private void validate() throws RrdException {
		if(!ArcDef.isValidConsolFun(consolFun)) {
			throw new RrdException("Invalid consolidation function in fetch request: " + consolFun);
		}
		if(fetchStart < 0) {
			throw new RrdException("Invalid start time in fetch request: " + fetchStart);
		}
		if(fetchEnd < 0) {
			throw new RrdException("Invalid end time in fetch request: " + fetchEnd);
		}
		if(fetchStart > fetchEnd) {
			throw new RrdException("Invalid start/end time in fetch request: " + fetchStart +
				" > " + fetchEnd);
		}
		if(resolution <= 0) {
			throw new RrdException("Invalid resolution in fetch request: " + resolution);
		}
	}