Enable Broker to try selecting the closest Datacenter to place VMs

[manoelcampos]

The DatacenterBrokerSimple and all available implementations select the first Datacenter to try placing all VMs. When the creation of some VM fails due to lack of suitable Hosts, the broker tries the next Datacenters.

Since the Datacenter has a timeZone attribute, it would be very useful to enable to broker to select the closest one to place each VM.

Detailed information about how the feature should work

To enable that, a timeZone attribute to indicate the time zone where a VM is expected to be placed needs to be introduced.

Since the broker already has a default policy to select the datacenter to try creating VMs, if you want it to select the closest datacenter instead, that feature should be enabled by setting some attribute.

An example scenario where this feature should be used

The researcher can set the time zone for VMs and then, place such VMs
at the closest Datacenter, aiming to reduce network delay.

A brief explanation of why you think this feature is useful

It will enable more realistic selection of Datacenters where to place VMs.
Cloud providers such as Amazon have datacenters in multiple regions across the globe
and the customer can select the region where he/she wants to place his/her VMs.

Examples Available

• DatacenterSelectionByTimeZoneExample.java