Paneque's Technology Blog

A cache is a component where data is stored so that future requests can be served faster. So for example, in the context of a web application responding to multiple requests,  instead of hitting your backend database or microservice every time, the application can remember the last value for a given computation or call. One particular flavor is a centralized cache system, provided by tools like Redis, Memcached, etc. A central place where we store data temporarily and all instances of our app (and even other apps) can use it. There are many uses, from storing session data in a multi-server web application to providing a performance advantage by keeping a value that is costly to calculate or obtain.  A centralized cache is a lifesaver. But it tends to be overused and there are some scenarios where we could reduce its usage or completely skip it, and in doing so, save costs and improve performance.  Reducing the usage of the centralized cache. Let's have an example of a web...

We are going to create a plain HTML+JS static web app with an Azure Function as backend API, and by "plain" I mean no framework like React, Angular, or Vue, but will use Bootstrap and JQuery. It will be a simple app with  2 input fields and 1 button. You will enter your name and last name and the app will say "hello" to Thanos and let you know if Thanos snapped you or not (Because you should not talk to the mad titan without permission). We are going to use ReCaptcha V3 to prevent abuse and a bootstrap form with client-side validation before sending the data back to the azure function. #1 Create the app from Visual Studio Code Let's create a "custom" framework static web app following these instructions , then add a /src folder and place a basic index.html file there with the text "hello world". Just make sure you use /src as "source path" and leave "build path" empty. You can confirm paths are correct by opening the GitHu...

Every time we talk about SCRUM, the length of the sprint is stated as a period of "two to four weeks", rarely, however, have I seen people going outside of the 2 weeks. This is not written on stone of course, and while 3 weeks might seems odd, there is a benefit to using a longer period for your sprints.  Image is taken from scrum.org Without any hard data to back that decision, the answer I get from asking about this decision seems to be related to "delivery speed", we assume that because we deliver value to the business every 2 weeks, we are in a more "agile" environment. Well, that might not be so true in every sense or for every project. Let's break some arguments: 1. Sprint length is not equal to the speed of delivery There is more to the speed of development and delivery than the timeframe of the delivery cycle, in a world with DevOps and full CI/CD implemented for your project, you could (should?) actually deliver features every single day all t...

Emergent architecture is a term I heard for the first time from a coworker a while ago. It was touted as a combination of agile and architecture, or perhaps as the way the shiny term "architecture" was inserted into something as face paced as Scrum, or as a way for the company justify not having architects, but to put it plainly, it's not a thing. There are a few things wrong with it... conceptually.  I have read a lot about it, looking for any source of information I could, presentations, blogs, some links here and there, and I could not find a solid base for what they claimed it was, or any reason for it to be claimed as a thing, except for the need to name something with "architecture" on it. Agile is a methodology, Scrum is a method, if you want to know a bit more about the difference just hit Wikipedia . They are related to  how to build software.  Now, architecture, is about structure, is about what you build. You can reach that structure with any me...

We need to talk about it How open is .NET Core and C#? How does it compare to a platform like Java? Well... let's see. Disclaimer: The post is a resumed version with lots of links, so be prepared to read it in a DFS or BFS way :)  .NET Core In November 2014, The Microsoft team announced that " NET Core is Open Source " Included C# and Visual Basic compilers Visual F#   ASP.NET Core Entity Framework Core NET Core Framework   In 2015, Microsoft releases Visual Studio Code , a cross-platform multi-language IDE.  All these released under an Open Source license. The MIT License . NET Core runs in Windows, Linux, Mac and ARM-based systems (IoT) Docker support existing Java Originally made open source by Sun in 2006 Released under GPLv2 CE license . The CE clause allows it to be used in a more restrictive scenario.  Oracle has a different licensing schema for "Enterprise Java". While the OpenJDK is still safe (and should remain so) Ente...

The words distributed and monolith are usually adversaries in software architecture, contrary to the monolith model,  a distributed approach will allow you to have isolated services as building blocks of functionality for your system. Let's assume you reached that architecture already, either from scratch or by decomposing an existing monolith. At this point you have a set of services.  Some people go and just say - "it's microservices!". Well..., that's not enough yet, but now you have all the pieces into individual services and the whole system working together.  This is a step into the right direction for scalability, but we can do more in other areas.  So, let's check: how do you deploy them ? If you deploy all services at once , you still have a lot to improve, for now you have a "distributed monolith" (Open to a better name for this), which I consider to be an antipattern, and this is more of a common practice than expected,...

A few weeks ago, I was solving a problem at HackerRank and after completing a solution that ran  under 100 milliseconds, the program would still timeout during execution. HackerRank limit is usually 1 second, so something was taking more than 900ms. It was the strings! Yes, we know handling strings is costly, but this time there was no way around it.  At the final stage of the problem I had to construct a string over 200k chars long from an array of Boolean values that represented the bits of the number.   Disclaimer : Strings are slow, mainly because they are immutable. Concatenating two strings, creates a third one and possibly 2 for the garbage collector to pickup. Looking through the code I noticed I was simply using " += " instead of StringBuilder.Append method. After using StringBuilder the solution was faster and the submission was approved. It was  fast now, but it got me thinking "how much faster indeed?" which ended with me measuring t...

After a relatively long hiatus as a writer I finally completed a new milestone. I coauthored a programming book and published it on Amazon. I must say I am glad that we finally completed it; while it was a fun and rewarding journey, it was a long one and it took a lot of time, effort and coordination.  The book is in Spanish, and it's 500+ pages long. Title: "Empiece a Programar. Un enfoque multiparadigma con C#" Format: Paperback The title translates to "Begin programming. A multi-paradigm approach with C#". The book is written in Spanish, not only because all the authors are Cubans, but also because we believe that the Spanish-speaking community deserves a fresh new book; instead of a translated one. We used C# throughout the book in order to teach programming, and we travel from the simple "Hello World" snippet to arrays, data structures, dynamic programming, recursion, inheritance, SOLID principles, functional programming and conc...

Quite too often we see discussion about what is and what is not REST, some developers excitedly discuss about REST purity. However, does it actually matter? Do you need that level of "purity"? I personally think that it does not and will try to explain why, although I am already convinced that will fail on my attempt. REST means REpresentational State Transfer, and while almost everybody will tell you that is not necessarily  related to HTTP (and technically isn't), in reality, it is, and that's a fact. So when we apply it to our Web Services, we have our new REST APIs or RESTful APIs mixed with HTTP flavors. Also consider that they do not conform a protocol, or a specification, is an architectural style. So, technically, they are a set of conventions and guidelines and not an actual set of unbreakable rules (like a protocol).   But they are great, RESTful, REST-like, almost RESTful APIs are all great. I have been writing and playing with APIs since aroun...

Unable to start the process. Failed to initialize CoreCLR, HRESULT: 0x80131500 I just installed ASP.NET Core RC2 and was able to get it working from the command line, on some new basic tests projects. But when I tried to do it from Visual Studio I got the following error.  If I tried to run "dotnet" in a console opened from Visual Studio, I would get the same error. So the issue was that something was off for the VS configuration/environment.  After verifying that "dotnet" was able to run perfectly everywhere else I took into the task of comparing the environment variables (dichotomically, of course). One particular variable made the difference: "JUSTMOCK_INSTANCE=XXXXX", so that lead me to notice that JustMock was interfering with it somehow.  So, if you use JustMock just turn it off for RC2 projects. (No need to uninstall it, just disable the profiler)

Working on a ReactJS project, got a small glitch while trying to read a JSON file and parse it as a javascript object. getDataObject() { var dataString = fs.readFileSync("./json/data.json", "utf8"); return JSON.parse(dataString); } output:   SyntaxError: Unexpected token   After checking, double and triple checking again that the file was correct I went deeper and realized that "fs.readFileSync" was returning me the BOM for the UTF file at the beginning of the string. So we just need to strip it out. getDataObject() { var dataString = fs.readFileSync("./json/data.json", "utf8"); return JSON.parse(dataString.replace(/^\uFEFF/, "")); } I then checked and there are "packages" for this, however I don't think is proper to just import a new dependency just to fix something this small. The big issue here is why is this considered correct. The BOM is not ...

Red blinking light? Check the power supply cord. I just got my Microsoft Display Dock courtesy of MS after pre-ordering a Lumia 950XL. But after the first attempt I just got a red blinking light on the front and nothing more. The phone won't recognize it and the display connected would just go to sleep. After playing with it a bit I realized the USB-C connector on the dock's power supply (identical to the "fast charger")  was a bit loose. I then compared to the one that came with the 950XL and voilà!  See the difference below. Left: Adapter from the 950xl box | Right: Adapter from the Display Dock Since it is shorter (manufacturer error? bad batch? who knows...)  the adapter packaged with the Display Dock won't reach the connector properly. However, it will fit in and charge the 950XL perfectly. I think one of the reasons is the thick casing in the Microsoft Display Dock. Check it out. The case is sturdy and thick. So if you happen to have a Micros...

The last Microsoft event on October 6 showed a few surprises, let me explain you why this is impressive and why I think the new Nadella direction at MS is different. Iris Scanner, Liquid Cooling, Continuum... A new Surface 4 tablet with Liquid Cooling The new Surface 4 was a really good upgrade, and a real big one. More resolution in the same size, up to 16GB of RAM and 1TB of HDD and Liquid Cooling . All that packaged in a device as think as this, only 8.5mm of depth. Check how the cooling works. New phones with Continuum and Liquid Cooling I know Windows only have 3% of the market on phones, and that's a bummer because we don't get to have all the apps. But now the new phones have continuum, a feature that allows using a phone as a full size computer. They also manage to get liquid cooling into a handheld device. That's a good direction. Let's just hope this new direction combined with universal apps will get more developers into the boat. A new Sur...

While using Visual Studio 2015 to edit and android layout file ( axml ) I got this error:   The installed Android SDK is too old. Version 24.3.4 or newer is required The number version might be different in your case. Here are a few possible causes for the error: 1) You actually need to upgrade your Android SDK. 2) You have the wrong path for the Android SDK installation on Visual Studio. (change it on Tools->Options->Xamarin) 3) Mixed Xamarin extensions (this was my case) After reinstalling the Android SDK and checking the everything was fine on that part I went to check on Visual Studio extensions ( Tools -> Extensions and Updates ). It turns out that  I caused a mix up of versions, since I already had Xamarin and Visual Studio 2013 side by side. and now 2015 had another one, my Visual Studio 2015 ended up with 2 extensions for Xamarin. Disabling one of them solved the problem and the designer was working again. The one that I disabled was titled "...

It is a big deal, and by no means I would defend them; I don't think anyone can. They did a cheap and horrible thing by installing a piece of adware junk, that not only was used to monetize on the buyers, it is also a major security breach. Many people are still upset at lenovo and blaming everything on the "chinese government" and talking about all sorts of conspiracies. But I don't want to talk about who did it or why, as I was reading about all this, I just could not stop wondering:   are they the only ones ? Of course not. The Gemalto hack But did you know about the Gemalto  SIM card hack ? A massive sim card hack that allegedly allows US and UK spies access to billions of phones. The Gemalto hack quoted here from PC World: " Gemalto, based in the Netherlands, produces about 2 billion SIM cards a year. About 450 mobile carriers, including AT&T, T-Mobile, Verizon Wireless and Sprint, use the company’s SIM cards. With the compromised encrypti...

Recommending a new device to somebody else requires a lot of analysis, first of all, they will think you are trying to push your own preferences. And that could be true, at least up to a certain point. For me, however, recommending a device becomes a more complex thing. As a developer I work with and own a lot of them: iPhone, iPad, Android phones and tablets, Windows tablets, both "RT" and regular x86. And while my own device is a Windows Phone (Lumia 925) the right device for you depends on a lot of factors. First, the Phones Let's compare the three platforms, but only phones for now, we'll be talking about tablets later. So we have iOS (iPhone), Android and Windows Phone. At some point the discussion must be about a specific brand, but at the end we will have to sort results by platform. Apps Most likely the app you need is available for both iOS and Android. There is a huge app gap, as well as a huge number of low quality apps in some stores, so my ...

Since we got the magic of async/await on C# things got much easier on the developer front. Working with Tasks is the key to it, but we also have two older approaches in .NET framework that we need to deal with.  APM (Asynchronous Programming Model) The pair of Being / End methods.  EAP (Event-based Asynchronous Programming) The Method Async / Method Completed pair. Converting from APM to Tasks is achieved by means of the   System.Threading.Tasks.TaskFactory   class and its generic counterpart. Now converting from EAP to Tasks  requires us to use the TaskCompletionSource<T> class and notify of the state of the task as it goes. See the example of a "handshake" operation in a WCF service. I am also using the approach from my older post regarding events and anonymous methods. The return type of the WCF operation is WrappedResultOfString , and that will be the actual generic parameter of the Task<T> that the HandshakeAsync method will produ...

Did you ever have a problem with a WCF client throwing exceptions you can't catch? If you have used WCF clients from Windows Phone, Silverlight or Xamarin.iOS, you might have noticed that it is not possible to create Synchronous or Task-Based operations; the functionality is reduced to the Event-based Asynchronous Pattern (EAP). That means that the way to call a WCF method and get the response is usually as follows: var client = new MyWCFClient(); client.DownloadDataCompleted += (sender, e) => { try { //accessing e.Result here might raise an exception in another //thread, that will not be captured by the 'catch' below. } catch(Exception ex) { } }; client.DownloadDataAsync(url); Our results are wrapped in an auto-generated class that inherits from  AsyncCompletedEventArgs , this class has a property  Error  of type  Exception , that will carry information about the error and a property  Result  with our expected return valu...

Batch as usual Recently I was in the need of modifying a huge amount of files across a network share. After installing Serviio media streaming service I noticed that it will crash "randomly". After checking the logs it was clear that ffmpeg was crashing when trying to open subtitle files that were not in the encoding indicated by the Serviio console. I needed a quick way to update all subtitle files to a common encoding, so I decided to convert all files to UTF8. Since I use a windows environment I went directly to PowerShell and wrote this.  Get-ChildItem -path .\ -filter *.srt -file  | ForEach-Object { (get-content $_.FullName) | Out-File $_.FullName -encoding utf8 } This worked almost right except for files with "[" or "]" (among other symbols) on the name or path. To solve it, just added the "-LiteralPath" switch to tell powershell not to consider any wildcards on the path name and just use it exactly as it is.  Get-ChildIt...