AWS Lambda is an awesome Serverless implementation. Lambdas are a bit tricky because they are ephemeral and short-lived so either they call another lambda or they will mutate some external state. Either an external data store like RDS, Aurora, S3, Kineses, Elasticache or they will call another microservices that does state mutation. In order to properly test Lambdas, we need to design for testability, the easier thing to do is always create more lambdas because you can check the input and output. So lambdas are not pure functions(functional programming) they often need to have side effects. So AWS has this…

Mock Server is an interesting and useful testing solution. Mock Server allows HTTP and HTTP Tests and verifications. Mock Server supports Java and NodeJS. Mock Server requires requests to match expectations. It’s not that different from a unit test from JUnit. However, Mock Server has the expectations in a central server and you could version those expectations as Json files for instances or use the standard API in order to create the with programmatic code in Java or NodeJS. So today I made a simple POC showing how we can use Mock Server, both with Java and JUNIT in an…

Lean / Kanban was always about managing work instead of managing people. Often mention as Manage the flow. Organizations are about organizing people, but they should be about organizing work instead. As organizations grow, it’s harder to make an impact and easier to get benefits. Safi Bahcall, the Loonshots book, says that as organizations are growing, the perks become much easier to get rather than impact(outcomes). That’s why politics and empire-building strike. Leaders need to be explicit about managing flow. Otherwise, organizations tend to focus on local hierarchies and produce local optimization(classical Lean issue). If we should manage work/flow instead…

Spring Boot is the most popular java stack nowadays. New languages like Go and Rust are capable of creating a single binary, self-contained with all deps to run the application. This is great for deployment simplicity but also easier to maintain. As time pass we want to have fast bootup times and do more with less. The native solutions are fast since they are statically compiled for a target platform or OS(in the case of UniKernels). Java was designed to be better as time pass(Runtime) and optimizations kick in. However thats not ideal for Serverless applications. GraalVM changes that since…

BOM(Bill of Materials) is an interesting technique to simplify dependency management. Dependency management is often a lost discipline nowadays and often developers dont care about dependencies. BOM is a way to make dependency management easier, however like anything in this world it can be abused. So be careful to not create a massive monolithic BOM with all your dependencies because that would be another microservices killer.

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Cheers,

Diego Pacheco

Originally published at http://diego-pacheco.blogspot.com on April 18, 2021.

Java SPI is a standard java way to have binding between contracts and implementations. SPI used for several use cases such as Currency, Locale, TimeZone, DateFormat, Number, JDBC Driver, JPA, Json, JasonB, and many more. I believe the most classical example is for JDBC/JPA use cases where you have one common spec(contract) and multiple implementations for each database driver such as MySQL, Postgres, etc… SPI is interesting, shower I would not use SPI for common bread a butter SOA / Microservices use cases. Because often you just have one contract and one implementation, for that case using the new keyword…

Lo4j is an old logging framework. Sometime ago Logback was faster than lo4j. Now, lo4j2 is the fastest and coolest kid on the block. Logs are the eldest and primitive form of observability. IMHO observability has many different use cases such as Troubleshooting, Business Discovery, Performance Troubleshooting, Reliability Assurance, and Testing. IMHO you could use logs for all those use cases, however, IMHO logs are best suited for troubleshooting and metrics and better suited for general observability. Logs can destroy application performance and often are the number 1 culprit of slowness. Log4j2 makes logging faster due to async logging and…

Design is not Subjective! I know we have bad actors out there and several times people do Bad Design and use subjectiveness as a way to control the dialog and shut down conversations. Today I want to explore more why I believe design is not subjective and Design is done by Design. Design is about Goals, Purpose, and Structure. Decisions are driven considering a particular problem Domain and thats an important matter. When we do design without considering a domain we often step into a code problem, not into a design problem. Just looking at the code misses the point…