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Read property files with PropertyPlaceholderConfigurer


1. Introduction Usually when we are concerned with multiple servers where the application is deployed before going into production, we can configure the environment-specific parameters in an external property file. It might be the database details, which is different for test server and the production server. So it’s better we we choose to keep the database configuration file in an external property file. Similarly, we can choose ...

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In Defense of Java


So we have an eBook, The Top 10 Java Performance Problems, that we tweet out from time to time. Without exception, a few people reply with some version of “the problem is you’re using Java.” Java, apparently, is constantly criticized, and people have been predicting its demise for some time. Sure, it’s not as cool, flexible, or fun as some ...

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Spark Streaming Example – How to Stream from Slack


Let’s write a Spark Streaming example in Scala, which streams from Slack. This post will show how to write, configure and execute the code, first. Then, the source code will be examined in detail. If you don’t have a Slack team, you can set one up for free. We’ll cover that too. Let’s start with a big picture overview of ...

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Spark Data Source API: Extending Our Spark SQL Query Engine


In my last post, Apache Spark as a Distributed SQL Engine, we explained how we could use SQL to query our data stored within Hadoop. Our engine is capable of reading CSV files from a distributed file system, auto discovering the schema from the files and exposing them as tables through the Hive meta store. All this was done to ...

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Introducing The Delegate Pattern


Delegate: a person who is chosen or elected to vote or act for others – Merriam-Webster. Delegate pattern: In software engineering, the delegation pattern is a design pattern in object-oriented programming where an object, instead of performing one of its stated tasks, delegates that task to an associated helper object – Wikipedia. Make things as simple as possible, but not simpler – Albert ...

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Improve Your JUnit Experience with this Annotation


JUnit is probably part of 90% of all Java projects. And the exciting thing is, we’ll soon have JUnit 5 with Java 8 support. We’ve blogged about an improvement recently. Back in JUnit 4 land, there’s this little trick that I can only recommend you put in all of your unit tests. Just add this little annotation here and you’ll ...

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Keycloak SSO Integration into jBPM and Drools Workbench


Introduction Single Sign On (SSO) and related token exchange mechanisms are becoming the most common scenario for the authentication and authorization in different environments on the web, specially when moving into the cloud. This article talks about the integration of Keycloak with jBPM or Drools applications in order to use all the features provided on Keycloak. Keycloak is an integrated SSO ...

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Java Remote Debug for Applications Running in Kubernetes


Kubernetes 1.2 was just released and is quickly becooming the defacto cluster management solution for containers (Docker, Rocket, Hyper, etc). Check it out if you haven’t already – here are some interesting tidbits about the 1.2 release: Cluster can now scale to 30,000 containers per cluster Graceful shutdown of nodes, transitioning to other running nodes in the cluster Custom defined ...

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Logging Requests to Elasticsearch


This is something I wanted to write down for years but never got down to completing the post. It can help you a lot with certain Elasticsearch setups by answering two questions using the slow log. Is my application talking to Elasticsearch? What kind of queries are being built by my application? A while ago I helped a colleague on ...

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