Dave Syer

Dave Syer

Senior Consulting Engineer | London

Founder of Spring Cloud, Spring Boot, Spring Batch, lead of Spring Security OAuth, and an active contributor to Spring Integration, Spring Framework, Spring AMQP, Spring Security. Experienced, delivery-focused architect and development manager. Has designed and built successful enterprise software solutions using Spring, and implemented them in major institutions worldwide.
Blog posts by Dave Syer

Client Side Development with Spring Boot Applications

Engineering | December 17, 2021 | ...

This article explores the different options that Spring Boot developers have for using Javascript and CSS on the client (browser) side of their application. Part of the plan is to explore some Javascript libraries that play well in the traditional server-side-rendered world of Spring web applications. Those libraries tend to have a light touch for the application developer, in the sense that they allow you to completely avoid Javascript, but still have nice a progressive "modern" UI. We also look at some more "pure" Javascript tools and frameworks. It’s kind of a spectrum, so as a TL;DR here…

Client Side Development with Spring Boot Applications - Part 2

Engineering | December 17, 2021 | ...

Part 1

Plain Javascript with SSE Stream

Vue isn’t really adding a lot of value in this simple HTML replacement use case, and it would add no value at all to the SSE example, so we will go ahead and implement that in vanilla Javascript. Here’s a stream tab:

<div class="tab-pane fade" id="stream" role="tabpanel">
	<div class="container">
		<div id="load"></div>
	</div>
</div>

and some Javascript to populate it:

<script type="module">
	var events = new EventSource("/stream");
	events.onmessage = e => {
		document.getElementById("load").innerHTML = e.data;
	}
</script>

Dynamic Content with React

"Wiremock" for RSocket

Engineering | June 02, 2021 | ...

If you have an application that connects to an RSocket server at runtime, how do you test it? We need a way for a test to start a server and tell us where it is listening, and then we need to be able to register request and response examples (a.k.a. "contracts"). That’s what this project provides - it’s like Wiremock but for RSocket.

Getting Started

The easiest way to use the project is as a JUnit (Jupiter) extension, e.g:

@SpringBootTest
@ExtendWith(RSocketServerExtension.class)
class SocketsApplicationTests {
	...
}

With this extension installed the Spring Boot tests will run with an RSocket server listening on a port given by test.rsocket.server.port, so the test can connect directly to it, or (more likely) the code that it is testing will connect to it. You might need to tell it where to connect via the @SpringBootTest annotation, e.g. if the application is looking for a property at runtime called rsocket.port

Spring Cloud Function Native Images

Engineering | May 04, 2020 | ...

Here's the latest graph of memory versus billing for Spring Cloud Function on AWS Lambda. It shows the billing metric GBsec as a function of memory allocation in Lambda for two custom runtimes, one in plain Java and one using a GraalVM native image, as described recently in this blog by Andy Clement:

aws-billing-3.x

In both cases the functionality is identical (a simple POJO-POJO function), and they both show only the results for cold start. Warm starts, where the function was already active when the request came in, were much faster and cheaper (except for the smallest memory setting they all cost the same…

Manual Bean Definitions in Spring Boot

Engineering | January 21, 2019 | ...

Suppose you want to use Spring Boot, but you don’t want to @EnableAutoConfiguration. What should you do exactly? In an earlier article I showed that Spring is intrinsically fast and lightweight, but one of the short pieces of advice improve startup time was to consider manually importing the Spring Boot autoconfigurations, instead of sucking them all in automatically. It won’t be the right thing to do for all applications, but it might help, and it certainly won’t hurt to understand what the options are. In this piece we explore various ways of doing manual configuration and assess their…

How Fast is Spring?

Engineering | December 12, 2018 | ...

Performance has always been one of the top priorities of the Spring Engineering team, and we are continually monitoring and responding to changes and to feedback. Some fairly intense and precise work has been done recently (in the last 2-3 years) and this article is here to help you to find the results of that work and to learn how to measure and improve performance in your own applications. The headline is that Spring Boot 2.1 and Spring 5.1 have some quite nice optimizations for startup time and heap usage. Here’s a graph made by measuring startup time for heap constrained apps:

heap-size-2.1.x

As you…

Spring Boot in a Container

Engineering | November 08, 2018 | ...

Many people are using containers to wrap their Spring Boot applications, and building containers is not a simple thing to do. This is an article for developers of Spring Boot applications, and containers are not always a good abstraction for developers - they force you to learn about and think about very low level concerns - but you will on occasion be called on to create or use a container, so it pays to understand the building blocks. Here we aim to show you some of the choices you can make if you are faced with the prospect of needing to create your own container.

We will assume that you know how to create and build a basic Spring Boot application. If you don’t, go to one of the Getting Started Guides, for example the one on building a REST Service. Copy the code from there and practise with some of the ideas below. There is also a Getting Started Guide on Docker

Functional Bean Registrations in Spring Cloud Function

Engineering | October 22, 2018 | ...

Spring Cloud Function has a couple of new features in 2.0 (still in milestone phase), and possibly the most dramatic is the ability to go "fully functional". This is made possible by changes in Spring Boot 2.1 together with Spring Framework 5.1, and it means a different way of thinking about bean definitions in Spring applications, but also significant improvements in startup performance.

AWS Cost Savings

It’s always good to start with a picture, especially if it tells a story. Here’s a graph that shows the improvement in Spring Cloud Function 2.0 over 1.0, comparing the cost of cold starts in…

Spring Cloud Function 2.0 and Azure Functions

Engineering | September 25, 2018 | ...

Spring Cloud Function has had support for Microsoft Azure Functions since version 1.0, but in the latest 2.0 releases (still in milestone phase) we decided to change the programming model a bit. This article describes what the changes mean for users, and provides a bit of background behind the shift. We in the Spring team had a lot of fun working on this and collaborating with the folks at Microsoft to get the best blend of the two technologies for our users.

Azure Functions for Java

Microsoft has had Java support in Azure Functions for a while, and it enables developers to easily write and deploy Java code that connects in a serverless way to a wide range of platform services (events, databases, storage, HTTP gateways, etc.) in Azure. It comes with an annotation-based programming model that puts the function implementations in Java methods. So you write a method and annotation it with @FunctionName

The Joy of Mustache: Server Side Templates for the JVM

Engineering | November 21, 2016 | ...

I don’t do much server-side templating, but when I do…​ well frankly, I tend to forget things. Every template language has its strengths and weaknesses, and they all have syntax to remember, and more frequently to forget. Recently I completed some work on the old Spring Petclinic, converting it to use Thymeleaf in the view layer, and re-organizing the code to be a bit more "modern". I enjoyed working with Thymeleaf 3, and found it a pleasant experience, but had to spend a lot of time scanning documentation and samples. Then I had another little project that needed some templates, and I…

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