Bidirectional streaming
The final streaming method is bidirectional (bidi) streaming. This involves having the client and the server streaming messages to each other. Messages are guaranteed to be received in the order they were sent (on both ends), but there is no need to wait for the other side to start or finish sending before you start sending messages.
Let’s take a look at an example application that uses bidi streaming. Here we’ll create a word counting application. The basic idea is to implement something like a distributed map/reduce job, where files are mapped by the tokenizer service, and the driver (client) handles the reduce step (i.e. merging the results).
Clients will stream files to the server, which for each message, will generate a map of word counts in the file. The client will then merge the results as they come in to form a final unified word map (occurrences in all of the files).
Creating the protobuf file
As always, let’s start by defining...