Practical Real-time Data Processing and Analytics

map and flatMap

The following are characteristics of the map function:

• This is one-to-one transformation of tuples
• Class has to implement MapFunction

Here is the example:

class UpperCase implements MapFunction {  @Override  public Values execute(TridentTuple input) {    return new Values(input.getString(0).toUpperCase());  }}

Input:

[this is a simple example of trident topology]

Output:

[THIS IS A SIMPLE EXAMPLE OF TRIDENT TOPOLOGY]

The following are characteristics of the FlatMap function:

• This is one-to-many transformation for tuple
• It's flattening the resulting elements into a new stream
• The Class has to implement FlatMapFunction

Here is the example:

class SplitMapFunction implements FlatMapFunction {  @Override public Iterable<Values> execute(TridentTuple ...