[DAS2] DAS intro

[Suzanna Lewis]

a few minor in-line edits below. trying to simplify and not confuse, as 
this is just an intro.

On Nov 25, 2005, at 7:21 AM, Andrew Dalke wrote:

> The front of the DAS doc starts
>
>   DAS 2.0 is designed to address the shortcomings of DAS 1.0, 
> including:
>
> That kinda assumes people know what DAS 1.0 is to understand DAS 2.0.
>
> How about this instead, as an overview/introduction.
>
>  ======
>
> DAS/2 describes a data model for genome annotations
,  THAT IS, DESCRIPTIONS OF FEATURES LOCATED ON THE GENOMIC SEQUENCE
> .  An annotation
> server provides

SUCH
> information
FOR
>  one or more genome
SEQUENCES.
> Each
GENOMIC SEQUENCE
> may have one or more versions.  Different versions are usually
> based on different assemblies.  As an implementation detail an
> assembly and corresponding sequence data may be distributed via a
> different machine, which is called the reference server.
(DELETED LAST 2 SENTENCES).


>
> Annotations are located on the genome with a start and end position.
> The range may be specified mutiple times if there are alternate
>
SEQUENCES THEY MAY BE PLACED UPON (REFERENCE FRAMES).

> An annotation may contain multiple non-continguous
> parts

(DELECTED PHRASE AND SENTENCE)

> Annotations have a type based on terms in SOFA
> (Sequence Ontology for Feature Annotation).  Stylesheets contain a set
> of properties used to depict a given type.
>
> Annotations can be searched by range, type, and a properties table
> associated with each annotation.  These are called feature filters.
>
> DAS/2 is implemented using a ReST architecture.  Each entity (also
> called a document or object) has a name, which is a URL.  Fetching the
> URL gets information about the entity.  The DAS-specific entities are
> all XML documents.  Other entities contain data types with an existing
> and frequently used file format.  Where possible, a DAS server returns
> data using existing formats.  In some cases a server may describe how
> to fetch a given entity in several different formats.
>  ======
>
>
> 					Andrew
> 					dalke at dalkescientific.com
>
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