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 The idea of a common request handling system and three controlling libraries is outdated; the threaded server now being the only sensible controlling library.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

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
graphql/4	Quasi-quotation syntax for embedding GraphQL in Prolog text.
graphql_auth_token_hook/2	Multifile, dynamic hook.
graphql_document_to_codes/3	Serialize Document, a Prolog term representing a GraphQL document as obtained from graphql_read_document/3 or the graphql/4 quasi-quotation, and unify Codes with the resulting list of character codes.
graphql_document_to_string/3	Serialize the GraphQL document Document and unify String with the resulting string.
graphql_execute_document/4	Send GraphQL document Document to be executed by the GraphQL endpoint at URI.
graphql_read_document/3	True when Document is a term representing the abstract syntax tree obtained from parsing Source as a GraphQL executable document.
html_decl.pl  -- HTML emitter analysis and IDE support
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_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/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_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_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 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.
htmx.pl  -- Support htmx.org
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_cookie.pl  -- HTTP client cookie handling
http_cors.pl  -- Enable CORS: Cross-Origin Resource Sharing
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_dirindex.pl  -- HTTP directory listings
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.
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_load.pl  -- Load Prolog code from a web server
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.
keep_alive/4	Callback when closing the range stream used to process the content of the reply.
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
try_proxy/4	Connection is via an HTTP proxy for socket: Use HTTP CONNECT.
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_files.pl  -- Serve files needed by modules from the server
http_server_health.pl  -- HTTP Server health statistics
health/2	Multifile extensible.
hide/1	Multifile hook.
server_health/1	HTTP handler that replies with the overall health of the server.
http_session.pl  -- HTTP Session management
http_sgml_plugin.pl  -- Parse of HTML and XML documents for the HTTP client libs
http_stream.pl  -- HTTP Streams
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_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  -- 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
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
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.
sse.pl  -- Server-Sent Events (SSE)
sse_comment/1	Emit Comment as one or more SSE comment lines (: lines) followed by a blank line and flush the stream.
sse_comment/2	Emit Comment as one or more SSE comment lines (: lines) followed by a blank line and flush the stream.
sse_open/0	Emit the HTTP response headers that turn the current response into a Server-Sent Events stream and write the blank line that ends the headers.
sse_open/1	Emit the HTTP response headers that turn the current response into a Server-Sent Events stream and write the blank line that ends the headers.
sse_send/1	Emit one or more SSE events and flush the stream.
sse_send/2	Emit one or more SSE events and flush the stream.
term_html.pl  -- Represent Prolog terms as HTML
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_mask/1	Produce a good random number of the mask of a client message.
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.
yadis.pl  -- Yadis discovery
ssl_verify/5	Accept all certificates.
xrds_dom/2	True when XRDS_DOM is a parsed XML document for the given resource.
xrds_location/2	Discover the location of the XRDS document from the given Id.