When we released version 1.2.4 of the SDK earlier this month, a couple of new features were released that didn't quite make it into the release notes. We think they're really cool features, so we wanted to take the time to highlight them.
The first feature is that when logged into your app as an administrator, App Engine will include a couple of extra headers in all the HTTP responses it sends you. As an example, here's what I see in Firefox's Live HTTP headers plugin when I load my blog:X-AppEngine-Resource-Usage: ms=293 cpu_ms=500 api_cpu_ms=236X-AppEngine-Estimated-CPM-US-Dollars: $0.012320
X-AppEngine-Resource-Usage: ms=293 cpu_ms=500 api_cpu_ms=236X-AppEngine-Estimated-CPM-US-Dollars: $0.012320
The first header tells me that it took 293 milliseconds to generate the page, and 500 CPU milliseconds were consumed, of which 236 milliseconds were spent doing API calls - such as accessing memcache or the datastore. The second header tells me that App Engine estimates that serving 1000 requests like this one would cost about $0.01 if I was above my free quota - not bad!
You can view these headers using plugins such as Firefox's Live HTTP Headers or Firebug. Note that only logged in administrators see these figures - ordinary users, and users who aren't logged in, won't see them at all.
The second new feature is that we've enabled 'wildcard' domains for App Engine apps serving off appspot.com. What this means is that you can now create multiple subdomains for your App Engine app, and have them all served by the same application. Thus, your users can access 'myapp.appspot.com', or 'developer.myapp.appspot.com', or 'news.myapp.appspot.com', with your app deciding how to handle each request. No setup is required to use the wildcard domains - simply configure your app to serve up requests to these subdomains however you wish. You can detect which domain a user requested by looking at the 'Host' header in the incoming request - for example, in Python's webapp framework you can access this with self.request.headers['Host'].
Every month or so, we compile a list of interesting things in the community related to App Engine. Here are some recent projects and resources that you might find interesting:
Ubisoft has released a fun game for Facebook called TickTock which challenges you to guess which of your friends have posted particular status updates. From the application page "TickTock is a Facebook trivia game that tests your knowledge of your friends. Use that knowledge to create playful devices to challenge others. Unlock items and create bigger challenges. Post them on your people's Facebook Walls, and see who knows their friends best!"
TickTock uses App Engine to serve the game content and store game information. We're excited to see this as a great example of a growing number of games which are using App Engine behind the scenes. Sign on to Facebook and give it a try.
Written by a group of engineers at VendAsta, asynctools is a rather nifty toolkit that allows you to execute datastore queries in parallel in the Python runtime. The interface is slightly more involved than using standard queries, but the ability to execute multiple queries in parallel can substantially reduce the render time for a page where you need to execute multiple independent queries.
Jason Collins has written a detailed article about how and why they wrote asynctools, which can be found here.
DryDrop is a new tool that lets you host your static site on Google App Engine and update it by pushing to GitHub. Thanks to GitHub post-receive hooks your App Engine site can be updated automatically when you push new content.
We have a new screencast up in the Developer's Channel on YouTube, this one covers Installing Google App Engine applications into Google Apps.
For more open source projects built on top of Google App Engine, see the Open Source Projects wiki page, and feel free to add your own open source projects to that page if you want to see them featured in an upcoming community update post.
Posted by Jeff Scudder, Nick Johnson, and Jason Cooper, App Engine Team
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We're psyched to release version 1.2.4 of the App Engine SDK for Python. Some highlights of what you'll find in this release:
For full details, please see the SdkReleaseNotes wiki page.
Downloads for Windows, Mac, and Linux are available on the Downloads page. This SDK update was for the Python runtime, so please post your feedback in the Python runtime discussion group.
We'd also like to draw your attention to two new articles from App Engine team members:
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