https://vgaltes.com/ Recent content on VGALTES blog Hugo -- gohugo.io en Sun, 23 Apr 2023 00:00:00 +0000 https://vgaltes.com/post/ambassador/ Sun, 23 Apr 2023 00:00:00 +0000 https://vgaltes.com/post/ambassador/ If you have a service in production (congratulations, by the way) you probably have a lot of questions from other parts of the company. Customer Service Customer Service can come to you with some weird scenario that a customer has suffered, or ask you to do that manual task that you still don’t have automated. Or maybe thay complain because the website they use is slow today. Operations Operations can ask you to import some new data in production. https://vgaltes.com/post/kotlin-variance-covariance/ Sat, 12 Nov 2022 00:00:00 +0000 https://vgaltes.com/post/kotlin-variance-covariance/ When we work with generics, sometimes we need to help the compiler in order to accomplish what we want. By doing that, we’ll be telling the compiler if two classes are covariant or contravariant. Let’s see a couple of examples to help understand these concepts. Covariance Imagine that we want to model a factory of toys. Let’s start by creating an interface that will take a generic type: 1 2 3 interface Factory<T> { fun create(name: String): T } Now we need to define what we want to produce https://vgaltes.com/post/kotlin-enums-sealed-classes/ Sun, 06 Nov 2022 00:00:00 +0000 https://vgaltes.com/post/kotlin-enums-sealed-classes/ In Kotlin we have two constructs that alow us to create a closed typed hierarchy: sealed classes and enums. Let’s take a look to them and see the differences amongst them. Sealed classes A sealed class is a class that we know all its subclasses at compile time. We can’t declare a subclass of a sealed class outside the module where it’s defined. One of the differences between a sealed class and an enum is that a subclass of a sealed class can have multiple instances, each with its own state. https://vgaltes.com/post/kotlin-abstract-classes-interfaces/ Sat, 05 Nov 2022 00:00:00 +0000 https://vgaltes.com/post/kotlin-abstract-classes-interfaces/ When you’re studying Kotlin and take a look at abstract classes and interfaces, your first impression is that they are two very similar constructs, or at least that was my first impression. You can use both of them to share state and behavior. So, let’s see what are they and what are the difference amongst them. Abstract classes With abstract classes, using the keyword abstract you can declare members without implementation. https://vgaltes.com/post/learning-kotlin-gradle-kotest/ Sat, 29 Oct 2022 00:00:00 +0000 https://vgaltes.com/post/learning-kotlin-gradle-kotest/ I’m about to start a new job. This will be a huge challenge for me, as I’m going to be developing in Kotlin. I’ve spent all of my professional life working with .Net, so I need to learn LOTS of things. As I believe that writing down what you learn is the best way to solidify it, I’ll be documenting all that I learn (maybe not all, but a bing chunk of it :D). https://vgaltes.com/post/retrospectiva-2020/ Wed, 30 Dec 2020 00:00:00 +0000 https://vgaltes.com/post/retrospectiva-2020/ No se donde va a llegar este artículo, pero empecemos rememorando lo que ha sido este 2020. El 2020 empezó como había acabado el 2019, es decir, trabajando como Technical Coach en Voxel. Esto quería decir trabajar 4 días a la semana, de 9 a 17, haciendo algo que me gusta como ayudar a un equipo a crecer, y trabajando desde casa. Respecto a mi último trabajo había perdido algo de poder adquisitivo (mismo rate pero en euros en lugar de libras y 4 días a la semana en lugar de cinco), pero había ganado mucha calidad de vida. https://vgaltes.com/post/lamda-dotnet/ Sun, 14 Jun 2020 00:00:00 +0000 https://vgaltes.com/post/lamda-dotnet/ This week I wanted to investigate how to use a Pub/Sub mechanism in an on-premise environment without needing to install anything else in our infrastructure, so using a managed service. I also wanted to make my first tests with CDK. Let me show you what I did. Goal What I want to accomplish is that a system that lives in our infrastructure communicates asynchronously with another system on it. It’s easy to simulate the sender of the message with a console application, but for the receiver I’ll need a public HTTP endpoint. https://vgaltes.com/post/lambda-destinations/ Sun, 29 Mar 2020 00:00:00 +0000 https://vgaltes.com/post/lambda-destinations/ AWS recently introduced lambda destinations for asynchronous invocations. So, if you have, let’s say, a lambda function attached to an SNS event, you can configure a destination when the execution is successful and a destination when the execution fails. The destination can be either an SQS queue, an SNS topic, EventBridge or another Lambda function. As usual, the serverless framework implemented this feature quickly. Let’s take a look how to do it and what’s the difference with a DLQ. https://vgaltes.com/post/using-mediatr-as-a-refactoring-strategy/ Thu, 13 Feb 2020 00:00:00 +0000 https://vgaltes.com/post/using-mediatr-as-a-refactoring-strategy/ Let me introduce you to Rachel, the new developer of the team. Rachel is an excellent developer eager to make a huge impact on the team and the organisation. When Rachel lands in the team, they treat them very well. They show her all the facilities, they teach her on how to make a good coffee with the new and shiny coffee machine and they even deploy to production in her first day. https://vgaltes.com/post/forwarding-correlation-ids-in-aspnetcore-version-2/ Wed, 29 Jan 2020 21:03:26 +0100 https://vgaltes.com/post/forwarding-correlation-ids-in-aspnetcore-version-2/ The minute after I published my last article about Capturing and forwarding correlation IDs, my very good friend Hugo Biarge send me a Direct Message telling me: “Hey man! Have you read this article? This is new from ASP .NET Core 3, and it’s an easier solution than the one you explain in the article.” So, I took a look, not only at the article but also at the traces that I was already generating, and voilà, everything was already there. https://vgaltes.com/post/forwarding-correlation-ids-in-aspnetcore/ Tue, 28 Jan 2020 15:03:26 +0100 https://vgaltes.com/post/forwarding-correlation-ids-in-aspnetcore/ When you have different services that communicate amongst them, you need to be able to correlate those calls to perform effective analysis of any problem you might have. The way to do this is using correlation ids and pass them along in all your call to the different services you use. In this article, I´m going to explain you a way to do this in ASP.NET Core. Correlation IDs Why do you need more than one correlation ID? https://vgaltes.com/post/serverless-patterns-implemented-sls-dlq/ Tue, 26 Nov 2019 00:00:00 +0000 https://vgaltes.com/post/serverless-patterns-implemented-sls-dlq/ In the last two articles (here and here) we implemented some of the Serverless Patterns described in this article from Jeremy Daly. In this article, we’re going to concentrate in just one pattern, the Notifier. We’re going to do this, because of the [recent announcement] from AWS that you can now use an SQS queue as a Dead Letter Queue for an SNS topic. If you read the article, you will see that this DLQ is complementary to the DLQ you might define in a function that is triggered by an SNS topic, as Otavio Ferreira explains here. https://vgaltes.com/post/serverless-patterns-implemented-part2/ Thu, 14 Nov 2019 00:00:00 +0000 https://vgaltes.com/post/serverless-patterns-implemented-part2/ In this article I will continue with the implementation of some Serverless Patterns described in this article from Jeremy Daly about [Serverless Patterns]. Check the first post here Let’s start! Common setup All the projects will have a common setup, which is fairly simple. First, initialize a NodeJS project: 1 yarn init Then install the serverless framework as a dev dependency 1 yarn add serverless --dev And finally create a script to deploy the project https://vgaltes.com/post/serverless-patterns-implemented-part1/ Wed, 13 Nov 2019 00:00:00 +0000 https://vgaltes.com/post/serverless-patterns-implemented-part1/ I think that the best way to learn something is to practice it and to try to explain it, so this is what I’m going to do in the next series of posts. These posts will be based on the amazing article from Jeremy Daly about Serverless Patterns. I’m not going to copy Jeremy’s words here, so for each pattern, go to the article and read it. I’ll provide a technical implementation here and I will mention more resources I found interesting. https://vgaltes.com/post/multi-region-backend/ Fri, 08 Nov 2019 00:00:00 +0000 https://vgaltes.com/post/multi-region-backend/ Congratulations! Your startup is starting to bring attention to many people and you’re starting to have clients from different countries and continents. But your lambdas and API gateway are still in your initial region, and that might add some latency to some users. Apart from that, you want to increase the reliability of your system. So, you decide to go multi-region. Can you do that easily? In this article, we’ll see how to do that. https://vgaltes.com/post/api-gateway-custom-domain/ Wed, 06 Nov 2019 00:00:00 +0000 https://vgaltes.com/post/api-gateway-custom-domain/ If you’re doing something more than a few tests with Lambda and API Gateway, there will be a time where you will like to stop using the AWS-created endpoints for your APIs and start using your own domain. You know, instead of telling your clients, “please, go to https://lk7z14x78h.execute-api.eu-west-1.amazonaws.com/dev/helloWorld", you will like to point them to something like “api.authenticatedservices.net/helloWorld”. In this article, we’ll see how to do that. Disclaimer This article is a summary of two articles (this one and this one) from Alex DeBrie (who you should follow if you’re interested in serverless). https://vgaltes.com/post/cognito-user-pools-google/ Thu, 31 Oct 2019 00:00:00 +0000 https://vgaltes.com/post/cognito-user-pools-google/ In the previous article, we saw how to secure an API Gateway endpoint using Cognito user pools. We used the built-in capabilities of the user pools to create the users, sign them up, etc. But many applications nowadays don’t create users on their own; they use [social login] and rely on third-party social services such as Facebook or Google to manage users for them. In this article, we’ll see how we can adapt our previous code to allow users to sign-up and sign-in to our service using their Google account. https://vgaltes.com/post/api-gw-basic-auth/ Fri, 18 Oct 2019 00:00:00 +0000 https://vgaltes.com/post/api-gw-basic-auth/ In many occasions, you don’t want your whole API open to the public. Maybe you want to make some endpoints available to authenticated users. In this article we’re going to see how to do that using Amazon Cognito User Pools and AWS Amplify. Let’s start! Amazon Cognito User Pools As the documentation says, a user pool is a user directory in Amazon Cognito. You can allow your users to sign-up, sign-in, etc. https://vgaltes.com/post/random-stuff-june/ Thu, 13 Jun 2019 00:00:00 +0000 https://vgaltes.com/post/random-stuff-june/ My good friend Edu Ferro has a very nice blog called eferro’s random stuff in which he posts the most interesting blogs, talks and podcasts he’s read, viewed and heard lately. I like the idea and, now that I have a bit more free time, I’ll try to do the same, at least once every month. I’m not going to post here podcasts and talks, basically because all the ones I listen I get them from Edu’s blog, so I’m just going to concentrate in blogs. https://vgaltes.com/post/mentoring/ Fri, 31 May 2019 00:00:00 +0000 https://vgaltes.com/post/mentoring/ Last September I turned 40. You know, in the movies, when someone turns forty he buys a new brand card, gets divorced and tries something new. I still don’t have a car and, although I’m not married, I still live with my partner, but I did start something new. In my case, was an old “aspiration” (I tried it 7 years ago): learning to play guitar. Not that I want to be the next Angus Young but I never had any musical education and I always wanted to be able to play an instrument, especially guitar.