Leaning Technologies

The home of Cheerp, CheerpJ, and CheerpX. Chat about virtual machines, compilers, and WebAssembly!

Leaning Technologies

The home of Cheerp, CheerpJ, and CheerpX. Chat about virtual machines, compilers, and WebAssembly!

4/29/2025

UnsupportedClassVersionError

Explcitly running with java 11, but sometimes on page refresh/app launch get this. ususally if I refresh again, the error is gone. But seems quite strange, since the class in question is a Java library class. In this case it is the BasicLookAndFeel class, but sometimes it is other JRE classes: java.lang.UnsupportedClassVersionError: Required Java version 45532, but CheerpJ only supports up to Java 11 at this time. Unsupported class: javax/swing/plaf/basic/BasicLookAndFeel...

JacobDK123

4/29/2025

cacerts No such file or directory

Expected to find the JRE trusted certs at, but got: Caused by: java.io.FileNotFoundException: /lt/11/lib/security/cacerts (No such file or directory)...

JacobDK123

4/29/2025

java.lang.UnsatisfiedLinkError 2

##4 Caused by: java.lang.UnsatisfiedLinkError: Java_java_io_ObjectStreamClass_initNative at java.io.ObjectStreamClass.<clinit>(Unknown Source) ~[na:na] at java.io.ObjectInputStream.readNonProxyDesc(Unknown Source) ~[na:na] at java.io.ObjectInputStream.readClassDesc(Unknown Source) ~[na:na]...

JacobDK123

4/29/2025

UnsatisfiedLinkError

Great with Java 11 suuport. I immediateliy tried our old desktop app, but quickly ran into these problems with the bundled java libraries. Am I doing somethin wrong, or is this simply corners of the JRE not addressed yet? Here's the stack traces: #1 Caused by: java.lang.UnsatisfiedLinkError: no management_ext in java.library.path: [.]...

SharkBaitDLS

4/27/2025

Licensing Confusion

I'm struggling to understand the licensing model a bit. I'm working on a FOSS project that has more contributors than just myself -- does that mean we're ineligible for the community license? Would that put us under the non-profit organization bucket?

User

4/23/2025

Why isn't the .jar file reading for the web test?

im a complete noob at this so tell me everything im doing wrong

oyin.bo

4/21/2025

VSCode extension

I want to build a VSCode extension running Linux+bash in WASM usig this CheerpX library. * Do I need a license? * Do I need any caveats in my extension Readme? My goal is to enable VSCode/web to run more development tasks in browser, without full local VSCode. Hopefully enabling software development at lower footprint, and using tablets and hand-held devices....

parvob19

3/17/2025

adding a file as a jar argument cheerpjRunJar

I have a jar file that asks for a config file as an argument as follows: example.jar --config /path/to/config.json It seems as if the applet cannot get access to this file. I have it in the same directory as the .jar file, and have tried adding the arg per cheerpj documentation: await cheerpjRunJar("/app/2009scape.jar", ["--config /app/config.json"]); am I missing something, or is adding external files a browser security issue that will not be easily solved?...

TimBarron

2/25/2025

Interacting with System.in

I'm looking into using CheerpJ to put together a website to showcase student projects in my intro programming class. I've been testing with projects from past semesters. Many are using swing and are working well, but some students' projects have user interaction in the terminal (REPL style). When I run non-gui applications I see stdout in the browser console which is a good start, but I'm not sure how to interact with stdin.

SS Zeklord

2/15/2025

I cannot get the example applet to work in my chrome browser on mac os

I tried cloning the example here - https://github.com/leaningtech/cheerpj-meta/tree/main/examples/Pitch-Applet But am not able to get it to run...

pescennius

2/10/2025

multiprocessing

Can I leverage my systems other cores via webvm or am I limited to single core execution?

pescennius

2/6/2025

webvm filesystem and headless

I was directed to Discord to learn more about using webvm with filesystem APIs. I hope this is the right place to ask. I want to run webvm headless, such that my Javascript executes shell commands but I display my own html/js frong end. I also want to be able to save files to the filesystem or at least as a stopgap serialize those files generated in my VM to Javascript to enable file downloads.

Stitch

2/6/2025

have a running Terminal on my website

Hello, guys if anyone could help me please I am trying to use Cheerpx to have a running Terminal on my website, I cant figure out a way to do it im using JS and html for now and im currently stuck I do not know how to set it up. The image above is what I have ofc there isnt an actual terminal,...

Alif

2/6/2025

cheerpJ usage patterns..?

The application does not launch, normally you should access another page. This is just the loading page

Axx

2/3/2025

Compatibility ?

I have a community card playground, quite old (developed more than 10 years ago). It works via JAVA applets. This playground is multiplayer. I tried the browser plugin, it doesn't work.

hcldan

1/23/2025

CheerpJ usage patterns... ?

For some background: We have a native application that we have ported to WASM. This native version has features that run a JVM, manage it, load and run code in it, and communicate over JNI/JNA. I'm trying to get a handle on how we might use CheerpJ here, and wondering where to start. It's not as simple as run this lib from this web address... jar files would exist on a WASM filesystem. We also use features like a security manager....

pmania

1/13/2025

Hello I am trying to open a webpage from an Asrock Rack motherboard so I can view the bios

of the motherboard through a webbrowser but it works wiht java, but I tried to open it but it won't open. I installed this extension but no luck yet.

NoOperation

1/8/2025

Possible?

Hello. I need to solve this on client side: Pull down a git repo of 3 mb and save all files client side in browser Run a python script to modify these files Upload to same git repo ...

Kameechewa

1/1/2025

Page Loads Blank

I am trying to access a Tripp Lite SNMPWEBCARD web interface that uses Java Applets. Currently I have to access it by using the Pale Moon browser along with JRE version lower than Update 8 v71 as apparently that version does not allow MD5 for certificates. I am not a developer and don't really know much about how this works. I am a systems administrator though so I'm not completely illiterate with computers. I am not sure what information I need to provide to help and I hope this is the right place to ask for help. When I load the page without CheerpJ it directs me to learn about appelets. With the extension it loads the "frame" that the interface would appear in but it's just a blank white page along with the learn about applets text below. The text part is normal....

Xiph3r

12/19/2024

JNLP file not loading

i downloaded the extension so i can use your extension to run a JNLP file to connect to my supermicro server, however it doesnt load and i can only download a blank file. clicking start application doesnt do anything

Gaming

Programming

Leaning Technologies

The home of Cheerp, CheerpJ, and CheerpX. Chat about virtual machines, compilers, and WebAssembly!

Leaning Technologies

The home of Cheerp, CheerpJ, and CheerpX. Chat about virtual machines, compilers, and WebAssembly!