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\subsection{library(http/http_files): Serve plain files from a hierarchy}

\label{sec:httpfiles}

\begin{tags}
    \tag{See also}
\predref{pwp_handler}{2} provides similar facilities, where .pwp files
can be used to add dynamic behaviour.
\end{tags}

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 \predref{http_reply_file}{3} and
\predref{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 \const{prefix} option to specify that it must handle all
paths that begin with the registed location of the handler.

\begin{code}
:- 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).
\end{code}

\vspace{0.7cm}

\begin{description}
    \predicate{http_reply_from_files}{3}{+Dir, +Options, +Request}
HTTP handler that serves files from the directory \arg{Dir}. This
handler uses \predref{http_reply_file}{3} to reply plain files. If the
request resolves to a directory, it uses the option \const{indexes} to
locate an index file (see below) or uses \predref{http_reply_dirindex}{3}
to create a listing of the directory.

\arg{Options}:

\begin{description}
    \termitem{indexes}{+List}
\arg{List} of files tried to find an index for a directory. The
default is \verb$['index.html']$.
\end{description}

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

When using \predref{http_handler}{3} to bind this predicate to an HTTP
location, make sure it is bound to a location that ends in a \verb$/$.
When using \qpredref{http}{location}{3} to define symbolic names to HTTP
locations this is written as

\begin{center}
\Sneck{} \verb$http_handler(aliasname(.), http_reply_from_files(srcdir, []), [prefix])$.
\end{center}

\begin{arguments}
\arg{Dir} & is either a directory or an path-specification as
used by \predref{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
\qpredref{user}{file_search_path}{2} clauses that define the same
alias. \\
\end{arguments}

\begin{tags}
    \tag{See also}
The hookable predicate \predref{file_mime_type}{2} is used to
determine the \verb$Content-type$ from the file name.
\end{tags}
\end{description}