Orbitz Vending Machine Coding Test author: Eric Hansen emhansen@gmail.com 414-324-0415 ====Overview=== An implementation of a service that can act as a vending machine. This application has authentication, uses a greedy algorithm to determine change, was created using test driven development, and was built using Maven. This project uses junit 4 for its tests. I added security to the stock product method so that only maintenance workers can stock the vending machine. I used Spring Security and the JSR 250 api for that functionality. This project is built with the Java 6 jdk, and must be since it uses the @Override annotation on methods that implement their interface's methods. I used a greedy algorithm to determine the optimal (minimal amount of coins) to return for the coin return method. This is okay in the US since that algorithm works for nickels, dimes, and quarters. I used synchronized keywords on all the services methods (except checkStock) and a ConcurrentMap to keep track of the remaining stock, which is returned as unmodifiable by the checkStock method. This approach ensures that only one thread will be changing the VendingMachineImpl's data structures at any moment. It also guarantees that any client will have the most up to date view of the stock. For concurrency concerns in an enterprise solution (or a solution that requires persistence) I would typically rely on a database and JTA . I thought that approach too heavy for such a simple problem and relied on in memory data structures instead. ====Run Tests==== If you have maven installed simply type in this directory: mvn test You should see output that says: Results : Tests run: 27, Failures: 0, Errors: 0, Skipped: 0 ====Install Maven==== Since the instructions stated to include only the source code I didn't bundle the required libraries. I recommend installing maven to build this project since it will download the correct versions of all necessary libraries for you. Download Maven: http://maven.apache.org/download.html Extract it somewhere and add Maven's bin directory to your environment PATH Ensure JAVA_HOME environment variable is pointing to a JDK 1.6 Configure a HTTP Proxy if you're behind one: http://maven.apache.org/guides/mini/guide-proxies.html Browse back to the directory this README is in and type: mvn test It will start the build, download all dependencies, and then run the tests. You should see output that says: Results : Tests run: 27, Failures: 0, Errors: 0, Skipped: 0 ====Problems==== If Maven is having problems, email me and I can send over the libraries.