Redis provides a neat command to iterate over all keys on a node. It’s the SCAN command that is used to scan over keys and to return a cursor to resume then the scanning from the cursor position. Complexity comes in when using Redis Cluster. In the previous scenario, all keys are located on one Redis node. With Redis Cluster keys are spread over some nodes.

At its heart, Heckenlights relies on MIDI and Live Video Streaming technologies to bring the live experience to website visitors. Let me tell you today how MIDI and Live Video Streaming is done at Heckenlights.

Redis transactions allow to group multiple commands and to execute them sequentially. The whole transactional state is isolated from other users and becomes visible once a transaction is committed.

A Redis transaction is different from transactions in, let’s say, relational databases. A Redis transaction feels more like a queue/stack of commands because commands are queued and the execution is deferred. This is true for reads and writes. The real surprise is the read commands because any return value is returned only upon transaction execution.

The plan for this year's Halloween: Built a scary thingy based on Arduino. Halloween is over now.

I built an Arduino-backed jack-o'-lantern with LED matrix panel eyes, an ultrasonic ranging sensor for the nose and a sound module to play scary Halloweenish sounds. It is impressive to see the whole thing assembled. They eyes move around, the thing can go into sleep if no one is around and wake if someone comes close to the pumpkin.

I consider myself very lucky for contributing to the open source space. Open source is one of the main building blocks of our digital world. For me, contributing is sharing, and sharing is giving back. I started contributing in early 2011. Transparency, quality, and purpose are my main reasons for my open source involvements. That is how I got in touch with the Spring Data team.

I just released lettuce 3.3.1.Final and lettuce 4.0.Final. I'm going to tell you in this post more about 4.0. You can find the full details about 3.3.1.Final and 4.0.Final on Github.

lettuce 4.0 is a major release that introduces numerous changes like stateful connections, the reactive API and many more. Lettuce 4.0 includes all features from lettuce 3.3.

Highlights of lettuce 4.0.Final

• Reactive API
• Stateful connections
• Cross-slot command execution
• Node Selection API/Execution of commands on multiple cluster nodes
• ReadFrom Settings/Redis Cluster slave reads
• Custom commands

This release contains some breaking changes. You may want to consult the wiki at Migration from 3.x to 4.x to check the migration guide.

I just released lettuce 3.4.Final and lettuce 4.1.Final. You can find the full details about 3.4.Final and 4.1.Final on Github.

These release contain numerous features and bugfixes. Lettuce introduces reusable client-resources, an EventBus, client metrics, and support for newly introduced commands. This versions work with Redis 3.2 RC3 but Redis expects a change in the format of CLUSTER NODES. So watch out for a new release of lettuce as soon as Redis 3.2 RC4 or a final is released.

I released spinach 0.2 today.

This release addresses minor issues and allows to use lettuce 3.3.Final. It adds support for more Disque commands and eases creation of a DisqueURI.

The Wiener process is a continuous-time stochastic process named in honor of Norbert Wiener. It’s commonly used to represent noise or financial development with a random component.

The geometric brownian motion can be calculated to visualize certain bounds (in quantiles) to hint about the absolute range.

I read The full stack developer is a myth story written by Scott Hadfield the other day. Once I got through the post, I realized a couple of things. The first major point is, there’s no uniform understanding what full stack developer means. More issues are the views of the commenters to the article and the opinion of companies mentioned in the article. It shares my experience how companies deal with so-called full stack developers. This article will clarify that view. Let me give you some context before I come back to full stack developers.