In the case of cabbage (or other greens), I've never noticed so much water as i have with belgian endive. It just seems to pour out of it. Even tonight, i made a salad with the endive and ten minutes later it was in a puddle of water.Most any green you dress and hold will render water. This isn't always bad as you usually want a little wilt in a cabbage slaw for example. But if you want to control your dressing, you need to manage the water.
often the cabbage will be pre salted and rinsed/drained before assembling the salad. This way the cabbage should be about done with losing water. Should work for endive too.
Another trick I've seen is to proceed as normal but invert a small to medium bowl in the bottom of your serving dish. This holds the slaw/salad up so water can drain out without the whole dish becoming watery. This isn't perfect as the dish may end up under-dressed as the liquid drips off so be prepared to correct the dish as needed.