Provide ability to create calculated item based on several discovered ones

Right now there seems to be no mechanism that could be used to perform a calculation on an unspecified number of items, which were created by discovery. Consider the following scenario:

• discovery rule is used with snmpwalk to iterate a number of switch interfaces, PDU legs, or filesystems
• to keep track of total switch traffic, current flowing through all legs on PDU, or total amount of stored data, a function similar to this would be great:

sum(last("ItemName[*]"))

This would allow to create more generic and flexible templates, and take better advantage of the wonderful framework of discovery.

Another option would be to have aggregate function that could be used within the template to be specific to said host.

keywords : lld