18. A graph engine at an entity in a distributed computing system, the graph engine comprising: an input arranged to connect to the distributed computing system and access a distributed computing graph associated with an activity to be carried out in the distributed computing system, the distributed computing graph representing currently executing processes in the distributed computing system; a processor arranged to provide a dynamic mapping between the distributed computing graph and a data structure at the entity holding a graph layout view of the distributed computing graph such that changes in the graph layout view are reflected in the distributed computing graph; a graphical user interface arranged to receive user input adding a first community in the graph layout view the first community comprising computing resources in the distributed computing system; the graphical user interface also being arranged to receive user input placing a first graphical element in the first community, the first graphical element representing at least a first one of the currently executing processes; the processor being arranged to update the distributed computing graph such that the first currently executing process runs on computing resources of the first community; the graphical user interface also being arranged to receive user input placing a second graphical element outside all communities displayed in the graph layout view, the second graphical element representing at least a second one of the currently executing processes; and the processor being arranged to update the distributed computing graph such that the second currently executing process runs on computing resources of a local machine.
18. A graph engine at an entity in a distributed computing system, the graph engine comprising: an input arranged to connect to the distributed computing system and access a distributed computing graph associated with an activity to be carried out in the distributed computing system, the distributed computing graph representing currently executing processes in the distributed computing system; a processor arranged to provide a dynamic mapping between the distributed computing graph and a data structure at the entity holding a graph layout view of the distributed computing graph such that changes in the graph layout view are reflected in the distributed computing graph; a graphical user interface arranged to receive user input adding a first community in the graph layout view the first community comprising computing resources in the distributed computing system; the graphical user interface also being arranged to receive user input placing a first graphical element in the first community, the first graphical element representing at least a first one of the currently executing processes; the processor being arranged to update the distributed computing graph such that the first currently executing process runs on computing resources of the first community; the graphical user interface also being arranged to receive user input placing a second graphical element outside all communities displayed in the graph layout view, the second graphical element representing at least a second one of the currently executing processes; and the processor being arranged to update the distributed computing graph such that the second currently executing process runs on computing resources of a local machine. 19. A graph engine as claimed in claim 18 having a memory arranged to store parameters specifying conditions that computing resources in the community are to meet.