Create a variety of xLights animations as multiple playback files
To animate your lights, you create special effects in the xLights program, then save these effects as a "sequence file" (also called a "show"). The show can be as fancy and you like and can run a long time. This page doesn't explain how to create shows in xLights, you can read how to do this in the xLights instruction manual here.
For Internet control of your Christmas lights, the idea is to allow people living in your neighborhood to watch your fancy show, but allow the show to be temporarily interrupted by people on the Internet who want to control your lights. When the Internet people have finished, your regular show starts again.
When you save a show in xLights, two files are created: an .xml file that allows you to edit the show later (adding or removing animations) and a .fseq file that is used for animating your actual lights. The fseq file tells which bulbs need to be which colors at any point in time during the show playback. It is like a canned recording of the animation.
My regular show is 8-1/2 minutes long. For Internet control, I make a series of small shows, only 30 seconds long. I save these as individual files (.xml and .fseq for each "mini show"). When someone from the Internet selects one of these mini shows, my regular show stops and the chosen mini show plays for 30 seconds. When the mini show is finished, the regular show starts again. Thus Internet people only have temporary control of your lights; when there is no one controlling them, your regular show plays for the people in your neighborhood as usual.
So, create a regular show (one large .fseq file) and lots of mini shows (multiple, smaller .fseq files). These files are saved in the xLight's "show" directory. Pressing [F9] in xLights will indicate where your show directory exists, but you will need to close xLights then open this folder with your operating system to reveal all of the .fseq files you have created.
The next step is setting up a Raspberry Pi computer to play these .fseq files, in the next part of these instructions.