Tag Archives: java

Analyze Tomcat Logs using PIG (hadoop)

In a previous post I illustrated the use of Hadoop to analyze Apache Tomcat log files (catalina.out). Below I perform the same Tomcat log analysis using PIG. The motivation behind PIG is the ability us a descriptive language to analyze large sets of data rather than writing code to process it, using Java or Python […]

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Use Hadoop to Analyze Java Logs (Tomcat catalina.out)

One of the Java applications I develop deploys in Tomcat and is load-balanced across a couple dozen servers. Each server can produce gigabytes of log output daily due to the high volume. This post demonstrates simple use of hadoop to quickly extract useful and relevant information from catalina.out files using Map Reduce. I followed Hadoop: […]

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Override Java Methods on Instantiation

Most Java programmers are very familiar with the mechanism to extend a class. To do this, you simply create a new class and specify that it extends another class. You can then add funtionality not available in the original class, AND you can also override any functionality that existed already. Imagine a simple class public […]

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Caching in Java using Aspect Oriented Programming (AOP)

As the scale of web applications increases, performance optimization considerations are more frequently included in initial design. One optimization technique used extensively is caching. A cache contains pre-processed data that is ready to use without redoing the processing. Processing may include extensive computation and accessing data over a network or on disk. Keep the details […]

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Using Java to work with Versioned Data

A few days ago I wrote about how to structure version details in MongoDB. In this and subsequent articles I’m going to present a Java based approach to working with that revision data. I have published all this work as an open source repository on github. Feel free to fork it: https://github.com/dwatrous/mongodb-revision-objects Design Decisions To […]

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Wicket + Guice including unittests

Last week I spent way too much time integrating Apache Wicket and Google Guice. Yikes! The most difficult part for me was getting the initialization to happen in the right order. A big Thank You to Dan Retzlaff on the Wicket list for helping work through these details. The details below were applied to a […]

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Redis as a cache for Java servlets

I’ve been refactoring an application recently to move away from a proprietary and inflexible in memory datastore. The drawbacks of the proprietary datastore included the fact that the content was static. The only way to update data involved a build and replication process that took much longer than the stakeholders were willing to wait. The […]

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RESTful Java Servlet: Serializing to/from JSON with Jackson

In a previous article I demonstrated one way to create a RESTful interface using a plain Java Servlet. In this article I wanted to extend that to include JSON serialization using Jackson. I found a very simple article showing a basic case mapping a POJO to JSON and back again. However, when I copied this […]

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RESTful Java Servlet

For a recent project I found that a RESTful interface would be appropriate. My first inclination was to use Jersey (or one of the JAX-RS implementations available). The environment where this new REST API would deploy is still using Java 1.5. This became a major roadblock when I was found that none of the JAX-RS […]

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Wicket + GAE automatic reload

One disappointment of developing for Wicket and Google App Engine (GAE) is that the automatic monitoring and reloading of modified HTML files didn’t work. It had something to do with the single threaded nature of the GAE platform. I had found a few previous efforts to make this work, but none of them worked with […]

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