Launchers 101

[Norman Feske]

Hi John,

> This seems like it would be a neat function to add to the Leitzentrale
> GUI - maybe a "Create Launcher" button inside the Component detail,
> beside "Restart" and "Remove".  ("Edit Config" would probably be nice
> also.)

that's a good idea. I wonder, what do you think about the following aspects?

- When creating a launcher for a deployed component, should the
  start node of the component in managed/deploy automatically be
  changed to refer to the new launcher?

- What should happen when deploying a new component that has the
  same name as an existing launcher? If this is allowed - like today -
  the start node of the deployed component would differ from the
  existing launcher. Would Sculpt need to detect this situation,
  offering an "update launcher" button?

- Should the reverse operation be supported via a "remove launcher"
  button - removing a launcher for running component, turning this
  component into a regular start node of the deploy config?

Intuitively, I tend to answer those questions with yes to foster the
consistency of the feature. On the downside, implementing those corner
cases with their possible intermediate states is not quite easy.

What do you think?

I also like your idea to make the config of a component easily
customizable without manually diving into the config/deploy or
config/launcher files. Sculpt's underlying mechanisms actually support
that today: When adding a customized <config> node inside a <start> node
in config/deploy, the component observes a config update.

For example, if you have the pkg/sticks_blue_backdrop deployed (and
copied /config/managed/deploy to /config/deploy), you can add the
following snippet to the start node in /config/deploy:

  <config>
    <libc/>
    <vfs> <rom name="genode_logo.png"/> </vfs>
    <fill color="#223344" />
    <image png="genode_logo.png" anchor="bottom_right" alpha="150"
                                 xpos="-20" ypos="-20" />
  </config>

You can even change all those attributes on the fly and the backdrop
adjusts. This way, the backdrop can easily be customized without
touching any depot content. The machinery it there. But I admit that the
process is not really intuitive. ;-)

A button that takes the <config> node from /config/managed/runtime to
/config/managed/deploy and shows the config in a text editor for live
editing - that would be quite inviting!

Cheers

Norman

-- 
Dr.-Ing. Norman Feske
Genode Labs

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