Jakub Korab

Category: ActiveMQ

  • New Book – Understanding Message Brokers

    If this blog has been unusually quiet over the last few months, it is with good reason – I wrote another book! Understanding Message Brokers has just been released for FREE download by O’Reilly. It is a 70 page concentrated brain dump of how to reason about messaging, based on a presentation I gave at…

  • How to reason about queue depth graphs

    Occasionally I come across something that seems really obvious to me, but actually isn’t obvious from an outsider’s perspective. A few weeks ago I spent some time with a client (and their client) in trying to understand the behaviour of a message-driven platform that made heavy use of ActiveMQ. Without going into too many details,…

  • Java DSLs for ActiveMQ config and testing

    As part of a larger project that I am working on, I needed to define numerous different ActiveMQ configurations inside non-trivial integration tests. Rather than instantiating brokers by hand using the internal ActiveMQ classes, or writing lots of similar-but-different XML configurations, I wrote a pair of Java DSLs to allow me to quickly spin up…

  • Running ActiveMQ Replicated LevelDB on VirtualBox

    I have wanted to spend some more time recently playing with Replicated LevelDB in ActiveMQ. Not wanting to hit a cloud environment such as EC2, I set up 3 VirtualBox nodes on my workstation running Fedora. The host system needs to be fairly beefy – you need at least a dedicated CPU core per image…

  • ActiveMQ Network Connectors Demystified

    When trying to get your head around how ActiveMQ’s networks of brokers work, it helps to have an understanding of the underlying mechanisms involved. I’ve always thought of it as the “Lego brick model” – once you understand the smaller pieces, you can reason about how they can be combined together. When a regular client…

  • Monitoring ActiveMQ via HTTP

    29/4/2014 The following information is a little bit stale. Since version 5.9.1 of ActiveMQ, Hawt.io is no longer part of the ActiveMQ distribution from Apache, but Jolokia is. Jolokia runs on http://localhost:8161/api/jolokia by default, so if you keep this in mind while reading this post, the remaining instructions are still correct. Dejan Bosanac has written…

  • Bootstrap Projects for Getting Started with ServiceMix 4

    Over the Christmas break I cleaned up and published a set of Maven projects for getting started with ServiceMix 4.4.1+ into GitHub. I found myself reusing the same code for a number of activities, and figured it may be of broader use to others. You can find it under FuseByExample/smx-bootstraps. smx-bootstraps contains within it a…

  • Understanding ActiveMQ Broker Networks

    Networks of message brokers in ActiveMQ work quite differently to more familiar models such as that of physical networks. They are not any harder to understand or reason about but we need to have an appreciation as to what exactly each of the pieces in the puzzle do by themselves in order to understand them…

  • Batching JMS messages for performance; not so fast

    Recently an idea had crossed my radar around speeding up performance of messaging producers; batching messages into a single transaction. The idea being that there is overhead in the standard behaviour of a message bus that can be optimised out if you group messages into a single transaction. My initial thoughts about this were that…

  • Configuring ActiveMQ transactions in Spring

    It’s easy to configure Message Driven POJOs over ActiveMQ with Spring, but slightly more involved once you want to get transactions working correctly; here’s how to do it. Start with a basic DefaultMessageListenerContainer config. An embedded broker is started, and a MessageListener (CountingMessageListener) is set up to pick up messages from a queue (sample.messages). MessageListenerContainers…