The goal of the DASL working group "is to define and develop an extensible DAV Searching and Locating protocol as an application of HTTP. The working group will define protocol elements that enable server-executed queries to locate resources based upon their property values and text content as expressed by the DAV data model. WEBDAV and HTTP enable client-side searching by defining a simple set of mechanisms (the PROPFIND and GET methods) to locate those resources meeting client-defined criteria. These mechanisms can be inefficient, do not adequately deal with some simple content-based queries, and do not take advantage of the advanced querying and caching capabilities of modern storage systems. The DASL Protocol will enable a HTTP/1.1 compliant scheme for server-side searching to address these limitations. The working group will define the following for a server-side searching mechanism: (1) How to express the search: the syntax and semantics of a query; (2) How to focus the query by identifying its scope; (3) How to discover the search capability of a resource; (4) The syntax for the search results. The Working Group Scope: A generalized search mechanism is a broad problem space. It encompasses a variety of object models, typing schemes, and media. By focusing on a subset of this space, the problem of locating resources based on property values and text content, the working group will leverage much of the existing work that has been done on querying under simple property and resource models. In-Scope items include: (1) typing, (2) comparisons (greater than,greater than or equal to, less than, less than or equal to, !=, ==), (3) internationalized content, (4) text content matching, (5) dealing with arbitrary XML values."
From the IETF Draft: "This document defines DAV Searching & Locating (DASL), an application of HTTP/1.1 forming a lightweight search protocol to transport queries and result sets and allows clients to make use of server-side search facilities. [DASLREQ] describes the motivation for DASL. DASL will minimize the complexity of clients so as to facilitate widespread deployment of applications capable of utilizing the DASL search mechanisms. DASL consists of: (1) the SEARCH method, (2) the DASL response header, (3)the DAV:searchrequest XML element, (4) the DAV:queryschema property, (5) the DAV:basicsearch XML element and query grammar, and (6) the DAV:basicsearchschema XML element. DASL relies on the resource and property model defined by [WebDAV]. DASL does not alter this model. Instead, DASL allows clients to access DAV-modeled resources through server-side search."
References:
DAV Searching & Locating - IETF INTERNET-DRAFT. June 24, 1999. "This document specifies a set of methods, headers, and content-types composing DASL, an application of the HTTP/1.1 protocol to efficiently search for DAV resources based upon a set of client-supplied criteria." [local archive copy]
See also: WEBDAV (IETF 'Extensions for Distributed Authoring and Versioning on the World Wide Web')
