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 libarys 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.

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

html_head.pl  -- Automatic inclusion of CSS and scripts links
html_current_resource/1	True when About is a currently known resource.
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/4	The predicate html/4 implements 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_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_authenticate/3	True if Request contains the information to continue according to Type.
http_authorization_data/2	Decode the HTTP Authorization header.
http_current_user/3	True when User is present in the htpasswd file File and Fields provides the additional fields.
http_read_passwd_file/2	Read a password file.
http_write_passwd_file/2	Write password data Data to File.
authenticate/3	Plugin for library(http_dispatch) to perform basic HTTP authentication.
http_client.pl  -- HTTP client library
post_data_hook/3	Hook to extend the datatypes supported by the post(Data) option of http_open/3.
http_convert_data/4	Multi-file hook to convert a HTTP payload according to the Content-Type header.
http_delete/3	Execute a DELETE method on the server.
http_disconnect/1	Close down some connections.
http_get/3	Get data from a URL server and convert it to a suitable Prolog representation based on the Content-Type header and plugins.
http_patch/4	Issue an HTTP PATCH request.
http_post/4	Issue an HTTP POST request.
http_put/4	Issue an HTTP PUT request.
http_read_data/3	Read data from an HTTP connection and convert it according to the supplied to(Format) option or based on the Content-type in the Request.
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
authenticate/3	Plugin for library(http_dispatch) to perform basic HTTP authentication.
authenticate_client/2	This hooks is called by http_open/3 with the following Action value:.
http_digest_challenge/4	Generate the content for a 401 WWW-Authenticate: Digest header field.
http_digest_password_hash/4	Compute the password hash for the HTTP password file.
http_digest_response/5	Formulate a reply to a digest authentication request.
http_parse_digest_challenge/2	Parse the value of an HTTP WWW-Authenticate header into a list of Name(Value) terms.
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_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_header.pl  -- Handling HTTP headers
http_address/2	HTML-rule that emits the location of the HTTP server.
mime_type_encoding/2	Encoding is the (default) character encoding for MimeType.
serialize_reply/2	Multifile hook to serialize the result of status_reply/3 into a term.
status_page/3	Hook called by http_status_reply/4 and http_status_reply/5 that allows for emitting custom error pages for the following HTTP page types:.
http_join_headers/3	Append headers from Default to Header if they are not already part of it.
http_parse_header/2	Header is a list of Name(Value)-terms representing the structure of the HTTP header in Text.
http_parse_header_value/3	Translate Value in a meaningful Prolog term.
http_post_data/3	Send data on behalf on an HTTP POST request.
http_read_header/2	Read Name: Value lines from FD until an empty line is encountered.
http_read_reply_header/2	Read the HTTP reply header.
http_read_request/2	Read an HTTP request-header from FdIn and return the broken-down request fields as +Name(+Value) pairs in a list.
http_reply/2	Compose a complete HTTP reply from the term Data using additional headers from HdrExtra to the output stream Out.
http_reply/3	Compose a complete HTTP reply from the term Data using additional headers from HdrExtra to the output stream Out.
http_reply/4	Compose a complete HTTP reply from the term Data using additional headers from HdrExtra to the output stream Out.
http_reply/5	Compose a complete HTTP reply from the term Data using additional headers from HdrExtra to the output stream Out.
http_reply/6	Compose a complete HTTP reply from the term Data using additional headers from HdrExtra to the output stream Out.
http_reply_header/3	Create a reply header using reply_header//3 and send it to Stream.
http_status_reply/4	Emit HTML non-200 status reports.
http_status_reply/5	Emit HTML non-200 status reports.
http_timestamp/2	Generate a description of a Time in HTTP format (RFC1123).
http_update_connection/4	Merge keep-alive information from Request and CGIHeader into Header.
http_update_encoding/3	Allow for rewrite of the header, adjusting the encoding.
http_update_transfer/4	Decide on the transfer encoding from the Request and the CGI header.
http_hook.pl  -- HTTP library hooks
convert_parameter/3	Hook to execute a step in the HTTP parameter conversion process.
http_connection_over_proxy/6	Try to connect to the host Endpoint via Proxy for the purposes of retrieving the resource identified by URLParts.
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
post_data_hook/3	Hook implementation that allows http_post_data/3 posting JSON objects using one of the forms below.
http_convert_data/4	Hook implementation that supports reading JSON documents.
http_read_json/2	Extract JSON data posted to this HTTP request.
http_read_json/3	Extract JSON data posted to this HTTP request.
http_read_json_dict/2	Similar to http_read_json/2,3, but by default uses the version 7 extended datatypes.
http_read_json_dict/3	Similar to http_read_json/2,3, but by default uses the version 7 extended datatypes.
is_json_content_type/1	True if ContentType is a header value (either parsed or as atom/string) that denotes a JSON value.
json_type/1	True if MediaType is a JSON media type.
reply_json/1	Formulate a JSON HTTP reply.
reply_json/2	Formulate a JSON HTTP reply.
reply_json_dict/1	As reply_json/1 and reply_json/2, but assumes the new dict based data representation.
reply_json_dict/2	As reply_json/1 and reply_json/2, but assumes the new dict based data representation.
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.
open_hook/6	Hook implementation that makes open_any/5 support http and https URLs for Mode == read.
http_parameters.pl  -- Extract parameters (GET and POST) from HTTP requests
http_convert_parameter/4	Conversion of an HTTP form value.
http_convert_parameters/2	Implements the parameter translation of http_parameters/2 or http_parameters/3.
http_convert_parameters/3	Implements the parameter translation of http_parameters/2 or http_parameters/3.
http_parameters/2	Get HTTP GET or POST form-data, applying type validation, default values, etc.
http_parameters/3	Get HTTP GET or POST form-data, applying type validation, default values, etc.
http_path.pl  -- Abstract specification of HTTP server locations
location/3	Multifile hook used to specify new HTTP locations.
http_absolute_location/3	Path is the HTTP location for the abstract specification Spec.
http_absolute_uri/2	URI is the absolute (i.e., starting with http://) URI for the abstract specification Spec.
http_clean_location_cache/0	HTTP locations resolved through http_absolute_location/3 are cached.
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.
http_ssl_plugin.pl  -- SSL plugin for HTTP libraries
http_connection_over_proxy/6	Facilitate an HTTPS connection via a proxy using HTTP CONNECT.
http_protocol_hook/5	Hook for http_open/3 to connect to an HTTPS (SSL-based HTTP) server.
open_options/2	Implementation of the multifile hook http:open_options/2 used by library(http/http_open).
ssl_server_create_hook/3	Extensible predicate that is called once after creating an HTTPS server.
ssl_server_open_client_hook/3	Extensible predicate that is called before each connection that the server negotiates with a client.
accept_hook/2	Implement the accept for HTTPS connections.
make_socket_hook/3	Hook into http_server/2 to create an SSL server if the option ssl(SSLOptions) is provided.
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
sni_options/2	Hook to provide Server Name Indication (SNI) for TLS servers.
http_certificate_hook/3	Hook called before starting the server if the --https option is used.
http_daemon/0	Start the HTTP server as a daemon process.
http_daemon/1	Start the HTTP server as a daemon process.
http_server_hook/1	Hook that is called to start the HTTP server.
http_wrapper.pl  -- Server processing of an HTTP request
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
current_hub/2	True when there exists a hub Hub with Name.
hub_add/3	Add a WebSocket to the hub.
hub_broadcast/2	Send Message to all websockets associated with Hub for which call(Condition, Id) succeeds.
hub_broadcast/3	Send Message to all websockets associated with Hub for which call(Condition, Id) succeeds.
hub_create/3	Create a new hub.
hub_send/2	Send message to the indicated ClientId.
jquery.pl  -- Provide JQuery
js_grammar.pl  -- JavaScript grammar
js_token/3	Matches and classifies the next JavaScript token.
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_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.
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
charset/3	Hook that determines the Charset for File that has media type MediaType.
mime_extension/2	Hook that is called by file_mime_type/2 before the default table is examined.
file_content_type/2	True if File should be served using ContentType: ContentType.
file_content_type/3	True if File should be served using ContentType: ContentType.
file_mime_type/2	True when MimeType is the mime-type to be used for sending FileName.
term_html.pl  -- Represent Prolog terms as HTML
blob_rendering/5	Hook to render blob atoms 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
http_open_websocket/3	Establish a client websocket connection.
http_upgrade_to_websocket/3	Create a websocket connection running call(Goal, WebSocket), where WebSocket is a socket-pair.
ws_close/3	Close a WebSocket connection by sending a close message if this was not already sent and wait for the close reply.
ws_open/3	Turn a raw TCP/IP (or any other binary stream) into a websocket stream.
ws_property/2	True if Property is a property WebSocket.
ws_receive/2	Receive the next message from WebSocket.
ws_receive/3	Receive the next message from WebSocket.
ws_send/2	Send a message over a websocket.