Project suited for Google App Engine?

I'm currently developing a small hobby project (open sourced at https://github.com/grav/mailbum) which quite simply takes images from a Gmail account a开发者_如何学Pythonnd puts them in albums on Picasa Web.

Since it's (currently) only dealing with Google-hosted data, I was thinking about hosting it on Google App Engine, but I'm not sure if it's well-suited for GAE:

• Will the maximum execution time be a problem? It's currently 10 minutes according to http://googleappengine.blogspot.com/2010/12/happy-holidays-from-app-engine-team-140.html, but I'd think the tasks (i.e. processing a single mail) would be easy to run in parallel. I'm also guessing that dealing with Google-hosted data would be quite efficient on GAE?

• Will the fact that it's written in Clojure be an obstacle? I've researched a bit in getting Clojure to run on GAE, but I've never tried it. Any pin-pointers?

Thanks for any advice and thoughts on the project!

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It seems like your application is doable on GAE. My points of concern would be:

1. Does your code ever store the images that it is processing to temporary files? If so it will need to be changed to do everything in memory, because GAE applications are sandboxed and not allowed to write to the filesystem (if you need temporary persistent storage, you might be able to work something out where you write your file data to a BLOB field in the GAE datastore).

2. How do you get the images into Picasa Web? If they provide a simple REST/HTTP API then all is well. If you need something more involved than that (like a raw TCP socket) then it won't work.

3. The 10-minute execution time limit only applies to background tasks. When actually servicing web requests the time limit is 30 seconds. So if you provide a web-based interface to your app, you need to structure things so that the interface is just scheduling jobs that run in the background (i.e. you can't fire off a job directly as part of servicing a web request).

If none of those sound like show-stoppers to you, then I think your app should work just fine on GAE.

Can't really say if Clojure will work though. I have, however, spent time in the past getting some third-party libraries to work on App-Engine. Generally all I had to do was remove/modify/disable any parts of the library that accessed features that are forbidden by the sandbox (for instance, I had to disable the automatic caching to disk to get commons-fileupload to work on GAE). Not sure if the same would apply to Clojure, or even what the scope would be on a task like that.

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I have been dabbling with Clojure and App Engine for a while now and I have to recommend appengine-magic. It abstracts most of the Java stuff away and is very easy to use. As a plus the project seems to be very active.