Resolving GAE deployment error - 'An error occured while deploying to AppEngine' I was doing some updates to my Guru JSON-RPC Tester recently and when it came to deploying my changes to AppEngine, I was presented with this very uninformative error message - "An error occured while deploying to AppEngine. See the error log for more details". That didn't give me any clue as to what the actual problem was, not to mention the obvious spelling mistake in the error message.
Generating dynamic images using HTML5 canvas with Google App Engine Not so long ago I wrote a small JSP page for my GAE based game that displayed all of the players and their basic stats plus an image representing their game map. This worked great on the development server, but on the production server no maps were being generated. Why? Because Google does not permit ImageIO classes to run on their servers. I started looking for other libraries to implement the same functionality and sadly didn't find much. So my solution was to do it in HTML5 instead.
JDO, you're dumped, App Engine and bi-directional relationships After searching high and low to find out how to add a child object to a parent in JDO efficiently and getting ever more frustrated with the lack of good documentation, I've decided to just write some of my own tests to see what's possible and how well it works.
Getting 100% JUnit Test Coverage for JDO objects in App Engine Once I started writing unit tests for the objects I was persisting into the HRD in App Engine via JDO, I've noticed that the coverage for all of my classes was below 100%. This didn't seem right to me because I was certain that I was testing everything.
Parents, Children and Ancestor queries in Google App Engine with JDO Fetching a child object by the ID of the parent using JDO had me stuck for a while. According to this article "reads, writes, and ancestor queries will always reflect the results of the commit" in the Google App Engine data store (HRD). After trying various things and reading lots of documentation and forum posts it all came down to how I modelled my objects. Now when I persist a parent object with an attached child, then immediately perform a query to fetch that child, the data returns as expected.
A simple JSON-RPC server with Google AppEngine I've started exploring the use of Google AppEngine for a project I'm working on. JSON was one of the technologies that was going to be used and JSON-RPC looked like an attractive way of exposing functionality without writing your own server network code.