Groovy, java, educational technologies

Groovy is an object oriented dynamic language for the JVM. Dynamically compiled to a bytecode and interoperable with most Java libraries, Groovy is a perfect candidate for writing lightweight scripts that still can benefit from the Java ecosystem. Also, it is really easy to learn since the good old Java syntax is usually valid in Groovy. There are, however, a few caveats that you should be aware of before start coding. This post shows some specific features, and also gives a few suggestions which will help to write a clear, groovy-style code.

Multithreading, concurrency, deadlock, java technologies

Concurrent programs is not a novelty today, almost every modern application executes in multiple threads. But as concurrency brought us better resource utilization and throughput, it also introduced a number of issues nonexistent in serial execution. One of them is deadlocks. A deadlock is a situation where in two or more competing actions are each waiting for the other to finish, and thus neither ever does.

Immutability, java technologies

An immutable object is one whose state cannot be changed after construction. All the beauty in these objects is that they are simple and safe. In multi-threaded applications all concurrency issues boil down to coordinating access to mutable state. The less mutable state, the easier it is to ensure thread safety. That’s why you should always consider making your objects immutable whenever it is feasible. Creating an immutable type is not a complex process, but you should follow a handful of rules to stay away from pitfalls it definitely implies.

Java, lock, educational technologies

Java locks often supersede synchronized blocks and methods by allowing to back out from the synchronization attempt. This post shows how to use the feature, and demonstrates some other basic concepts, like the lock fairness and reentrant locks, which should help you to get started with the lock-based synchronization.

Authorize.net, java technologies

In the previous post I’ve told how to bill a customer with a minimal fuss. But oftentimes returning customers wish to add or change their billing information or maybe you want to delete the old ones. Let’s dive deeper and see what’s possible to do with Authorize.Net Customer Information Manager by remote procedure calls using, as previously, Java SDK.