com.xerox.amazonws.sqs2
Class MessageQueue

java.lang.Object
  com.xerox.amazonws.common.AWSConnection
      com.xerox.amazonws.common.AWSQueryConnection
          com.xerox.amazonws.sqs2.MessageQueue

public class MessageQueue
extends AWSQueryConnection

This class provides an interface with the Amazon SQS message queue. It provides methods for sending / receiving messages and deleting queues and messsages on queues.

Author:

D. Kavanagh, developer@dotech.com

Field Summary

static int	MAX_MESSAGES
protected String	queueId

Fields inherited from class com.xerox.amazonws.common.AWSConnection

headers

Constructor Summary

protected

MessageQueue(String queueUrl, String awsAccessId, String awsSecretKey, boolean isSecure, int port, String server)

Method Summary

void	addPermission(String label, String accountId, String action) Adds a permission to this message queue.
static List<MessageQueue>	createList(String[] queueUrls, String awsAccessId, String awsSecretKey, boolean isSecure, int port, String server, org.apache.http.client.HttpClient hc)
void	deleteMessage(Message msg) Deletes the message identified by message object on the queue this object represents.
void	deleteMessage(String receiptHandle) Deletes the message identified by receiptHandle on the queue this object represents.
void	deleteQueue() Deletes the message queue represented by this object.
int	getApproximateNumberOfMessages() Gets the visibility timeout for the queue.
Map<String,String>	getQueueAttributes(QueueAttribute qAttr) Gets queue attributes.
URL	getUrl() This method provides the URL for the message queue represented by this object.
int	getVisibilityTimeout() Gets the visibility timeout for the queue.
boolean	isEncoding() This method returns the state of the base64 encoding flag.
protected <T> T	makeRequestInt(org.apache.http.client.methods.HttpRequestBase method, String action, Map<String,String> params, Class<T> respType)
protected URL	makeURL(String resource) Overriding this because the queue name is baked into the URL and QUERY assembles the URL within the baseclass.
Message	receiveMessage() Attempts to receive a message from the queue.
Message	receiveMessage(int visibilityTimeout) Attempts to receive a message from the queue.
protected Message[]	receiveMessages(BigInteger numMessages, BigInteger visibilityTimeout, List<String> attributes) Internal implementation of receiveMessages.
Message[]	receiveMessages(int numMessages) Attempts to retrieve a number of messages from the queue.
Message[]	receiveMessages(int numMessages, int visibilityTimeout) Attempts to retrieve a number of messages from the queue.
Message[]	receiveMessages(int numMessages, int visibilityTimeout, List<String> attributes) Attempts to retrieve a number of messages from the queue.
void	removePermission(String label) Removes a permission from this message queue.
String	sendMessage(String msg) Sends a message to a specified queue.
void	setEncoding(boolean enable) This method sets the state of the encoding flag.
void	setMessageVisibilityTimeout(Message msg, int timeout) Sets the message visibility timeout.
void	setMessageVisibilityTimeout(String receiptHandle, int timeout) Sets the message visibility timeout.
void	setQueueAttribute(String attribute, String value) Sets a queue attribute.
void	setVisibilityTimeout(int timeout) Sets the visibility timeout of the queue.

Methods inherited from class com.xerox.amazonws.common.AWSQueryConnection

close, close, getConnectionManagerTimeout, getConnectionTimeout, getHeaders, getHttpClient, getMaxConnections, getMaxRetries, getServerTimeZone, getSoTimeout, getString, httpDate, makeRequest, setConnectionManagerTimeout, setConnectionTimeout, setHttpClient, setMaxConnections, setMaxRetries, setProxyValues, setProxyValues, setProxyValues, setServerTimeZone, setSoTimeout, useSystemProxy

Methods inherited from class com.xerox.amazonws.common.AWSConnection

encode, encode, getAlgorithm, getAwsAccessKeyId, getPort, getResourcePrefix, getSecretAccessKey, getServer, getSignatureVersion, isSecure, setResourcePrefix, setServer, setSignatureVersion, urlencode

Methods inherited from class java.lang.Object

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

Field Detail

MAX_MESSAGES

public static final int MAX_MESSAGES

See Also:

Constant Field Values

queueId

protected String queueId

Constructor Detail

MessageQueue

protected MessageQueue(String queueUrl,
                       String awsAccessId,
                       String awsSecretKey,
                       boolean isSecure,
                       int port,
                       String server)
                throws SQSException

Throws:

SQSException

Method Detail

getUrl

public URL getUrl()

This method provides the URL for the message queue represented by this object.

Overrides:

getUrl in class AWSConnection

Returns:

generated queue service url

isEncoding

public boolean isEncoding()

This method returns the state of the base64 encoding flag. By default, all messages are encoded on send and decoded on receive.

Returns:

state of encoding flag

setEncoding

public void setEncoding(boolean enable)

This method sets the state of the encoding flag. Use this to override the default and turn off automatic base64 encoding.

Parameters:

enable - the new state of the encoding flag

sendMessage

public String sendMessage(String msg)
                   throws SQSException

Sends a message to a specified queue. The message must be between 1 and 256K bytes long.

Parameters:

msg - the message to be sent

Throws:

SQSException - wraps checked exceptions

receiveMessage

public Message receiveMessage()
                       throws SQSException

Attempts to receive a message from the queue. The queue default visibility timeout is used.

Returns:

the message object

Throws:

SQSException - wraps checked exceptions

receiveMessage

public Message receiveMessage(int visibilityTimeout)
                       throws SQSException

Attempts to receive a message from the queue.

Parameters:

visibilityTimeout - the duration (in seconds) the retrieved message is hidden from subsequent calls to retrieve.

Returns:

the message object

Throws:

SQSException - wraps checked exceptions

receiveMessages

public Message[] receiveMessages(int numMessages)
                          throws SQSException

Attempts to retrieve a number of messages from the queue. If less than that are availble, the max returned is the number of messages in the queue, but not necessarily all messages in the queue will be returned. The queue default visibility timeout is used.

Parameters:

numMessages - the maximum number of messages to return

Returns:

an array of message objects

Throws:

SQSException - wraps checked exceptions

receiveMessages

public Message[] receiveMessages(int numMessages,
                                 int visibilityTimeout)
                          throws SQSException

Attempts to retrieve a number of messages from the queue. If less than that are availble, the max returned is the number of messages in the queue, but not necessarily all messages in the queue will be returned.

Parameters:

numMessages - the maximum number of messages to return

visibilityTimeout - the duration (in seconds) the retrieved message is hidden from subsequent calls to retrieve.

Returns:

an array of message objects

Throws:

SQSException - wraps checked exceptions

receiveMessages

public Message[] receiveMessages(int numMessages,
                                 int visibilityTimeout,
                                 List<String> attributes)
                          throws SQSException

Attempts to retrieve a number of messages from the queue. If less than that are availble, the max returned is the number of messages in the queue, but not necessarily all messages in the queue will be returned.

Parameters:

numMessages - the maximum number of messages to return

visibilityTimeout - the duration (in seconds) the retrieved message is hidden from subsequent calls to retrieve.

attributes - the attributes you'd like to get (SenderId, SentTimestamp, All, ApproximateReceiveCount, ApproximateFirstReceiveTimestamp)

Returns:

an array of message objects

Throws:

SQSException - wraps checked exceptions

receiveMessages

protected Message[] receiveMessages(BigInteger numMessages,
                                    BigInteger visibilityTimeout,
                                    List<String> attributes)
                             throws SQSException

Internal implementation of receiveMessages.

Parameters:

numMessages - the maximum number of messages to return

visibilityTimeout - the duration (in seconds) the retrieved message is hidden from subsequent calls to retrieve.

attributes - the attributes you'd like to get (SenderId, SentTimestamp)

Returns:

an array of message objects

Throws:

SQSException - wraps checked exceptions

deleteMessage

public void deleteMessage(Message msg)
                   throws SQSException

Deletes the message identified by message object on the queue this object represents.

Parameters:

msg - the message to be deleted

Throws:

SQSException - wraps checked exceptions

deleteMessage

public void deleteMessage(String receiptHandle)
                   throws SQSException

Deletes the message identified by receiptHandle on the queue this object represents.

Parameters:

receiptHandle - the handle of the message to be deleted

Throws:

SQSException - wraps checked exceptions

deleteQueue

public void deleteQueue()
                 throws SQSException

Deletes the message queue represented by this object. Will delete non-empty queue.

Throws:

SQSException - wraps checked exceptions

setMessageVisibilityTimeout

public void setMessageVisibilityTimeout(Message msg,
                                        int timeout)
                                 throws SQSException

Sets the message visibility timeout.

Parameters:

msg - the message

timeout - the duration (in seconds) the retrieved message is hidden from subsequent calls to retrieve.

Throws:

SQSException - wraps checked exceptions

setMessageVisibilityTimeout

public void setMessageVisibilityTimeout(String receiptHandle,
                                        int timeout)
                                 throws SQSException

Sets the message visibility timeout.

Parameters:

receiptHandle - the handle of the message to be deleted

timeout - the duration (in seconds) the retrieved message is hidden from subsequent calls to retrieve.

Throws:

SQSException - wraps checked exceptions

getVisibilityTimeout

public int getVisibilityTimeout()
                         throws SQSException

Gets the visibility timeout for the queue. Uses getQueueAttributes(QueueAttribute).

Throws:

SQSException - wraps checked exceptions

getApproximateNumberOfMessages

public int getApproximateNumberOfMessages()
                                   throws SQSException

Gets the visibility timeout for the queue. Uses getQueueAttributes(QueueAttribute).

Throws:

SQSException - wraps checked exceptions

getQueueAttributes

public Map<String,String> getQueueAttributes(QueueAttribute qAttr)
                                      throws SQSException

Gets queue attributes. This is provided to expose the underlying functionality. Currently supported attributes are; ApproximateNumberOfMessages CreatedTimestamp LastModifiedTimestamp VisibilityTimeout RequestPayer Policy

Returns:

a map of attributes and their values

Throws:

SQSException - wraps checked exceptions

setVisibilityTimeout

public void setVisibilityTimeout(int timeout)
                          throws SQSException

Sets the visibility timeout of the queue. Uses setQueueAttribute(String, String).

Parameters:

timeout - the duration (in seconds) the retrieved message is hidden from subsequent calls to retrieve.

Throws:

SQSException - wraps checked exceptions

setQueueAttribute

public void setQueueAttribute(String attribute,
                              String value)
                       throws SQSException

Sets a queue attribute. This is provided to expose the underlying functionality, although the only attribute at this time is visibility timeout.

Parameters:

attribute - name of the attribute being set

value - the value being set for this attribute

Throws:

SQSException - wraps checked exceptions

addPermission

public void addPermission(String label,
                          String accountId,
                          String action)
                   throws SQSException

Adds a permission to this message queue.

Parameters:

label - a name for this permission

accountId - the AWS account ID for the account to share this queue with

action - a value to indicate how much to share (SendMessage, ReceiveMessage, ChangeMessageVisibility, DeleteMessage, GetQueueAttributes)

Throws:

SQSException - wraps checked exceptions

removePermission

public void removePermission(String label)
                      throws SQSException

Removes a permission from this message queue.

Parameters:

label - a name for the permission to be removed

Throws:

SQSException - wraps checked exceptions

makeURL

protected URL makeURL(String resource)
               throws MalformedURLException

Overriding this because the queue name is baked into the URL and QUERY assembles the URL within the baseclass.

Overrides:

makeURL in class AWSConnection

Parameters:

resource - The resource name (bucketName + "/" + key).

Throws:

SQSException - wraps checked exceptions

MalformedURLException

makeRequestInt

protected <T> T makeRequestInt(org.apache.http.client.methods.HttpRequestBase method,
                               String action,
                               Map<String,String> params,
                               Class<T> respType)
                    throws SQSException

Throws:

SQSException

createList

public static List<MessageQueue> createList(String[] queueUrls,
                                            String awsAccessId,
                                            String awsSecretKey,
                                            boolean isSecure,
                                            int port,
                                            String server,
                                            org.apache.http.client.HttpClient hc)
                                     throws SQSException

Throws:

SQSException