org.apache.cocoon.pipeline
Interface Pipeline<T extends PipelineComponent>

All Known Implementing Classes:

AbstractPipeline, AsyncCachePipeline, CachingPipeline, NonCachingPipeline

public interface Pipeline<T extends PipelineComponent>

A pipeline expects one or more PipelineComponents that passed by using addComponent(PipelineComponent). Then these components get linked with each other in the order they were added. The setup(OutputStream, Map) method, calls the setup method on all pipeline components and assembles the pipeline. Finally the execute() method produces the result and writes it to the OutputStream which has been passed to the setup(OutputStream, Map) method.

A pipeline works based on two fundamental concepts:

• The first component of a pipeline is of type Starter. The last component is of type Finisher.
• In order to link components with each other, the first has to be a Producer, the latter Consumer.

When the pipeline links the components, it merely checks whether the above mentioned interfaces are present. So the pipeline does not know about the specific capabilities or the compatibility of the components. It is the responsibility of the Producer to decide whether a specific Consumer can be linked to it or not (that is, whether it can produce output in the desired format of the Consumer or not). It is also conceivable that a Producer is capable of accepting different types of Consumers and adjust the output format according to the actual Consumer.

Method Summary

void	addComponent(T pipelineComponent) Add a PipelineComponent to the pipeline.
void	execute() After the pipeline has been setup (setup(OutputStream, Map), this method can be invoked in order to produce the result.
String	getContentType() Get the mime-type of the content produced by the pipeline.
long	getLastModified() Get the time of the last modification.
void	setConfiguration(Map<String,? extends Object> parameters) Pass pipeline specific configuration parameters to the pipeline component in a generic way.
void	setup(OutputStream outputStream) After the pipeline has been prepared (addComponent(PipelineComponent), this method can be invoked in order to setup and initialize the pipeline and its components.
void	setup(OutputStream outputStream, Map<String,Object> parameters) The same as setup(OutputStream) but also allows passing parameters to the pipeline components.

Method Detail

addComponent

void addComponent(T pipelineComponent)

Add a PipelineComponent to the pipeline. The order of when the components are passed is significant.

Parameters:

pipelineComponent - The PipelineComponent.

execute

void execute()
             throws Exception

After the pipeline has been setup (setup(OutputStream, Map), this method can be invoked in order to produce the result.

Throws:

Exception - Any problem that might occur while processing the pipeline.

getContentType

String getContentType()

Get the mime-type of the content produced by the pipeline.

Returns:

The mime-type of the content.

getLastModified

long getLastModified()

Get the time of the last modification.

Returns:

The last modification date

setup

void setup(OutputStream outputStream)

After the pipeline has been prepared (addComponent(PipelineComponent), this method can be invoked in order to setup and initialize the pipeline and its components.

Parameters:

outputStream - An OutputStream where the pipeline execution result is written.

setup

void setup(OutputStream outputStream,
           Map<String,Object> parameters)

The same as setup(OutputStream) but also allows passing parameters to the pipeline components.

Parameters:

outputStream - An OutputStream where the pipeline execution result is written.

parameters - A Map of parameters that are available to all PipelineComponents.

setConfiguration

void setConfiguration(Map<String,? extends Object> parameters)

Pass pipeline specific configuration parameters to the pipeline component in a generic way. This is useful in environments that automatically assemble pipelines with their components and can't use the pipeline's constructors or setters.

Parameters:

configuration - The Map of configuration parameters.