Package org.rribbit

Class DefaultRequestResponseBus

java.lang.Object

org.rribbit.DefaultRequestResponseBus

All Implemented Interfaces:

RequestResponseBus

public class DefaultRequestResponseBus
extends Object
implements RequestResponseBus

Default implementation of RequestResponseBus. Provides all behaviour specified in that interface.

The DefaultRequestResponseBus supports multiple RequestDispatchers and every request will be sent to ALL of them. The responses will then be aggregated. Please keep performance considerations in mind when adding multiple RequestDispatchers to a DefaultRequestResponseBus, especially when using RRiBbit Remoting. In that case, every request will be sent to ALL remote machines and the DefaultRequestResponseBus will have to wait until all of them have returned.

If this is undesirable, an alternative is to create multiple DefaultRequestResponseBuses, each with its own RequestDispatcher. This does however, require the sender of the request to have knowledge about where the receiver is located (i.e. which RequestResponseBus to call). Although this contradicts the principle behind event buses (in that the sender does not have to know anything about the receiver), it could be a worthwile sacrifice for performance considerations.

Author:

G.J. Schouten

Field Summary

Fields

Modifier and Type	Field	Description
protected List<RequestDispatcher>	requestDispatchers

Constructor Summary

Constructors

Constructor	Description
DefaultRequestResponseBus()	Whenever you use this constructor, be sure to set the RequestDispatcher with the setter provided by this class.
DefaultRequestResponseBus(RequestDispatcher... requestDispatchers)	This constructor is recommended, since it forces you to specify a RequestDispatcher.

Method Summary

Modifier and Type	Method	Description
void	addRequestDispatcher(RequestDispatcher requestDispatcher)	Adds a RequestDispatcher to this DefaultRequestResponseBus.
protected <T> List<T>	dispatchRequestAndProcessResponse(Request request)	Sends the given Request to all available RequestDispatchers and aggregates the Responses.
List<RequestDispatcher>	getRequestDispatchers()	Returns all RequestDispatchers that are used by this DefaultRequestResponseBus.
<T> T	send(String hint, Object... parameters)	Equivalent to RequestResponseBus.sendForSingleWithHint(String, Object...), since that is probably the most widely used method, because generally, when you know the hint, you know the returntype and you don't have to pass it specifically.
<T> Collection<T>	sendForMultipleOfClass(Class<T> returnType, Object... parameters)	Send a request to all Listeners that satisfy the following requirements.
<T> Collection<T>	sendForMultipleOfClassWithHint(Class<T> returnType, String hint, Object... parameters)	Send a request to all Listeners that satisfy the following requirements.
<T> Collection<T>	sendForMultipleWithHint(String hint, Object... parameters)	Send a request to all Listeners that satisfy the following requirements.
void	sendForNothing(Object... parameters)	Send a request to all Listeners that satisfy the following requirements.
void	sendForNothingWithHint(String hint, Object... parameters)	Send a request to all Listeners that satisfy the following requirements.
<T> T	sendForSingleOfClass(Class<T> returnType, Object... parameters)	Send a request to all Listeners that satisfy the following requirements.
<T> T	sendForSingleOfClassWithHint(Class<T> returnType, String hint, Object... parameters)	Send a request to all Listeners that satisfy the following requirements.
<T> T	sendForSingleWithHint(String hint, Object... parameters)	Send a request to all Listeners that satisfy the following requirements.
void	setRequestDispatcher(RequestDispatcher requestDispatcher)	Removes all RequestDispatchers from this DefaultRequestResponseBus and adds only the given one.

Methods inherited from class java.lang.Object

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

Field Details

requestDispatchers

protected List<RequestDispatcher> requestDispatchers

Constructor Details

DefaultRequestResponseBus

public DefaultRequestResponseBus()

Whenever you use this constructor, be sure to set the RequestDispatcher with the setter provided by this class. If you don't, runtime NullPointerExceptions will occur.

DefaultRequestResponseBus

public DefaultRequestResponseBus(RequestDispatcher... requestDispatchers)

This constructor is recommended, since it forces you to specify a RequestDispatcher. Passing a null value will result in a runtime NullPointerException whenever the DefaultRequestResponseBus is used.

Parameters:

requestDispatchers - The RequestDispatchers to be used by this DefaultRequestResponseBus

Method Details

sendForSingleOfClass

public <T> T sendForSingleOfClass(Class<T> returnType,
 Object... parameters)

Description copied from interface: RequestResponseBus

Send a request to all Listeners that satisfy the following requirements.

• They return an Object that the parameter 'returnType' is assignable from and
• they belong to a method with parameters that match the given 'parameters' objects

Specified by:

sendForSingleOfClass in interface RequestResponseBus

Parameters:

returnType - the return type that has to be assignable from the return type of the Listeners

parameters - the parameters to give to the Listeners

Returns:

a single return value from one of the listeners that executed (which one is unspecified) or 'null' if no matching Listeners were found

sendForMultipleOfClass

public <T> Collection<T> sendForMultipleOfClass(Class<T> returnType,
 Object... parameters)

Description copied from interface: RequestResponseBus

Send a request to all Listeners that satisfy the following requirements.

• They return an Object that the parameter 'returnType' is assignable from and
• they belong to a method with parameters that match the given 'parameters' objects

The number of Listeners that are executed may be larger than the number of return values that is returned, because some Listeners may return nothing (void).

Specified by:

sendForMultipleOfClass in interface RequestResponseBus

Parameters:

returnType - the return type that has to be assignable from the return type of the Listeners

parameters - the parameters to give to the Listeners

Returns:

all return values from the listeners that executed or an empty Collection if no matching Listeners were found. This method never returns null.

sendForNothing

public void sendForNothing(Object... parameters)

Description copied from interface: RequestResponseBus

Send a request to all Listeners that satisfy the following requirements. Ignore all return values and return nothing.

• They belong to a method with parameters that match the given 'parameters' objects

Specified by:

sendForNothing in interface RequestResponseBus

Parameters:

parameters - the parameters to give to the Listeners

sendForSingleWithHint

public <T> T sendForSingleWithHint(String hint,
 Object... parameters)

Description copied from interface: RequestResponseBus

Send a request to all Listeners that satisfy the following requirements.

• They have a hint that is equals to the 'hint' parameter and
• they belong to a method with parameters that match the given 'parameters' objects

Specified by:

sendForSingleWithHint in interface RequestResponseBus

Parameters:

hint - the hint that has to be equal to the hint of the Listeners

parameters - the parameters to give to the Listeners

Returns:

a single return value from one of the listeners that executed (which one is unspecified) or 'null' if no matching Listeners were found or none of them returned anything

sendForMultipleWithHint

public <T> Collection<T> sendForMultipleWithHint(String hint,
 Object... parameters)

Description copied from interface: RequestResponseBus

Send a request to all Listeners that satisfy the following requirements.

• They have a hint that is equals to the 'hint' parameter and
• they belong to a method with parameters that match the given 'parameters' objects

The number of Listeners that are executed may be larger than the number of return values that is returned, because some Listeners may return nothing (void).

Specified by:

sendForMultipleWithHint in interface RequestResponseBus

Parameters:

hint - the hint that has to be equal to the hint of the Listeners

parameters - the parameters to give to the Listeners

Returns:

all return values from the listeners that executed or an empty Collection if no matching Listeners were found or none of them returned anything. This method never returns null.

sendForNothingWithHint

public void sendForNothingWithHint(String hint,
 Object... parameters)

Description copied from interface: RequestResponseBus

Send a request to all Listeners that satisfy the following requirements. Ignore all return values and return nothing.

• They have a hint that is equals to the 'hint' parameter and
• they belong to a method with parameters that match the given 'parameters' objects

Specified by:

sendForNothingWithHint in interface RequestResponseBus

Parameters:

hint - the hint that has to be equal to the hint of the Listeners

parameters - the parameters to give to the Listeners

sendForSingleOfClassWithHint

public <T> T sendForSingleOfClassWithHint(Class<T> returnType,
 String hint,
 Object... parameters)

Description copied from interface: RequestResponseBus

Send a request to all Listeners that satisfy the following requirements.

• They return an Object that the parameter 'returnType' is assignable from and
• they have a hint that is equals to the 'hint' parameter and
• they belong to a method with parameters that match the given 'parameters' objects

Specified by:

sendForSingleOfClassWithHint in interface RequestResponseBus

Parameters:

returnType - the return type that has to be assignable from the return type of the Listeners

hint - the hint that has to be equal to the hint of the Listeners

parameters - the parameters to give to the Listeners

Returns:

a single return value from one of the listeners that executed (which one is unspecified) or 'null' if no matching Listeners were found

sendForMultipleOfClassWithHint

public <T> Collection<T> sendForMultipleOfClassWithHint(Class<T> returnType,
 String hint,
 Object... parameters)

Description copied from interface: RequestResponseBus

Send a request to all Listeners that satisfy the following requirements.

• They return an Object that the parameter 'returnType' is assignable from and
• they have a hint that is equals to the 'hint' parameter and
• they belong to a method with parameters that match the given 'parameters' objects

The number of Listeners that are executed may be larger than the number of return values that is returned, because some Listeners may return nothing (void).

Specified by:

sendForMultipleOfClassWithHint in interface RequestResponseBus

Parameters:

returnType - the return type that has to be assignable from the return type of the Listeners

hint - the hint that has to be equal to the hint of the Listeners

parameters - the parameters to give to the Listeners

Returns:

all return values from the listeners that executed or an empty Collection if no matching Listeners were found. This method never returns null.

send

public <T> T send(String hint,
 Object... parameters)

Description copied from interface: RequestResponseBus

Equivalent to RequestResponseBus.sendForSingleWithHint(String, Object...), since that is probably the most widely used method, because generally, when you know the hint, you know the returntype and you don't have to pass it specifically.

This method is just a convenience shorthand method with a shorter name.

Specified by:

send in interface RequestResponseBus

Parameters:

hint -

parameters -

Returns:

same as sendForSingleWithHint

dispatchRequestAndProcessResponse

protected <T> List<T> dispatchRequestAndProcessResponse(Request request)

Sends the given Request to all available RequestDispatchers and aggregates the Responses. If there are any Throwables, then an Exception is thrown, otherwise, the aggregated return values are returned.

Parameters:

request - The Request to be dispatched to the RequestDispatchers

Returns:

All return values returned by all RequestDispatchers

getRequestDispatchers

public List<RequestDispatcher> getRequestDispatchers()

Returns all RequestDispatchers that are used by this DefaultRequestResponseBus.

Returns:

All RequestDispatchers that are used by this DefaultRequestResponseBus

addRequestDispatcher

public void addRequestDispatcher(RequestDispatcher requestDispatcher)

Adds a RequestDispatcher to this DefaultRequestResponseBus.

Parameters:

requestDispatcher - The RequestDispatcher that needs to be added to this DefaultRequestResponseBus

setRequestDispatcher

public void setRequestDispatcher(RequestDispatcher requestDispatcher)

Removes all RequestDispatchers from this DefaultRequestResponseBus and adds only the given one. After invoking this method, only the given RequestDispatcher will be used by this DefaultRequestResponseBus.

Parameters:

requestDispatcher - The RequestDispatcher that must be the sole RequestDispatcher used by this DefaultRequestResponseBus