Explicit vs Implicit configuration in Spring

With the move to annotations for use of Spring, many projects have become based on component-scanning, auto-wiring and property-placeholder injection — an ‘implicit’ approach to configuration.

However, it can still be very useful to specify ‘explicit’ configuration. This gives us control of top-level application config & enables extensible configuration using the Strategy pattern.

Gaining control of configuration is crucial to enable per-customer/ per-application customization. Continue reading

Silent Thread death from unhandled exceptions

Threading is easy in Java, but today I was reminded of another of its pitfalls.

In Java- or container-provided threads, unhandled exceptions from our code will be printed or logged to the console. Create your own Thread or use SwingWorkerThreadPoolExecutor, and it’s a different story..

Threaded code tends to die silently. Nothing on the console or logs. Unhandled exceptions are invisible, and leave very few clues. Let’s look at why.

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Linear Block Allocator – a superior alternative to Hi/Lo

While SQL & Hibernate are mostly portable, one crucial area remains subject to incompatibility. Primary keying is the foundation of our tables, but key allocation is non-standard.

Most other SQL elements are standard & compatible, especially with the help of Hibernate. Joins, columns, mappings & queries will generally port without a hitch.

But when we get to identifier generation, the picture falls apart. Some databases use auto-increment/  identity columns, others sequences. Syntaxes differ, retrieving generated keys is variable at best. With such divergence, how can we possibly allocate keys portably? Continue reading

Logging — our most effective debugging tool?

Logging frameworks have become a standard part of projects, since Servlets and Log4J first emerged. But how should we log? Are we getting the most we can from it?

Many developers see logging & debugging as separate tasks. When confronted with a problem we set breakpoints, step through, inspect variables, and trace through loops – often finishing hours later..

Finding problems this way is hard. Does it have to be so difficult? Could there be a way to get right to the problem area, in just minutes? Sometimes without even needing to step through? Continue reading

Fuzzy String Search in SQL

Users often enter data approximately or inaccurately.. But sometimes, we need to search or match this inaccurate data anyway!

For example, users should match existing customer records rather than creating unwanted duplicates.

There are standard algorithms for measuring string-distances, but we’ll need a few extra steps to make this work efficiently against a database..  Continue reading