Getting a field value from pipe in outside the pipe in Hadoop Cascading - hadoop

Question

Regarding above subject, is there any way to get the value of a field from a pipe. And use that value outside the pipe's scope in Hadoop Cascading? The data has delimiter as '|':
first_name|description
Binod|nothing
Rohit|nothing
Ramesh|abc
From above pipe I need to get a value from the description, whatever that is 'nothing' or 'abc'.

Answer 1

Hadoop Cascading is developed with a concept of creating real case scenario by flowing data between pipe and executing parallely it over Map-Reduce Hadoop system.
Execution of java program is unnecessary to depend with rest of the cascading flow (from creating source tap to sink tap), and what Hadoop Cascading does is: it executes those two different processes in different independent JVM instances and they will be unable to share their values.
Following code and its output shows brief hints:
System.out.println("Before Debugging");
m_eligPipe = new Each(m_eligPipe, new Fields("first_name"), new Debug("On Middle", true));
System.out.println("After Debugging");
Expected ouput:
Before Debugging
On Middle: ['first_name']
On Middle: ['Binod']
On Middle: ['Rohit']
On Middle: ['Ramesh']
After Debugging
Actual output:
Before Debugging
After Debugging
...
...
On Middle: ['first_name']
On Middle: ['Binod']
On Middle: ['Rohit']
On Middle: ['Ramesh']

Answer 2

I don't understand what you are trying to say. Do you to mean to extract the value of field ${description} outside the scope of the pipe. If possible something like this in pseudo code.
str = get value of description in inputPipe (which is in the scope of the job rather than function or buffer)

Answer 3

I assume this is what you want: you have a pipe with one field, that is the concatenation of ${first_name} and ${description}. And you want the output to be a pipe with field that is ${description}.
If so, this is what I'd do: implement a function that extracts description and have your flow execute it.
You function (let's call it ExtractDescriptionFunction) should override method operate with something like this:
#Override
public void operate(FlowProcess flowProcess, FunctionCall<Tuple> functionCall) {
TupleEntry arguments = functionCall.getArguments();
String concatenation = arguments.getString("$input_field_name");
String[] values = concatenation.split("\\|"); // you might want to have some data sanity check here
String description = values[1];
Tuple tuple = functionCall.getContext();
tuple.set(0, description);
functionCall.getOutputCollector().add(tuple);
}
Then, in your flow definition, add this:
Pipe outputPipe = new Each(inputPipe, new ExtractDescriptionFunction());
Hope this helps.