From the biodas.org website:
The distributed annotation system (DAS) is a client-server system in which a single client integrates information from multiple servers. It allows a single machine to gather up genome annotation information from multiple distant web sites, collate the information, and display it to the user in a single view. Little coordination is needed among the various information providers.
While I prefer the earliest versions, written primarily in PERL, by Lincoln Stein and Robin Dowell, there appear to be a number of DAS server projects from which to choose.
It has been suggested we look into the Dazzle server. Dazzle is implemented as a Java servlet, using the BioJava APIs. First pass reading shows an excellent pedigree as it was developed at the Wellcome Trust Sanger Institute by Thomas Down. A keen eye notices there has been no development on this project since the 31st August 2004.
Perhaps new development is waiting on the DAS2 specification? So far, I like what I see:
DAS 2.0 is implemented using a ReST architecture. Each document (also called an entity or object) has a name, which is a URL. Fetching the URL gets information about the document. The DAS-specific documents are all in XML. Other data types have existing widely used formats, and sometimes more than one for the same data. A DAS server may provide a distinct document for each of these formats, along with information about which formats are available.
DAS 2.0 addresses some shortcomings of the DAS 1.x protocol, including:
- Better support for hierachical structures (e.g. transcript + exons)
- Ontology-based feature annotations
- Allow multiple formats, including formats only appropriate for some feature types
- A lock-based editing protocol for curational clients
- An extensible namespacing system that allows annotations in non-genomic coordinates (e.g. uniprot protein coordinates or PDB structure coordinates)
The dissertation introducing the ReST architecture by Roy Thomas Fielding includes a rather interesting analysis of Java and JavaScript languages (section 6.5.4.3). I tend to agree.
People who manage Java-based production services deployed under Tomcat are wary of that environment. I’m looking for DAS deployment alternatives.
Currently the server of interest is ProServer DAS server also from the Sanger Center. ProServer is a lightweight DAS server written in Perl. It should be simple to install and configure and has adaptors for a wide variety of data sources. It claims to be easily extensible allowing adaptors to be written for other data sources.
ProServer DAS is under active development. Though not currently DAS2 compliant it will likely be one of the first to support the specification.