Dropwizard Deep Dive – Part 3: Multitenancy

Hello once again! This is Part 3 of a three-part series on extending Dropwizard to have custom authentication, authorization, and multitenancy. In Part 1, we set up custom authentication in Dropwizard, and in Part 2, we extended that to have role-based authorization. For this final part, we are going to diverge slightly and tackle the related but different concept of multitenancy.
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Dropwizard Deep Dive – Part 2: Authorization

Welcome back! This is Part 2 of a three-part series on extending Dropwizard to have custom authentication, authorization, and multitenancy. In Part 1, we set up custom authentication. When we left off, we had just used the Java annotations @RolesAllowed and @PermitAll to authenticate our resource methods, so they will only run for credentialed users. In this part, we’ll cover Dropwizard authorization. We are going to extend the code we added to check the role assigned to a user and further restrict our methods based on whether that matches.
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How to Write a Custom Serializer with Jackson

Jackson is a great framework for translating Java to JSON. It comes packaged with a number of features that make it easy to turn a Plain Old Java Object (POJO) into JSON with little effort. However, sometimes more complex translation is necessary and the out-of-the-box features don’t cut it. Fortunately, Jackson provides a way to write custom code and control how any object is translated to JSON.
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Unsubscribing from an RxJava Observable Mid-Stream

Imagine a scenario where you need to create an Observable sequence that will acquire a resource, do some processing, and release the resource when unsubscribed from. An example of something like this might be an Observable that acquires a lock and releases it when unsubscribed from. That “lock” signal could be merged with a second signal that does some work that should only be done after the lock has been acquired.

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Taking Control of Logging in Clojure

Clojure inherits some interesting tradeoffs as a result of being built atop the Java Virtual Machine. One upside is the availability of many full-featured and mature Java libraries. But one downside is the need to survey the historical as well as technical landscape of your available choices.

Unsurprisingly, when it came time to add proper logging to my project, I had to make sense of the several available Java logging libraries. Here’s what I found. Read more on Taking Control of Logging in Clojure…

Hooking up Custom Jersey Servlets in Dropwizard

I’ve been using the Dropwizard Java framework for about a year. It’s a great web application stack for making RESTful service with Java.

I recently ran into a situation where I wanted to add custom servlets to a Dropwizard application. Read more on Hooking up Custom Jersey Servlets in Dropwizard…

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Serving Static Assets with DropWizard

Over the last few months, I’ve had the opportunity to do a lot of work with DropWizard, an awesome Java web framework for developing RESTful web services.

I was recently prototyping a small application, and I wanted to serve static files directly from DropWizard. While this isn’t what DropWizard is primarily designed to do, I didn’t want to go through the process of setting up another web server just to serve static assets for a prototype. While DropWizard has some out-of-the-box support for serving static assets, I found the documentation surrounding it to be incomplete and confusing. It actually took me a couple hours of debugging to figure out how to do exactly what I wanted, So I thought I would document what I learned here.

My end goal was to serve a small single page JavaScript app on the root of my DropWizard application, while having my DropWizard REST endpoints available at /api. The limited documentation around serving assets in DropWizard suggest that setting up an AssetsBundle for / and changing the application context path in your config file should be enough to achieve this, but that did not work for me. I had to do the following steps: Read more on Serving Static Assets with DropWizard…

Simple Flow Control Made Easy

We are currently working on a product that utilizes a long-range and low-bandwidth network. Moreover, the devices that are being communicated with are severely limited with regard to memory availability and CPU cycles. Given these constraints, it’s important that the network and devices are not overwhelmed with traffic.

Recently, we encountered an acute problem where the network and devices could easily be overwhelmed if they are powered on and join the network at approximately the same time.

Problem

When the devices join they communicate with a server, informing it that it has just joined and that it needs to be configured (name, time, etc.). It will continue to send these configuration requests at a steady rate until it receives all of the necessary configuration information. The problem is that the server would gladly respond to every request, even if the information it is sending is duplicated.

We had to make sure that duplicate messages were dropped within a certain time period. Read more on Simple Flow Control Made Easy…