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Author Archives: Ant Kutschera

Ant is a freelance Java architect and developer. He has been writing a blog and white papers since 2004 and writes about anything he finds interesting, related to Java or software. Most recently he has been working on enterprise systems involving Eclipse RCP, Google GWT, Hibernate, Spring and J2ME. He believes very strongly in being involved in all parts of the software life cycle.

Eleven Patterns, Problems & Solutions related to Microservices and in particular Distributed Architectures

The wish to fulfil certain system quality attributes lead us to choose microservice architectures, which by their very nature are distributed, meaning that calls between the services are effectively calls to remote processes. Even without considering microservices, we distribute software in order to meet scalability and availabilty requirements, which also causes calls to be remote. By choosing to support such quality attributes, we ...

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Kafka Record Patterns for Data Replication

java-interview-questions-answers

Imagine going down to your local milkshake bar and signing a contract with the owner so that you could purchase bespoke drinks at a set price. Let’s say you agreed on fresh milk with 3.5% fat and one tablespoon of chocolate powder, per 500ml of milk.  Putting that into a table might look like this: PKcontract_numberstartfat_contentchocolate_powder100123456782021-01-013.5%1 tbsp After a few ...

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Java problem with mutual TLS authentication when using incoming and outgoing connections simultaneously

java-interview-questions-answers

In most enterprise environments some form of secure communication (e.g. TLS or SSL) is used in connections between applications. In some environments mutual (two-way) authentication is also a non-functional requirement. This is sometimes referred to as two-way SSL or mutual TLS authentication. So as well as the server presenting it’s certificate, it requests that the client send it’s certificate so ...

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Several Patterns for Binding Non-transactional Resources into JTA Transactions

java-interview-questions-answers

I recently published an article about how to bind non-transactional resources like web services / microservices into global distributed transactions so that recovery is handled automatically. Over the years I have often had to integrate “non-transactional” systems into Java EE application servers and data consistency was often a topic of discussion or even a non-functional requirement. I’ve put “non-transactional” into ...

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Mysql versions prior to 5.7 do not fully support two phase commit

While doing some tests for the recently released generic JCA adapter which is capable of binding remote calls to microservices (as well as other things) into JTA transactions, I discovered a bug in Mysql 5.6 which has been around for nearly ten years. The test scenario was a crash after the “prepare” phase of the XA transaction, after both the ...

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Global Data Consistency in Distributed (Microservice) Architectures

I’ve published a generic JCA resource adapter on Github available from Maven (ch.maxant:genericconnector-rar) with an Apache 2.0 licence. This let’s you bind things like REST and SOAP web services into JTA transactions which are under the control of Java EE application servers. That makes it possible to build systems which guarantee data consistency, with as little boiler plate code as ...

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Is Asynchronous EJB Just a Gimmick?

java-interview-questions-answers

In previous articles (here and here) I showed that creating non-blocking asynchronous applications could increase performance when the server is under a heavy load. EJB 3.1 introduced the @Asynchronous annotation for specifying that a method will return its result at some time in the future. The Javadocs state that eithervoid  or a Future must be returned. An example of a ...

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