@grmpyprogrammer umm, probably thinking about one option for everything, not consodering the use case, the data structure, is a mistake. If you are transmitting ojects and programming variables, etc., Non critical data, between homogeneous layers, simple api calls JSon is great. If you are managing critical data, complex content or encoding complex configurations it is probably an xml case IMO. The readability also, xml may be more apropriate for complex content, mixed data, etc.