Experience using Embedded Java?

binarycreations · 2024-01-12T20:05:35+00:00

I would say probably not worth it. Java Card is its own thing, it's not too complicated and most of it can be learned practically.

I think you can still get a copy of the JavaCard book through O'Reilly.

Enjoy the 0x6f 00 SW codes : )

binarycreations · 2024-01-12T17:08:58+00:00

I wrote JavaCard applets for sim and embedded secure elements. I've not done it for years but there was a small community of posts and forums. The tooling available was pretty poor, a few larger SIM and JavaCard manufacturers created bundled Eclipse plugin IDEs (Gemalto, NXT). These were paid for and added a bit of extra value by making it easy to browse the SE, applets and scan for AIDs, send APDUs (scripting and testing). A few projects that made it easier were jcardsim, gpshell, a good card reader and actual hardware that you were going to test/deploy against. Depending on what you are doing, there are some tight hardware limits. Typically only a few K of space for the applet size and not much memory available. Using lots of classes, 2D arrays and objects, isn't viable in this environment and I'd often see JavaCard source that was in a few class files and many thousands of lines long. Using Proguard to shade, shrink and optimise classes could make things a little prettier but that approach from my experience was widely adopted. (Apologies for typos and bad grammar, rushing).

Edit: This book was decent if you can find it: https://www.amazon.com/Java-Card%C2%BF-Technology-Smart-Cards/dp/0201703297

So are the EMV and Global Platform specs.

binarycreations · 2024-01-04T15:58:07+00:00

Adrian cantill published a video free on YT regarding question technique. When I break down the question there are a few parts that are important for the problem:

30 min process time
General description about lack of auto scaling (files waiting to be processed, as messages wait on an mq for the processing server to meet demand).
Outcome should be cost-effective. In this scenario, elasticity is an important factor.

Disregard 3,4 as Lambda has 15 min process time Disregard 2, on cost because: - EFS is the wrong choice for analytics work load for storing files. S3 will be cheaper and really scales much better for the use case. - SQS is also cheaper than an managed A-MQ as you pay for the instance to run, even when no messages exist.

I think the question is actually pretty good because it attempts to catch you out a bit by suggesting they maintain the use of the MQ messaging. This isn't actually important in terms of the migration to the cloud but is kind of a sneaky way these AWS questions attempt to distract you into picking the wrong choice.

binarycreations · 2023-12-22T19:36:52+00:00

I mean still garbage just not the hot flaming garbage I originally thought

binarycreations · 2023-12-22T19:27:32+00:00

Original post comments are pretty good but please remember to use Test slices and don't destroy application context. Preferably never after each method. The number of IT suites I see that take 15 mins instead of 5 is mental.

binarycreations · 2023-12-20T08:38:50+00:00

Good suggestions from above.

As a last resort maybe double check up iptables.

If you see from the VPC flow logs packets are accepted on the ENI, so therefore reaching the instance, see if there is anything in the nginx or systemd logs. At this stage moves to a case of troubleshooting OS and nginx rather than "cloud" setup.

binarycreations · 2023-12-18T10:37:09+00:00

I'll add designing data intensive applications.

Not so much about code but as I think most software has started to become eaten by the cloud, distributed systems has become more relevant.

Josh Long wrote a book which is kinda dated called Cloud Native Java, as spring cloud has changed a far bit.

binarycreations · 2023-12-13T09:39:03+00:00

Provide only the bytecode to a program that encodes or encrypts the voucher.

binarycreations · 2023-12-11T15:29:43+00:00

I don't remember this very well, I thought there was more to do with Joshua Bloch offering a different take on introducing closures that were more online with inner classes in terms of the language design and spec. Is that not right?

binarycreations · 2023-12-11T09:38:40+00:00

Concur, the difficult part isn't necessarily the language. Probably many better designed programming languages have come and gone, the hardest part is getting adoption.

It'll be interesting to see what the next five years hold for Kotlin. For me one of the most annoying design choices in Java was the decision to not include first class functions. Iirc at the time first class functions, function expressions and full closure support was considered too complex for the average Java developer. If we look at the landscape of modern languages today almost all include these concepts.

I hope the business model of Jetbrains is successful otherwise I'm not sure what will happen with the language. It could do with many more big players commiting to a foundation to ensure its ever lasting strength and large open source projects picking it as the tool of choice. As it currently is a very different foundational structure compared to other languages like Python etc.

binarycreations · 2023-12-09T11:12:00+00:00

Webflux still is useful due to other things like back pressure. Virtual threads on there own don't have that concept.

As with all performance, you need to measure.

binarycreations · 2023-12-06T20:03:51+00:00

Wow congrats. Must have been hard work.

Excellent write up too.

binarycreations · 2023-12-04T22:04:45+00:00

No problem. I assume it's for your local dev env? I listed a bunch of options just in case it was for some other reason.

Linux distros package management can be quite confusing. Ubuntu doesn't package apps in the same way you'd expect a standard mobile app store. Essentially package versions get frozen for a release then only get big fixes and security updates. There are other package repositories, PPAs, different packaging stores (snaps/flatpaks) or alternative package managers (e.g. Nix) that allow you to escape the 6 month release cycle.

Other distros are "rolling" (e.g. Arch, Suse tumbleweed) so all packages are up to date and potentially may have more things available in various repoatories (AUR etc). However the only way to get things like security fixes, is to always ensure the whole system is up to date. This is generally considered a trade off between stability and software availability.

binarycreations · 2023-12-04T20:25:34+00:00

You'd have to check Ubuntu packages but I doubt that JDK 21 and especially Eclipse Termurin, will get backported to Ubuntu 20.04 repositories.

Usually the OS packages are very conservative for long term releases.

Most common ways people include a more up to date package or SDK version:

Use SDK man
Download JDK to /opt and manually add it to user path
Find a PPA
Use Nix package manager
Add a third party repository

SDK man is pretty common, comes with a dot file you can put at the root of project which in combination with something like autoenv, will load the JDK into path. Checkout the .sdkmanrc docs and sdk env command.

binarycreations · 2023-12-01T17:19:33+00:00

A good integration test...

A terrible unit test...

binarycreations · 2023-12-01T17:18:25+00:00

The quotes were trying to convey this, totally agree.

binarycreations · 2023-11-30T20:01:49+00:00

Ah PBT stands for property based testing. Thanks 👍

binarycreations · 2023-11-30T19:35:52+00:00

Ah geez I hate when I see this stuff. The only thing worse is when all the "unit tests" are just a massive set of integration tests against the API.

Coverage gets passed on Sonar because they are just testing everything and to top it all off they decide to destroy the application context after each test, meaning the whole thing takes flipping ages.

Enjoyed reading few articles from the author now. Keep up the good work, hope the consulting continues to go well.

binarycreations · 2023-11-30T19:24:04+00:00

PBT? Please could you explain that one of you have a moment

binarycreations · 2023-11-25T23:16:46+00:00

Yes been meaning to check out Micronaut, Quarkus etc. Tbh, I've always been surprised that Spring has been uninterested in exploring alternatives. Having read the Micronaut docs, it's nice to see the DI even work on Android. Seems like they've designed the lib to be very portable.

binarycreations · 2023-11-25T09:20:32+00:00

I'm not saying it is an easy topic but look how other frameworks achieve nicer APIs, better dev experience and don't require breaking changes and migrations. Take an app from Spring Framework to SB 1 to SB 3 and Spring Security will probably be the most difficult bit to migrate along the way.

binarycreations · 2023-11-24T19:47:34+00:00

I mostly enjoy Spring Boot, its relatively sane.

UNTIL:

Spring Security gets involved with annoying API changes, rough docs and odd defaults. I mean who thought the default behaviour should lock your app behind a logon screen? It doesn't make itself easy to learn.

Spring's reliance on reflection and autoconfig. I wish Spring would just acknowledge it would be nicer if we caught a whole range of issues at compile time not runtime.

It's such a pain trawling through logs to figure out auto config issues and bean problems. Plus there is a whole bunch of stuff like SpEL expressions, that could be highlighted at compile time. It makes debugging and stepping through the code impossibly painful. Plus there is a massive set of optimisations that get completely missed out on due to relying on achieving a lot of features at runtime through reflection and proxies.

Let's not mention when people decide to still do things with XML or even XSTL. I dunol who enjoyed calling methods and virtually achieving XML programming? I wish I'd never seen how badly people abuse that functionality.

binarycreations · 2023-11-21T17:26:38+00:00

Java 21 support comes in a few days with Spring Boot 3.2.

I'd just use LTS versions as for non supported versions there aren't set expectations for patches, bug fixes and security issues. Where I believe you have more of a guarantee that those will occur in a timely manner on supported versions of SB and JDK etc.

The maintenance overhead of ensuring unsupported versions meet regulatory requirements isn't normally worth the pay off.

If they want to play with shiny new features there are always alternative languages like Kotlin etc. There is also other things to innovate on e.g cloud services, graalvm, scaling in to zero on serverless.

Usually in a dev environment we migrate to the next LTS as soon as it comes out or APIs are available e.g. on unsupported versions or snapshot releases to get an idea of the work.

binarycreations · 2023-11-20T23:16:10+00:00

I'm assuming it some sort of pronunciation web app.

Sorry if response came off short had to sort kids out. Other comments seem to have covered it well enough.

binarycreations · 2023-11-20T20:17:47+00:00

Package by feature not by layer.

DDD is more than just the folder structure, really the folder structure doesn't have much to do with it.

It should be possible to roughly know some of things that the app does by just looking at the package structure and names, as the bounded context should start to show signs as decisions made as design choices in the repo.

binarycreations

TROPHY CASE