cascading.fluid

Class Fluid

java.lang.Object

cascading.fluid.Fluid

public class Fluid
extends java.lang.Object

The Fluid class is the starting point for constructing new Pipe Assemblies via this API.

To get started, a new assembly builder must be created:

   AssemblyBuilder.Start builder = Fluid.assembly();
 

Next a branch must be started:

  Pipe pipe = builder.startBranch( "rhs" )
    .groupBy( Fields.ALL )
      .every( Fields.ALL ).aggregator( new Count() ).outgoing( Fields.ALL )
    .completeGroupBy()
     .each( Fields.ALL ).filter( new RegexFilter( "" ) )
       .coerce().coerceFields( Fields.fields( "foo", int.class ) ).end()
  .completeBranch();
 

Note completeBranch() is a factory, it will return a Pipe instance. Also note the assembly builder is stateful, and will keep the return Pipe as a known assembly tail.

fields(Comparable[]) is a convenience for new Fields("..."). Type Fields itself also has many fluent helper methods, for example Fluid.fields( "average").applyTypes(long.class);

Calling:

  Pipe[] tails = assembly.completeAssembly();
 

Will return a Pipe[] with a single entry, the same called from the completeBranch() call previously.

To begin a join, two or more pipes will need to be created prior to the next call:

  Pipe lhsUpperLower = assembly
    .startHashJoin()
      .lhs( pipeLhs ).lhsJoinFields( fields( "num" ) )
      .rhs( upperLower ).rhsJoinFields( fields( "numUpperLower" ) )
      .declaredFields( fields( "numLhs", "charLhs", "numUpperLower", "charUpperLower", "num2UpperLower", "char2UpperLower" ) )
    .createHashJoin();
 

This is a factory and must be added to the assembly via:

 lhsUpperLower = assembly
  .continueBranch( lhsUpperLower )
    .each( Fields.ALL ).function
      (
      function().Identity().fieldDeclaration( Fields.ALL ).end()
      )
    .outgoing( Fields.RESULTS )
  .completeBranch();
 

If the two given pipes (pipeLhs and pipeRhs) were previously tails in the assembly, they will be no longer tails within the assembly, replaced by the result of completeBranch().

Finally notice in the above code, function() is used to create a new Function for use in the assembly.

In the first example at the top, new Count() was called. This call could have been replaced with function().Count().end().

AggregateBy sub-classes also have factory helpers than can be used when adding a base AggregateBy to the pipe assembly.

 Pipe rhs = builder
  .startBranch( "rhs" )
    .aggregateBy()
      .groupingFields( fields( "grouping" ) )
      .assemblies
        (
          Fluid.aggregateBy().AverageBy().valueField( fields( "value" ) ).averageField( fields( "average" ) ).end(),
          Fluid.aggregateBy().SumBy().valueField( fields( "value" ) ).sumField( fields( "sum", long.class ) ).end()
        )
    .end() // end aggregateBy builder
  .completeBranch();
 

Method Summary

Methods

Modifier and Type	Method and Description
static AggregateByBuilder<java.lang.Void>	aggregateBy() Method aggregateBy returns a new AggregateBy factory builder.
static AggregatorBuilder<java.lang.Void>	aggregator() Method aggregator returns a new Aggregator factory builder.
static AssemblyBuilder.Start	assembly() Method assembly returns a new assembly builder.
static BufferBuilder<java.lang.Void>	buffer() Method buffer returns a new Aggregator factory builder.
static Fields	fields(java.lang.Comparable... fields) Method fields is a convenience helper factory for creating a new Fields instance.
static Fields	fields(java.lang.Comparable field, java.lang.reflect.Type type) Method fields is a convenience helper factory for creating a new Fields instance.
static FilterBuilder<java.lang.Void>	filter() Method filter returns a new Filter factory builder.
static FunctionBuilder<java.lang.Void>	function() Method function returns a new Function factory builder.
static GroupAssertionBuilder<java.lang.Void>	groupAssertion() Method groupAssertion returns a new GroupAssertion factory builder.
static ValueAssertionBuilder<java.lang.Void>	valueAssertion() Method valueAssertion returns a new ValueAssertion factory builder.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

fields

public static Fields fields(java.lang.Comparable... fields)

Method fields is a convenience helper factory for creating a new Fields instance.

The Fields class is also fluent, so adding types to the result is as simple as calling Fields.applyTypes(java.lang.reflect.Type...).

Parameters:

fields - is a set of integer ordinals or field names.

Returns:

a new Fields instance.

See Also:

Fields

fields

public static Fields fields(java.lang.Comparable field,
            java.lang.reflect.Type type)

Method fields is a convenience helper factory for creating a new Fields instance.

Parameters:

field - is a an integer ordinal or field name.

type - is the Type of the given field

Returns:

a new Fields instance.

See Also:

Fields

assembly

public static AssemblyBuilder.Start assembly()

Method assembly returns a new assembly builder.

An assembly is a collection of branches.

To add a new branch, call AssemblyBuilder_2m1_4f_2m2_4f_2m3_4f_2m4_4f_2m5_4f_2m6_4f_2m7_4f_2m8_4f_2m9_4f_2m10_4f_2m11_4f_2m12_4f.startBranch(String).

To complete the current branch, call completeBranch() on the builder.

To complete the assembly, call AssemblyBuilder_2m1_4f_2m2_4f_2m3_4f_2m4_4f_2m5_4f_2m6_4f_2m7_4f_2m8_4f_2m9_4f_2m10_4f_2m11_4f_2m12_4f.completeAssembly().

Returns:

a new Assembly builder instance

function

public static FunctionBuilder<java.lang.Void> function()

Method function returns a new Function factory builder.

Unlike the assembly builder, a Function factory builder provides a simple api for constructing known Function types, that should ba added after an each() builder method is called.

Factory builders retain no internal state, and can be shared and re-used across assembly builders.

Returns:

a new Function builder instance

See Also:

Function

filter

public static FilterBuilder<java.lang.Void> filter()

Method filter returns a new Filter factory builder.

Unlike the assembly builder, a Filter factory builder provides a simple api for constructing known Filter types, that should ba added after an each() builder method is called.

Factory builders retain no internal state, and can be shared and re-used across assembly builders.

Returns:

a new Filter builder instance

See Also:

Filter

aggregator

public static AggregatorBuilder<java.lang.Void> aggregator()

Method aggregator returns a new Aggregator factory builder.

Unlike the assembly builder, a Aggregator factory builder provides a simple api for constructing known Aggregator types, that should ba added after an every() builder method is called.

Factory builders retain no internal state, and can be shared and re-used across assembly builders.

Returns:

a new Aggregator builder instance

See Also:

Aggregator

buffer

public static BufferBuilder<java.lang.Void> buffer()

Method buffer returns a new Aggregator factory builder.

Unlike the assembly builder, a Buffer factory builder provides a simple api for constructing known Buffer types, that should ba added after an every() builder method is called.

Factory builders retain no internal state, and can be shared and re-used across assembly builders.

Returns:

a new Buffer builder instance

See Also:

Buffer

valueAssertion

public static ValueAssertionBuilder<java.lang.Void> valueAssertion()

Method valueAssertion returns a new ValueAssertion factory builder.

Unlike the assembly builder, a ValueAssertion factory builder provides a simple api for constructing known ValueAssertion types, that should ba added after an each() builder method is called.

Factory builders retain no internal state, and can be shared and re-used across assembly builders.

Returns:

a new ValueAssertion builder instance

See Also:

ValueAssertion

groupAssertion

public static GroupAssertionBuilder<java.lang.Void> groupAssertion()

Method groupAssertion returns a new GroupAssertion factory builder.

Unlike the assembly builder, a GroupAssertion factory builder provides a simple api for constructing known GroupAssertion types, that should ba added after an every() builder method is called.

Factory builders retain no internal state, and can be shared and re-used across assembly builders.

Returns:

a new GroupAssertion builder instance

See Also:

GroupAssertion

aggregateBy

public static AggregateByBuilder<java.lang.Void> aggregateBy()

Method aggregateBy returns a new AggregateBy factory builder.

Unlike the assembly builder, an AggregateBy factory builder provides a simple api for constructing known AggregateBy sub-types that should be passed to a parent AggregateBy for concurrent aggregation of multiple values.

Factory builders retain no internal state, and can be shared and re-used across assembly builders.

Returns:

a new AggregateBy builder instance

See Also:

AggregateBy