	Delete handler for Spec.
http_dispatch/1	Dispatch a Request using http_handler/3 registrations.
http_handler/3	Register Closure as a handler for HTTP requests.
http_link_to_id/3	HREF is a link on the local server to a handler with given ID, passing the given Parameters.
http_location_by_id/2	True when Location represents the HTTP path to which the handler with identifier ID is bound.
http_redirect/3	Redirect to a new location.
http_reload_with_parameters/3	Create a request on the current handler with replaced search parameters.
http_reply_file/3	Options is a list of.
http_request_expansion/2	Register Goal for expanding the HTTP request handler.
http_safe_file/2	True if FileSpec is considered safe.
http_switch_protocol/2	Send an "HTTP 101 Switching Protocols" reply.
http_dyn_workers.pl  -- Dynamically schedule HTTP workers.
schedule_workers/1	Called if there is no immediately free worker to handle the incomming request.
http_error.pl  -- Decorate uncaught HTTP exceptions with stack-trace
http_exception.pl  -- Map Prolog exceptions to HTTP errors
bad_request_error/2	If an exception of the term error(Formal, context(Stack, Context)) is caught and subsumes_term(ContextTemplate, Context) is true, translate the exception into an HTTP 400 exception.
in_or_exclude_backtrace/2	Remove the stacktrace from the exception, unless setting http:client_backtrace is true.
map_exception_to_http_status/4	Map certain exceptions to HTTP status codes.
http_files.pl  -- Serve plain files from a hierarchy
http_reply_from_files/3	HTTP handler that serves files from the directory Dir.
http_header.pl  -- Handling HTTP headers
http_hook.pl  -- HTTP library hooks
http_host.pl  -- Obtain public server location
http_current_host/4
http_public_host/4	Current global host and port of the HTTP server.
http_public_host_url/2	True when URL is the public URL at which this server can be contacted.
http_public_url/2	True when URL is an absolute URL for the current request.
http_json.pl  -- HTTP JSON Plugin module
http_load.pl  -- Load Prolog code from a web server
ssl_verify/5	Currently we accept all certificates.
prolog_load_file/2	Hook into load_files/2 that loads http:// and https:// resources directly from the web.
http_log.pl  -- HTTP Logging module
http_multipart_plugin.pl  -- Multipart form-data plugin
http_convert_data/4	Convert multipart/form-data messages for http_read_data/3.
http_open.pl  -- HTTP client library
disable_encoding_filter/1	Do not use the Content-encoding as Transfer-encoding encoding for specific values of ContentType.
http_close_keep_alive/1	Close all keep-alive connections matching Address.
http_open/3	Open the data at the HTTP server as a Prolog stream.
http_set_authorization/2	Set user/password to supply with URLs that have URL as prefix.
map_method/2	Support additional METHOD keywords.
open_hook/6	Hook implementation that makes open_any/5 support http and https URLs for Mode == read.
http_openid.pl  -- OpenID consumer and server library
http_parameters.pl  -- Extract parameters (GET and POST) from HTTP requests
http_path.pl  -- Abstract specification of HTTP server locations
http_proxy.pl  -- Use HTTP network proxies
http_pwp.pl  -- Serve PWP pages through the HTTP server
http_redis_plugin.pl  -- Hook session management to use Redis
http_server.pl  -- HTTP server library
http_server/1	Create an HTTP server using http_dispatch/1 for handling requests.
http_server_files.pl  -- Serve files needed by modules from the server
serve_files_in_directory/2	Serve files from the directory Alias from the path-info from Request.
http_session.pl  -- HTTP Session management
http_close_session/1	Closes an HTTP session.
http_current_session/2	Enumerate the current sessions and associated data.
http_in_session/1	True if SessionId is an identifier for the current session.
http_open_session/2	Establish a new session.
http_session_assert/1	Versions of assert/1, retract/1 and retractall/1 that associate data with the current HTTP session.
http_session_assert/2	Versions of assert/1, retract/1 and retractall/1 that associate data with an explicit HTTP session.
http_session_asserta/1	Versions of assert/1, retract/1 and retractall/1 that associate data with the current HTTP session.
http_session_asserta/2	Versions of assert/1, retract/1 and retractall/1 that associate data with an explicit HTTP session.
http_session_cookie/1	Generate a random cookie that can be used by a browser to identify the current session.
http_session_data/1	True if Data is associated using http_session_assert/1 to the current HTTP session.
http_session_data/2	Versions of assert/1, retract/1 and retractall/1 that associate data with an explicit HTTP session.
http_session_id/1	True if SessionId is an identifier for the current session.
http_session_option/1	True if Option is a current option of the session system.
http_session_retract/1	Versions of assert/1, retract/1 and retractall/1 that associate data with the current HTTP session.
http_session_retract/2	Versions of assert/1, retract/1 and retractall/1 that associate data with an explicit HTTP session.
http_session_retractall/1	Versions of assert/1, retract/1 and retractall/1 that associate data with the current HTTP session.
http_session_retractall/2	Versions of assert/1, retract/1 and retractall/1 that associate data with an explicit HTTP session.
http_set_session/1	Overrule a setting for the current or specified session.
http_set_session/2	Overrule a setting for the current or specified session.
http_set_session_options/1	Set options for the session library.
session_setting/2	Find setting for SessionID.
http_sgml_plugin.pl  -- Parse of HTML and XML documents for the HTTP client libs
http_ssl_plugin.pl  -- SSL plugin for HTTP libraries
http_stream.pl  -- HTTP Streams
current_transfer_encoding/1	True if Encoding is supported.
encoding_filter/3	Install a filter to deal with chunked encoded messages.
cgi_discard/1	Discard content produced sofar.
cgi_open/4	Process CGI output.
cgi_property/2	Inquire the status of the CGI stream.
cgi_set/2	Change one of the properies.
cgi_statistics/1	Return statistics on the CGI stream subsystem.
http_chunked_open/3	Create a stream to realise HTTP chunked encoding or decoding.
is_cgi_stream/1	True if Stream is a CGI stream created using cgi_open/4.
multipart_open/3	DataStream is a stream that signals end_of_file if the multipart boundary is encountered.
multipart_open_next/1	Prepare DataStream to read the next part from the multipart input data.
stream_range_open/3	DataStream is a stream whose size is defined by the option size(ContentLength).
http_unix_daemon.pl  -- Run SWI-Prolog HTTP server as a Unix system daemon
http_wrapper.pl  -- Server processing of an HTTP request
cgi_hook/2	Hook called from the CGI processing stream.
http_current_request/1	Returns the HTTP request currently being processed.
http_peer/2	True when PeerIP is the IP address of the connection peer.
http_relative_path/2	Convert an absolute path (without host, fragment or search) into a path relative to the current page.
http_send_header/1	This API provides an alternative for writing the header field as a CGI header.
http_spawned/1	Internal use only.
http_wrap_spawned/3	Internal use only.
http_wrapper/5	Simple wrapper to read and decode an HTTP header from `In', call :Goal while watching for exceptions and send the result to the stream `Out'.
hub.pl  -- Manage a hub for websockets
jquery.pl  -- Provide JQuery
js_grammar.pl  -- JavaScript grammar
js_write.pl  -- Utilities for including JavaScript
javascript/4	Quasi quotation parser for JavaScript that allows for embedding Prolog variables to substitude identifiers in the JavaScript snippet.
js_arg/3	Same as js_expression//1, but fails if Expression is invalid, where js_expression//1 raises an error.
js_arg_list/3	Write javascript (function) arguments.
js_call/3	Emit a call to a Javascript function.
js_expression/3	Emit a single JSON argument.
js_new/4	Emit a call to a Javascript object declaration.
js_script/3	Generate a JavaScript script element with the given content.
json.pl  -- Reading and writing JSON serialization
atom_json_dict/3	Convert between textual representation and a JSON term represented as a dict.
atom_json_term/3	Convert between textual representation and a JSON term.
is_json_term/1	True if Term is a json term.
is_json_term/2	True if Term is a json term.
json_dict_pairs/2	This hook may be used to order the keys of an object.
json_read/2	Read next JSON value from Stream into a Prolog term.
json_read/3	Read next JSON value from Stream into a Prolog term.
json_read_dict/2	Read a JSON object, returning objects as a dicts.
json_read_dict/3	Read a JSON object, returning objects as a dicts.
json_write/2	Write a JSON term to Stream.
json_write/3	Write a JSON term to Stream.
json_write_dict/2	Write a JSON term, represented using dicts.
json_write_dict/3	Write a JSON term, represented using dicts.
json_write_hook/4	Hook that can be used to emit a JSON representation for Term to Stream.
json_convert.pl  -- Convert between JSON terms and Prolog application terms
current_json_object/3	Multifile predicate computed from the json_object/1 declarations.
json_object/1	Declare a JSON object.
json_to_prolog/2	Translate a JSON term into an application term.
prolog_bool_to_json/2	JSON is the JSON boolean for Prolog.
prolog_to_json/2	Translate a Prolog application Term into a JSON object term.
mimepack.pl  -- Create a MIME message
mime_pack/3	Pack a number of inputs into a MIME package using a specified or generated boundary.
mimetype.pl  -- Determine mime-type for a file
term_html.pl  -- Represent Prolog terms as HTML
term/4	Render a Prolog term as a structured HTML tree.
thread_httpd.pl  -- Threaded HTTP server
schedule_workers/1	Hook called if a new connection or a keep-alive connection cannot be scheduled immediately to a worker.
http_add_worker/2	Add a new worker to the HTTP server for port Port.
http_close_connection/1	Close connection associated to Request.
http_current_server/2	True if Goal is the goal of a server at Port.
http_current_worker/2	True if ThreadID is the identifier of a Prolog thread serving Port.
http_enough_workers/3	Check that we have enough workers in our queue.
http_requeue/1	Re-queue a connection to the worker pool.
http_server/2	Create a server at Port that calls Goal for each parsed request.
http_server_property/2	True if Property is a property of the HTTP server running at Port.
http_spawn/2	Continue this connection on a new thread.
http_stop_server/2	Stop the indicated HTTP server gracefully.
http_workers/2	Query or set the number of workers for the server at this port.
message_level/2	Determine the message stream used for exceptions that may occur during server_loop/5.
websocket.pl  -- WebSocket support
yadis.pl  -- Yadis discovery