3.4 library(http/http_files): Serve plain files from a hierarchy

See also

pwp_handler/2 provides similar facilities, where .pwp files can be used to add dynamic behaviour.

Although the SWI-Prolog Web Server is intended to serve documents that are computed dynamically, serving plain files is sometimes necessary. This small module combines the functionality of http_reply_file/3 and http_reply_dirindex/3 to act as a simple web-server. Such a server can be created using the following code sample, which starts a server at port 8080 that serves files from the current directory (’.’). Note that the handler needs a prefix option to specify that it must handle all paths that begin with the registed location of the handler.

:- use_module(library(http/http_server)).
:- use_module(library(http/http_files)).

:- http_handler(root(.), http_reply_from_files('.', []), [prefix]).

:- initialization(http_server([port(8080)]), main).

http_reply_from_files(+Dir, +Options, +Request)

HTTP handler that serves files from the directory Dir. This handler uses http_reply_file/3 to reply plain files. If the request resolves to a directory, it uses the option indexes to locate an index file (see below) or uses http_reply_dirindex/3 to create a listing of the directory.

Options:

indexes(+List)

List of files tried to find an index for a directory. The default is ['index.html'].

not_found(+Action)

Action defines what happens if the target file was not found. Options: fail makes the handler fail silently. 404 make the handler call http_404/2. Default is fail.

Note that this handler must be tagged as a prefix handler (see http_handler/3 and module introduction). This also implies that it is possible to override more specific locations in the hierarchy using http_handler/3 with a longer path-specifier.

When using http_handler/3 to bind this predicate to an HTTP location, make sure it is bound to a location that ends in a /. When using http:location/3 to define symbolic names to HTTP locations this is written as

:- http_handler(aliasname(.), http_reply_from_files(srcdir, []), [prefix]).

Dir

is either a directory or an path-specification as used by absolute_file_name/3. This option provides great flexibility in (re-)locating the physical files and allows merging the files of multiple physical locations into one web-hierarchy by using multiple user:file_search_path/2 clauses that define the same alias.

See also

The hookable predicate file_mime_type/2 is used to determine the Content-type from the file name.