Posts

One of the first requirement of Netty ISO8588 client connector is the support for automatic reconnect.

One of the first receipts I came across was Thomas Termin’s one. He suggests adding a ChannelHandler which will schedule the calling of client’s connect() method once a Channel becomes inactive. Plus adding ChannelFutureListener which will re-create a bootstrap and re-connect if initial connection was failed.

Although this is a working solution, I had a feeling that something is not optimal. Namely, the new Bootstrap is being created on every connection attempt.

So, I created a FutureListener which should be registered once a Channel is closed.

User authentication is an important part of the web service API design. One of the common approaches is the Hash-based Message Authentication Code – HMAC. Used together with transport level security, it provides a reliable mechanizm of user authentication and message integrity validation.

For those, who not yet familiar with Scrum, I highly recommend to watch the “Scrum Training Series” presentations and the AgileMethodology.org website.

A Scrum Reference Card is also useful to understand what the Scrum is, it’s processes, roles and practices.

The presentations describes the Scrum process step by step.

Introduction to Scrum #

Setting entropy pool for Java server on linux is fair simple. Just add a system property to specify a device to read from.

Chronicle by Peter Lawrey:

This library is an ultra low latency, high throughput, persisted, messaging and event driven in memory database. The typical latency is as low as 80 nano-seconds and supports throughput of 5-20 million messages/record updates per second.

This library also supports distributed, durable, observable collections (Map, List, Set) The performance depends on the data structures used, but simple data structures can achieve throughput of 5 million elements or key/value pairs in batches (eg addAll or putAll) and 500K elements or key/values per second when added/updated/removed individually.

It uses almost no heap, trivial GC impact, can be much larger than your physical memory size (only limited by the size of your disk) and can be shared between processes with better than 1/10th latency of using Sockets over loopback. It can change the way you design your system because it allows you to have independent processes which can be running or not at the same time (as no messages are lost) This is useful for restarting services and testing your services from canned data. e.g. like sub-microsecond durable messaging. You can attach any number of readers, including tools to see the exact state of the data externally. e.g. I use; od -t cx1 {file} to see the current state.

When configuring executors in multithreaded application, do not forget to assign names to your threads. It simplifies later profiling a lot, when you see a meaningful thread names in your profiler.

For example, you may use CustomizableThreadFactory from SpringFramework.