Basic Computer Science Skills

Contents

• Learn to Code
• Get Familiar with Git
• Agile Development
  • Why Is Agile So Important?
  • Agile Rules I Learned Over the Years
  • Agile Frameworks
    • Scrum
    • OKR
• Software Engineering Culture
• Learn How a Computer Works
• Data Network Transmission
• Security and Privacy
  • SSL Public and Private Key Certificates
  • JSON Web Tokens
  • GDPR Regulations
• Linux
  • OS Basics
  • Shell Scripting
  • Cron Jobs
  • Packet Management
• Docker
  • What is Docker and How it Works
  • Kubernetes Container Deployment
  • Why and How To Do Docker Container Orchestration
  • Useful Docker Commands
• The Cloud
  • IaaS vs. PaaS vs. SaaS
  • AWS Azure IBM Google
  • Cloud vs. On-Premises
  • Security
  • Hybrid Clouds
• Data Scientists and Machine Learning
  • Machine Learning Workflow
  • Machine Learning Model and Data

Learn to Code

Why this is important: Without coding you cannot do much in data engineering. I cannot count the number of times I needed a quick hack to solve a problem.

The possibilities are endless:

• Writing or quickly getting some data out of a SQL DB.

• Testing to produce messages to a Kafka topic.

• Understanding the source code of a Webservice

• Reading counter statistics out of a HBase key-value store.

So, which language do I recommend then?

If you would asked me a few years ago I would have said Java, 100%. Nowadays though the community moved heavily to Python. I highly recommend starting with it.

When you are getting into data processing with Spark you can use Scala which is a JVM language, but Python is also very good here.

Python is a great choice. It is super versatile.

Where to Learn Python? There are free Python courses all over the internet.

• I have a beginner one in my Data Engineering academy: Introduction to Python course
• I also have a Python for Data Engineers one one in my Data Engineering academy: Python for Data Engineers course

Keep in mind to always keep it practical: Learning by doing!

I talked about the importance of learning by doing in this podcast: https://anchor.fm/andreaskayy/episodes/Learning-By-Doing-Is-The-Best-Thing-Ever---PoDS-035-e25g44

Get Familiar with Git

Why this is important: One of the major problems with coding is to keep track of changes. It is also almost impossible to maintain a program you have multiple versions of.

Another problem is the topic of collaboration and documentation, which is super important.

Let's say you work on a Spark application and your colleagues need to make changes while you are on holiday. Without some code management, they are in huge trouble:

Where is the code? What have you changed last? Where is the documentation? How do we mark what we have changed?

But, if you put your code on GitHub, your colleagues can find your code. They can understand it through your documentation (please also have in-line comments).

Developers can pull your code, make a new branch, and do the changes. After your holiday, you can inspect what they have done and merge it with your original code, and you end up having only one application.

Where to learn: Check out the GitHub Guides page where you can learn all the basics: https://guides.github.com/introduction/flow/

This great GitHub commands cheat sheet saved my butt multiple times: https://www.atlassian.com/git/tutorials/atlassian-git-cheatsheet

Also look into:

• Pull

• Push

• Branching

• Forking

GitHub uses markdown to write pages, a super simple language that is actually a lot of fun to write. Here's a markdown cheat cheatsheet: https://www.markdownguide.org/cheat-sheet/

Pandoc is a great tool to convert any text file to and from markdown: https://pandoc.org

Agile Development

Agility is the ability to adapt quickly to changing circumstances.

These days, everyone wants to be agile. Big and small companies are looking for the "startup mentality."

Many think it's the corporate culture. Others think it's the process of how we create things that matters.

In this article, I am going to talk about agility and self-reliance, about how you can incorporate agility in your professional career.

Why Is Agile So Important?

Historically, development has been practiced as an explicitly defined process. You think of something, specify it, have it developed, and then build in mass production.

It's a bit of an arrogant process. You assume that you already know exactly what a customer wants, or how a product has to look and how everything works out.

The problem is that the world does not work this way!

Oftentimes the circumstances change because of internal factors.

Sometimes things just do not work out as planned or stuff is harder than you think.

You need to adapt.

Other times you find out that you built something customers do not like and needs to be changed.

You need to adapt.

That's why people jump on the Scrum train -- because Scrum is the definition of agile development, right?

Agile Rules I Learned Over the Years

Is the Method Making a Difference?

Yes, Scrum or Google's OKR can help to be more agile. The secret to being agile, however, is not only how you create.

What makes me cringe is people trying to tell you that being agile starts in your head. So, the problem is you?

No!

The biggest lesson I have learned over the past years is this: Agility goes down the drain when you outsource work.

The Problem with Outsourcing

I know on paper outsourcing seems like a no-brainer: development costs against the fixed costs.

It is expensive to bind existing resources on a task. It is even more expensive if you need to hire new employees.

The problem with outsourcing is that you pay someone to build stuff for you.

It does not matter who you pay to do something for you. He needs to make money.

His agenda will be to spend as little time as possible on your work. That is why outsourcing requires contracts, detailed specifications, timetables, and delivery dates.

He doesn't want to spend additional time on a project, only because you want changes in the middle. Every unplanned change costs him time and therefore money.

If so, you need to make another detailed specification and a contract change.

He is not going to put his mind into improving the product while developing. Firstly, because he does not have the big picture. Secondly, because he does not want to.

He is doing as he is told.

Who can blame him? If I were the subcontractor, I would do exactly the same!

Does this sound agile to you?

Knowledge Is King: A lesson from Elon Musk

Doing everything in house -- that's why startups are so productive. No time is wasted on waiting for someone else.

If something does not work or needs to be changed, there is someone on the team who can do it right away.

One very prominent example who follows this strategy is Elon Musk.

Tesla's Gigafactories are designed to get raw materials in on one side and spit out cars on the other. Why do you think Tesla is building Gigafactories that cost a lot of money?

Why is SpaceX building its own space engines? Clearly, there are other, older companies who could do that for them.

Why is Elon building tunnel boring machines at his new boring company?

At first glance, this makes no sense!

How You Really Can Be Agile

If you look closer, it all comes down to control and knowledge. You, your team, your company, needs to do as much as possible on your own. Self-reliance is king.

Build up your knowledge and therefore the team's knowledge. When you have the ability to do everything yourself, you are in full control.

You can build electric cars, build rocket engines, or bore tunnels.

Don't largely rely on others, and be confident to just do stuff on your own.

Dream big, and JUST DO IT!

PS. Don't get me wrong. You can still outsource work. Just do it in a smart way by outsourcing small independent parts.

Agile Frameworks

Scrum

There's an interesting Medium article with a lot of details about Scrum: https://medium.com/serious-scrum

Also, this Scrum guide webpage has good info: https://www.scrumguides.org/scrum-guide.html

OKR

I personally love OKR and have been using it for years. Especially for smaller teams, OKR is great. You don't have a lot of overhead and get work done. It helps you stay focused and look at the bigger picture.

I recommend doing a sync meeting every Monday. There you talk about what happened last week and what you are going to work on this week.

I talked about this in this podcast: https://anchor.fm/andreaskayy/embed/episodes/Agile-Development-Is-Important-But-Please-Dont-Do-Scrum--PoDS-041-e2e2j4

There is also this awesome 1,5-hour startup guide from Google: https://youtu.be/mJB83EZtAjc I really love this video; I rewatched it multiple times.

Software Engineering Culture

The software engineering and development culture is super important. How does a company handle product development with hundreds of developers? Check out this podcast:

| Podcast episode: #070 Engineering Culture At Spotify |------------------ |In this podcast, we look at the engineering culture at Spotify, my favorite music streaming service. The process behind the development of Spotify is really awesome. |Watch on YouTube \ Listen on Anchor|

Some interesting slides:

https://labs.spotify.com/2014/03/27/spotify-engineering-culture-part-1/

https://labs.spotify.com/2014/09/20/spotify-engineering-culture-part-2/

Learn How a Computer Works

CPU,RAM,GPU,HDD

Differences Between PCs and Servers

I talked about computer hardware and GPU processing in this podcast: https://anchor.fm/andreaskayy/embed/episodes/Why-the-hardware-and-the-GPU-is-super-important--PoDS-030-e23rig

Data Network Transmission

OSI Model

The OSI Model describes how data flows through the network. It consists of layers starting from physical layers, basically how the data is transmitted over the line or optic fiber.

Check out this article for a deeper understanding of the layers and processes outlined in the OSI model: https://www.studytonight.com/computer-networks/complete-osi-model

The Wikipedia page is also very good: https://en.wikipedia.org/wiki/OSI_model

Which Protocol Lives on Which Layer?

Check out this network protocol map. Unfortunately, it is really hard to find it theses days: https://www.blackmagicboxes.com/wp-content/uploads/2016/12/Network-Protocols-Map-Poster.jpg

IP Subnetting

Check out this IP address and subnet guide from Cisco: https://www.cisco.com/c/en/us/support/docs/ip/routing-information-protocol-rip/13788-3.html

A calculator for subnets: https://www.calculator.net/ip-subnet-calculator.html

Switch, Layer-3 Switch

For an introduction to how ethernet went from broadcasts, to bridges, to Ethernet MAC switching, to ethernet & IP (layer 3) switching, to software-defined networking, and to programmable data planes that can switch on any packet field and perform complex packet processing, see this video: https://youtu.be/E0zt_ZdnTcM?t=144

Router

Firewalls

I talked about network infrastructure and techniques in this podcast: https://anchor.fm/andreaskayy/embed/episodes/IT-Networking-Infrastructure-and-Linux-031-PoDS-e242bh

Security and Privacy

SSL Public and Private Key Certificates

https://www.cloudflare.com/learning/ssl/how-does-ssl-work/

https://www.kaspersky.com/resource-center/definitions/what-is-a-ssl-certificate

https://www.ssl.com/faqs/what-is-a-certificate-authority/

JSON Web Tokens

Link to the Wiki page: https://en.wikipedia.org/wiki/JSON_Web_Token

GDPR Regulations

The EU created the GDPR \"General Data Protection Regulation\" to protect your personal data like: name, age, address, and so on.

It's huge and quite complicated. If you want to do online business in the EU, you need to apply these rules. The GDPR is applicable since May 25th, 2018. So, if you haven't looked into it, now is the time.

The penalties can be crazy high if you make mistakes here.

Check out the full GDPR regulation here: https://gdpr-info.eu

By the way, if you do profiling or analyse big data in general, look into it. There are some important regulations, unfortunately.

I spend months with GDPR compliance. Super fun. Not! Hahaha

Privacy by Design

When should you look into privacy regulations and solutions?

Creating the product or service first and then bolting on the privacy is a bad choice. The best way is to start implementing privacy right away in the engineering phase.

This is called privacy by design. Privacy is an integral part of your business, not just something optional.

Check out the Wikipedia page to get a feeling for the important principles: https://en.wikipedia.org/wiki/Privacy_by_design

Linux

Linux is very important to learn, at least the basics. Most big-data tools or NoSQL databases run on Linux.

From time to time, you need to modify stuff through the operating system, especially if you run an infrastructure as a service solution like Cloudera CDH, Hortonworks, or a MapR Hadoop distribution.

OS Basics

Show all historic commands:

history | grep docker

Shell scripting

Ah, creating shell scripts in 2019? Believe it or not, scripting in the command line is still important.

Start a process, automatically rename, move or do a quick compaction of log files. It still makes a lot of sense.

Check out this cheat sheet to get started with scripting in Linux: https://devhints.io/bash

There's also this Medium article with a super-simple example for beginners: https://medium.com/@saswat.sipun/shell-scripting-cheat-sheet-c0ecfb80391

Cron Jobs

Cron jobs are super important to automate simple processes or jobs in Linux. You need this here and there, I promise. Check out these three guides:

https://linuxconfig.org/linux-crontab-reference-guide

https://www.ostechnix.com/a-beginners-guide-to-cron-jobs/

And, of course, Wikipedia, which is surprisingly good: https://en.wikipedia.org/wiki/Cron

Pro tip: Don't forget to end your cron files with an empty line or a comment, otherwise it will not work.

Packet Management

Linux tips are the second part of this podcast: https://anchor.fm/andreaskayy/embed/episodes/IT-Networking-Infrastructure-and-Linux-031-PoDS-e242bh

Docker

What is Docker, and What Do You Use It for?

Have you played around with Docker yet? If you're a data science learner or a data scientist, you need to check it out!

It's awesome because it simplifies the way you can set up development environments for data science. If you want to set up a dev environment, you usually have to install a lot of packages and tools.

Don't Mess Up Your System

What this does is basically mess up your operating system. If you're just starting out, you don't know which packages you need to install. You don't know which tools you need to install.

If you want to, for instance, start with Jupyter Notebooks, you need to install that on your PC somehow. Or, you need to start installing tools like PyCharm or Anaconda.

All that gets added to your system, and so you mess up your system more and more and more. What Docker brings you, especially if you're on a Mac or a Linux system, is simplicity.

Preconfigured Images

Because it is so easy to install on those systems, another cool thing about Docker images is you can just search them in the Docker store, download them, and install them on your system.

Running them in a completely pre-configured environment, you don't need to think about stuff. You go to the Docker library, and you search for Deep Learning, GPU and Python.

You get a list of images you can download. You download one, start it up, go to the browser and hit up the URL, and just start coding.

Start doing the work. The only other thing you need to do is bind some drives to that instance so you can exchange files. And, then that's it!

There is no way that you can crash or mess up your system. It's all encapsulated into Docker. Why this works is because Docker has native access to your hardware.

Take It With You

It's not a completely virtualized environment like a VirtualBox. An image has the upside that you can take it wherever you want. So, if you're on your PC at home, use that there.

Make a quick build, take the image, and go somewhere else. Install the image, which is usually quite fast, and just use it like you're at home.

It's that awesome!

Kubernetes Container Deployment

I am getting into Docker a lot more myself. For a some different reasons.

What I'm looking for is using Docker with Kubernetes. With Kubernetes, you can automate the whole container deployment process.

The idea is that you have a cluster of machines. Lets say you have a 10-server cluster and you run Kubernetes on it.

Kubernetes lets you spin up Docker containers on demand to execute tasks. You can set up how much resources like CPU, RAM, and network your Docker container can use.

You can basically spin up containers, on the cluster on demand, whenever you need to do an analytics task.

That's perfect for data science.

How to Create, Start, Stop a Container

Docker Micro-Services?

Kubernetes

Why and How to Do Docker Container Orchestration

Podcast about how data science learners use Docker (for data scientists): https://anchor.fm/andreaskayy/embed/episodes/Learn-Data-Science-Go-Docker-e10n7u

Useful Docker Commands

Create a container:

docker run CONTAINER --network NETWORK

Start a stopped container:

docker start CONTAINER NAME

Stop a running container:

docker stop

List all running containers:

docker ps

List all containers including stopped ones:

docker ps -a

Inspect the container configuration (e.g. network settings, etc.):

docker inspect CONTAINER

List all available virtual networks:

docker network ls

Create a new network:

docker network create NETWORK --driver bridge

Connect a running container to a network:

docker network connect NETWORK CONTAINER

Disconnect a running container from a network:

docker network disconnect NETWORK CONTAINER

Remove a network:

docker network rm NETWORK

The Cloud

IaaS vs. PaaS vs. SaaS

Check out this podcast. It will help you understand the difference and how to decide what to use.

| Podcast episode: #082 Reading Tweets With Apache Nifi & IaaS vs PaaS vs SaaS |------------------| |In this episode, we talk about the differences between infrastructure as a service, platform as a service, and application as a service. Then, we install the Nifi Docker container and look into how we can extract the twitter data. | Watch on YouTube \ Listen on Anchor|

AWS, Azure, IBM, Google

Each of these have their own answer to IaaS, Paas, and SaaS. Pricing and pricing models vary greatly between each provider. Likewise, each provider's service may have limitations and strengths.

AWS

Here is the full list of AWS services. Studying for the AWS Certified Cloud Practitioner and/or AWS Certified Solutions Architect exams can be helpful to quickly gain an understanding of all these services. Here are links for free digital training for the AWS Certified Cloud Practitioner and AWS Certified Solutions Architect Associate.

Here is a free 17 hour Data Analytics Learning plan for AWS's Analytics/Data Engineering services.

Azure

Full list of Azure services. Get started with mini courses.

IBM

Google

Google Cloud Platform offers a wide, ever-evolving variety of services. List of GCP services with brief description. In recent years, documentation and tutorials have com a long way to help getting started with GCP. You can start with a free account, but to use many of the services, you will need to turn on billing. Once you do enable billing, always remember to turn off services that you have spun up for learning purposes. It is also a good idea to turn on billing limits and alerts.

Cloud vs. On-Premises

| Podcast episode: #076 Cloud vs. On-Premise |------------------| |How to choose between cloud and on-premises, pros and cons and what you have to think about. There are good reasons to not go cloud. Also, thoughts on how to choose between the cloud providers by just comparing instance prices. Otherwise, the comparison will drive you insane. My suggestion: Basically use them as IaaS and something like Cloudera as PaaS. Then build your solution on top of that.
| Watch on YouTube \ Listen on Anchor|

Security

Listen to a few thoughts about the cloud in this podcast: https://anchor.fm/andreaskayy/embed/episodes/Dont-Be-Arrogant-The-Cloud-is-Safer-Then-Your-On-Premise-e16k9s

Hybrid Clouds

Hybrid clouds are a mixture of on-premises and cloud deployment. A very interesting example for this is Google Anthos:

https://cloud.google.com/anthos/

Data Scientists and Machine Learning

Data scientists aren't like every other scientist.

Data scientists do not wear white coats or work in high tech labs full of science fiction movie equipment. They work in offices just like you and me.

What differs them from most of us is that they are math experts. They use linear algebra and multivariable calculus to create new insight from existing data.

How exactly does this insight look?

Here's an example:

An industrial company produces a lot of products that need to be tested before shipping.

Usually such tests take a lot of time because there are hundreds of things to be tested. All to make sure that your product is not broken.

Wouldn't it be great to know early if a test fails ten steps down the line? If you knew that you could skip the other tests and just trash the product or repair it.

That's exactly where a data scientist can help you, big-time. This field is called predictive analytics and the technique of choice is machine learning.

Machine what? Learning?

Yes, machine learning, it works like this:

You feed an algorithm with measurement data. It generates a model and optimises it based on the data you fed it with. That model basically represents a pattern of how your data is looking. You show that model new data and the model will tell you if the data still represents the data you have trained it with. This technique can also be used for predicting machine failure in advance with machine learning. Of course the whole process is not that simple.

The actual process of training and applying a model is not that hard. A lot of work for the data scientist is to figure out how to pre-process the data that gets fed to the algorithms.

In order to train an algorithm you need useful data. If you use any data for the training the produced model will be very unreliable.

An unreliable model for predicting machine failure would tell you that your machine is damaged even if it is not. Or even worse: It would tell you the machine is ok even when there is a malfunction.

Model outputs are very abstract. You also need to post-process the model outputs to receive the outputs you desire

Machine Learning Workflow

Data Scientists and Data Engineers. How does that all fit together?

You have to look at the data science process. How stuff is created and how data science is done. How machine learning is done.

The machine learning process shows, that you start with a training phase. A phase where you are basically training the algorithms to create the right output.

In the learning phase you are having the input parameters. Basically the configuration of the model and you have the input data.

What you're doing is you are training the algorithm. While training the algorithm modifies the training parameters. It also modifies the used data and then you are getting to an output.

Once you get an output you are evaluating. Is that output okay, or is that output not the desired output?

if the output is not what you were looking for? Then you are continuing with the training phase.

You're trying to retrain the model hundreds, thousands, hundred thousands of times. Of course all this is being done automatically.

Once you are satisfied with the output, you are putting the model into production. In production it is no longer fed with training data it's fed with the live data.

It's evaluating the input data live and putting out live results.

So, you went from training to production and then what?

What you do is monitoring the output. If the output keeps making sense, all good!

If the output of the model changes and it's on longer what you have expected, it means the model doesn't work anymore.

You need to trigger a retraining of the model. It basically gets to getting trained again.

Once you are again satisfied with the output, you put it into production again. It replaces the one in production.

This is the overall process how machine learning. It's how the learning part of data science is working.

Machine Learning Model and Data

Now that's all very nice.

When you look at it, you have two very important places where you have data.

You have in the training phase two types of data: Data that you use for the training. Data that basically configures the model, the hyper parameter configuration.

Once you're in production you have the live data that is streaming in. Data that is coming in from from an app, from a IoT device, logs, or whatever.

A data catalog is also important. It explains which features are available and how different data sets are labeled.

All different types of data. Now, here comes the engineering part.

The Data Engineers part, is making this data available. Available to the data scientist and the machine learning process.

So when you look at the model, on the left side you have your hyper parameter configuration. You need to store and manage these configurations somehow.

Then you have the actual training data.

There's a lot going on with the training data:

Where does it come from? Who owns it? Which is basically data governance.

What's the lineage? Have you modified this data? What did you do, what was the basis, the raw data?

You need to access all this data somehow. In training and in production.

In production you need to have access to the live data.

All this is the data engineers job. Making the data available.

First an architect needs to build the platform. This can also be a good data engineer.

Then the data engineer needs to build the pipelines. How is the data coming in and how is the platform connecting to other systems.

How is that data then put into the storage. Is there a pre processing for the algorithms necessary? He'll do it.

Once the data and the systems are available, it's time for the machine learning part.

It is ready for processing. Basically ready for the data scientist.

Once the analytics is done the data engineer needs to build pipelines to make it then accessible again. For instance for other analytics processes, for APIs, for front ends and so on.

All in all, the data engineer's part is a computer science part.

That's why I love it so much :)