App Engine Datastore access

Is it possible to query App Engine's Datastore from outside the cloud, i.e. a client application?

I could possibly write an app to be housed within AppStore and query the Datastore returning XML-formatted data; I want to know, however, if there are any Datastore endpoints which would allow me to do it directly.

Also, in case it is possible, am I able to do so via SSL?

How do I access GCP Datastore?

In the Google Cloud console, go to the VM Instances page. Click the Create instance button. In the Identity and API access section, set Access scopes to provide access for Datastore.

What is Datastore in Google App Engine?

Datastore is a NoSQL document database built for automatic scaling, high performance, and ease of application development. Datastore features include: Atomic transactions. Datastore can execute a set of operations where either all succeed, or none occur.

Yes. The remote_api library supports exactly this use-case. If you're using Java, there's a Java remote_api handler available, and the client will be available at some point in the future.

You can use this over SSL in the same way as any other handler.

There's no reason you couldn't create your own app engine application that exposes the datastore as a web service (either http or https). In fact, here is a link to a python version.