Pass URL filename and URL parameters to browser

[jhgoebbert]

Some webservices can be initialized directly by passing parameters in the URL - for example this is the case for Xpra:
http://localhost:10000/index.html?username=test&password=123456

If one wants to use jupyter-server-proxy to start a xpra html5 desktop one would first start xpra on the server, generate a one-time-password and might think it would be fine to add this password using a mappath command as the password uri parameters to /index.html

But this is will not work (!),
because the index.html of Xpra wants to reads the password through the url parameters with javascript on the client side, too.

Proposed change

Url parameters should be passed to the browser.

Alternative options

The url parameters are shown to the user and he has to add it manually to the URL in the browsers address line.

Who would use this feature?

Any webservice, which extracts information from the url parameter (using JavaScript) on client side.

[jhgoebbert]

To be more concrete, I have written an Xpra proxy for jupyter-server proxy:
https://github.com/FZJ-JSC/jupyter-xprahtml5-proxy

Here I would like to use password/encryption of Xpra through the URI parameters, which is not possible at the moment.

[jhgoebbert]

The following pull request adds this feature to jupyter-server-proxy: #226

How it is used can be seen here:
https://github.com/FZJ-JSC/jupyter-xprahtml5-proxy/blob/v0.3.0_devel/jupyter_xprahtml5_proxy/__init__.py#L125