Tag Archives: programming

Learning Go Episode 5 – Functions (and Methods and lots of other things)

Episode Post & Video Links:  1, 2, 3, 4, 5 (this post), 6, 7, and 8. Non-linked are in the works! Videos available now on Youtube however, so check em’ out!

In this session we covered a host of topics around Go Functions. Along with some troubleshooting, debugging, and other features in Jetbrains Goland IDE.

If you’d like to go through this material too in book form, I highly suggest “The Go Programming Language” by Alan A.A. Donovan & Brian W. Kernighan as a starting point. I’m using it as a simple guideline, but also doing a lot more in each stream that includes ecosystem, dependency management with godep, IDE use of Goland from Jetbrains, and more. In this session I get specifically into: functions, signatures, declarations, recursion, return values, and more.

Video Time Points & Topics

2:50 – Introduction to the snowy wonderland of Seattle and episode 5 of the Learning Go series. Introduction to the various screen transitions and such.
6:40 – Getting started, opening up JetBrains Goland and creating a new project. The project exists on Github as https://github.com/adron/learning-go-….
12:18 – Starting with functions in Go. See the blog entry I wrote on the topic for more additional information around this first code session within the episode 5 session.

Code – This first example I setup a basic function in Go that is called by the main function. The sample function below I’ve named exampleExecutor, and the signature is made up of an int parameter called this, a string parameter called that, and a return parameter of type int and one of type string. In summary for the function signature we have two input parameters going in and two return parameters coming out.

The function does very little besides print the parameters passed in and then return the parameters back out as the return parameters.

Recursion with Go & HTML Parsing

28:10 – Here I get into recursion and the application example, largely taken from the book but with some very distinctive modifications, that parses HTML and the various nodes within an HTML document.

For the recursion section I use an example from the book with an expanded sample set of HTML. The HTML is included in the repo under the function-recursion branch. For this example I setup a set of types and variables up that are needed throughout the code.

First a type setup called NodeType of type int32. A constant array of ErrorNode, TextNode, DocumentNode, ElementNode, CommentNode, and DoctypeNode for determining the different nodes within an HTML document. Then a general struct called Node with Type, Data, Attr for attribute, and FirstChild with NextSibling setup as a pointer to *Node, which gives a type of memory recursion to the underlying type. Then finally the Attribute struct with a Key a Value.

One of the first functions I then end up with is the visit function. It turns out as shown below. Here the function takes a links parameter that is of type string array, a parameter name n that is a pointer reference to an a node within html, and then the function returns a parameter of type string array.

After that function I worked through and created two additional functions, one for countsWordsAndImages and one called CountWordsAndImages. The casing being specific to scope and use of the functions, and they respectively look like this in completion.

Then all that is wrapped up, with recursive calls and more, in the main function for program execution.

Starting Error Handling && Anonymous Functions

1:32:40 – At this point in the episode 5 session I get into a simple Error handling function, and further into function signatures and how to set them up.
1:52:24 – Setting up some anonymous functions and reviewing what they are.
1:59:00 – Introduction to panics in Go. After this short introduction I also discuss some of the pedantic specifics of methods vs functions and related verbiage around the Go language. Additionally I provide more examples around these specifics for declaring functions, various scope, and other types for function calls and related usage.

With that done the wrap up of the session is then a short introduction to anonymous functions.

Cassie Schema Migrator >> CaSMa

A few weeks back I started working on a schema migration tool for Apache Cassandra and DataStax Enterprise. Just for context, here are the short definitions of what each of the elements of CaSMa are.

  • cstar-iconApache Cassandra
    • Definition: Apache Cassandra is a free and open-source, distributed, wide column store, NoSQL database management system designed to handle large amounts of data across many commodity servers, providing high availability with no single point of failure.
    • History: Avinash Lakshman, one of the authors of Amazon’s Dynamo, and Prashant Malik initially developed Cassandra at Facebook to power the Facebook inbox search feature. Facebook released Cassandra as an open-source project on Google code in July 2008. In March 2009 it became an Apache Incubator project. On February 17, 2010 it graduated to a top-level project. Facebook developers named their database after the Trojan mythological prophet Cassandra, with classical allusions to a curse on an oracle.
  • dse-logoDataStax Enterprise
    • Definition: DataStax Enterprise, or routinely just referred to as DSE, is an extended version of Apache Cassandra with multi-model capabilities around graph, search, analytics, and other features like security capabilities and a core data engine 2x speed improvement.
    • History: DataStax was formed in 2009 by Jonathan Ellis and Matt Pfeil and originally named Riptano. In 2011 Riptano changes names to DataStax. For more history check out the Wikipedia page or company page for a timeline of events.
  • command-toolsSchema Migration
    • Definition:In software engineering, schema migration (also database migration, database change management) refers to the management of incremental, reversible changes to relational database schemas. A schema migration is performed on a database whenever it is necessary to update or revert that database’s schema to some newer or older version. Migrations are generally performed programmatically by using a schema migration tool. When invoked with a specified desired schema version, the tool automates the successive application or reversal of an appropriate sequence of schema changes until it is brought to the desired state.
    • Addition reference and related materials:

iconmonstr-twitch-5Over the next dozen weeks or so as I work on this application via the DataStax Devs Twitch stream (next coding session events list) I’ll also be posting some blog posts in parallel about schema migration and my intent to expand on the notion of schema migration specifically for multi-model databases and larger scale NoSQL systems; namely Apache Cassandra and DataStax Enterprise. Here’s a shortlist for the next three episodes;

The other important pieces include the current code base on Github, the continuous integration build, and the tasks and issues.

Alright, now that all the collateral and context is listed, let’s get into at a high level what this is all about.

CaSMa’s Mission

Schema migration is a powerful tool to get a project on track and consistently deployed and development working against the core database(s). However, it’s largely entrenched in the relational database realm. This means it’s almost entirely focused on a schema with the notions of primary and foreign keys, the complexities around many to many relationships, indexes, and other errata that needs to be built consistently for a relational database. Many of those things need to be built for a distributed columnar store, key value, graph, time series, or a million other possibilities too. However, in our current data schema world, that tooling isn’t always readily available.

The mission of CaSMa is to first resolve this gap around schema migration, first and foremost for Apache Cassandra and prospectively in turn for DataStax Enterprise and then onward for other database systems. Then the mission will continue around multi-model systems that should, can, and ought to take advantage of schema migration for graph, and related schema modeling. At some point the mission will expand to include other schema, data, and state management focused around software development and data needs within that state

As progress continues I’ll publish additional posts here on the different data model concepts and nature behind various multi-model database options. These modeling options will put us in a position to work consistently, context based, and seamlessly with ongoing development efforts. In addition to all this, there will be the weekly Twitch sessions where I’ll get into coding and reviewing what coding I’ve done off camera too. Check those out on the DataStax Devs Channel.

If you’d like to get into the project and help out just ping me via Twitter @Adron or message me here.

Learning Go Episode 4 – Composite Types, Slices, Arrays, Etc.

Episode Post & Video Links:  1, 2, 3, 4 (this post), 5, 6, 7, and 8. Non-linked are in the works! Videos available now on Youtube however, so check em’ out!

If you’d like to go through this material too in book form, I highly suggest “The Go Programming Language” by Alan A.A. Donovan & Brian W. Kernighan. I use it throughout these sessions to provide a guideline. I however add a bunch of other material about IDE’s, development tips n’ tricks and other material.

8:00 Starting the core content with some notes. Composite types, arrays, slices, etc.
11:40 Announcement of my first reload – https://compositecode.blog/2019/02/11/… – second successful time blogged here) of the XPS 15 I have, which – https://youtu.be/f0z1chi4v1Q – actually ended in catastrophe the first time!
14:08 Starting the project for this session.
16:48 Setting up arrays, the things that could be confusing, and setup of our first code for the day. I work through assignment, creation, new vs. comparison, and various other characteristics of working with arrays during this time.

29:36 Creation of a type, called Currency, of type int, setting up constants, and using this kind of like an enumerator to work with code that reads cleaner. Plus of course, all the various things that you might want to, or need for a setup of types, ints, and related composite types like this.

43:48 Creating an example directly from the aforementioned book enumerating the months of the year. This is a great example I just had to work through it a bit for an example.

52:40 Here I start showing, and in the process, doing some learning of my own about runes. I wasn’t really familiar with them before digging in just now!

1:09:40 Here I break things down and start a new branch for some additional examples. I also derail off into some other things about meetups and such for a short bit. Skip to the next code bits at the next time point.
1:23:58 From here on to the remainder of the video I work through a few examples of how to setup maps, how make works, and related coding around how to retrieve, set, and otherwise manipulate the maps one you’ve got them.

That’s it for this synopsis. Until next episode, happy code thrashing and go coding!

Learning Go Episode 3 – More Data Types, Casting, Rendering an SVG file, and writing to Files.

Episode Post & Video Links:  1, 2, 3 (this post), 4, 5, 6, 7, and 8. Non-linked are in the works! Videos available now on Youtube however, so check em’ out!

Episode 3 of my recurring “Learning Go” Saturday stream really got more into the particulars of Go data types including integers, strings, more string formatting verbs, concatenation, type casting, and lots of other pedantic details. In the episode I also delve into some OBS details with the audience, and we get the Twitch interface I’ve setup a bit more streamlined for easier readability. Overall, I think it’s looking much better than just the last episode! Hats off to the conversational assist from the audience.

Here’s the play by play of what was covered in episode 3 with the code in gists plus the repo is available on Github. Video below the timeline.

Timeline

0:00 Intro
6:08 The point I fix the sound. Just skip that first bit!
6:24 Re-introducing the book I’m using as a kind of curriculum guide for these go learning sessions.
7:44 Quick fix of the VM, a few updates, discussion of Goland updates, and fixing the Material Theme to a more visually less caustic theme. Also showing where it is in the IDE.
9:52 Getting into the learning flow, starting a new project with Go 1.11.4 using the Goland IDE new project dialog.

10:50 Creating the Github repo for learning-go-episode-3.
12:14 Setting up the initial project and CODING! Finally getting into some coding. It takes a while when we do it from nothing like this, but it’s a fundamentally important part of starting a project!
13:04 From nothing, creating the core basic elements of a code file for go with main.go. In this part I start showing the various ways to declare types, such as int and int64 with options on style.
14:14 Taking a look at printing out the various values of the variables using formatter verbs via the fmt.Printf function.
17:00 Looking at converting values from one type to another type. There are a number of ways to do this in Go.

I also, just recently, posted a quick spot video and code (blog entry + code) on getting the minimum and maximum value in Go for a number of types. This isn’t the course video, just a quick spot. Keep reading for the main episode below.


18:16 Oh dear the mouse falls on the ground. The ongoing battle of streaming, falling objects! But yeah, I get into adding a function – one of the earlier functions being built in the series – and we add a signature with a return int64 value. I continue, with addition of another function and looking at specifics of the signature.
25:50 Build this code and take a look at the results. At this point, some of the formatting is goofed up so I take a look into the formatter verbs to figure out what should be used for the output formatting.
33:40 I change a few things and take a look at more output from the various calculations that I’ve made, showing how various int, int64, and related calculations can be seen.
37:10 Adding a constant, what it is, and when and where and why to declare something as a constant.
38:05 Writing out another for loop for output results of sets.
42:40 A little git work to create a branch, update the .gitignore, and push the content to github. Repo is here btw: https://github.com/Adron/learning-go-episode-3

At this point I had to take a short interruption to get my ssh keys setup for this particular VM so I could push the code! I snagged just a snippet of the video and made a quick spot video out of it too. Seems a useful thing to do.

47:44 Have to add a new ssh key for the virtual machine to github, so this is a good little snippet of a video showing how that is done.
56:38 Building out a rendering of an SVG file to build a graphic. The complete snippet is below, watch the video for more details, troubleshooting, and working through additions and refactoring of the code.

1:15:32 We begin the mission of bumping up the font size in Goland. It’s a little tricky but we get it figured out.
1:33:20 Upon realization, we need to modify for our work, that this outputs directly to a file instead of just the console. Things will work better that way so I work into the code a write out to file.
1:40:05 Through this process of changing it to output to file, I have to work through additional string conversions, refactoring, and more. There’s a lot of nuance and various things to learn during this section of the video, albeit a little slow. i.e. LOTS of strconv usage.
2:01:24 First view of the generated SVG file! Yay! Oh dear!
2:09:10 More troubleshooting to try and figure out where the math problem is!
2:22:50 Wrapping up with the math a little off kilter, but sort of fixed, I move on to getting a look into the build but also pushing each of the respective branches on github. Repo is here btw: https://github.com/Adron/learning-go-episode-3

Learning Go Episode 1 – Environment, Go Workspace, GOPATH/GOROOT, Types, and more Introduction

Episode Post & Video Links:  1 (this post), 2, 3, 4, 5, 6, 7, and 8. Non-linked are in the works! Videos available now on Youtube however, so check em’ out!

This is episode one of a multi-part series on “The Go Programming Language“. Not necessary, but if you’d like to follow along you can also pick up the book “The Go Programming Language” by Alan A. A. Donovan and Brian W. Kernighan. At the bottom of the description I have a link to the book publisher’s website and the respective book. I’ll be using that as a guideline and using a number of examples from the book. However I’ll also be adding a lot of additional material around Goland IDE from Jetbrains and Visual Studio Code. The video link to this session is at the bottom of the post, scroll all the way down and it’s waiting for you there.

3:28 – Getting started, introducing that the session I’m starting with a completely new Ubuntu Linux load so that I ensure we cover all of the steps to get up and running. These steps, even though they’re on Linux are reproducible on Windows 10 and MacOS, so any operating system is usable to follow along with, with only minor discrepancies.

5:04 – Introducing the book that I’ll be using as a guideline reference so that viewers can also follow along with a physical book. I’m a big fan of multisensory learning, so between a book, the stream, being able to ask questions in the channel, it’ll give viewers a chance to learn and undertake their coding adventures in Go using all sorts of methods.

Book Reference: “The Go Programming Language” by Alan A. A. Donovan and Brian W. Kernighan

6:58 – Discussing where Go is located on the web related to Github and the golang.org site that is useful in that one can even try out little snippets of Go code itself, on the site!
Github: https://github.com/golang/go
Golang: https://golang.org
10:40 – Setting export in the .bashrc file (or .bash_profile on MacOS or environment variables on Windows 10). Speaking of Windows 10 specifically, Linda Gregier wrote up a great blog post on getting Go setup on Windows specifically.
14:50 – Setting up the Go workspace path for GOPATH using the standard Go convention. From here I get into the first “Hello World!” with Go.
15:34 – Mention of setting up Go on a Docker container and how it is easier, but we’re staying focused on setting it up completely from scratch.
18:20 – Starting first code, a standard “Hello World” program.
19:50 – First build of that “Hello World” program.
20:34 – Here I introduce go run and how to execute a singular file instead of building an entire project.
21:32 – Installing some IDE’s to use for developing Go applications. The first two up for installation is Visual Studio Code and JetBrains Goland.
29:00 – A first variable, what is it, and how to declare one in Go in one of the ways one can declare a variable in Go!
31:08 – Introducing the terminal in Visual Studio Code.
37:12 – A little example of OBS, how I’m using it, and how I interact back and forth with chat and related tooling plus the virtual machine itself.
42:36 – Changing themes and adding plugins for Goland. In the plugins I also find the most epic of status bars, the Nyan Cat!
59:00 – Here I start to get back into some more specific Go details. Starting off with a Go command line parsing application. At this point I also cover several additional ways to declare variables, speak more about short declarations, and other ways to declare, assign, and use variables in Go.

At this point I also go through a number of examples to exemplify how to go about declaring variables, build, run, and explore the details of the code. Further along I also get into string formatting, concatenating, and related string manipulation with Go.

Other details include taking a look at extra ways to figure out Go code using autocomplete inside Goland and other exploratory features. Eventually before wrapping up I broach pointers, tuple declaration techniques, and how to declare additional functions beyond func main().
1:58:40 – Adding dependencies and generating random data. At this point I bring in a dependency. But before pulling in the dependency, after introducing it, I show how to go about doing.
2:00:10 – New machine, and I run into git not being available. The go get command uses git to pull dependencies so I go about why this is needed and the steps to install on Ubuntu.
2:09:20 – Introduction to more concepts around dependencies, what go get does versus managing dependencies with Go Dep.
2:10:00 – Installing Go Dep; MacOS, using curl, Linux installation, and a question sort of remains to get it running on Windows. The easiest method is using chocolatey however, so check that out if you’re going the Windows route.
2:15:20 – Setting up Go Dep integration with Goland.
2:23:55 – Showing off Goland’s commit dialog and some of the respective options.

Creating Distributed Database Application Starter Kits

I’ve boarded a bus, and as always, when I board a bus I almost always code. Unless of course there are people I’m hanging out with then I chit chat, but right now this is the 212 and I don’t know anybody on this chariot anyway. So into the code I go.

I’ve been re-reviewing the Docker and related collateral we offer at DataStax. In that review it seems like it would be worth having some starter kit applications along with these “default” Docker options. This post I’ve created to provide the first language & tech stack of several starter kits I’m going to create.

Starter Kit – The Todo List Template

This first set of starter kits will be based upon a todo list application. It’s really simple, minimal in features, and offers a complete top to bottom implementation of a service, and an application on top of that service all built on Apache Cassandra. In some places, and I’ll clearly mark these places, I might add a few DataStax Enterprise features around search, analytics, or graph.

The Todo List

Features: The following detail the features, from the users perspective, that this application will provide. Each implementation will provide all of these features.

  • A user wants to create a user account to create todo lists with.
  • A user wants to be able to store a username, full name, email, and some simple notes with their account.
  • A user wants to be able to create a todo list that is identified by a user defined name. (i.e. “Grocery List”, “Guitar List”, or “Stuff to do List”)
  • A user want to be able to logout and return, then retrieve a list from a list of their lists.
  • A user wants to be able to delete a todo list.
  • A user wants to be able to update a todo list name.
  • A user wants to be able to add items to a todo list.
  • A user wants to be able to update items in the todo list.
  • A user wants to be able to delete items in a todo list.

Architecture: The following is the architecture of the todo list starter kit application.

  • Database: Apache Cassandra.
  • Service: A small service to manage the data tier of the application.
  • User Interface: A web interface using React/Vuejs ??

As you can see, some of the items are incomplete, but I’ll decide on them soon. My next review is to check out what I really want to use for the user interface, and also to get a user account system figured out. I don’t really want to create the entire user interface, but instead would like to use something like Auth0 or Okta.

May I Ask?

There are numerous things I’d love help with. Are there any user stories you think are missing? Should I add something? What would make these helpful to you? Leave a comment, or tweet at me @Adron. I’d be happy to get some feedback and other’s thoughts on the matter so that I can ensure that these are simple, to the point, usable, and helpful to people. Cheers!

Twitz Coding Session in Go – Cobra + Viper CLI with Initial Twitter + Cassandra Installation

Part 2 of 3 – Coding Session in Go – Cobra + Viper CLI for Parsing Text Files, Retrieval of Twitter Data, Exports to various file formats, and export to Apache Cassandra.

UPDATED PARTS:

  1. Twitz Coding Session in Go – Cobra + Viper CLI for Parsing Text Files
  2. Twitz Coding Session in Go – Cobra + Viper CLI with Initial Twitter + Cassandra Installation (this post)
  3. Twitz Coding Session in Go – Cobra + Viper CLI Wrap Up + Twitter Data Retrieval

Updated links to each part will be posted at bottom of  this post when I publish them. For code, written walk through, and the like scroll down below the video and timestamps.

Hacking Together a CLI Installing Cassandra, Setting Up the Twitter API, ENV Vars, etc.

0:04 Kick ass intro. Just the standard rocking tune.

3:40 A quick recap. Check out the previous write “Twitz Coding Session in Go – Cobra + Viper CLI for Parsing Text Files” of this series.

4:30 Beginning of completion of twitz parse command for exporting out to XML, JSON, and CSV (already did the text export previous session). This segment also includes a number of refactorings to clean up the functions, break out the control structures and make the code more readable.

In the end of refactoring twitz parse came out like this. The completed list is put together by calling the buildTwitterList() function which is actually in the helpers.go file. Then prints that list out as is, and checks to see if a file export should be done. If there is a configuration setting set for file export then that process starts with a call to exportParsedTwitterList(exportFilename string, exportFormat string, ... etc ... ). Then a simple single level control if then else structure to determine which format to export the data to, and a call to the respective export function to do the actual export of data and writing of the file to the underlying system. There’s some more refactoring that could be done, but for now, this is cleaned up pretty nicely considering the splattering of code I started with at first.

50:00 I walk through a quick install of an Apache Cassandra single node that I’ll use for development use later. I also show quickly how to start and stop post-installation.

Reference: Apache Cassandra, Download Page, and Installation Instructions.

53:50 Choosing the go-twitter API library for Go. I look at a few real quickly just to insure that is the library I want to use.

Reference: go-twitter library

56:35 At this point I go through how I set a Twitter App within the API interface. This is a key part of the series where I take a look at the consumer keys and access token and access token secrets and where they’re at in the Twitter interface and how one needs to reset them if they just showed the keys on a stream (like I just did, shockers!)

57:55 Here I discuss and show where to setup the environment variables inside of Goland IDE to building and execution of the CLI. Once these are setup they’ll be the main mechanism I use in the IDE to test the CLI as I go through building out further features.

1:00:18 Updating the twitz config command to show the keys that we just added as environment variables. I set these up also with some string parsing and cutting off the end of the secrets so that the whole variable value isn’t shown but just enough to confirm that it is indeed a set configuration or environment variable.

1:16:53 At this point I work through some additional refactoring of functions to clean up some of the code mess that exists. Using Goland’s extract method feature and other tooling I work through several refactoring efforts that clean up the code.

1:23:17 Copying a build configuration in Goland. A handy little thing to know you can do when you have a bunch of build configuration options.

1:37:32 At this part of the video I look at the app-auth example in the code library, but I gotta add the caveat, I run into problems using the exact example. But I work through it and get to the first error messages that anybody would get to pending they’re using the same examples. I get them fixed however in the next session, this segment of the video however provides a basis for my pending PR’s and related work I’ll submit to the repo.

The remainder of the video is trying to figure out what is or isn’t exactly happening with the error.

I’ll include the working findem code in the next post on this series. Until then, watch the wrap up and enjoy!

1:59:20 Wrap up of video and upcoming stream schedule on Twitch.

UPDATED SERIES PARTS

    1. Twitz Coding Session in Go – Cobra + Viper CLI for Parsing Text Files
    2. Twitz Coding Session in Go – Cobra + Viper CLI with Initial Twitter + Cassandra Installation (this post)
    3. Twitz Coding Session in Go – Cobra + Viper CLI Wrap Up + Twitter Data Retrieval