Webdav

[vava]

Can anyone explain to me what webDAV is? Is it a new protocol, or some sort of API?

Is it compatible over regular HTTP (1.1)?What software is required to run webDAV? and is it compatible with most common web server technology eg. Apache?

 

Any input would be appreciated.

[Sip]

Vava jan, this is the first I hear of it but here's a quote from the intro section of the current WebDAV spec (the parts I've highlighted should be 200 words or less ):

 

This document describes an extension to the HTTP/1.1 protocol that allows clients to perform remote web content authoring operations. This extension provides a coherent set of methods, headers, request entity body formats, and response entity body formats that provide operations for:

 

Properties: The ability to create, remove, and query information about Web pages, such as their authors, creation dates, etc. Also, the ability to link pages of any media type to related pages.

 

Collections: The ability to create sets of documents and to retrieve a hierarchical membership listing (like a directory listing in a file system).

 

Locking: The ability to keep more than one person from working on a document at the same time. This prevents the "lost update problem," in which modifications are lost as first one author then another writes changes without merging the other author's changes.

 

Namespace Operations: The ability to instruct the server to copy and move Web resources.

 

Requirements and rationale for these operations are described in a companion document, "Requirements for a Distributed Authoring and Versioning Protocol for the World Wide Web" [RFC2291].

 

The sections below provide a detailed introduction to resource properties (section 4), collections of resources (section 5), and locking operations (section 6). These sections introduce the abstractions manipulated by the WebDAV-specific HTTP methods described in section 8, "HTTP Methods for Distributed Authoring".

 

In HTTP/1.1, method parameter information was exclusively encoded in HTTP headers. Unlike HTTP/1.1, WebDAV encodes method parameter information either in an Extensible Markup Language (XML) [REC-XML] request entity body, or in an HTTP header. The use of XML to encode method parameters was motivated by the ability to add extra XML elements to existing structures, providing extensibility; and by XML's ability to encode information in ISO 10646 character sets, providing internationalization support. As a rule of thumb, parameters are encoded in XML entity bodies when they have unbounded length, or when they may be shown to a human user and hence require encoding in an ISO 10646 character set. Otherwise, parameters are encoded within HTTP headers. Section 9 describes the new HTTP headers used with WebDAV methods.

 

In addition to encoding method parameters, XML is used in WebDAV to encode the responses from methods, providing the extensibility and internationalization advantages of XML for method output, as well as input.

 

XML elements used in this specification are defined in section 12.

 

The XML namespace extension (Appendix 4) is also used in this specification in order to allow for new XML elements to be added without fear of colliding with other element names.

 

While the status codes provided by HTTP/1.1 are sufficient to describe most error conditions encountered by WebDAV methods, there are some errors that do not fall neatly into the existing categories. New status codes developed for the WebDAV methods are defined in section 10. Since some WebDAV methods may operate over many resources, the Multi-Status response has been introduced to return status information for multiple resources. The Multi-Status response is described in section 11.

 

WebDAV employs the property mechanism to store information about the current state of the resource. For example, when a lock is taken out on a resource, a lock information property describes the current state of the lock. Section 13 defines the properties used within the WebDAV specification.

 

Finishing off the specification are sections on what it means to be compliant with this specification (section 15), on internationalization support (section 16), and on security (section 17).

 

The full text to the current spec is here.

 

So to answer your question, it seems to be an extention to the HTTP 1.1 protocol spec to fascilitate "distributed authoring".

[vava]

I really like the distributed authoring concept - and it I think I understand the necesssity of XML to set the method parameters to enable features such as locking... but how is webDAV any different than a well implemented work-group/collaboration server solution? And I noticed that the document you linked to was copywritten in 1999 - is this something that just never caught on? (especially since you had never heard of it... )

[Sasun]

2-3 years ago I heard about webDAV as the next big thing coming and never understood why it is big.

[Sip]

Doesn't sound like it's dead ... according to http://www.webdav.org the IETF just published an updated version of the spec as an RFC so it's still alive. The FAQ on that site is also pretty informative.