AggregateMessages provides a functional abstraction for aggregating neighborhood information in Spark graphs. This operator applies a user-defined
sendMsg function to each edge in the graph using
EdgeContext class accesses the required information about the edge and passes that information to its source node and/or destination node using the
sendToDst methods respectively. After all messages have been received by the nodes, the
mergeMsg function is used to aggregate those messages at each node.
In the next chapter, we will introduce another operator called
Pregel, which will be useful for creating custom iterative graph-processing algorithms.