JVM performance: OpenJ9 uses least memory. GraalVM most. OpenJDK distributions differ.

In a previous blog post I created a setup to compare JVM performance of several JVMs. I received some valuable feedback on the measures I conducted and requests to add additional JVMs. In this second post I'll look at some more JVMs and I've added some measures like process memory usage and startup time. Also I've automated the test and reduced the complexity of the setup by removing haproxy and testing a single JVM at a time.

Comparing JVM performance; Zulu, OpenJDK, Oracle JDK, GraalVM CE

There are many different choices for a JVM for your Java application. Which would be the best to use? This depends on various factors. Performance being an important one. Solid performance research however is difficult. In this blog post I'll describe a setup I created to perform tests on different JVMs at the same time and show some interesting results! I also looked at the effect of resource isolation (assigning specific CPUs and memory to the process). This effect was negligible. My test application consisted of a reactive (non-blocking) Spring Boot REST application and I've used Prometheus to poll the JVMs and Grafana for visualization.

Below is an image of the used setup. Everything was running in Docker containers except SoapUI.

Monitoring Spring Boot applications with Prometheus and Grafana

In order to compare the performance of different JDKs for reactive Spring Boot services, I made a setup in which a Spring Boot application is wrapped in a Docker container. This makes it easy to create different containers for different JDK's with the same Spring Boot application running in it. The Spring Boot application exposes metrics to Prometheus. Grafana can read these metrics and allows to make nice visualizations from it. This blog post describes the setup. A next post will show the results. You can download the code here (in the complete folder). To indicate how easy this is, getting this setup up and running and write this blog post took me less than 1.5 hours total. I did not have much prior knowledge on Prometheus and Grafana save for a single workshop at AMIS by Lucas Jellema.

Running Reactive Spring Boot on GraalVM in Docker

GraalVM is an open source polyglot VM which makes it easy to mix and match different languages such as Java, Javascript and R. It has the ability (with some restrictions) to compile code to native executables. This of course offers great performance benefits. Recently, GraalVM Docker files and images have become available. See here.

Since Spring Boot is a popular Java framework and reactive (non blocking) RESTful services/clients implemented in Spring Boot are also interesting to look at, I thought; lets combine those and produce a Docker image running a reactive Spring Boot application on GraalVM.

I've used and combined the following

• Building a Reactive RESTful Web Service
• Spring Boot with Docker and Running Spring Boot in a Docker container on OpenJDK, Oracle JDK, Zulu on Alpine Linux, Oracle Linux, Ubuntu
• Oracle's GraalVM Docker images
• (my very own) Ubuntu Development VM (requires VirtualBox, Vagrant)

As a base I've used the code provided in the following Git repository here. In the 'complete' folder (the end result of the tutorial) is a sample Reactive RESTful Web Service and client.

Securing Oracle Service Bus REST services with OAuth2 (without using additional products)

OAuth2 is a popular authentication framework. As a service provider it is thus common to provide support for OAuth2. How can you do this on a plain WebLogic Server / Service Bus without having to install additional products (and possibly have to pay for licenses)? If you just want to implement and test the code, see this installation manual. If you want to know more about the implementation and choices made, read on!

Oracle SOA: Sending delayed JMS messages

Sometimes you might want to put something on a JMS queue and make it available after a certain period has passed to consumers. How can you achieve this using Oracle SOA Suite?

Docker host and bridged networking. Running library/httpd on different ports

Docker provides different networking options. When using the Docker host networking, you don't have the option to create port mappings. When using images like library/httpd:2.4, you don't have the option to update the port on which it runs; it runs by default on port 80. Suppose you want to use the host networking feature and want to run library/httpd:2.4 on different ports, how would you do this?

In this blog I'll explain 2 mechanisms by which you can expose library/httpd on different ports using host networking and how you can do the same using bridged networking. I'll describe several features of the different solutions and consequences for connectivity / host lookup options. At the end of the post I'll give some tips on how to test connectivity between containers.

Running Spring Tool Suite and other GUI applications from Docker containers

Running an application within a Docker container helps in isolating the application from the host OS. Running GUI applications like for example an IDE from a Docker container, can be challenging. I'll explain several of the issues you might encounter and how to solve them. For this I will use Spring Tool Suite as an example. The code (Dockerfile and docker-compose.yml) can also be found here. Due to (several) security concerns, this is not recommended in a production environment.

Automate the installation of Oracle JDK 8 and 10 on RHEL and Debian derivatives

Automating the Oracle JDK installation on RHEL derivatives (such as CentOS, Oracle Linux) and Debian derivatives (such as Mint, Ubuntu) differs. This is due to different package managers and repositories. In this blog I'll provide quick instructions on how to automate the installation of Oracle JDK 8 and 10 on different Linux distributions. I chose JDK 8 and 10 since they are currently the only Oracle JDK versions which receive public updates (see here).

VirtualBox networking explained

VirtualBox networking is extremely flexible. With this flexibility comes the challenge of making the correct choices. In this blog, the different options are explained and some example cases are elaborated. Access between guests, host and other members of the network is explained and the required configuration is shown. This information is also available in the following presentation here.

Securely access remote content using a proxy server accessed with SSH

There are numerous occasions that I was limited in my work because of connectivity which could not be trusted. For example;

• I could not download large installers due to a proxy anti virus tool which manipulated downloads causing files to become corrupted.
• I needed to visit a website to find a solution to a problem, but the local proxy server found the content offensive and disallowed me to visit the site. 
• I have stayed in hotels in which I was not sure that my internet traffic was not being monitored. I was hesitant to access remote services which required credentials.
• At the airport, the public Wifi can sometimes not be trusted. Someone could run a local hotspot with the same name and become a man in the middle intercepting credentials of people connecting to it.

The method described in this blog allows you to access external resources with few limitations in a relatively secure way. It makes it easy to circumvent most content scanning/manipulation. Do mind that this method might be a violation of certain rules/regulations/policies. When in doubt, first confirm you're allowed to use it.

In short what you do is

• Run an SSH server on a different location on port 443
• On the same server which runs an SSH server, run your own HTTP/HTTPS proxy server (or use the SSH server itself as SOCKS proxy)
• Connect to the SSH server
• Map the proxy port to your local machine
• Use the configured port as proxy server in your browser configuration. 

This might seem complex but it is easier than you might think and once setup, it is easy to re-use. Also it is easier, more flexible and in some cases also more secure than using a VPN.

SOA Suite 12c in Docker containers. Only a couple of commands, no installers, no third party scripts

For developers, installing a full blown local SOA Suite environment has never been a favorite (except for a select few). It is time consuming and requires you to download and run various installers after each other. If you want to start clean and haven't done your installation inside a VM and created a snapshot, you can start all over again.

There is a new and easy way to get a SOA Suite environment up and running without downloading any installers in only a couple of commands without depending on scripts provided by any party other than Oracle. The resulting environment is an Oracle Enterprise Edition database, an Admin Server and a Managed Server. All of them running in separate Docker containers with ports exposed to the host. The 3 containers can run together within an 8Gb VM.

The documentation Oracle provides in its Container Registry for the SOA Suite images, should be used as base, but since you will encounter some errors if you follow it, you can use this blog post to help you solve them quickly.

A simple dashboard to monitor HTTP endpoints

To monitor different environments, it is not unusual to use a monitoring dashboard to obtain information about the status of different servers. This blog describes some considerations for implementing a simple monitoring dashboard and some of the challenges I encountered. The simple-dashboard I've used in this blog runs solely from a browser and does not have a server side component.

Running Spring Boot in a Docker container on OpenJDK, Oracle JDK, Zulu on Alpine Linux, Oracle Linux, Ubuntu

Spring Boot is great for running inside a Docker container. Spring Boot applications 'just run'. A Spring Boot application has an embedded servlet engine making it independent of application servers. There is a Spring Boot Maven plugin available to easily create a JAR file which contains all required dependencies. This JAR file can be run with a single command-line like 'java -jar SpringBootApp.jar'. For running it in a Docker container, you only require a base OS and a JDK. In this blog post I'll give examples on how to get started with different OSs and different JDKs in Docker. I'll finish with an example on how to build a Docker image with a Spring Boot application in it.

Application Container Cloud Service (ACCS): Using the Application Cache from a Spring Boot application

Spring Boot allows you to quickly develop microservices. Application Container Cloud Service (ACCS) allows you to easily host Spring Boot applications. Oracle provides an Application Cache based on Coherence which you can use from applications deployed to ACCS. In order to use the Application Cache from Spring Boot, Oracle provides an open source Java SDK. In this blog post I'll give an example on how you can use the Application Cache from Spring Boot using this SDK. You can find the sample code here.

Java: How to fix Spring @Autowired annotation not working issues

Spring is a powerful framework, but it requires some skill to use efficiently. When I started working with Spring a while ago (actually Spring Boot to develop microservices) I encountered some challenges related to dependency injection and using the @Autowired annotation. In this blog I'll explain the issues and possible solutions. Do note that since I do not have a long history with Spring, the provided solutions might not be the best ones.

Automate calls to SOAP and REST webservices using simple Python scripts

Probably not many people will tell you running batches over webservices is a good idea. Sometimes though, it can be handy to have a script available to generate webservice calls based on a template message with variables and automate processing the response messages. In addition, if you have a large number of calls, executing the calls in parallel might save you a lot of time if your service platform can handle the concurrency.

Getting started with Spring Boot microservices. Why and how.

In order to quickly develop microservices, Spring Boot is a common choice. Why should I be interested in Spring Boot? In this blog post I'll give you some reasons why looking at Spring Boot is interesting and give some samples on how to get started quickly. I'll shortly talk about microservices, move on to Spring Boot and end with Application Container Cloud Service which is an ideal platform to run and manage your Spring Boot applications on. This blog touches many subjects but they fit together nicely. You can view the code of my sample Spring Boot project here. Most of the Spring Boot knowledge has been gained by the following free course by Java Brains.