I need some help with the diagrams (class, object & activity diagrams). Please let me know if you think you can help. Thanks
It's good to have a set of UML diagrams to keep track of what is happening, but to remember in the end that documentation decays - your code is your design. That said, UML are good for planning and recalling bits and parts.
The document shouldn't decay as you should keep it up to date..... making future changes to a large complex application/ website is much easier when you have full flow diagrams/ process maps/ UML. The amount of money that is wasted having to redocument or reverse engineer things when a mid size change is desired a couple of years down the road is staggering compared to the effort it would have taken just to keep things up to date in the first place.