Get in the Queue, your locks don't work here

By Michael Foord -
Threading, locking and concurrency are all hot topics at the moment. One place where threading and locking don't work as a way of controlling access to shared resources are in distributed web applications. This blog entry by Tarn Barford discusses the use of Queues from IronPython (with plenty of example code) when working with web apps on the Azure platform.
I am, of course, talking about a pattern in high scale web application design, Queues. More specifically the Queue service on the Windows Azure cloud computing platform.
So when do you use Queues?

Its common to use thread synchronization objects in a web application to serialize access to a resource, but this thread synchronization approach doesn't work so well when you have multiple applications, over multiple servers competing for exclusive access to a global resource.

The first scenario I've found which suits the Queue service is in a user driven content ranking system. I suspect I'll find many more places to use the Queue services as I continue to learn more about developing and designing applications on the cloud platform.

In the web application I'm building I want users to be able to rate dynamic content and I also want to record the number of views. This is a very common concept which allows the users to provide feedback which can then be shared with other users and used to dynamically rank the content.

Comments

Post a Comment

Popular posts from this blog

Extending Abobe Flash Player and AIR with Python and Ruby

By Michael Foord -
An intriguing blog entry about an Adobe experimental project. It is a C/C++ cross- compiler for the flash player and AIR. This means that you can (will be able to?) cross-compile the Python / Ruby/ lots of other language runtimes and then run them in Flash. The blog entry contrasts this approach to the DLR which requires the re-implementation of dynamic languages - hence IronPython and IronRuby. The project is already beyond proof-of concept, they even have Quake III cross-compiled and running in Flash. Extending Adobe Flash Player and AIR with C/C++ Cross-Compiler Quake 3 has already been ported to managed code , but this is even more impressive. Whether the Python interpreter can be cross-compiled to run on top of another runtime (with completely different basic types), without changing the language semantics at all, has yet to be proved - but it is a very interesting project. (It also means that Python/Ruby will possibly be enabled only by additional optional downloads - but don...
Read more

IronPython Tools for Visual Studio CTP3

By Michael Foord -
At PyCon this year Dino Veihland announced IronPython Tools for Visual Studio, an extension to Visual Studio 2010 for working with IronPython. It features Python syntax highlighting, awesome auto-complete (intellisense) and a host of other features for working with IronPython code in Visual Studio. It can be used with the free Visual Studio shell and doesn't require you to own a full copy of Visual Studio. The third CTP (Community Technology Preview) has been made available for download. IronPython Tools for Visual Studio We are happy to announce a minor update to the IronPython Tools for Visual Studio.  IronPython Tools for Visual Studio (IPyTools) is a set of extensions available for Visual Studio 2010 which supports development of IronPython applications.  This release is our 3rd Community Technical Preview (CTP) and builds upon the previous two releases.  The release is a minor update which includes bug fixes and a number of small features.  You can download...
Read more

Further Adventures of the Debugger

By Michael Foord -
Harry Pierson (Microsoft IronPython PM) has been experimenting with writing an IronPython debugger ( ipydbg ) on top of the .NET MDbg APIs. When we last left him , he had implemented Just My Code (JMC) support allowing you to step into IronPython code. Since then he has made a lot of progress including a colourful REPL (interactive console) and solving some difficult problems around getting to real values behind boxed IronPython variables (needed for showing local variables). He has blogged extensively on what he has been up to (more recent posts last): Showing Source Code Colorful Console IronPython ConsoleColorMgr (the colorful console code pulled out into a separate IronPython module) A Little Hack...err...Cleanup Getting Local Variables Displaying Values Command Routing Getting Arguments REPL Console A lot of functionality is now present. In the command routing entry Harry outlines the seven commands supported by the debugger so far: Continue, Quit, Show Stack Trace, Show Locals, ...
Read more