MicroProfile support in Java EE Application servers

Introduction

With Java EE, you can create enterprise-type application quickly as you can concentrate on implementing the business logic.
You are also able to create applications which are more micro-service oriented, but some handy ‘features’ are not yet standardised. Standardisation is a process of specifying the best practices which of course takes some time to discover and validate these best practices.

The MicroProfile group wants to create standards for those micro-services concepts which are not yet available in Java EE. Their motto is

Optimising Enterprise Java for a micro-services architecture

This ensures that each application server, following these specifications, is compatible, just like Java EE itself. And it prepares the introduction of these specifications into Java EE, now Jakarta EE under the governance of the Eclipse Foundation.

Specification

There are already quite some specifications available under the MicroProfile flag. Have a look at the MicroProfile site and learn more about them over there.

The topics range from Configuration, Security (JWT tokens), Operations (Metric, Health, Tracing), resilience (Fault tolerance), documentation (OpenApi docu), etc …

Implementations

Just as with Java EE, there are different implementations available for each spec. The difference is that there is no Reference Implementation (RI), the special implementation which goes together with the specification documents.
All implementations are equally.

You can find standalone implementations for all specs within the SmallRye umbrella project or at Apache (mostly defined under the Apache Geronimo umbrella)

There exists also specific ‘server’ implementations which are specifically written for MicroProfile. Mostly based on Jetty or Netty, all implementations are added to have a compatible server.
Examples are KumuluzEE, Hammock, Launcher, Thorntail (v4 version) and Helidon for example.

But implementations are also made available within Java EE servers which brings both worlds tightly integrated. Examples are Payara and OpenLiberty but more servers are following this path like WildfFly and TomEE.

Using MicroProfile in Stock Java EE Servers

When you have your large legacy application which still needs to be maintained, you can also add the MicroProfile implementations to the server and benefits from their features.

It can be the first step in taking out parts of your large monolith and place it in a separate micro-service. When your package structure is already defined quite well, the separation can be done relatively easily and without the need to rewrite your application.

Although adding individual MicroProfile applications to the server is not always successful due to the usage of the advanced CDI features in MicroProfile implementations. To try things out, take one of the standalone implementations from SmallRye or Apache (Geronimo) – Config is the probably easiest to test, add it to the lib folder of your application server.

Dedicated Java EE Servers

There is also the much easier way to try out the combination which is choosing a certified Java server which has already all the MicroProfile implementations on board. Examples today are Payara and OpenLiberty. But also other vendors are going this way as the integration has started for WildLy and TomEE.

Since the integration part is already done, you can just start using them. Just add the MicroProfile Maven bom to your pom file and you are ready to go.

<dependency>
   <groupId>org.eclipse.microprofile</groupId>
   <artifactId>microprofile</artifactId>
   <version>2.0.1</version>
   <type>pom</type>
   <scope>provided</scope>
</dependency>

This way, you can define how much Java EE or MicroProfile stuff you want to use within your application and can achieve the gradual migration from existing Java EE legacy applications to a more micro-service alike version.

In addition, there exists also maven plugins to convert your application to an uber executable jar or you can run your WAR file also using the hollow jar technique with Payara Micro for example.

Conclusion

With the inclusion of the MicroProfile implementations into servers like Payara and OpenLiberty, you can enjoy the features of that framework in your Java EE Application server which you are already familiar with.

It allows you to make use of these features when you need them and create even more micro-service alike applications and make a start of the decomposition of your legacy application into smaller parts if you feel the need for this.

Enjoy it.

The advantages of the monolith

Introduction

There are various possible ‘architectures’ to use in your application. Monoliths, micro-services and self-contained systems to name a few. When something is a hype, one can easily forget that there is no silver bullet, that we should use the best solution for your problem.

And these days, a lot of people forget that monoliths are powerful when used correctly, in certain use cases.

So let’s have a look at the simplicity, easy integration and consistency aspects of the monolith.

Simplicity

Monoliths are simple in structure. You just have 1 code source repository which is compiled and packaged in one command to produce your single artifact which you need to deploy.

So for a new team member, getting up and running is easily and fast. Get the link to the source code, download and package it and run it on the local machine. Even if you need an application server, it can be simple as executing a script which sets it up correctly.

This in contrast with micro-services for instance. You have several code repositories, different packaging systems because you have different development languages and frameworks, additional instances for the configuration service, API gateway, the discovery service and so one.

Easy / fast integration

In a bigger monolith, the integration between different parts is easy and efficient.

Since everything is running within the same JVM integration is as simple as calling another java method. There is no need that the data is converted to JSON for example. So it is faster and you have no pitfalls with the conversion which can happen in some corner cases.

And since everything is running in the same process, you don’t have to take into account the fallacies of the distributed computing. Which is forgotten by the developers anyway. So no issues with network failures, latency, bandwidth latency, changing topology and all those pitfalls which arise when your application is distributed between different machines.

Consistent

The consistency of your UI is very important for your end user. Each screen must be built in a similar manner with the same look and feel and layout. When the different parts of your application looks differently or behave differently, it is for the end user much more difficult to use it and makes it inefficient (and probably he will no longer use it)

With your monolith, you are using a single code language and the same framework for generating the UI. So with a bit of discipline of the developer (and a good UI/UX design), it is fairly easy to create uniform screens.

In the case of micro-services where you have maybe different frameworks for the UI for different parts of the application, it will be very difficult to achieve this uniformity.

Or even worse, you built a giant monolithic SPA on top of your fine-grained micro-services which breaks an important concept of the architectural vision, the independently deployable artifacts.

Monolith as the start

Since it is so easy to get started with a monolith, every application should begin as a monolith. You have your first production artifact ready much faster.

In the following phases, you can gradually split it up and evolve into a distributed system if your use cases mandate it.

Just be aware of your package structure within the monolith application. Make sure there is already a clean separation so that the extraction of the different pieces can be smooth.

Conclusion

The advantages of the monolith are often forgotten these days. However, it has all the features that can give you a quick first success with your application. And the time to market is in many cases shorter due to its simplicity and easy integration. And if you carefully pay attention to the structure of your code, you can even create large monolith successfully.

Have fun.

How small are micro-services?

Introduction

Sometimes you see heated discussions about the size of a micro-service. After all, they should be small as you can read from the definition. But small is a subjective concept and in the end, size doesn’t have the do anything with micro-services.

This is part of my monolith, micro-service and self-contained systems comparison blog series.

Single responsibility or Domain Driven Design (DDD)

Some people are so focused on the size (lines of code or number of classes) of their micro-service that they split up a micro-service or create some kind of strange construct.

But the single responsibility principle of a micro-service is much more important. The services are created to handle the logic of a domain.

In an online webshop, you could have some micro-services related to the order, product or payment management for example. And when there is some part of your application that needs the logic of that domain, it can call that micro-service.

Pizza someone?

Other people try to control the size of the micro-service by defining the number of people who are working in the team creating it.

Since each micro-service is ‘owned’ by a team, they define the team size as the number of people who has enough with 2 pizzas. The so-called pizza team.

But if you have ‘big eaters’ your team has then 3 persons, 1 analyst, 1 developer and 1 tester? The pizza team as a metric for the size of a micro-service doesn’t make any sense.

How small is small?

Well, as small or big as needed to create the logic around the domain for which the micro-service is designed. And in the case it happens to be 1 million lines of code, so be it. Ok, you should try to split your micro service then into different parts, each related to a subdomain in that case. But in a sense, there nothing wrong with bigger micro-services.

The lines of code is not an issue as long as it isn’t blocking the continuous delivery to production. When it tends to become a monolith where the development of a feature blocks the release of the micro-service to production, then you have an issue.

Conclusion

Forget about the lines of code or the number of people in the team which is creating the micro-service as a metric. That is not a good way to handle your micro-service architecture.

The main reason why you should do micro-services is that you have separate services, one for each domain of your application. And keep in mind that you should be able to go into production at any time with your micro-service. Don’t let a big feature block you to release some small updates you have done in your code.

Have fun.