MapReduce – User Interfaces

This section provides some detail about user-facing aspects of the MapReduce framework. This will help you implement, configure, and tune your jobs in a fine-grained manner. However, note that the javadoc for each class/interface remains the most comprehensive documentation available; this document is only meant to be a tutorial.

Let's first look at the Mapper and Reducer interfaces. Applications typically implement them to provide the map and reduce methods:
We will then discuss other core interfaces including Job,Partitioner, InputFormat,OutputFormat, OutputCommitter, and others:
Finally, we will finish by discussing some useful features of the framework, such as the DistributedCache, IsolationRunner, and others: