Backend
Backend instances in Google App Engine are transparent,
described in XML. Applications and tasks can be made to
run on a backend instance of a certain configuration without additional changes to the program. Backends remove
the time limit for tasks in the task queue allowing them to
run indefinitely (or so long as the free quota is available).
Backend instances are of various types, e.g. the most powerful type provides 4.8 GHz of CPU and 1024 MB RAM,
which is still eight-fold lower than the RAM in the machine
used for the experiments. Without backends, the allocation
of CPU and memory to application instances is dynamic so
an application may be able to get more CPU on the default
instance than on a specific backend.