Software As If It Matters

David Dossot

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Top Stories by David Dossot

To be able to do anything useful, an ESB must be configured with all sorts of parameters, from endpoint connection URIs to message transformation scripts to content-based routing definitions. Moreover, ESBs like Mule can host custom components, which will process messages and perform user-specific actions on them. Deploying a new version of an ESB configuration raises the question of whether it will break anything. How can we build confidence that everything will be just fine? If unit testing did it for standard software development, what can it do in the realm of the ESB? Since ESBs are becoming increasingly familiar in corporate IT, getting concrete answers is of interest to more and more people. This article details the testing strategies I employ for Mule ESB-driven projects, which I think contain elements that could be generalized to other platforms. I am cer... (more)

The Holy Grail of Persistence?

One of the very first CTO-grade decision I had to take in the making of Snoget was to pick what would become our main transactional persistence engine. Since we're using Erlang exclusively for our production servers, the solution seemed easy: use Mnesia. But I settled for PostgreSQL. At this point, anyone who's been dealing with O/R mapping (like Ted Neward who said: "Object/relational mapping is the Vietnam of Computer Science"), should cry fool: Mnesia would offer me persistence without any impedence mismatch with the application runtime environment and I preferred a SQL databa... (more)

Is Test Overlap A Necessary Evil?

In a recent blog post titled "The Limitations of TDD", Jolt Awards colleague Andrew Binstock shared some reservations Cédric Beust has about TDD. When a person of extensive experience like Cédric speaks about testing, you pay attention. And I did. Among the very interesting quotes from Cédric that Andrew has reproduced, the following really struck me: Another important point is that unit tests are a convenience for *you*, the developer, while functional tests are important for your *users*. When I have limited time, I always give priority to writing functional tests. Your duty is... (more)

Grafting Mule Endpoints

In Mule ESB, outbound dispatching to a destination whose address is known at runtime only is a pretty trivial endeavor. A less frequent practice consists in programmatically defining inbound service endpoints. I recently had to do such thing for a little side project I'm running where Mule is used as a frontal bus and load throttler in front of a R nodes exposed over RMI. The goal was to have a non-fixed number of file inbound endpoints defined in a simple properties file and declare them on a particular service during the initialization sequence of Mule. As an integration framewo... (more)

Monitoring RabbitMQ with Zabbix

If you use RabbitMQ as your message oriented middleware and Zabbix as your monitoring and graphing tool, you're probably wondering how to monitor the former with the latter. Here is the Zabbix Agent configuration I use to keep track of the number of messages pending delivery and the total number of queues (this second parameter may not make sense for you if you don't create a lot of dynamic queues): UserParameter=rabbitmq.local.queues.count[*],sudo rabbitmqctl -q list_queues -p $1 | wc -l UserParameter=rabbitmq.local.messages_ready.count[*],sudo rabbitmqctl -q list_queues -p $1 m... (more)