expressjs | This is the repository for my course , Building a Website | Runtime Evironment library

If your file structure is:

To communicate safely between threads, Electron some time ago introduced the use of a prelaod.js script. This script is effectively the gatekeeper between the main thread and render thread(s). Electron's Context Isolation page will explain this in more detail.

In addition to this, communication between threads is performed by Inter-Process Communication. These IPC commands are used to initiate and listen for communication over 'channels'. Channels are just names of your choosing along with which data can be attached (if needed).

The main component one needs to understand and implement is the preload.js script.

Here, you include whitelisted channel names. Any name format can be used. Any channel name not included in these lists will be denied communication between threads.

PS: Many people (including some Electron documentation) include actual function implementation directly within the preload script. Whilst there is nothing wrong with this it definitely does make things more complicated than necessary. Using the preload script to manage channel names only, frees up implementation of the channel names elsewhere which greatly simplifies things. IE: Separation of Concerns.

preload.js (main thread)

This might be a client-side issue with the browser caching.

I set up a test server based on your sample (side note, always helpful to include a Minimal, Reproducible Example...makes it quicker and easier for others to troubleshoot/reproduce your problem)

Running express on the command line invokes the functionality provided by express-generator (if you have it installed). Any output from this program would be specific to express-generator and not to express itself.

What you're seeing is the version of express-generator that's installed on your system, not the core of express itself. Use the output of npm list [-g] to discern what version of "core" Express is installed on your system or in your project.

I have mirrored Your project with small improvements.

From Your folder & file structure and index.html exactly from this line below :

At line 125 of the resume-openfont.cls comment the command \faExternalLink, which inserts such symbol and the link. The \Project command is the one that inserts the hyperlink.

I have done some research on this.

As it has been discussed in this post: AWS API Gateway Websockets -- where is the connectionID?, the accepted answers (the solution I was trying in my question above) are assuming your are using Lambda as the backend integration.

However, I am using Express JS running in EC2 instance and VPC Link.

In my case, the issue actually is solved by one of the upvoted answers (but not the accepted one): https://stackoverflow.com/a/65639742/3703783.

The official documentation is here:Setting up data mapping for WebSocket APIs.

The above method will add the connectionId to the header of the integration request, but only having the connectionId is not enough - we also need the info like username so that the backend is able to know which connectionId to use when sending message to a particular user. This will do:

The reason why there is no response when you connect to the websocket is because you do not have the HTTP endpoint setup in your backend express app.

When you connect to the AWS API Gateway WebSocket API, WebSocket API takes action set by your $connect integration. In your current configuration, you have set the VPC Link integration with HTTP Method Any on the target url. Thus, for your backend endpoint to be called, you need to create a HTTP endpoint and set the address of the endpoint to "Endpoint URL."

For example, let's say you have the following route set up.

I got the same thing in my nodejs application. My middleware was crashing in the application, and after some time of the crash, the unhandlesPromiseRejectionException was raised. The middleware is not async, but this crash is stopping the execution of the code (if try catch is not used to handle it), thereby terminating the entire process and then after a while the exception is raised.

If you notice the time of error receiving on the client, you could see that you get the error on the client sooner and the PromiseException gets raised later. I would ask you to check, if the error you get on the client, is that a timeout error, or the error code that you have thrown

I think Express just raises unhandled exception in middlewares as unhandledPromiseRejection By default as it is a break in its api hittin process which is asynchronous by default. EVen though your middleware is synchronous, but it is placed in an asynchronous process of an API route, and if anything crashes in it which is not handled, it will raise an UnhandledPromiseRejectionException as it is a crash in an asynchronous process.

Try to think of it as this : -