Ritically assess the attractions of commodities as an asset class over the short and long-term

Assessment Criteria-Essay should cover equally the following ares:
characteristics of commodity investment; means of commodity investment; historical performance; changing economic factors

Note: Please make sure that references are given properly according to harvard style and they should be clearly marked whether there are from book or internet site hence no pilagarism at all. You can use sources as many as you like.
Thank you