axLazyElement not able to identify whether remote element is stopped or running

[edgarjoao]

Hi there, I'm running in an issue using axLazyElement, I do have a shell and MFE running in separated http servers. Every time I have to stop the MFE I'm expecting axLazyElement directive identify whether the MFE is running or not. Is there a way to setup this feature?

Thanks

[DanielBou99]

Hi @edgarjoao did you try to use ng-template like this?

<ng-template #error>Loading failed...</ng-template>
<mwc-button *axLazyElement="url; errorTemplate: error; module: true">
  Submit
</mwc-button>

[edgarjoao]

Hi @DanielBou99, Adding tag is working just once, but if you stop the web server where your MFE is running, the ng-template does not catch that.

[DanielBou99]

@edgarjoao when it happens, did you try in another browser or anonymous Page? It appears to be cached by the browser

[edgarjoao]

Hi @DanielBou99 this is happened in any browser.

This is my Shell Driver app. The shell app is running in port 4200 and my MFE is running in port 4202, Im using angular proxy. As soon I kill the MFE process Im expecting the axLazyElement tag library identify it and then remove the MFE from the shell app. At this moment the MFE is not running and the shell still have it cached in their side.

The only way to identify whether a MFE is running or not, it’s reloading the page, but this is not good for SPA.

Is there a way that axLazyElement library to not cache the MFE and listen when is not running?

[DanielBou99]

@edgarjoao I'll try to see. @tomastrajan can you help?

[DanielBou99]

@tomastrajan also, is it possible to send the repo of your projects?

[DanielBou99]

After several tests, I finally found the problem. Apparently when the elements extension service send the first HTTP request to get the micro front-end code, the browser saves this response. After that, for the next requests, the browser automatically returns the response it saved from the first request. For this reason, the main project is not detecting changes in the front-end micro because browser it's caching the first result.

I believe the solution is to somehow force the browser to make the request again, I am studying a way to do this.

[DanielBou99]

@edgarjoao I just solved the issue!

Solution: I was running the micro frontend server with the command npx http-server witch by default send in the header cache-control 3600 (seconds). To solve this problem, I just run the command like this npx http-server -p 4444 -c-1 to disable caching. Probably your issue is the same, check if this is happen.

[edgarjoao]

Hi @DanielBou99 Make sense, in some way the shell/driver app is caching the request to the MFE. At the end of the day the shell and MFE's would be deployed in a Web Server (http-server, apache, nginx, etc) where we can disable the option to cache.

I'm using ng serve to run the MFE and driver app, is there a way to disable the cache there?

[tomastrajan]

In general it works the best to use E-tags when serving element (webcomponents) bubdles.

Url will always stay the same(no hash in filename), FE will make a preflight request to BE to figure out if content of the bundle changed since last request.

Hope that helps!

[DanielBou99]

@edgarjoao probably yes, I can check it out if you push the projects to your repository.

[edgarjoao]

Hi @DanielBou99 and @tomastrajan, Taking a look in the code, I can see a line where the script is appended to to document.body in case everything is good. https://github.com/angular-extensions/elements/blob/master/projects/elements/src/lib/lazy-elements/lazy-elements-loader.service.ts#L169

I think a remove element would be an option in case an error trying to load the javascript. Adding this remove element in cleanup function. https://github.com/angular-extensions/elements/blob/master/projects/elements/src/lib/lazy-elements/lazy-elements-loader.service.ts#L157

[DanielBou99]

Hi @DanielBou99, Taking a look in the code, I can see a line where the script is appended to to document.body in case everything is good. https://github.com/angular-extensions/elements/blob/master/projects/elements/src/lib/lazy-elements/lazy-elements-loader.service.ts#L169

I think a remove element would be an option in case an error trying to load the javascript. Adding this remove element in cleanup function. https://github.com/angular-extensions/elements/blob/master/projects/elements/src/lib/lazy-elements/lazy-elements-loader.service.ts#L157

I understand but it would be necessary to reproduce your error to understand what is happening because in my project I managed to solve it.