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 libraries 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 The idea of a common request handling system and three controlling libraries is outdated; the threaded server now being the only sensible controlling library.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

html_decl.pl
html_meta/1	This directive can be used to declare that an HTML rendering rule takes HTML content as argument.
html_no_content/1	True when Element has no content.
html_head.pl  -- Automatic inclusion of CSS and scripts links
html_quasiquotations.pl  -- HTML quasi quotations
html_write.pl
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_post/4	Reposition HTML to the receiving Id.
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 channel 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.
reply_html_partial/1	Reply with partial HTML document.
xhtml_ns/4	Demand an xmlns:id=Value in the outer html tag.
http_client.pl
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
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_dispatch.pl  -- Dispatch requests in the HTTP server
http_dyn_workers.pl  -- Dynamically schedule HTTP workers.
http_exception.pl
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
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	Convert between a SWI-Prolog time stamp and a string 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
http_host.pl
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_log.pl
http_log/2	Write message from Format and Args to log-stream.
http_log_close/1	If there is a currently open HTTP logfile, close it after adding a term server(Reason, Time).
http_log_stream/1	True when Stream is a stream to the opened HTTP log file.
http_logrotate/1	Rotate the available log files.
http_schedule_logrotate/2	Schedule log rotation based on maintenance broadcasts.
nolog/1	Multifile predicate that can be defined to hide request parameters from the request logfile.
password_field/1	Multifile predicate that can be defined to hide passwords from the logfile.
post_data_encoded/2	Encode the POST body for inclusion into the HTTP log file.
http_multipart_plugin.pl  -- Multipart form-data plugin
http_open.pl  -- HTTP client library
http_parameters.pl
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
http_redis_plugin.pl  -- Hook session management to use Redis
http_server.pl  -- HTTP server library
http_server_files.pl  -- Serve files needed by modules from the server
http_server_health.pl  -- HTTP Server health statistics
http_session.pl  -- HTTP Session management
http_stream.pl
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 so far.
cgi_open/4	Process CGI output.
cgi_property/2	Inquire the status of the CGI stream.
cgi_set/2	Change one of the properties.
cgi_statistics/1	Return statistics on the CGI stream subsystem.
http_chunked_add_trailer/3	Add a trailer key/value to DataStream.
http_chunked_flush/2	Emits the next chunk flush_output/1 on DataStream, but in addition adds extension parameters to the chunk.
http_chunked_open/3	Create a stream to realise HTTP chunked encoding or decoding.
http_is_chunked/1	True if DataStream is created using http_chunked_open/3.
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
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_opt_help/2	Allow reusing http option processing.
http_opt_meta/2	Allow reusing http option processing.
http_opt_type/3	Allow reusing http option processing.
http_server_hook/1	Hook that is called to start the HTTP server.
http_wrapper.pl
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.
hub.pl
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_member/2	True when Id is a member of the hub HubName.
hub_send/2	Send message to the indicated ClientId.
js_write.pl  -- Utilities for including JavaScript
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
thread_httpd.pl
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