SQS

Although your data is an image, it is still sent up to Amazon SQS as a string.

This ensures that the request to Amazon SQS cannot simply be captured by an attacker and replayed, thus mimicking the valid user.

SmugMug built their own queuing service, but you could just as easily use Amazon's own SQS.

Without knowledge of these characteristics, you might find working with Amazon SQS to be frustrating and confusing initially.

It is instructive to compare the steps used for the local queue with the steps required to connect to Amazon's SQS queue.

SQS will try to preserve the order in messages, but it is not guaranteed that you will receive messages in the exact order you sent them.

The second important characteristic of Amazon SQS is the concept of eventual consistency.

Each of your messages is stored on multiple servers by SQS to provide redundancy and high availability.

In this article, you use the query interface by way of a third-party library to communicate with SQS.

You see it set below in the SendMessageRequest object used to send the message to the Amazon SQS queue (see Listing 14).

Upon receiving a purchase order, it creates an order summary and sends it to the reseller using a different Amazon SQS queue.

Now that messages are being placed on an SQS queue, I need to pop them off of the queue and do some processing.

It is helpful to know a few characteristics of Amazon SQS before you delve into Amazon SQS development.

SQS does not guarantee deletion of a message in the queue.

Amazon has another notification service, Simple Queue Service (SQS), using a polling-based approach to messaging.

Use Amazon SimpleDB to store the structured data and put a handle to the items in the Amazon SQS message.

To make the service scalable and highly available, the design of the service is message-driven, utilizing SQS's reliable message delivery.

The first step is to create a connection object to SQS using the Amazon Web Services access keys you exported earlier to your environment.

SQS does not guarantee order of the messages in a queue.

This month, I introduce a cloud-based alternative to such labor-intensive messaging: Amazon's Simple Queue Service (SQS).

To minimize any disruptions, use the latest version of the API when creating new applications with SQS.

SQS does not guarantee that all the messages in the queue will be returned when queried.

Combining the extensibility of XML with Amazon SQS provides a highly scalable and flexible application.

SQS reserves the right to automatically delete queues if there has been no activity in the queue for 30 consecutive days.

In this article, you'll learn how Amazon SQS elevates the burden of installing and maintaining a message-queuing system.

As I previously mentioned, SQS reading is done polling-style; what's more, the receiveMessage method is non-blocking.

Now use the receiveMessage method to attempt to receive a message from the Amazon SQS queue (see Listing 19).

The policies for the Amazon SQS operate at the cloud service provider, of course.

Amazon suggests sending the notifications to an SQS queue when delivery is critical.

As described at the outset, the hybrid application processes data locally and makes use of the Amazon SQS cloud service.

The medical organization securely writes the X-ray images to an Amazon SQS queue, where they are temporarily stored.

With the Amazon SQS service, you can design the lock window based on the unique processing requirements of the messages stored in the queue.

The client also enables users to browse inventory, view orders, and view the Amazon SQS message queues.

In Listing 8, I've enlisted the help of the right_aws Ruby gem to assist me in working with SQS.

SQS is probably the most obvious choice for this particular hybrid application.

Decouple your application components by using the unlimited reliable messaging provided by Amazon Simple Queue Service (SQS).

On the cloud side, the Amazon SQS service provides a queuing service between applications, even when they are on unconnected networks.

Consequently, reading an SQS queue requires those few additional lines of code.

This change is transparent to the medical applications, which continue to write their X-ray image files to the Amazon SQS queue.

Amazon's SQS elevates the burden of installing and maintaining a queuing system.

That is the next step, in which you create the queue on the Amazon SQS cloud service.

If you omit a value for the timeout, boto will create the queue with the default value of 30 seconds provided by SQS.

With Amazon SQS, however, you can do it easily in any web application, regardless of platform.

The HybridCloud application uses Amazon SQS to write data to a queue, and then to later read data back from the queue.

Now that you've created you Amazon SQS queue, turn your attention to the local aspects of this hybrid application.

Writing a message to an SQS queue takes three lines of code.

Now send your message to the Amazon SQS Queue by using the sendMessage method of your Amazon SQS object (see Listing 16).

Read local data (from a JMS queue) and put it onto the Amazon SQS queue.

Finally, you must delete the purchase order queue item from the Amazon SQS queue.

Navigate to the SQS home page.

SQS will automatically delete any messages that have been in your queues longer than four days.

Something else to note is that messages placed on SQS are durable: they are there until you remove them.

For Amazon SQS, that means you pay $0. 000001 per message.

Keep in mind that once you have a handle to a valid message, SQS locks it.

Now, send the message containing the purchase order to the Amazon SQS queue using the code in Listing 14.

A developer must register a credit card with Amazon Web Services in order to use services such as SQS.

There are two versions of SQS available: the original version (2007-05-01) and a 2008-01-01 version.

You can also set policies that control access to our SQS queue based on date, time, and source IP Address, as in Listing 2.

SQS-interface. wsdl -- WSDL service implementation description for a stock quote service

SQS. wsdl -- WSDL service interface description for a stock quote service

Once you have an Amazon Web Services account, you must enable Amazon SQS service for your account