Alexander Reelsen

Backend developer, productivity fan, likes distributed systems & the new serverless era



Community @Elastic - The why, what and how

This talk gives an overview over how we do community work at Elastic. What does community mean to us, how are we setup from an organization perspective, what can you do to increase adoption, where we do we as a company and our products come from and what are the challenges, personal as well as from a department perspective. Held at the inaugural DevRelMunich meetup.

Extending Elasticsearch - Writing plugins

A quick overview about how to write Elasticsearch plugins, what extension points exist, how plugins and modules are loaded when Elasticsearch starts up, how plugins are tested most efficiently with gradle. Also one ingest plugin and one query plugin were demoed as part of the presentation. Held at the Java User Group Essen.

What’s new in the Elastic Stack - 7.0 Edition

Covering what is new in the Elastic Stack 6.7, 7.0 and a brief glimpse in the Elasticsearch 7.1 release, showing a lot of Elasticsearch topics like faster top-k retrieval, Zen2, adaptive replica selection, rank feature(s), the new script score query and support for nanosecond precisions. Held at a BBL in Munich and at the Elastic RheinRuhr Meetup.

Running a Serverless Lucene Reverse Geocoder

This presentation talks about the possibility of running a reverse geocoder based on lucene in a serverless environment. The talk features the serverless framework, lucene geo capabilities using points and shapes, and last but not least mentions graalvm to reduce start up times.

This presentation was held at the Search Meetup Munich in April 2019, at the JUG Nürnberg and at the Karlsruhe Search Meetup.

Working distributed - but how?

This is a talk about distributed work, how it is done at Elastic. How do we work together, how does the development process look like, what are the hard parts about distributed work, what does work exceptionally well?

This presentation was held at the VillageCon 2019 in Vechta.

Custom AWS Lambda Runtimes

This presentation gives an introduction into the concept of function as a service. After a quick introduction into crystal it is shown how easy it is to write a custom AWS lambda runtime using the crystal programming language.

This presentation was held at the serverless munich meetup in early 2019.


Elasticsearch Ingest Processors

A BoF session at the elastic on tour stop in Frankfurt, talking about a quick update about the latest and greatest in ingest nodes, before talking about customer use of the Elasticsearch ingest node.

Open Source as a Business

A general talk about Open Source as a Business, what this means and especially what this does not. Held at an Elastic Event in Munich.

Elasticsearch - Securing a search engine while maintaining usability

Elasticsearch is running on tens of thousands of nodes world-wide, so despite all the functionality squeezed into new releases, we also have to think about security, all the time. This talk will cover different aspects of Elasticsearch, explain some features and (sometimes unpopular) decisions and the reasoning behind. The goal of this talk is not (only) to show off Elasticsearch features. You start thinking about these non-functional requirements in your own applications as well! Held at the Java User Group Munich, at the Mathema Campus, the Search Meetup Munich, the CFCamp, the Java User Group Erlangen/Nürnberg, the VillageCon ‘19 the Delex Conf ‘19 in Minsk (video) the JUG Nürnberg and at the Karlsruhe Search Meetup.


Inside the Elastic Stack: Testing and Releasing a Well Known Open Source Stack

Maintaining a well known open source stack is no easy task. Despite fixing bugs and adding features, releases need to be aligned among products and each product needs to be tested on its own. This talk starts at the lowest level of Elasticsearch, explaining how we run unit tests, moves up to integration tests, packaging tests, backwards compatibility tests, performance tests, including commercial extensions in testing phases - all of this on different operating systems and JVM versions. Attendees will get to know how our CI looks and how all of our products (Elasticsearch, Logstash, Kibana, Beats and all of its commercial extensions) are released at the same moment in order to ease the upgrade process for our end users. Held at the Ryte Tech Meetup, also available on video and the TestCon Moscow 2018 and the Delex Conf in Minsk (video).

What’s x-citing in x-pack?

A quick overview about the commercial plugins for the Elastic Stack, where I covered the alerting backend part during ElasticON 2017. Also available on video.

Introduction into the Elasticsearch Ingest Node

This is a short introduction into the Elasticsearch Ingest Node featuring some live coding to create a new processor, that extracts URLs from text. The corresponding blog post is is on the elastic blog. Held at the Search Meetup Munich, the Search Meetup NRW and the Search User Group Berlin (plus video).


Serverless - Apps without infrastructure

A small introduction in the serverless paradigm and introduces the serverless and claudia frameworks for node.js, provides some more information about other language alternatives and of course also about the drawbacks to be aware of. Held at the Munich Node User Group, also available as video.

Awesome Logging Infrastructure using the Elastic Stack

The Elastic stack consisting of Elasticsearch, Logstash, Kibana and Beats offers easy-to-use components to ingest, parse, analyze and visualize your data. In this talk we will focus on the aspect of log files, and in addition to the already known capabilities of the ELK stack new features in Elasticsearch simplifying your logging life and the relatively new Beats and their respective implementations will be covered as well. Held as a keynote at the Cloudconf in Italy (video), at Infoshare at Gdansk, at CFCamp in Munich and at JUGH in Kassel (video).

Security, Alerting, Monitoring, and More With the Elastic Stack

A quick overview about the commercial plugins for the Elastic Stack, where I covered the alerting part during ElasticON 2016. Also available on video.

Elastic(search) - News from the machine room

A short overview about the latest and greatest features across the Elastic Stack, covering Elasticsearch, Beats, Logstash and Kibana. Covers features from the 2.x releases like Pipeline Aggregations and future features like the Ingest Node. Held at the OOP Konferenz in Munich and the Elasticsearch Meetup Cologne.


Elasticsearch 2.0 - What’s cooking

A quick overview over the most important features and improvements of the upcoming Elasticsearch 2.0 release, held at the Search Meetup Munich.

Shield Your cluster - Security with Elasticsearch

A basic introduction into shield and its features covering some standard use-cases as well as why shield is better to use than a home-grown solution. Also explores the future of shield by talking about some of the future features. Held at Goto Amsterdam 2015.

Elasticsearch - Speed is key

An introduction into Elasticsearch along with some details, what actually makes a search fast, going into some interesting details like full-text search, filters, aggregations, probabilistic data structures, the operating system as well as a quick outlook on the next Elasticsearch & Lucene releases. Held at the Enterprise Search Meetup Warsaw (video), the developer camp in Munich (video), the CraftConf in Budapest (video), the ElasticVienna Meetup, the first ever german Elastic webinar, the Elasticsearch Zurich Meetup, the Hamburg Search Technology Meetup, the Elasticsearch Meetup Cologne, the CFCamp in Munich, the JUG Kassel (video) and the DevTernity conference in Riga.

Elasticsearch - Life of a document

This talk explains the when, where and why of your document’s life inside of Elasticsearch. Held with my colleague Boaz at the first Elasticon in San Francisco, video is available as well.

Elasticsearch - Using the percolator for simple classification

A small introduction in how to use the percolator feature of Elasticsearch in order to classify documents, using car ads. Held at the Search Meetup Munich.

ELK Stack - Bessere Entscheidungen durch bessere Daten

A german introduction to the ELK stack, very high level and not too technical. Held at the OOP Conference 2015 in Munich, video available as well.


Introduction into harp

A quick introduction into harp alongside with a quick demo. Held at the MNUG, also on video.

Maintaining performance in distributed systems

An overview about some performance fallacies, not only in distributed systems. Held at the Munich Software Performance Meetup.

Introduction into the ELK stack

Another high level introduction into the ELK stack talking about what problem this stack solves as well as a quick overview over the different products. Held at the code.talks (video) in Hamburg as well as at the Open Source Monitoring Conference (OSMC) in Nuremberg.

Using the ELK stack for continuous improvement of your data

A very highlevel talk about why you need something like the ELK stack to make better business decisions, and why we (as a company) think, that this different pieces of software are needed. Held at the mimacom days in Zurich in June available as video.

Elasticsearch under the hood - Managing performance in a distributed system

A talk not so much about elasticsearch (even though it features a quick intro), but about the full stack ranging from hardware, operating system, jvm, garbage collection, libraries and some elasticsearch examples to make you aware of the complexities of having performance in such a complex distributed system and how to optimize a few of them. Held at the NoSQL User Group in Munich and at TNG Consulting in Munich (thanks for inviting me!).

What’s new in Elasticsearch? Feature overview

A brief overview about recent elasticsearch features, continously updated from 1.0 onwards over the year. This presentation was held at the day of the elasticsearch 1.1 release at the first Elasticsearch Meetup in Stuttgart, at the first KA Search Meetup in Karlsruhe, the first Elasticsearch Meetup in Copenhagen, the Elasticsearch Meetup in Zurich, the first Elasticsearch Meetup in Vienna.

Using elasticsearch, logstash and kibana to create realtime dashboards

A small overview of logstash, followed by a live demonstration about how to create a nice dashboard using the reservation stream. Held at the Lightweight Java User Group in Munich, a free GOTO night in Berlin, the devcamp in Karlsruhe, BEDCon in Berlin, the Elasticsearch Meetup in Hamburg, a the 9th jimdo session, which is available as video as well.

Introduction into elasticsearch, logstash and kibana

A very long introduction, covering a lot of ground about Elasticsearch, logstash & Kibana, with a special chapter about elasticsearch 1.0. Held as part of the Elasticsearch special day at OOP conference in Munich.

Elasticsearch in Ecommerce

A talk about several use-cases of elasticsearch in ecommerce environments and where to pay special attention. Held at the Ecommerce Hacktable in Hamburg. Thanks to Matthias Lau from Jimdo for inviting me!


My main presentation for 2013, introducing elasticsearch but talking about aggregation and analytics functionality in particular. Held at the Enterprise Java User Group in Linz, the GotoCON in Aarhus, the WJAX conference in Munich, the Developer conference in Hamburg (video).

Elasticsearch - Completion Suggester

A 5 minute session at the Elasticsearch Amsterdam Meetup, where a couple of us engineers talked about some elasticsearch features, as we had a gathering in our office for a week.

Extending Elasticsearch

This talk was held at the Berlin Buzzwords Barcamp and talked about possibilities to extend elasticsearch.

Elasticsearch - Introduction

Another introduction into elasticsearch, held at the JUG Karlsruhe (video) and the JUG Erlangen Nürnberg.

Elasticsearch - Search made easy

An introduction into search and analytics in general, alongside with pointing out, how elasticsearch can help for your concrete implementation. Held at NoSQL roadshow munich and JUG Augsburg (Video available as well).


Elasticsearch - introduction & plugin development

An introduction into elasticsearch including a code deep dive how to write plugins. Held at Smarchive/Gini (thx for inviting me!).

Using dropwizard with MongoDB

A short introduction into dropwizard in combination with MongoDB. Held at the Berlin Expert Days Conference.

Elasticsearch - Search made easy for (web) developers

A long introduction into elasticsearch, made with reveal.js. Held at the Java User Group Munich and the Berlin Expert Days Conference.


Elasticsearch - Introduction

A ten minute introduction at the Webmontag Munich November, held in front of a mainly non-technical crowd.

Play Framework Introduction

An introductory presentation about the play framework held in October 2011 at TNG technologies in Munich. Thanks to them for giving me the opportunity to talk.

Play Framework - A look inside the machine room

This presentation tries to go further than the standard introductory presentations and takes a look in the inner works of the play framework. This presentation was held at the Play!Ground event in Rotterdam in September. Thanks to Peter Hilton and Lunatech for inviting me!


Play framework introduction

An introductory presentation about the play framework held in June 2010 at the Java User Group Munich.