Cloud Application Layer Part II.

	Ph. D. Julio Fernandez Vilas
	¿Any comments? jfvilas@gmail.com

One of the strongest arguments to defend cloud computing is its cost model, as we have seen in previous articles. Although performing control on costs is important, to move from a model based on CAPEX and OPEX to a pay per use model (CAPEX = 0, there is no CAPEX and OPEX is lineal), it remains especially important being able to be tied to a provider.

It is vital to be able to change provider without cost or at least paying the minimum possible cost, since the prices offered by vendors will probably be subject to revision, which could undermine the competitive advantages of the pay-per-use model.

A change of provider must be performed, typically by modifying configuration files or any kind of helper-class if needed.

Again, it is necessary, when we are talking about integrating cloud services into business applications, to create an intermediate layer that isolates applications from using the cloud services they use.

We are talking again about the Cloud Access Layer, which in this case is embodied in a software layer, typically a connector or adapter. This piece of software is what (inside our cloud computing stack) we call the cloud access point.

Develop or adapt applications that accesses the cloud via access points in the future ensures the ease of changing a provider.

This ease of switching providers will take advantage of competitive rates for the same service (form different providers), so that the cost of changing the provider is so small that could exploit the slightest variation in the cost of cloud services that we are using.

Now that we have introduced the concept of provider as an important element within the cloud computing stack, we will redesign the stack. This is CCS2.0 (Cloud Computing Stack 2.0).