Resilient

When implementing distributed systems, client-server architectures and simple applications with network related functionalities, everything is fine when we’re in the development or in the testing stage because the network is reliable and the communicating systems are not as stressed as they are in production. But to sleep well we want to validate how resilient we have implemented our systems, how they behave when the network fails, the latency rises, the bandwidth is limited, connections time out and so on. ...

When dealing with remote services or APIs there is always the risk of latency issues, failures or connection losses. The worst thing to happen is when the remote service is down and our application hangs until the underlying protocol’s (e.g. TCP) connection timeout is reached and we’re receiving an exception. Until this moment is reached, our application might hang, memory is allocated for threads or bound objects and at last, our continuous requests might prevent the remote system from recovering. ...

Though having written about other configuration management libraries for Java before, I would like to demonstrate another one today: Netflix Archaius. Archaius offers some nice features like dynamic typed properties, thread-safe operations, an event system for property changes/updates, a JMX MBean to read and update properties and adaptors for a variety of dynamic configuration sources like Amazon DynamoDB, JDBC, URLs and Apache ZooKeeper. In the following tutorial I’d like to demonstrate how to read and update application configuration properties with Archaius and data sources like property-files, system-properties, JMX and Apache ZooKeeper. ...

The Reactive Manifesto specifies responsive, resilient, elastic and message-driven as attributes for a reactive application. When implementing specific mechanisms to achieve this requirements, we often need to deal with timeout and retry-operations in our application and depending on our setup and environment, different tools and libraries exist to help us here. In the following short tutorial I’d like to demonstrate how to handle exceptions and operation retries on service boundaries with a lesser know, slim library named Retry4j. ...