Like the Distributed Annotation System (DAS) (Dowell et al., 2001), track data hubs provide access to annotation over the Internet, but they differ in that the server hosting a track data hub requires only HTTP access instead of a dedicated DAS server. In contrast to the extensible mark-up language format of DAS, which may be easier for a simple application to access, track data hubs present data in the native format of the data files with a rich set of options for controlling how that data should displayed. Although this requires more complicated logic on the client end to parse and display, it offers the data contributor more options for configuring and presenting the data.
