Blocker

Blocker is a lightweight project skeleton that implements CRUD operations in a RESTful manner using standard Clojure libraries. It should give new Clojure developers a reasonable starting point from which to build their web applications.

The following components have been pre-wired:

H2 database has been embedded to provide JDBC-compliant durable storage.
ClojureQL is used to map Clojure expressions to relational database queries.
Enlive is used to merge pure XHTML views with data models.
Compojure is used to define routes, mapping our RESTful URLs to their respective handlers.
Ring provides our Jetty adapter and core HTTP abstraction.

Usage

This example assumes you have Git, Leiningen, and Emacs installed and configured. For help setting up your development environment, you can check out these guides for Windows or Linux.

In your shell:

rrc@X ~/projects
$ git clone git://github.com/rcampbell/blocker.git
Initialized empty Git repository in ~/projects/blocker/.git/
remote: Counting objects: 17, done.
remote: Compressing objects: 100% (12/12), done.
remote: Total 17 (delta 1), reused 0 (delta 0)
Receiving objects: 100% (17/17), done.
Resolving deltas: 100% (1/1), done.

rrc@X ~/projects
$ cd blocker

rrc@X /projects/blocker (master)
$ lein deps
Copying 13 files to ~/projects/blocker/lib
Copying 18 files to ~/projects/blocker/lib/dev

rrc@X /projects/blocker (master)
$ lein swank
user=> Connection opened on local port  4005
#<ServerSocket ServerSocket[addr=localhost/127.0.0.1,port=0,localport=4005]>

In Emacs, connect to our swank server:

M-x slime-connect

Once you are connected you can initialize the database by evaluating the init.clj script in the REPL:

user> (load "blocker/db" "blocker/init")

You should now open up core.clj and compile it:

C-c C-k

You can now open http://localhost:3000/ in your browser to see the running application. Any changes you make to your Clojure source files require only a recompile to appear in the running application. You can interact with the running application through your REPL:

user> (require '[blocker.db :as db])
nil
user> (db/create-block! "foobar")
"IqPWJb"
user> @(db/get-block *1) ; *1 is bound to the last value printed
({:text #<JdbcClob clob4: 'foobar'>})
user> (clojure.java.browse/browse-url (str "http://localhost:3000/blocks/" *2))
"http://localhost:3000/blocks/IqPWJb"

You can also run the server from the shell using the Ring plugin for Lein:

lein ring server

With this method, you only have to save your Clojure source files for changes to appear in the running application.

TODO

Support different formats (JSON, XML) via Accept and Content-Type headers
cURL examples w/GET, PUT, POST, DELETE
Figure out how to get a swank server running inside lein ring server so we don't need two JVM instances (blows up H2)

License

Distributed under the Eclipse Public License, the same as Clojure.