Distributed data flow

Distributed data flow (also abbreviated as distributed flow) refers to a set of events in a distributed application or .

Distributed data flows serve a purpose analogous to variables or method parameters in programming languages such as Java, in that they can represent state that is stored or communicated by a layer of software. Unlike variables or parameters, which represent a unit of state that resides in a single location, distributed flows are dynamic and distributed: they simultaneously appear in multiple locations within the network at the same time. As such, distributed flows are a more natural way of modeling the semantics and inner workings of certain classes of distributed systems. In particular, the distributed data flow abstraction has been used as a convenient way of expressing the high-level logical relationships between parts of distributed protocols.

A distributed data flow satisfies the following informal properties.

Formally, we represent each event in a distributed flow as a quadruple of the form (x,t,k,v), where x is the location (e.g., the network address of a physical node) at which the event occurs, t is the time at which this happens, k is a version, or a sequence number identifying the particular event, and v is a value that represents the event payload (e.g., all the arguments passed in a method call). Each distributed flow is a (possibly infinite) set of such quadruples that satisfies the following three formal properties.

In addition to the above, flows can have a number of additional properties.

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