com.squirrel.rabbit

Class RabbitMQListener

java.lang.Object

com.squirrel.rabbit.RabbitMQListener

All Implemented Interfaces:

Runnable, org.hobbit.core.rabbit.DataHandler

public class RabbitMQListener
extends Object
implements Runnable, org.hobbit.core.rabbit.DataHandler

The interface between the RabbitMQ and the Web-Service Or better to say: Listener for the RabbitMQ - receives and organize the SquirrelWebObjects and the VisualisationGraphs

Author:

Philipp Heinisch

Field Summary

Fields

Modifier and Type	Field and Description
private com.rabbitmq.client.Channel	channel
private com.rabbitmq.client.Connection	connection
private List<com.SquirrelWebObject>	dataQueue
private org.slf4j.Logger	logger
private static int	MAXLENGTHOFHISTORY
private static String	QUEUE_INPUT_GENERAL_NAME
private static String	QUEUE_OUTPUT_URI_NAME
private org.dice_research.squirrel.data.uri.serialize.Serializer	serializer
private Semaphore	terminationMutex

Constructor Summary

Constructors

Constructor and Description
RabbitMQListener()

Method Summary

Modifier and Type	Method and Description
private <T> void	addElementToLimitedList(@NotNull List<T> list, T insertedElement) Adds a element to a List, but checks in addition before, if a certain size limit (MAXLENGTHOFHISTORY) is reached.
void	close()
int	countSquirrelWebObjects() Counts the number of SquirrelWebObject
com.graph.VisualisationGraph	getCrawledGraph() Gets the fected crawled graph from Frontier.
com.graph.VisualisationGraph	getCrawledGraph(int index) Gets the fetched crawled graph from Frontier.
private <T> T	getObject(List<T> list, int index)
com.SquirrelWebObject	getSquirrel() Gets the fetched data from the Frontier.
com.SquirrelWebObject	getSquirrel(int index) Gets the fetched data from the Frontier.
void	handleData(byte[] bytes)
(package private) boolean	publishURI(String uri) Just publishes a URI to the queue (connected with the Frontier): for serialising, a Serializer is used.
private boolean	queueDeclare(String queueName)
private boolean	rabbitConnect(int triesLeft) recursive function, that tries to connect with the rabbit container
void	run()

Methods inherited from class java.lang.Object

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

Field Detail

dataQueue

private List<com.SquirrelWebObject> dataQueue

QUEUE_INPUT_GENERAL_NAME

private static final String QUEUE_INPUT_GENERAL_NAME

See Also:

Constant Field Values

QUEUE_OUTPUT_URI_NAME

private static final String QUEUE_OUTPUT_URI_NAME

See Also:

Constant Field Values

connection

private com.rabbitmq.client.Connection connection

channel

private com.rabbitmq.client.Channel channel

terminationMutex

private Semaphore terminationMutex

serializer

private org.dice_research.squirrel.data.uri.serialize.Serializer serializer

logger

private org.slf4j.Logger logger

MAXLENGTHOFHISTORY

private static final int MAXLENGTHOFHISTORY

See Also:

Constant Field Values

Constructor Detail

RabbitMQListener

public RabbitMQListener()

Method Detail

run

public void run()

Specified by:

run in interface Runnable

queueDeclare

private boolean queueDeclare(String queueName)

rabbitConnect

private boolean rabbitConnect(int triesLeft)

recursive function, that tries to connect with the rabbit container

Parameters:

triesLeft - the number of left tries. 5s are in between 2 tries

Returns:

true, if the connection to the RabbitMQ was established, otherwise false

close

public void close()
           throws IOException,
                  TimeoutException

Throws:

IOException

TimeoutException

getSquirrel

public com.SquirrelWebObject getSquirrel()

Gets the fetched data from the Frontier. Contains many information about the current crawling status and so on

Returns:

the latest SquirrelWebObject

getSquirrel

public com.SquirrelWebObject getSquirrel(int index)

Gets the fetched data from the Frontier. Contains many information about the current crawling status and so on

Parameters:

index - All received SquirrelWebObject are stored in a list. Index 0 is the oldest entry, Index size-1 is the latest one

Returns:

the SquirrelWebObject

getCrawledGraph

public com.graph.VisualisationGraph getCrawledGraph()

Gets the fected crawled graph from Frontier.

Returns:

the latest VisualisationGraph

getCrawledGraph

public com.graph.VisualisationGraph getCrawledGraph(int index)

Gets the fetched crawled graph from Frontier.

Parameters:

index - All received VisualisationGraph are stored in a list. Index 0 is the oldest entry, Index size-1 is the latest one

Returns:

the VisualisationGraph

getObject

private <T> T getObject(List<T> list,
                        int index)

countSquirrelWebObjects

public int countSquirrelWebObjects()

Counts the number of SquirrelWebObject

Returns:

the number of SquirrelWebObject-objects, that were received from the WebService

addElementToLimitedList

private <T> void addElementToLimitedList(@NotNull
                                         @NotNull List<T> list,
                                         @NotNull
                                         T insertedElement)

Adds a element to a List, but checks in addition before, if a certain size limit (MAXLENGTHOFHISTORY) is reached. If yes, the method truncates every second element from the list. Attention: if the list is bigger than MAXLENGTHOFHISTORY*2, then the truncate procedure will execute multiple times.

Type Parameters:

T - this method is generic

Parameters:

list - the List, in that the element should be added. Must not be null.

insertedElement - the element, that should be added Must not be null.

publishURI

boolean publishURI(String uri)

Just publishes a URI to the queue (connected with the Frontier): for serialising, a Serializer is used. Until yet, it's common to use as the Serializer implementation the GzipJavaUriSerializer. If it changes, you should adpat this method!

Parameters:

uri - the URI

Returns:

true if and only if the publish to the Channel succeeded!

handleData

public void handleData(byte[] bytes)

Specified by:

handleData in interface org.hobbit.core.rabbit.DataHandler