io.continual.services.processor.engine.model

Interface StreamProcessingContext

All Known Implementing Classes:

SimpleStreamProcessingContext

public interface StreamProcessingContext

A stream processing context is provided to all processing components in a program and is consistent across messages (but not across streams). It's a good place to store stream-specific data.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	StreamProcessingContext.NoSuitableObjectException No suitable object found.

Method Summary

Modifier and Type	Method and Description
StreamProcessingContext	addNamedObject(String name, Object o) Add a named object of any type.
boolean	checkFlag(String flagName) Get the value of a given flag.
boolean	clearFlag(String flagName) Clear a flag
String	evalExpression(String expression) Evaluate a ${} expression in the context of this stream processor
void	fail(String warningText) Report that the stream processing has failed.
boolean	failed() Returns true if fail() has been called
MetricsCatalog	getMetrics() Get the metrics catalog into which this processing context reports.
Object	getNamedObject(String name) Get a raw object reference for the instance with the given name
<T> T	getNamedObject(String name, Class<T> clazz) Get a typed object with the given name.
Identity	getOperator() Get the identity of the operator running this process.
<T> T	getReqdNamedObject(String name, Class<T> clazz) Get a typed object with the given name and throw an exception if it's not available.
Source	getSource() Get this stream's source
StreamProcessingContext	removeNamedObject(String name) Remove a named object from this context, if it exists
void	requeue(MessageAndRouting mr) Requeue a message
boolean	setFlag(String flagName) Set a boolean flag
void	warn(String warningText) report a warning about processing the stream

Method Detail

getSource

Source getSource()

Get this stream's source

Returns:

a source instance

warn

void warn(String warningText)

report a warning about processing the stream

Parameters:

warningText -

fail

void fail(String warningText)

Report that the stream processing has failed.

Parameters:

warningText -

failed

boolean failed()

Returns true if fail() has been called

Returns:

getOperator

Identity getOperator()

Get the identity of the operator running this process.

Returns:

an identity, or null

addNamedObject

StreamProcessingContext addNamedObject(String name,
                                       Object o)

Add a named object of any type.

Parameters:

name -

o -

Returns:

this context

getNamedObject

Object getNamedObject(String name)

Get a raw object reference for the instance with the given name

Parameters:

name -

Returns:

an object, or null of none is known to this context

getNamedObject

<T> T getNamedObject(String name,
                     Class<T> clazz)
              throws ClassCastException

Get a typed object with the given name.

Parameters:

name -

clazz -

Returns:

the named object cast to T, null of none exists.

Throws:

ClassCastException

getReqdNamedObject

<T> T getReqdNamedObject(String name,
                         Class<T> clazz)
                  throws StreamProcessingContext.NoSuitableObjectException

Get a typed object with the given name and throw an exception if it's not available.

Parameters:

name -

clazz -

Returns:

the named object cast to T

Throws:

StreamProcessingContext.NoSuitableObjectException

removeNamedObject

StreamProcessingContext removeNamedObject(String name)

Remove a named object from this context, if it exists

Parameters:

name -

Returns:

this context

setFlag

boolean setFlag(String flagName)

Set a boolean flag

Parameters:

flagName -

Returns:

value before this call

checkFlag

boolean checkFlag(String flagName)

Get the value of a given flag.

Parameters:

flagName -

Returns:

true if set, false if clear or unknown

clearFlag

boolean clearFlag(String flagName)

Clear a flag

Parameters:

flagName -

Returns:

the value before this call

evalExpression

String evalExpression(String expression)

Evaluate a ${} expression in the context of this stream processor

Parameters:

expression -

Returns:

a value, which may be an empty string

requeue

void requeue(MessageAndRouting mr)

Requeue a message

Parameters:

mr -

getMetrics

MetricsCatalog getMetrics()

Get the metrics catalog into which this processing context reports. Processors may create/use metrics objects at the top-level, which is scoped properly during the call.

Returns:

a metrics catalog