DAS architecture

DAS architecture is based on several components:
  • common core library
    • analytics DB
    • mapping DB
    • caching DB
    • merging DB
    • logging DB
  • data-service plugins, each plugin contains
    • data-service handler class
    • API map
    • notation map
  • cache server
  • client web server

The last two components, cache and client servers, are optional. The code itself can work without cache/client servers with the CLI tool which uses core libraries. But their existence allows the introduction of DAS pre-fetch strategies, DAS robots, which can significantly improve responsiveness of the system and add multi-user support into DAS. The following picture represents current DAS architecture:


It consists of DAS web server with RESTful interface, DAS cache server, DAS Analytics/Mapping/Cache DBs and DAS robots (for pre-fetching queries). The DAS cache server uses multithreading to consume and work on several user requests at the same time. All queries are written to the DAS Analytics DB. A mapping between data-service and DAS notations is stored in the DAS Mapping DB. Communication with end-users is done via set of REST calls. User can make GET/POST/DELETE requests to fetch or delete data in DAS, respectively. The DAS workflow can be summarised as:

For more information please see the DAS workflow page. The DAS DBs use the MongoDB document-oriented database (see [Mongodb]), although during design/evaluation process we considered a number of other technologies, such as different RDMS flavors, memcached [Memcached] and other key-value based data stores (eg CouchDB [Couchdb]), etc.