This manual is for an old version of Hazelcast Jet, use the latest stable version.

Hazelcast Jet provides high performance in-memory data processing by modeling a computation as a Directed Acyclic Graph (DAG) of processing vertices. Each vertex performs a step in the computation and emits data items for the vertices it is connected to. A single vertex's computation work is performed in parallel by many instances of the Processor type around the cluster. The different vertices are linked together through edges.

One of the major reasons to divide the full computation task into several vertices is data partitioning: the ability to split the data stream traveling over an edge into slices which can be processed independently of each other. To make this work, a function must be defined which computes the partitioning key for each item and makes all related items map to the same key. The computation engine can then route all such items to the same processor instance. This makes it easy to parallelize the computation: each processor will have the full picture for its slice of the entire stream.

Edges determine how the data is routed from individual source processors to individual destination processors. Different edge properties offer precise control over the flow of data.