DEPRECATED - moved to migae

migae

Resources for implementing GAE webapps using Clojure.

Status

This project started life as a fork from appengine-magic, but it has changed so radically that I started over. It does use code from appengine-magic, but conceptually it is a completely different creature. In particular, it is modularized (each GAE service is separately packaged), supports multiple servlets and filters, and does not use the embedded Jetty server for testing, as appengine-magic does. Instead it uses a hack that gets you quasi-repl interactivity using the Google dev server.

Most of the services implementation is taken directly from appengine-magic, but some is original (e.g. datastore). It is not finished, so don't use it for any serious work. But it seems to work well enough if you want to explore or lend a hand.

This documentation is reasonably accurate as of Sept 19 2013, but is unstable and subject to frequent change.

Structure

The project actually includes:

• migae - collection of libraries wrapping GAE API, one per GAE service
• migae-template - a leiningent template
• lein-migae - a leiningen plugin
• migae-examples - some examples of how to do servlet programming with or without GAE

Libraries

• migae.migae-blobstore
• migae.migae-channel
• migae.migae-datastore
• etc.

Installation (NOT YET RELEASED)

[migae/migae-blobstore "0.1.0-SNAPSHOT"]
[migae/migae-channel "0.1.0-SNAPSHOT"]
etc. (these include migae-core)
[migae "x.y.z"] ;; everything

For now you have to clone the repo, build the libs, and "lein install" them to make available on your local system.

Getting Started

1 $ lein new migae app <appname>:<gae-proj-id> /path/to/sdk

2 $ cd <appname>

3 $ lein migae libdir - copy required jars to war/WEB-INF/lib

4 $ lein migae config - instantiate templates from <appname>/etc

5 $ lein compile

6 $ /path/to/sdk/bin/dev_appserver.sh war

NOTE: you might need to adjust the version number of the plugin in project.clj. Check clojars.

  :profiles {:dev {:plugins [[lein-migae "0.1.6-SNAPSHOT"]

Developing and Testing

To make the GAE dev_appserver act like a repl, use the nasty GAE REPL hack.

First install migae-save-buffer.el. Instructions in etc/migae-save-buffer.el. (If you don't use emacs, you're out of luck for the moment.)

This will replace the ordinary save-buffer command with one that first executes the standard save-buffer command and then copies the saved file to war/WEB-INF/classes. It only does this if you are editing a *.clj file below the /src directory containing a .dir-locals.el file. This file, in turn, is generated from a template in /etc when you run $ lein migae config.

The upshot of this is that when you edit a file, it gets copied to war/WEB-INF/classes, which is on the classpath, so it can be reloaded by the clojure runtime. This, in turn, is controlled by a filter - see reload_filter.clj in the sample project. Edit code, save, reload webpage. It's not as fast as the repl, but it's usually just fast enough.

Servlet Configuration

Everything is controlled by the project.clj file. The data in the :servlets stanza is used to generate war/WEB-INF/web.xml from the template file etc/web.xml.mustache. You should never need to edit the template file. To change a servlet name or path, edit the project.clj file and rerun lein migae config.