WebDAV: This is how the HTTP extension works

WebDAV is a transmission protocol which makes it possible to make files or complete directories available through the Internet and  transmit them to various devices. In this article, we explain what this protocol is all about exactly, what its benefits are and what WebDAV alternatives are available.

The WebDAV protocol was developed by three working groups of the IETF (Internet Engineering Task Force). The initiator was Jim Whitehead, who founded the group in 1996 after a meeting with Sir Tim Berners Lee, the inventor of the World Wide Web. Sir Tim Berners Lee had originally planned the Internet so that web pages could not only be read by anyone, but also edited by anyone. However, as the editing options were not able to be implemented with the basic protocol set for practical reasons, Whitehead and Lee jointly developed the idea into WebDAV. A first version of the protocol was specified in 1999 in RFC 2518. The current version of the transmission protocol can be found in RFC 4918.

In order to use WebDAV to transfer data, both client and server must support the protocol. Since this is an established standard, all popular web servers actually enable corresponding implementation. And various operating systems such as Windows (since XP), macOS or Linux now also offer standard support for transmissions via the WebDAV protocol.

For example, with Windows you don’t need any additional software or drivers. You can set up and establish a WebDAV connection to a server within Explorer, which then displays the appropriate platform for data exchange as if it were a computer drive. Conversely, this also means that you can open, edit and erase files stored there or save them to the server as usual in Windows. The transfer protocol enables users access to cloud files or files on a separate server in real time, without the hassle of downloading, caching, editing and uploading.

Setting up a connection with WebDAV varies for each provider. Usually, there is the possibility to set up access management or a log-in on the server. This access can then later be used to transfer files via the protocol. In addition to an individual username and password, these log-in details always include, among other things, the IP address of the server.

Setting up a connection to a WebDAV server on Windows is relatively easy. Follow these steps:

1. Open Windows Explorer.
2. Click with the right mouse button on “This PC” and select the option “Add network location”.
3. Click on “Choose a custom network location” and enter the IP address of the WebDAV server.
4. Click “Next”.
5. In the now opened window, enter your log-in details and confirm this to complete the setup process.
6. Under “This PC” you should now also find the newly established access to the WebDAV server, among other things.

Since WebDAV uses HTTP, it also uses HTTP standard port 80 for the transmission, which is not usually blocked by firewalls. With alternate transfer methods such as FTP or SSH, additional ports often require authorization in the firewall settings. This is not only associated with an increased configuration effort, but also entails additional security risks. When transmitting via WebDAV, however, data security is not endangered by such problems. As the additional setup effort is otherwise omitted, (especially as a WebDAV server can be easily integrated within an existing HTTP server) system administrators also save a lot of time and effort.

Which servers and clients are compatible with the WebDAV protocol? The following list provides an overview.

• Apache HTTP Server: various WebDAV modules based on either the Linux tool davfs2 or the version management Apache Subversion (SVN)
• Microsoft IIS: proprietary WebDAV module
• NGINX: proprietary, very limited WebDAV module or option to purchase a third-party module
• SabreDAV: PHP application that can be used in Apache or NGINX as a WebDAV attachment instead of the supplied modules
• ownCloud: Cloud storage application with full WebDAV support
• Nextcloud: ownCloud subsidiary, which also provides WebDAV support
• lighttpd: optional module available
• Caddy: optional module available

• Git
• Linux
• macOS (including native support for CalDAV and CardDAV, which rely on WebDAV)
• Microsoft Windows
• Microsoft Office

WebDAV is part of the Internet protocol family. The alternatives to the WebDAV protocol are listed below. The two most commonly used alternatives to the WebDAV protocol are FTP and SFTP:

• FTP (File Transfer Protocol): Simple network protocol that allows the transfer of files in computer networks; can be combined with SSL/TLS (FTPS) for secure data traffic
• SSH File Transfer Protocol (SFTP): A supplement to FTP through the Secure Shell (SSH) protocol, which provides the transport protocol with additional secure file transfer capabilities

There are also the following alternatives:

• Rsync: Protocol and tool for synchronizing files
• AtomPub: HTTP-based protocol for creating and updating web resources
• Content Management Interoperability Services (CMIS): Open standard that enables various content management systems to exchange information over the Internet
• Wiki software: For example, MediaWiki
• Linked Data Platform (LDP): Specification for linked data