Posts Tagged ‘app engine’

Keeping data secure in Google App Engine

Thursday, April 10th, 2008

While going through the “Getting Started” documentation provided for Google App Engine, I noticed something interesting in the “Using the Datastore” section. The datastore included in the App Engine is not a relational database, but it has some similarities. When querying the datastore, you can use GQL, which is similar to SQL. For instance:

greetings = Greeting.gql("WHERE author = :1 ORDER BY date DESC", users.get_current_user())

Notice the parameter replacement where “:1” is replaced with the value of “users.get_current_user()“. The documentation states:

Unlike SQL, GQL queries may not contain value constants: Instead, GQL uses parameter binding for all values in queries.

As Wikipedia points out, using a parameterized statement like this GQL parameter binding is one way to mitigate an SQL injection attack. The SQL injection is mitigated because the parameter value can consistently be properly escaped within the execution of the parameter binding. I find it very interesting that Google decided, in implementing GQL, to enforce the use of parameter binding. This must have been a conscious decision to help App Engine developers to make their apps more secure. I think that this is a good decision.

Worked through the Google App Engine “Getting Started” introduction

Tuesday, April 8th, 2008

I just finished trying out the Google App EngineGetting Started” introduction. I haven’t programmed in Python for a very long time. The introduction was pretty cool.

Except for the problem with Windows in the static file CSS example. I found a discussion about the issue by Googling “App Engine InvalidAppConfigError”. They have a simple work-around to get the sample to work. But it looks like there will have to be fix in the API for the problem to be resolved.

But all in all, this is a pretty neat framework. I look forward to playing with the SDK some more.

(And being a pilot, I am a bit biased toward the App Engine logo. You can see it at the home page. It is a jet engine with wings and a vertical stabilizer. 🙂 )