A developer friendly GraphQL client

By Jasper van Heijst on 21-12-2018
Category: Blog, Development Tags: Java software engineering GraphQL

At bol.com we use GraphQL in our IT landscape, and we’ve found a convenient way of working with these API’s we would like to share. By generating our GraphQL queries from Java objects by using annotations, developers don’t need to worry about the query, and don’t need to maintain both a query and a domain object anymore.

Finding the longest matching string prefix … fast

By ir. drs. Niels Basjes on 10-12-2018
Category: Data Science & AI, Development Tags: Java Software Open source DataScience Algorithms

In many systems at bol.com the response speed of our systems is very important. This blog is about the data structures and algorithms we used to make a specific analysis step a lot faster: Finding the longest matching string prefix.

Using Elasticsearch as the Primary Data Store

By Volkan Yazici on 3-12-2018
Category: Development Tags: Java elasticsearch search etl

The biggest e-commerce company in the Netherlands and Belgium, bol.com, set out on a 4 year journey to rethink and rebuild their entire ETL (Extract, Transform, Load) pipeline, that has been cooking up the data used by its search engine since the dawn of time.

Part 3: Talks Spaces Summit v2.0

By Sjors van Berkel on 25-09-2018
Category: Blog, Culture, Development Tags: Java Kotlin conference Organizing JVM

Last June, Spaces Summit was organized by and for bol.com employees. At Techlab, we want to celebrate this event by highlighting two presentations every month. This month, let’s get meta, and talk about organizing a conference. After that, we’ll go full geek again and look at Kotlin, to cure the Java headache you probably didn’t realize you were having in the first place.

How (not) to sink a data stream to files? Journeys from Kafka to Parquet.

By Gabor Hermann on 30-07-2018
Category: Development Tags: Java Scalability BigData Open source distributed

Last year the Measuring 2.0 team at bol.com has started measuring user behavior on the bol.com website. Of course, we wanted to make the data widely accessible within the whole organization.

Making sense of the user agent string

By ir. drs. Niels Basjes on 30-03-2017
Category: Development Tags: Java Open source UX DataScience

Ever since I’ve started working for a WebAnalytics company in 2005 I’ve been working on problems related to making sense of web data. One of the most difficult elements in this type of analysis is making sense of the user agent.
Very often the raw web data I work with is stored in Apache HTTPD access log files that have been compressed using gzip.

My baby was leaky and now it’s not

By Roy Jacobs on 7-02-2017
Category: Development Tags: Hazelcast Java

When you build a service at bol.com your responsibility doesn’t end once the build is green. You’re actually supposed to run it (and keep it running) in production, too. Luckily, our team doesn’t have to do this all by ourselves: there are platform and infrastructure teams to turn to and other development teams to harass over coffee. It’s a bit like caring for a newborn baby I suppose: you try to do a lot yourself but when the baby starts crying for the first time you’ll need all the help…