r tasks register to a balancer, which 
      on receiving a request from a client for a certain job,
      forwards the request to one of the registered providers
      of this job. Internally, the register balances the request,
      such that, with more than one provider currently registered,
      two consecutive requests will not be served
      by the same provider.
      Note that registers provide different modes of using providers:
      a load balancer will send a request to only one of its provide