Machine learning is a branch of applied computer science in which we build models of real-world phenomena on the basis of existing data available for analysis, and then using that model, we predict certain characteristics of data never seen before by the model. Machine learning techniques are one of the important ways in which decisions are made in applications. As most of the applications operate in real time, using machine learning with Storm is a great way to implement decision making in real-time applications.

Graphically, the process of machine learning can be represented by the following diagram:

Machine learning

The process of building the model from data is called training in the machine learning terminology. Training can happen in real time on a stream of data or can also be done on historical data. When the training is done in real time, the model evolves over time with the changed data. This kind of learning is referred to as online learning, and when...