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    Ongoing observations by End Point Dev people

    Writing integration tests for an ASP.NET Web API

    Kevin Campusano

    By Kevin Campusano
    May 13, 2024

    A concrete wall is patchily covered in shadows from a tree or something similar. Standing out against the sporadic texture of the shadows is the shadow of an arm and hand pointing up and to the right in a thumbs-up.

    Integration tests exercise a system by instantiating major components and making them interact with each other. They are great for validating important use case scenarios in an end-to-end or close to end-to-end manner.

    Full integration tests seldom use mocks or fake objects. Usually, the full stack is tested as if the entire system were running for real. For REST APIs, that generally means tests that involve issuing HTTP requests, validating HTTP responses, and asserting on changes made to a persistent data store, like a database.

    In this article, we’re going to discuss how to write such tests for a Web API built using ASP.NET.

    Introducing the project

    I’ll use an existing ASP.NET Web API project to demonstrate how to write these tests. The API is part of a system that calculates the value of used cars and offers quotes for them. As such, the API has an endpoint for calculating a vehicle quote, given its information and condition: POST /api/Quotes. It also has an endpoint for administration purposes that returns all the quotes that have been stored in the system’s database: GET /api/Quotes. These are the two endpoints that we’ll want to test.

    The source …

    testing dotnet aspdotnet csharp rest api

    An OpenStreetMap Editor for Adding Public Transit Data Using GTFS

    Dmitry Kiselev

    By Dmitry Kiselev
    May 8, 2024

    The OpenStreetMap GTFS editor. The right side is a map with a darkened map, and blue, red, and black dots overlayed along the roads where public transit stops are. In the corner, the map reads “Leaflet | copyright OpenStreetMap”. It has controls to zoom, change between satellite and OpenStreetMap, darken the map, and open in JOSM. The left side has navigation buttons reading “Import” (which is selected), “Stops”, “Routes”, “Trips”, and “Changes”. Below there is text on several lines: “gtfs.zip. Loaded 5246 stops” then a button reading “Query OSM data”. Then, “OSM Tag with GTFS stop code:

    You can think of OpenStreetMap (OSM) as Wikipedia for maps. While it may not be as well known as Google Maps or Apple Maps, OSM becomes indispensable when you need data, rather than just a visual representation on your phone. The only other real option for data retrieval is to consult a local agency, so if you’re in search of a comprehensive and global cartographic dataset, OSM is the go-to choice.

    OSM also excels in providing navigation for pedestrians and cyclists. For the past decade, I’ve navigated the US, Canada, and Europe using OSM through the OsmAnd app, a dedicated Android application for OpenStreetMap.

    Overall, my experience has been quite positive, except for one significant weakness: public transportation. Specifically, I’ve been missing the convenient access to timetables for buses, trams, or any other form of public transit.

    A significant part of the challenge in making public transportation data readily available on OSM and its associated applications is the fact that the OSM data model isn’t particularly well suited for this type of information. While OSM can store the location of bus and train stops, the actual timetables change so often that …

    gis visionport open-source

    Using Razor templates to render HTML emails in .NET

    Kevin Campusano

    By Kevin Campusano
    April 30, 2024

    Several power lines of varying sizes appear as black lines covering the center third of the image, rising from the bottom left to the top right across a pure blue sky. In the bottom left, on one line sits a bird, far enough away that it is a small blob. In the top right, centered between two of the lines, is the bright gibbous moon.

    When it comes to sending emails, Ruby on Rails has an excellent solution in the form of Action Mailer.

    The basic idea is that you can define email templates using ERB files. This is the same templating engine/​language used for normal web application views. Then, application-level SMTP settings are configured for email delivery. Finally, a “Mailer” class can be developed that leverages the templates and the underlying email sending mechanism to send emails.

    In Rails, all this comes right out the box. Setup is minimal, so this approach is a huge time saver for a task that’s very common in web applications.

    In ASP.NET Core (or .NET in general), we don’t have such a convenient, built-in solution. However, it is possible to implement our own using the framework’s features.

    In this article, I’m going to explain step by step what I did in a recent .NET project to develop functionality similar to what Action Mailer provides.

    Throughout this article, I will be using a demo Web API application for code examples. If you’d like to see what the final implementation looks like, you can find all the code on GitHub. The API is about calculating quotes …

    email dotnet csharp

    Passing Data Between Components in Vue.js: An Overview

    Tuğrul Gökbel

    By Tuğrul Gökbel
    April 3, 2024

    A still life painting. One the left side of the image, a parrot stays perched on a table; to the right the table is covered in artichokes, cherries, and light blue, red, and white flowers. The scene is lit from the top left with a gentle diagonal of light, contrasted with deep shadow.
    Artwork: Still Life with Artichokes and a Parrot, 17th century, Italian. CC0.

    Vue.js, with its simplicity and flexibility, is one of the most popular JavaScript frameworks on the web. One of the key aspects of building dynamic and interactive web applications with Vue is efficiently passing data between components. In this blog post, we will explore methods and good practices for data communication between Vue components.



    Directional data flow: Props are primarily used for establishing a unidirectional flow of data from parent components to child components — they allow parents to pass data down to their children.


    Simplicity: Props provide a simple and straightforward mechanism for passing data.


    One-Way Binding: It’s a one-way data binding mechanism, meaning that data flows from parent to child only, not from child to parent.

    // ParentComponent.vue
      <ChildComponent :data-prop="parentData" />
    export default {
      data() {
        return {
          parentData: "Hello from parent!",
    // ChildComponent.vue
      <div>{{ dataProp }}</div> …

    vue javascript programming

    Making a Loading Spinner with tkinter

    Matt Vollrath

    By Matt Vollrath
    March 5, 2024

    An overhead shot of a carpeted spiral staircase, with spiraling railings on either side. The staircase is cut off at the bottom by a wall, so that only half of the circle of stairs is visible. The stairs are enclosed by a semicircular wall, and lit by sunlight streaming through a window on the left. On the right is a window whose view is filled with green leaves.

    When you need a loading spinner, you really need a loading spinner. Interested in putting something on the screen without installing a pile of dependencies, I reached deep into the toolbox of the Python standard library, dug around a bit, and pulled out the tkinter module.

    The tkinter module is an interface to the venerable Tcl/Tk GUI toolkit, a cross-platform suite for creating user interfaces in the style of whatever operating system you run it on. It’s the only built-in GUI toolkit in Python, but there are many worthy alternatives available (see the end of the post for a list).

    Here I’ll demonstrate how to make a loading spinnner with tkinter on Ubuntu 22.04. It should work on any platform that runs Python, with some variations when setting up the system for it.


    My vision for the loading spinner is some spinning dots and a logo, since this is such a convenient branding opportunity. To accomplish this we’ll be extending tkinter with Pillow’s ImageTk capability, which can load a PNG with transparency.

    To produce that PNG with transparency, first we may need to rasterize an SVG file, because wise designers work in vectors. This is made …

    linux graphics python ubuntu user-interface visionport

    Key Takeaways from Practical Object-Oriented Design by Sandi Metz

    Kevin Campusano

    By Kevin Campusano
    February 27, 2024

    View upward at a bright sky, with lines drawn down at an angle toward the left center by a tree trimmed into a rectangular prism and one trimmed into a vague cone. The lens is imperfect, leaving the corner of the square tree in focus while the rest of the green foliage and blue and bright white sky is somewhat distorted by the lens.

    Practical Object-Oriented Design: An Agile Primer Using Ruby by Sandi Metz is one of those books that everybody who writes or aspires to write object-oriented code should read. Indeed, reading through this book will be valuable for seasoned practitioners and inexperienced novices alike. Whether it be to discover new concepts, remember why they are important, or articulate the reasons behind that warm fuzzy feeling you get in your stomach when you read well designed code, POODR can help.

    I personally really like this book, and here at End Point it does have quite a following as well; it was the subject of a study group that we ran back in 2016. I like to dust it off every now and then to give it a re-read. To help with that, I’ve come up with a list of key takeaways from the book, with some of my own interpretations sprinkled in. For me, it serves as a sort of summary to help commit the book’s contents to memory. I thought I’d share it with you today.

    While this book uses the Ruby language for its examples and discussions, the concepts it describes are equally applicable to any classical object-oriented language. Dynamically typed language users do get a little …

    design ruby csharp books programming

    Setting User-Specific Resource Limits with systemd

    Seth Jensen

    By Seth Jensen
    February 3, 2024

    In the center of a dim street lined with houses and cars, the sun illuminates and sillhouettes green foliage. It projects a triangle of light on the ground, first the street and then the grass, centered in the frame. On either side of the light, centered verticaly, a white car catches the light.

    We recently encountered an issue on one of our servers where some processes were hogging CPU time and slowing down the entire machine to unusable speeds. It turned out that a couple of our developers were using the VS Code extension “Remote - SSH,” which gets SSH credentials to a server from you, logs in by SSH, figures out what kind of server it’s running on, and runs some server-side components that it talks to.

    This is fine in principle, but with larger projects it frequently spins out of control and eats up all available CPU and RAM on the server. The developer using VS Code on their desktop likely won’t even notice, leaving a system administrator to kill the VS Code processes after it causes issues for other users.

    Our answer to this problem was setting resource limits. In many cases, you could use ulimit to control a user’s resource limits. But ulimit only controls resources for the shell it’s running in, and since VS Code was connecting through SSH and spawning a bunch of processes, we didn’t have a reasonable way to do this.

    Instead of using ulimit, you can use control groups (cgroups) to set overall user limits, not just limits …

    linux sysadmin systemd vscode

    Building a real-time application with SignalR, .NET, and three.js

    Bimal Gharti Magar

    By Bimal Gharti Magar
    January 13, 2024

    A white watchface, without any other parts, sits on a surface with a dotted texture
    Image by Pixabay on Pexels

    When data in a web application is changing in real time, users want to see those updates reflected in real time without refreshing the application. Adding real-time functionality to a .NET application is easy with the SignalR library.

    Depending on the capabilities of the client and server, SignalR can use WebSockets, server-sent events, or long polling to establish a persistent connection between the client and the server. From the server side, SignalR pushes code to connected clients. SignalR is good for applications that require high-frequency updates from the server, such as real-time gaming.

    C# code can be used to write SignalR hubs, which easily integrate with other ASP.NET features like dependency injection, authentication, authorization, and scalability.

    What we’ll build

    We will learn how to use SignalR for real-time communication to send the camera position of a cube, built using three.js, to all users on the page.

    Two browser windows are open side by side, to the same web app. On both, under a “Receiver” title is a window showing a 3D cube, after which a “Controller” title is followed by a “Request Control” button. In the left browser window, the mouse clicks the blue “Request Control” button, which turns green and displays a message underneath saying “Control granted: 120 seconds remaining”, with the number counting down every second. Another identical 3D cube window opens beneath. The clicks and drags in this bottom window, which rotates the cube. After a short delay, the other two cubes in the “Receiver” section follow and move to the position where the controller moved the cube.

    You can see the demo here.

    Here is the description of our testing app:

    • A user can request control of a cube for 2 minutes
    • Control can be released manually, or it will be automatically released after 2 minutes
    • A user can control …

    dotnet javascript
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