Speaking

The Java API allows a lot: sending packets over the network, compiling code, etc. If you put an application in an production environment, you need to make sure it doesn’t do more than it’s supposed to do. Consider a Java application in a private banking system. A new network administrator is hired, and while going around, he notices that the app is making network calls to an unknown external endpoint. After some investigation, it’s found that this app has been sending for years confidential data to a competitor (or a state, or hackers, whatever). This is awkward. Especially since it could have been avoided. Code reviews are good to improve the hardening of an application, but what if the malicious code was planted purposely? Some code buried in a commit could extract code from binary content, compile it on the fly, and then execute the code in the same JVM run... By default, the JVM is not secured! Securing the JVM for a non-trivial application is complex and time-consuming but the risks of not securing it could be disastrous. In this talk, I’ll show some of the things you could do in an unsecured JVM. I’ll also explain the basics of securing it, and finally demo a working process on how to do it.

Kotlin is one of those 'new' JVM languages that are currently rocking the boat. Although it’s made a great impact on Android, it’s equally good on the server side. As Domain-Specific Languages are constrained by the language they run on, Kotlin frees developers from Java fluent builders to propose something better. Using the Vaadin web framework as an example, I’ll demo how one could design its own DSL with Kotlin.

When one’s app is challenged with poor performances, it’s easy to set up a cache in front of one’s SQL database. It doesn’t fix the root cause (e.g. bad schema design, bad SQL query, etc.) but it gets the job done. If the app is the only component that writes to the underlying database, it’s a no-brainer to update the cache accordingly, so the cache is always up-to-date with the data in the database. Things start to go sour when the app is not the only component writing to the DB. Among other sources of writes, there are batches, other apps (shared databases exist unfortunately), etc. One might think about a couple of ways to keep data in sync i.e. polling the DB every now and then, DB triggers, etc. Unfortunately, they all have issues that make them unreliable and/or fragile. You might have read about Change-Data-Capture before. It’s been described by Martin Kleppmann as turning the database inside out: it means the DB can send change events (SELECT, DELETE and UPDATE) that one can register to. Just opposite to Event Sourcing that aggregates events to produce state, CDC is about getting events out of states. Once CDC is implemented, one can subscribe to its events and update the cache accordingly. However, CDC is quite in its early stage, and implementations are quite specific. In this talk, I’ll describe an easy-to-setup architecture that leverages CDC to have an evergreen cache.

Years after Kent Beck provided JUnit, unit testing is part of most developer teams tooling. However, there’s a trend that tends to threaten unit testing, claiming only integration testing can truly detects defects in software. In this talk, we will first define what unit testing and integration testing are, and their respective pros, cons and uses. Then, we will have a look at the unique challenges posed by integration testing. Finally, tools and techniques will be presented to somewhat remedy to that so that integration testing becomes a true asset in each software developer bag of tricks.

Kubernetes allows a lot. After discovering its features, it’s easy to think it can magically transform your application deployment process into a painless no-event. For Hello World applications, that is the case. Unfortunately, not many of us do deploy such applications day-to-day because we need to handle state. Though it would be much easier to have stateless apps, and despite our best efforts in this direction, state is found in (at least) two places: sessions and databases. You need to think keeping the state while stopping and starting application nodes. In this talk, I’ll demo how to update a Spring Boot app deployed on a Kubernetes cluster with a non-trivial database schema change with the help of Hazelcast, while keeping the service up during the entire update process.

Unit testing ensures your production code is relevant. But what does ensure your testing code is relevant? Come discover mutation testing and make sure your never forget another assert again. In the realm of testing, the code coverage metrics is the most often talked about. However, it doesn't mean that the test has been useful or even that an assert has been coded. Mutation testing is a strategy to make sure that the test code is relevant. In this talk, we will explain how Code Coverage is computed, what its inherent flaw is and how Mutation Testing can help us in this regard.

When one’s app is challenged with poor performances, it’s easy to set up a cache in front of one’s SQL database. It doesn’t fix the root cause (e.g. bad schema design, bad SQL query, etc.) but it gets the job done. If the app is the only component that writes to the underlying database, it’s a no-brainer to update the cache accordingly, so the cache is always up-to-date with the data in the database. Things start to go sour when the app is not the only component writing to the DB. Among other sources of writes, there are batches, other apps (shared databases exist unfortunately), etc. One might think about a couple of ways to keep data in sync i.e. polling the DB every now and then, DB triggers, etc. Unfortunately, they all have issues that make them unreliable and/or fragile. You might have read about Change-Data-Capture before. It’s been described by Martin Kleppmann as turning the database inside out: it means the DB can send change events (SELECT, DELETE and UPDATE) that one can register to. Just opposite to Event Sourcing that aggregates events to produce state, CDC is about getting events out of states. Once CDC is implemented, one can subscribe to its events and update the cache accordingly. However, CDC is quite in its early stage, and implementations are quite specific. In this talk, I’ll describe an easy-to-setup architecture that leverages CDC to have an evergreen cache.

In Kubernetes, operators allow the API to be extended to your heart content. If one task requires too much YAML, it’s easy to create an operator to take care of the repetitive cruft, and only require a minimum amount of YAML. On the other hand, since its beginnings, the Go language has been advertised as closer to the hardware, and is now ubiquitous in low-level programming. Kubernetes has been rewritten from Java to Go, and its whole ecosystem revolves around Go. For that reason, It’s only natural that Kubernetes provides a Go-based framework to create your own operator. While it makes sense, it requires organizations willing to go down this road to have Go developers, and/or train their teams in Go. While perfectly acceptable, this is not the only option. In fact, since Kubernetes is based on REST, why settle for Go and not use your own favorite language? In this talk, I’ll describe what is an operator, how they work, how to design one, and finally demo a Java-based operator that is as good as a Go one.

Kubernetes allows a lot. After discovering its features, it’s easy to think it can magically transform your application deployment process into a painless no-event. For Hello World applications, that is the case. Unfortunately, not many of us do deploy such applications day-to-day because we need to handle state. Though it would be much easier to have stateless apps, and despite our best efforts in this direction, state is found in (at least) two places: sessions and databases. You need to think keeping the state while stopping and starting application nodes. In this talk, I’ll demo how to update a Spring Boot app deployed on a Kubernetes cluster with a non-trivial database schema change with the help of Hazelcast, while keeping the service up during the entire update process.

Kubernetes allows a lot. After discovering its features, it’s easy to think it can magically transform your application deployment process into a painless no-event. For Hello World applications, that is the case. Unfortunately, not many of us do deploy such applications day-to-day because we need to handle state. Though it would be much easier to have stateless apps, and despite our best efforts in this direction, state is found in (at least) two places: sessions and databases. You need to think keeping the state while stopping and starting application nodes. In this talk, I’ll demo how to update a Spring Boot app deployed on a Kubernetes cluster with a non-trivial database schema change with the help of Hazelcast, while keeping the service up during the entire update process.

As 'the Cloud' becomes more and more widespread, now is a good time to assess how you can containerize your Java application. I assume you’re able to write a a Dockerfile around the generated JAR. However, each time the application’s code will change, the whole image will need to be rebuilt. If you’re deploying to a local Kubernetes cluster environment, this increases that much the length of the feedback loop. In this demo-based talk, I’ll present different ways to get your Java app in a container: Dockerfile, Jib, and Cloud Native Buildpacks. We will also have a look at what kind of Docker image they generate, how they layer the images, whether those images are compatible with skaffold, etc.

Lorsque votre application affiche de mauvaises performances, il est facile de configurer un cache en façade de votre base de données SQL. Ca ne corrige pas la cause principale (par exemple, une mauvaise conception de schéma, une mauvaise requête SQL, etc.) mais ca permet de continuer à utiliser l'application de manière norminale. Si cette dernière est le seul composant qui écrit dans la base de données sous-jacente, il est facile de mettre à jour le cache en conséquence, afin que celui-ci soit toujours à jour avec les données de la base. La situation se complique lorsque l'application n'est pas le seul composant à écrire. Parmi les autres sources d'écritures, on peut citer les traitements par lot, d'autres applications (des bases de données partagées existent malheureusement), etc. On peut imaginer plusieurs manières pour conserver les données synchronisées : interroger la base de données de temps en temps, des triggers, etc. Malheureusement, toutes ces approches ont des problèmes qui les rendent peu fiables et / ou fragiles. Vous avez peut-être déjà entendu parler de Change-Data-Capture. CDC a été décrit par Martin Kleppmann comme turning the database inside out : cela signifie que la base de données peut être utilisée pour envoyer des événements de modification (SELECT, DELETE et UPDATE) auxquels on peut s'abonner. A l'opposé de Event Sourcing qui agrège les événements pour produire l'état, CDC consiste à extraire les événements de l'état. Une fois CDC implémenté, on peut s'abonner aux événements et mettre à jour le cache en conséquence. Cependant, CDC en est à ses débuts et les implémentations sont assez spécifiques. Dans cette présentation, je décrirai une architecture typique qui exploite CDC pour bénéficier d'un cache toujours à jour.

Unit testing ensures your production code is relevant. But what does ensure your testing code is relevant? Come discover mutation testing and make sure your never forget another assert again. In the realm of testing, the code coverage metrics is the most often talked about. However, it doesn't mean that the test has been useful or even that an assert has been coded. Mutation testing is a strategy to make sure that the test code is relevant. In this talk, we will explain how Code Coverage is computed, what its inherent flaw is and how Mutation Testing can help us in this regard.

Par le passé, beaucoup ont annoncé que Java mourrait mais que la JVM serait son héritage. Effectivement, celle-ci a connu un énorme succès. Wikipédia répertorie de nombreux langages qui s'exécutent dessus, certains d'entre eux proches de Java p.e. Kotlin, d'autres plus éloignés comme Clojure. Mais de nos jours, le Cloud devient omniprésent. La conteneurisation est le moyen d'éviter de retrouver prisonnier des technologies propriétaires des fournisseurs. Kubernetes est devenu la plateforme de référence. Si Kubernetes doit tuer un conteneur pour une raison quelconque (consommation de ressources, etc.), un nouveau doit le remplacer le plus rapidement possible. Dans ce contexte, la JVM semble être une impasse : son temps de démarrage est élevé par rapport à un processus natif. De même, elle consomme beaucoup de mémoire ce qui ne fait qu'augmenter la facture mensuelle. Qu'est-ce que cela signifie pour nous les développeurs ? Tout le temps consacré à l'apprentissage de l'écosystème JVM a-t-il été investi sans espoir de retour sur investissement ? Devrons-nous investir encore plus de temps dans de nouveaux langages, frameworks, bibliothèques, etc. ? C'est certainement une possibilité Mais nous pouvons également tirer parti de nos connaissances existantes et adopter le Cloud et les conteneurs à l'aide de certains outils. Dans cette présentation, je vais créer un raccourcisseur d'URL simple avec une pile "standard" : Kotlin, JAX-RS et Hazelcast. Ensuite, avec l'aide de Quarkus et de GraalVM, je transformerai cette application en un exécutable natif où tout la partie liée au Cloud / Container est gérée dans le processus de construction.

From Wikipedia, Reactive Programming is 'a declarative programming paradigm concerned with data streams and the propagation of change.' The programming model is complex to master. It requires a lot of experience to feel comfortable with it. However, there’s no denying that it fits the cloud ecosystem perfectly. Since on-premises infrastructure is oversized, running a program that executes a couple of additional CPU cycles won’t change anything. On the other hand, you will pay for them if you host the same program on third-party infrastructure. Depending on the number of those cycles, and the number of nodes the program runs on, it can make a huge difference in your monthly bill. In this talk, I’ll demo how you can migrate a traditional sample Spring Boot application written in Kotlin to coroutines one step at a time via a hands-on demo.

At a point in the past, it was forecast that Java would die, but the JVM platform would be its legacy. And in fact, for a long time, the JVM has been tremendously successful. Wikipedia itself list a bunch of languages that run on it, some of them close to Java e.g. Kotlin, some of them very remote e.g. Clojure. But nowadays, the Cloud is becoming ubiquitous. Containerization is the way to go to alleviate some of the vendor lock-in issues. Kubernetes is a de facto platform. If a container needs to be killed for whatever reason (resource consumption, unhealthy, etc.), a new one needs to replace it as fast as possible. In that context, the JVM seems to be a dead-end: its startup time is huge in comparison to a native process. Likewise, it consumes a lot of memory that just increase the monthly bill. What does that mean for us developers? Has all the time spent in learning the JVM ecosystem been invested with no hope of return over investment? Shall we need to invest even more time in new languages, frameworks, libraries, etc.? That is one possibility for sure. But we can also leverage our existing knowledge, and embrace the Cloud and containers ways with the help of some tools. In this talk, I’ll create a simple URL shortener with a 'standard' stack: Kotlin, JAX-RS and Hazelcast. Then, with the help of Quarkus and GraalVM, I’ll turn this application into a native executable with all Cloud/Container related work has been moved to the build process.

When your application starts slowing down, the reason is probably a bottleneck somewhere in the execution chain. Sometimes, this bottleneck is due to a bug. Sometimes, somebody didn’t set up the optimal configuration. And sometimes, the process of fetching the data is the bottleneck. One option would be to change your whole architecture. Before moving to such a drastic, and probably expensive measure, one can consider a trade-off: instead of getting remote data every time, you can store the data locally after the first read. This is the trade-off that caching offers: stale data vs. speed. Deciding to use caching is just the first step in a long journey. The next step is to think about how your application and the cache will interact. This talk focuses on your options regarding those interactions.

When your application starts slowing down, the reason is probably a bottleneck somewhere in the execution chain. Sometimes, this bottleneck is due to a bug. Sometimes, somebody didn’t set up the optimal configuration. And sometimes, the process of fetching the data is the bottleneck. One option would be to change your whole architecture. Before moving to such a drastic, and probably expensive measure, one can consider a trade-off: instead of getting remote data every time, you can store the data locally after the first read. This is the trade-off that caching offers: stale data vs. speed. Deciding to use caching is just the first step in a long journey. The next step is to think about how your application and the cache will interact. This talk focuses on your options regarding those interactions.

While a microservices architecture is more scalable than a monolith, it has a direct hit on performance. To cope with that, one performance improvement is to set up a cache. It can be configured for database access, for REST calls or just to store session state across a cluster. In this demo-based talk, I’ll show how Hazelcast In-Memory Data Grid can help you in each one of those areas and how to configure it. Hint: it’s much easier than one would expect.

Kubernetes allows a lot. After discovering its features, it’s easy to think it can magically transform your application deployment process into a painless no-event. For Hello World applications, that is the case. Unfortunately, not many of us do deploy such applications day-to-day because we need to handle state. Though it would be much easier to have stateless apps, and despite our best efforts in this direction, state is found in (at least) two places: sessions and databases. You need to think keeping the state while stopping and starting application nodes. In this talk, I’ll demo how to update a Spring Boot app deployed on a Kubernetes cluster with a non-trivial database schema change with the help of Hazelcast, while keeping the service up during the entire update process.

When one’s app is challenged with poor performances, it’s easy to set up a cache in front of one’s SQL database. It doesn’t fix the root cause (e.g. bad schema design, bad SQL query, etc.) but it gets the job done. If the app is the only component that writes to the underlying database, it’s a no-brainer to update the cache accordingly, so the cache is always up-to-date with the data in the database. Things start to go sour when the app is not the only component writing to the DB. Among other sources of writes, there are batches, other apps (shared databases exist unfortunately), etc. One might think about a couple of ways to keep data in sync i.e. polling the DB every now and then, DB triggers, etc. Unfortunately, they all have issues that make them unreliable and/or fragile. You might have read about Change-Data-Capture before. It’s been described by Martin Kleppmann as turning the database inside out: it means the DB can send change events (SELECT, DELETE and UPDATE) that one can register to. Just opposite to Event Sourcing that aggregates events to produce state, CDC is about getting events out of states. Once CDC is implemented, one can subscribe to its events and update the cache accordingly. However, CDC is quite in its early stage, and implementations are quite specific. In this talk, I’ll describe an easy-to-setup architecture that leverages CDC to have an evergreen cache.

From Wikipedia, Reactive Programming is 'a declarative programming paradigm concerned with data streams and the propagation of change.' The programming model is complex to master. It requires a lot of experience to feel comfortable with it. However, there’s no denying that it fits the cloud ecosystem perfectly. Since on-premises infrastructure is oversized, running a program that executes a couple of additional CPU cycles won’t change anything. On the other hand, you will pay for them if you host the same program on third-party infrastructure. Depending on the number of those cycles, and the number of nodes the program runs on, it can make a huge difference in your monthly bill. In this talk, I’ll demo how you can migrate a traditional sample Spring Boot application written in Kotlin to coroutines one step at a time via a hands-on demo.

At a point in the past, it was forecast that Java would die, but the JVM platform would be its legacy. And in fact, for a long time, the JVM has been tremendously successful. Wikipedia itself list a bunch of languages that run on it, some of them close to Java e.g. Kotlin, some of them very remote e.g. Clojure. But nowadays, the Cloud is becoming ubiquitous. Containerization is the way to go to alleviate some of the vendor lock-in issues. Kubernetes is a de facto platform. If a container needs to be killed for whatever reason (resource consumption, unhealthy, etc.), a new one needs to replace it as fast as possible. In that context, the JVM seems to be a dead-end: its startup time is huge in comparison to a native process. Likewise, it consumes a lot of memory that just increase the monthly bill. What does that mean for us developers? Has all the time spent in learning the JVM ecosystem been invested with no hope of return over investment? Shall we need to invest even more time in new languages, frameworks, libraries, etc.? That is one possibility for sure. But we can also leverage our existing knowledge, and embrace the Cloud and containers ways with the help of some tools. In this talk, I’ll create a simple URL shortener with a 'standard' stack: Kotlin, JAX-RS and Hazelcast. Then, with the help of Quarkus and GraalVM, I’ll turn this application into a native executable with all Cloud/Container related work has been moved to the build process.

When one’s app is challenged with poor performances, it’s easy to set up a cache in front of one’s SQL database. It doesn’t fix the root cause (e.g. bad schema design, bad SQL query, etc.) but it gets the job done. If the app is the only component that writes to the underlying database, it’s a no-brainer to update the cache accordingly, so the cache is always up-to-date with the data in the database. Things start to go sour when the app is not the only component writing to the DB. Among other sources of writes, there are batches, other apps (shared databases exist unfortunately), etc. One might think about a couple of ways to keep data in sync i.e. polling the DB every now and then, DB triggers, etc. Unfortunately, they all have issues that make them unreliable and/or fragile. You might have read about Change-Data-Capture before. It’s been described by Martin Kleppmann as turning the database inside out: it means the DB can send change events (SELECT, DELETE and UPDATE) that one can register to. Just opposite to Event Sourcing that aggregates events to produce state, CDC is about getting events out of states. Once CDC is implemented, one can subscribe to its events and update the cache accordingly. However, CDC is quite in its early stage, and implementations are quite specific. In this talk, I’ll describe an easy-to-setup architecture that leverages CDC to have an evergreen cache.

When one’s app is challenged with poor performances, it’s easy to set up a cache in front of one’s SQL database. It doesn’t fix the root cause (e.g. bad schema design, bad SQL query, etc.) but it gets the job done. If the app is the only component that writes to the underlying database, it’s a no-brainer to update the cache accordingly, so the cache is always up-to-date with the data in the database. Things start to go sour when the app is not the only component writing to the DB. Among other sources of writes, there are batches, other apps (shared databases exist unfortunately), etc. One might think about a couple of ways to keep data in sync i.e. polling the DB every now and then, DB triggers, etc. Unfortunately, they all have issues that make them unreliable and/or fragile. You might have read about Change-Data-Capture before. It’s been described by Martin Kleppmann as turning the database inside out: it means the DB can send change events (SELECT, DELETE and UPDATE) that one can register to. Just opposite to Event Sourcing that aggregates events to produce state, CDC is about getting events out of states. Once CDC is implemented, one can subscribe to its events and update the cache accordingly. However, CDC is quite in its early stage, and implementations are quite specific. In this talk, I’ll describe an easy-to-setup architecture that leverages CDC to have an evergreen cache.

When your application starts slowing down, the reason is probably a bottleneck somewhere in the execution chain. Sometimes, this bottleneck is due to a bug. Sometimes, somebody didn’t set up the optimal configuration. And sometimes, the process of fetching the data is the bottleneck. One option would be to change your whole architecture. Before moving to such a drastic, and probably expensive measure, one can consider a trade-off: instead of getting remote data every time, you can store the data locally after the first read. This is the trade-off that caching offers: stale data vs. speed. Deciding to use caching is just the first step in a long journey. The next step is to think about how your application and the cache will interact. This talk focuses on your options regarding those interactions.

Kubernetes allows a lot. After discovering its features, it’s easy to think it can magically transform your application deployment process into a painless no-event. For Hello World applications, that is the case. Unfortunately, not many of us do deploy such applications day-to-day because we need to handle state. Though it would be much easier to have stateless apps, and despite our best efforts in this direction, state is found in (at least) two places: sessions and databases. You need to think keeping the state while stopping and starting application nodes. In this talk, I’ll demo how to update a Spring Boot app deployed on a Kubernetes cluster with a non-trivial database schema change with the help of Hazelcast, while keeping the service up during the entire update process.

While 'software is eating the world', those who are able to manage the huge mass of data will emerge out on the top. The batch processing model has been faithfully serving us for decades. However, it might have reached the end of its usefulness for all but some very specific use-cases. As the pace of businesses increases, most of the time, decision makers prefer slightly wrong data sooner, than 100% accurate data later. Stream processing matches this usage: instead of managing the entire bulk of data, manage pieces of them as soon as they become available. In this talk, I’ll define the context in which the batch processing model was born, the reasons that are behind the new stream processing one, how they compare, what are their pros and cons, and a list of existing technologies implementing the latter with their most characteristics. I’ll conclude by describing one possible use-case of data streaming that is not possible with batches: display in (near) real-time all trains in Switzerland and their position on a map. I’ll go through all requirements and the design. Finally, using an OpenData endpoint and the Hazelcast platform, I’ll try to impress attendees with a demo of it.

When one’s app is challenged with poor performances, it’s easy to set up a cache in front of one’s SQL database. It doesn’t fix the root cause (e.g. bad schema design, bad SQL query, etc.) but it gets the job done. If the app is the only component that writes to the underlying database, it’s a no-brainer to update the cache accordingly, so the cache is always up-to-date with the data in the database. Things start to go sour when the app is not the only component writing to the DB. Among other sources of writes, there are batches, other apps (shared databases exist unfortunately), etc. One might think about a couple of ways to keep data in sync i.e. polling the DB every now and then, DB triggers, etc. Unfortunately, they all have issues that make them unreliable and/or fragile. You might have read about Change-Data-Capture before. It’s been described by Martin Kleppmann as turning the database inside out: it means the DB can send change events (SELECT, DELETE and UPDATE) that one can register to. Just opposite to Event Sourcing that aggregates events to produce state, CDC is about getting events out of states. Once CDC is implemented, one can subscribe to its events and update the cache accordingly. However, CDC is quite in its early stage, and implementations are quite specific. In this talk, I’ll describe an easy-to-setup architecture that leverages CDC to have an evergreen cache.

As 'the Cloud' becomes more and more widespread, now is a good time to assess how you can containerize your Java application. I assume you’re able to write a a Dockerfile around the generated JAR. However, each time the application’s code will change, the whole image will need to be rebuilt. If you’re deploying to a local Kubernetes cluster environment, this increases that much the length of the feedback loop. In this demo-based talk, I’ll present different ways to get your Java app in a container: Dockerfile, Jib, and Cloud Native Buildpacks. We will also have a look at what kind of Docker image they generate, how they layer the images, whether those images are compatible with skaffold, etc.

While 'software is eating the world', those who are able to manage the huge mass of data will emerge out on the top. The batch processing model has been faithfully serving us for decades. However, it might have reached the end of its usefulness for all but some very specific use-cases. As the pace of businesses increases, most of the time, decision makers prefer slightly wrong data sooner, than 100% accurate data later. Stream processing matches this usage: instead of managing the entire bulk of data, manage pieces of them as soon as they become available. In this talk, I’ll define the context in which the batch processing model was born, the reasons that are behind the new stream processing one, how they compare, what are their pros and cons, and a list of existing technologies implementing the latter with their most characteristics. I’ll conclude by describing one possible use-case of data streaming that is not possible with batches: display in (near) real-time all trains in Switzerland and their position on a map. I’ll go through all requirements and the design. Finally, using an OpenData endpoint and the Hazelcast platform, I’ll try to impress attendees with a demo of it.

When one’s app is challenged with poor performances, it’s easy to set up a cache in front of one’s SQL database. It doesn’t fix the root cause (e.g. bad schema design, bad SQL query, etc.) but it gets the job done. If the app is the only component that writes to the underlying database, it’s a no-brainer to update the cache accordingly, so the cache is always up-to-date with the data in the database. Things start to go sour when the app is not the only component writing to the DB. Among other sources of writes, there are batches, other apps (shared databases exist unfortunately), etc. One might think about a couple of ways to keep data in sync i.e. polling the DB every now and then, DB triggers, etc. Unfortunately, they all have issues that make them unreliable and/or fragile. You might have read about Change-Data-Capture before. It’s been described by Martin Kleppmann as turning the database inside out: it means the DB can send change events (SELECT, DELETE and UPDATE) that one can register to. Just opposite to Event Sourcing that aggregates events to produce state, CDC is about getting events out of states. Once CDC is implemented, one can subscribe to its events and update the cache accordingly. However, CDC is quite in its early stage, and implementations are quite specific. In this talk, I’ll describe an easy-to-setup architecture that leverages CDC to have an evergreen cache.

The Java API allows a lot: sending packets over the network, compiling code, etc. If you put an application in an production environment, you need to make sure it doesn’t do more than it’s supposed to do. Consider a Java application in a private banking system. A new network administrator is hired, and while going around, he notices that the app is making network calls to an unknown external endpoint. After some investigation, it’s found that this app has been sending for years confidential data to a competitor (or a state, or hackers, whatever). This is awkward. Especially since it could have been avoided. Code reviews are good to improve the hardening of an application, but what if the malicious code was planted purposely? Some code buried in a commit could extract code from binary content, compile it on the fly, and then execute the code in the same JVM run... By default, the JVM is not secured! Securing the JVM for a non-trivial application is complex and time-consuming but the risks of not securing it could be disastrous. In this talk, I’ll show some of the things you could do in an unsecured JVM. I’ll also explain the basics of securing it, and finally demo a working process on how to do it.

At a point in the past, it was forecast that Java would die, but the JVM platform would be its legacy. And in fact, for a long time, the JVM has been tremendously successful. Wikipedia itself list a bunch of languages that run on it, some of them close to Java e.g. Kotlin, some of them very remote e.g. Clojure. But nowadays, the Cloud is becoming ubiquitous. Containerization is the way to go to alleviate some of the vendor lock-in issues. Kubernetes is a de facto platform. If a container needs to be killed for whatever reason (resource consumption, unhealthy, etc.), a new one needs to replace it as fast as possible. In that context, the JVM seems to be a dead-end: its startup time is huge in comparison to a native process. Likewise, it consumes a lot of memory that just increase the monthly bill. What does that mean for us developers? Has all the time spent in learning the JVM ecosystem been invested with no hope of return over investment? Shall we need to invest even more time in new languages, frameworks, libraries, etc.? That is one possibility for sure. But we can also leverage our existing knowledge, and embrace the Cloud and containers ways with the help of some tools. In this talk, I’ll create a simple URL shortener with a 'standard' stack: Kotlin, JAX-RS and Hazelcast. Then, with the help of Quarkus and GraalVM, I’ll turn this application into a native executable with all Cloud/Container related work has been moved to the build process.

Kubernetes allows a lot. After discovering its features, it’s easy to think it can magically transform your application deployment process into a painless no-event. For Hello World applications, that is the case. Unfortunately, not many of us do deploy such applications day-to-day because we need to handle state. Though it would be much easier to have stateless apps, and despite our best efforts in this direction, state is found in (at least) two places: sessions and databases. You need to think keeping the state while stopping and starting application nodes. In this talk, I’ll demo how to update a Spring Boot app deployed on a Kubernetes cluster with a non-trivial database schema change with the help of Hazelcast, while keeping the service up during the entire update process.

Kubernetes allows a lot. After discovering its features, it’s easy to think it can magically transform your application deployment process into a painless no-event. For Hello World applications, that is the case. Unfortunately, not many of us do deploy such applications day-to-day because we need to handle state. Though it would be much easier to have stateless apps, and despite our best efforts in this direction, state is found in (at least) two places: sessions and databases. You need to think keeping the state while stopping and starting application nodes. In this talk, I’ll demo how to update a Spring Boot app deployed on a Kubernetes cluster with a non-trivial database schema change with the help of Hazelcast, while keeping the service up during the entire update process.

While 'software is eating the world', those who are able to manage the huge mass of data will emerge out on the top. The batch processing model has been faithfully serving us for decades. However, it might have reached the end of its usefulness for all but some very specific use-cases. As the pace of businesses increases, most of the time, decision makers prefer slightly wrong data sooner, than 100% accurate data later. Stream processing matches this usage: instead of managing the entire bulk of data, manage pieces of them as soon as they become available. In this talk, I’ll define the context in which the batch processing model was born, the reasons that are behind the new stream processing one, how they compare, what are their pros and cons, and a list of existing technologies implementing the latter with their most characteristics. I’ll conclude by describing one possible use-case of data streaming that is not possible with batches: display in (near) real-time all trains in Switzerland and their position on a map. I’ll go through all requirements and the design. Finally, using an OpenData endpoint and the Hazelcast platform, I’ll try to impress attendees with a demo of it.

A couple of years ago, continuous integration in the JVM ecosystem meant Jenkins. Since that time, a lot of other tools have been made available. But new tools don’t mean new features, just new ways. Beside that, what about continuous deployment? There’s no tool that allows to deploy new versions of a JVM-based application without downtime. The only way to achieve zero downtime is to have multiple nodes deployed on a platform, and let that platform achieve that e.g. Kubernetes. And yet, achieving true continuous deployment of bytecode on one single JVM instance is possible if one changes one’s way of looking at things. What if compilation could be seen as changes? What if those changes could be stored in a data store, and a listener on this data store could stream those changes to the running production JVM via the Attach API? In that talk, I’ll demo exactly that using Hazelcast and Hazelcast Jet – but it’s possible to re-use the principles that will be shown using other streaming technologies.

At a point in the past, it was forecast that Java would die, but the JVM platform would be its legacy. And in fact, for a long time, the JVM has been tremendously successful. Wikipedia itself list a bunch of languages that run on it, some of them close to Java e.g. Kotlin, some of them very remote e.g. Clojure. But nowadays, the Cloud is becoming ubiquitous. Containerization is the way to go to alleviate some of the vendor lock-in issues. Kubernetes is a de facto platform. If a container needs to be killed for whatever reason (resource consumption, unhealthy, etc.), a new one needs to replace it as fast as possible. In that context, the JVM seems to be a dead-end: its startup time is huge in comparison to a native process. Likewise, it consumes a lot of memory that just increase the monthly bill. What does that mean for us developers? Has all the time spent in learning the JVM ecosystem been invested with no hope of return over investment? Shall we need to invest even more time in new languages, frameworks, libraries, etc.? That is one possibility for sure. But we can also leverage our existing knowledge, and embrace the Cloud and containers ways with the help of some tools. In this talk, I’ll create a simple URL shortener with a 'standard' stack: Kotlin, JAX-RS and Hazelcast. Then, with the help of Quarkus and GraalVM, I’ll turn this application into a native executable with all Cloud/Container related work has been moved to the build process.

Kubernetes allows a lot. After discovering its features, it’s easy to think it can magically transform your application deployment process into a painless no-event. For Hello World applications, that is the case. Unfortunately, not many of us do deploy such applications day-to-day because we need to handle state. Though it would be much easier to have stateless apps, and despite our best efforts in this direction, state is found in (at least) two places: sessions and databases. You need to think keeping the state while stopping and starting application nodes. In this talk, I’ll demo how to update a Spring Boot app deployed on a Kubernetes cluster with a non-trivial database schema change with the help of Hazelcast, while keeping the service up during the entire update process.

When one’s app is challenged with poor performances, it’s easy to set up a cache in front of one’s SQL database. It doesn’t fix the root cause (e.g. bad schema design, bad SQL query, etc.) but it gets the job done. If the app is the only component that writes to the underlying database, it’s a no-brainer to update the cache accordingly, so the cache is always up-to-date with the data in the database. Things start to go sour when the app is not the only component writing to the DB. Among other sources of writes, there are batches, other apps (shared databases exist unfortunately), etc. One might think about a couple of ways to keep data in sync i.e. polling the DB every now and then, DB triggers, etc. Unfortunately, they all have issues that make them unreliable and/or fragile. You might have read about Change-Data-Capture before. It’s been described by Martin Kleppmann as turning the database inside out: it means the DB can send change events (SELECT, DELETE and UPDATE) that one can register to. Just opposite to Event Sourcing that aggregates events to produce state, CDC is about getting events out of states. Once CDC is implemented, one can subscribe to its events and update the cache accordingly. However, CDC is quite in its early stage, and implementations are quite specific. In this talk, I’ll describe an easy-to-setup architecture that leverages CDC to have an evergreen cache.

Créer une application ne consiste pas à écrire un code source immuable auquel plus personne ne prêtera attention. Au contraire, c’est un code fait pour être relu, maintenu et modifié. Or si les choses sont très claires en théorie, la pratique est comme toujours beaucoup plus complexe. Aujourd’hui, que nous soyons développeur ou SRE, nous sommes tous confrontés à l’écriture de code. Mais un code qui fait le job est-il nécessairement un bon code ? Est-ce que mon code est clair et compréhensible pour être maintenu par quelqu’un d’autre que moi ? Et en définitive, comment puis-je m’améliorer ?