David Salgado

Communication

I am an excellent communicator, with the ability to write clearly and convey information such that it is both easy to understand and, just as importantly, difficult to misunderstand.

I can talk to both technical and business people in ways that make sense, explaining technical concepts and constraints to the non-technical, and business realities to technical staff, without making either group feel belittled or frustrated.

I am an experienced and capable presenter, comfortable both on stage and on camera.

• Video discussing Mattereum's Smart Property Register
• Presentation on Elixir for Rubyists

Blockchain

I have been interested in the potential of this space since 2015, and have studied and networked extensively to build up a deep understanding of different aspects of the underlying technology and the potential it offers.

As a result of this, I represented the MoJ in some cross-government initiatives to explore the the potential for blockchain technology to contribute to society, and was subsequently recruited to work as head of operations at Mattereum.

Programming Languages

• Ruby

  I have been working primarily in Ruby since 2005, both in Rails applications and also using it with a variety of other frameworks, as well as standalone applications.

• JavaScript

  It is impossible to write or maintain any significantly-complex web application these days, without using JavaScript. Admoda was no exception, making heavy use of JavaScript for interactivity. This became even more true when we undertook a significant rewrite, replacing much of the ‘JQuery-style’ JS code with React.js components.

• Go (Golang)

  Some of the tools we are using and developing for the MoJ Cloud Platform are written in go, as you would expect in a kubernetes environment. In particular, I am one of the developers of our CLI tool.

• Elixir

  I started using Elixir in production systems in October 2015, rewriting the core of the Admoda ad-serving code from a PHP monolith to a multi-application Elixir system built on top of the Plug library.

• Ethereum (Solidity)

  I created prototypes and proofs of concept for Mattereum as distributed applications consisting of interacting Ethereum smart contracts written in Solidity, with front-end web applications written in React/NextJS.

• Bash Scripting

  The ubiquity of bash on Unix systems makes it a good choice for implementing quick pieces of ‘glue’ code, to combine existing components. A lot of people underestimate bash scripting, but it is possible to write elegant and maintainable code in bash.

• PHP

  When we created Admoda in 2006, we used an existing, open-source PHP ad-serving script as our initial starting point, largely because the then-leading mobile device detection library was only available in PHP or Java. So, I spent much of the following 10 years coding in PHP.

Frameworks

• Ruby on Rails

  I have built and maintained many applications in all versions of Ruby on Rails since version 2. The customer-facing web application at the heart of Admoda started as a Rails 2 application, and I developed, maintained, and upgraded it several times. By March 2016 it was a Rails 4.2 application using React.js components, built using Google‘s Material Design principles.

• Padrino / Sinatra / Rack

  For simple web endpoints, when Rails is overkill, these are the libraries I use to get things up and running quickly.

• Phoenix

  I started using Elixir/Phoenix in production since October 2015, and very much enjoyed it. It provides almost all the developer benefits of Rails, without compromising performance or introducing too much ‘magic’.

• React.js

  In May 2015 we started replacing the ‘JQuery-style’ JavaScript code in the Admoda web application with React.js components. Encapsulating in a single JSX file both the behaviour of a component and the layout on which it operates made the application a lot easier to maintain and develop.

DevOps Tools

• Kubernetes

  From Feb. 2019 to Feb. 2021 I worked as Senior Technical Architect on the MoJ Cloud Platform team. The Cloud Platform is a hosting platform for the MoJ's digital services, consisting of a kubernetes cluster plus ancillary products and services including Elastic Search Prometheus, Kibana, Grafana, Fluentd, Concourse, CircleCI, Auth0 and probably a few more things I've forgotten.

• Terraform

  The MoJ Cloud Platform makes extensive use of Terraform, with the entire platform being defined across several open-source github repositories.

• Docker

  I‘ve been using Docker since the end of 2014, when I used it as a key part of the Admoda adserver infrastructure.

• Unix System Administration

  I have been using Linux (mostly Ubuntu) in one form or another since 2001. I am very comfortable with the unix command-line, and administering and maintaining unix servers, both for development and production purposes.

• Puppet

  I used Puppet as the primary configuration management tool for Admoda, building and managing a wide variety of server types. Configuration management gave us a lot of flexibility, enabling machines to be replaced or upgraded very quickly, and keeping our infrastructure nimble.

• Ansible & Chef

  Although I‘ve used these a lot less, I like the lightweight ‘push’ nature of Ansible. I tend to use it for my own projects, and I might consider using it, instead of Puppet, for a large project, depending on the requirements. I have played with Chef, but haven‘t used it in production.

Cloud Computing Platforms

• Amazon Web Services

  The Ministry of Justice uses AWS extensively, so I used it extensively during my work there.

• Google Compute Engine

  Admoda moved virtually all of our infrastructure to GCE in May/June 2015, taking advantage of several unique features including live migration, pre-emptible VMs, and Google Container Registry for our Docker images.

• Google BigQuery

  Admoda generated around 1TB of transaction data every day. While I was running Admoda, we used Google BigQuery to analyse this data and expose summary information for our customers in a best-in-class analytics tool, to help advertisers target their campaigns, and publishers to get the best value from their mobile traffic.

• Heroku

  I started using Heroku when doing some contract programming for 38 degrees, a UK non-profit campaigning organisation. I don‘t have a lot of experience with it, but I like what I‘ve seen, so far. I think it‘s an excellent choice when you want to keep your devops workload to a minimum and if, as is usually the case, hosting costs are not a significant factor.

• Rackspace

  When I was running Admoda, we used Rackspace as our primary hosting provider until May 2015.

Feb. 2019 - Feb. 2021 Senior Technical Architect at the Ministry of Justice

Technical Architect on the Cloud Platform team, responsible for ongoing development and support of the kubernetes-based hosting platform, as well as encouraging and assisting in the adoption of the platform throughout the wider organisation.

Jan. 2018 - Jan. 2019 Head of Operations at Mattereum

Described by TechCrunch as "perhaps the world’s weirdest and most daring startup," Mattereum aims to bring blockchain smart contracts into the real world in a way that will be genuinely practical for international trade, with a rigorous legal foundation.

As a member of the management team, I worked closely with a group of insanely smart founders and experts to realise this vision.

I also developed proof of concept applications which combined Ethereum smart contracts (written in Solidity) with web applications written in React/NextJS and Ruby on Rails.

2016 – 2018 Senior Technical Architect at the Ministry of Justice

Working as part of multi-disciplinary, agile teams, I worked on a variety of projects including Appeal to the Tax Tribunal, taking the service through to public beta.

I designed and helped to implement an architecture based on loosely-coupled services intended to be drop-in components that other services can use (e.g. a virus-scanning file-uploader).

I also helped to create a design pattern for Ruby on Rails, applicable to any forms-based service that needs to classify users based on their path through a flowchart (aka a decision-tree).

A more developed version of this design underpins the Appeal to the Tax Tribunal service.

I also participated in discussions and research on potential uses for distributed ledger (blockchain) technology, both within the Ministry of Justice, and in working groups with a broader government perspective.

2006 – 2016 CTO & Co-Founder of Admoda

We created Admoda in 2006, and were the second mobile ad network to launch (we thought we were the first, but Admob beat us by a week). Admoda was a self-serve system which enabled owners of applications and websites to earn money from their mobile traffic by showing ads. Advertisers registered pre-pay accounts on the system, and then created and managed ad campaigns using our online tools to upload and manage their creative assets, and control the targeting of their campaigns (country, mobile network, device manufacturer, operating system, etc.)

We were up and running within three months of the initial decision to launch, and were profitable within another three. We continued to be profitable for the next ten years. Initially, I worked on the system in my spare time, gradually transitioning to working on it full-time by early 2009.

The front-end was a Ruby on Rails application that went through various incarnations, including a major rewrite to incorporate React.js with a complete re-skin to use Material Design.

The back end initially consisted of servers running an open source PHP ad-serving script, which I had modified to add mobile device detection and targeting capabilities. By the time we wound up the business, the back end was a cloud-hosted auto-scaling “farm” of stateless adservers, each of which comprised a number of loosely-coupled micro-services (geo-location, device recognition, ad selection, etc.), with each service running in its own Docker container. The primary core of the system was written in Elixir, with RabbitMQ as the messaging backbone, with everything orchestrated via a Consul service discovery cluster.

At busy times, there would be hundreds of adservers, scaling down to just a handful at quiet periods. The system was highly resilient, with no single points of failure, and was very closely monitored by several different services. This enabled us to keep hosting and system administration costs to a minimum, yet still handle billions of transactions per day, and millions of pounds of turnover, with a team of just three people (that‘s the whole company, not just the technical team).

2005 – 2009 Technical Architect at Mobile Interactive Group

I was the fourth person, and the first technical hire, at this startup. I helped build and lead the development team, designing, creating and managing a wide variety of applications around different mobile customer experiences (such as voting, ticketing, mobile payments and customer rewards systems), handling traffic loads up to several million transactions per hour.

We worked in Perl initially, but quickly transitioned to Ruby in 2006, using Rails for our front-end applications.

Amongst other projects, I worked on the voting application used for TV shows such as The X Factor, the SMS ticket lottery for the Live8 charity concert, and a loyalty rewards programme for customers of the Orange mobile phone network.

By the time I left, in 2009, the company had grown to 100+ staff, with twelve in the technical team.

2001 – 2005 Developer at O2 UK

Working mostly in Perl but also using some Python, I created and maintained a wide variety of applications for O2 as part of their in-house development team. In particular, I designed and built the first SMS voting system for interactive TV shows including “I‘m a Celebrity, Get Me Out Of Here”, Big Brother and Pop Idol.

My open source projects include the following.
All my open-source repositories can be seen on my github page.

My side projects include the following;

• Fair Shares

  A very simple progressive web application (PWA) used to split a restaurant bill unevenly between a group of people (e.g. because some didn't drink the wine and others ordered dessert).

• Ticket Poker

  

  A zero-signup Elixir/React application using websockets for realtime communication. The application facilitates blind voting for distributed development teams, during 'planning poker' sessions (estimating the effort required by different project tickets).

• Cryptoassettracker

  

  An Elixir/Phoenix + React application to track cryptocurrency portfolios, pulling altcoin data from the APIs of a variety of providers in the space.

I was a regular attendee at the London Ruby User Group from 2006 until I left the UK in 2020, and an occasional presenter. My most recent presentations were on rewriting software in September 2016;

https://digitalronin.github.io/2016/09/24/total-rewrite-presentation-lrug.html

and Elixir, in March 2016;

https://digitalronin.github.io/2016/03/25/elixir-presentation-lrug.html

When time permits, I mentor developers learning Ruby on Rails at “Women Who Code” events in London;

http://www.meetup.com/Women-Who-Code-London/

Upper Second B.Sc. in Computer Science & Electronic Engineering from University College, London.

Aerial Circus skills

I started learning aerial circus skills in 2010 and got instantly hooked. My first aerial discipline was Static Trapeze, and I later moved on to Rope and Chinese Pole.

Others

• Kitesurfing
• Snowboarding
• Kayaking
• Scuba-diving
• Languages: I'm working on my Japanese - I think I'm currently around N2 on the official scale, although I haven't taken the JPLT. I also speak conversational French and Spanish