file: README.NETFILES		G. Moody	14 September 1999
				Last revised:	   27 May 2005

WFDB software reads its input from files that can be located on local
disks or (if NETFILES support is present) on remote web and FTP servers.

This version of the WFDB software package contains NETFILES support in the
WFDB library, which is compiled if you have previously installed libcurl
(see http://curl.haxx.se/) or libwww (see http://www.w3.org/Library/).
NETFILES support is known to work well under FreeBSD, GNU/Linux, Mac OS X,
MS-Windows, and Solaris.

To use NETFILES once this software has been compiled and installed, the WFDB
path should contain one or more components that refer to remote files available
via http or ftp.  If NETFILES support is included, the default WFDB path
(defined in lib/wfdblib.h) is
	. /usr/database http://www.physionet.org/physiobank/database
(i.e., the first component is the current (local) directory, the second is
/usr/database in the local file system, and the third component is the
top-level PhysioBank database directory).  If you use a local PhysioBank
mirror, you may wish to change www.physionet.org to the hostname of your local
mirror in lib/wfdblib.h before compiling the WFDB library.  You may always
override this path by setting the WFDB environment variable.

Provided that a remote path component (one beginning with http:// or ftp://)
is included in the WFDB path, all WFDB applications that read local files will
then be able to read remote files with no other changes.  Note that the default
setting allows access by WFDB applications to any of the PhysioBank records by
prefixing the additional path information to the record name, as in these
examples:

	rdsamp -r mitdb/100 -t .1     (MIT-BIH Arrhythmia Database, record 100)
	rdann -r slpdb/slp67x -a st   (MIT-BIH Polysomnographic Database,
				       record slp67x)
	wave -r mimicdb/237/237	-a al (MIMIC Database, record 237 -- note that
				       since each MIMIC record is kept in its
				       own subdirectory of mimicdb, two levels
				       of additional path information are
				       necessary)

If you have built the WFDB library using libcurl, version 7.12.0 or later,
then WFDB applications can also read password-protected files.  The simplest
way to use this feature is to create a text file named .netrc containing
entries such as

    machine www.physionet.org
        login testuser
        password PhysioNet

If your .netrc contains the three lines as shown above, and your WFDB library
was compiled with libcurl 7.12.0 or later, you can test this feature with a
command such as:

	rdann -r access-demo/100s -a atr

which will read 'atr' annotations from a password-protected copy of the
sample record (100s) on the master PhysioNet server.  Your browser can read the
same files at http://physionet.org/physiobank/database/access-demo/ (enter
"testuser" and "PhysioNet" respectively when prompted for a user name and
a password).  This demo uses digest authentication (the password is transmitted
in encrypted form, and compared against an encrypted copy on the server), but
basic authentication (in which the password is transmitted in cleartext) is
also supported.  Note, however that the data retrieved from the server travel
across the net in cleartext. If you wish to provide restricted access to
protected health information on your server to WFDB applications, we recommend
seting up SSL on your server, and using the SSL-enabled version of libcurl;
using SSL, the data travel in encrypted form across the net.

NETFILES support was originally implemented by Michael Dakin as part of his
summer 1999 UROP project at MIT.  Mike used the W3C's libwww in his original
implementation.  The libwww maintainers last updated the library in June, 2002,
and in January, 2004, the W3C formally announced that it would not continue
development of libwww, although the library remains freely available.  In May,
2005, Benjamin Moody reimplemented NETFILES using libcurl.  The primary
advantages of libcurl over libwww are that libcurl is smaller and faster, it
supports access to password-protected files, and it is actively maintained.
Both libraries are freely available on all popular platforms.