1. A method at an entity in a distributed computing system comprising: providing 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; arranging a processor 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; receiving user input adding an icon in the graph layout view the icon having associated specified functionality; and using the processor to update the distributed computing graph to provide the specified functionality, the icon representing a bus and the associated specified functionality being that a plurality of the currently executing processes which are connected by the bus in the graph layout view are able to read and/or write data to the bus such that any data written to the bus is visible to all those processes connected to the bus which are able to read, and wherein: the method further comprises arranging the processor to add at least one data store to the distributed computing graph at a location on the bus selected by the processor using rules, that data store being arranged to store data written to it at specified intervals and providing a user interface enabling control of the activity using the graph layout view and wherein the data store is not part of the graph layout view such that a user viewing a display of the graph layout view does not see the data store; the method further comprises arranging the processor to, for each process able to write to the bus, observe feeds to that process using the distributed computing graph and to use the observations to decide whether existing data stored in the data store may be written to the bus; or the distributed computing graph comprises at least one community being a region of the distributed computing graph containing specified ones of the currently executing processes, and wherein the processor is arranged to add a first data store at a location on the bus inside the community and a second data store at a location on the bus outside the community, and to store the same data in the first and second data stores.