Currently going through the class DasDataProvider, which is used to set up the DasDataProvider. The initialize() method is used to retrieve the dsn response from https://genome.ucsc.edu/cgi-bin/das/dsn this URL and store all the available genomes in genomeContextRootMap with the sourceid as key and MapMaster URL as value. The getAvailableDataSets() is used to get all the available datasets (types) for the selected genome and its version by using https://genome.ucsc.edu/cgi-bin/das/hg38/types this URL. The URL connection, request, and getting a response are done in the DasServerUtils class, retrieveDsnResponse() and retrieveDasTypesResponse() are the corresponding methods.

The other functions in DasDataProvider are getAssemblyInfo(), used to get info (id and stop point) about segments in the entry point of a genome (https://genome.ucsc.edu/cgi-bin/das/hg38/entry_points) and getSequence() which is used to retrieve dna for a sequence span which contains the genome type, segment required and start and end points (https://genome.ucsc.edu/cgi-bin/das/hg38/dna?segment=M:1,16569). DasSymloader is used to get segment region specific feature information (https://genome.ucsc.edu/cgi-bin/das/hg16/features?segment=1:1,100000;type=refGene). DasResiduesHandler getDasResidues() function is used to parse the retrieved DNA and return it as a string.