Custom operator development

As our example application has the LineSplitter operator, which is not part of the Apex library, we will use it as an example to illustrate the process of developing a custom operator.

Splitting a line into words is, of course, a simple stateless operation. Connectors and stateful transformations will be more involved, and there are many examples in the Apex library to look at for this.

Here is the line splitter:

public class LineSplitter extends BaseOperator 
{ 
  // default pattern for word-separators 
  private static final Pattern nonWordDefault =    Pattern.compile
    ("[\\p{Punct}\\s]+"); 
 
  private String nonWordStr;              // configurable regex 
  private transient Pattern nonWord;      // compiled regex 
 
  /** 
   * Output port on which words from the current file are emitted 
   */ 
  public final transient DefaultOutputPort<String> output = new 
    DefaultOutputPort<>(); 
 
  /** 
   * Input port on which lines from the current...