Microsoft has opened their APIs to allow for increased integration and deployment of solutions to help fill these gaps – as well as enabling their partners to offer their unique take on the solution to improve overall cost and general feature set availability. Your choice of deployment model will depend on your organization’s current infrastructure, risk tolerance, feature requirements, and budget. An important concept to be aware of is that vendors all have their own unique take on the integration level they offer, the ways in which they deploy it, and the way in which cost is structured.