… Pyretic’s policies-as-abstract-functions approach … helps support modular programming … Pyretic programmers must discard the rule-based mental programming model and adopt the functional one. … raises the level of abstraction and enables the creation of modular software.
in Frenetic project, we are designing simple, reusable, high-level abstractions for programming SDNs; and efficient runtime system that automatically generate and install the corresponding low-level rules on switches. our abstractions cover the main facets of managing network specifying packet-forwarding policy, monitoring network conditions, and dynamically updating policy to respond to network events.
offer an API that is a thin “wrapper” around these operations
policies-as-abstract-functions — from input located packets (i.e., packet and its location) to an output set of located packets. … in traditional OpenFlow programming, the programmer cannot write application modules independently without worrying that they might interfere with one another.
| syntax | summary |
|---|---|
modify (f=v) |
returns packet with field f set to v |
fwd (a) |
'modify (port=a) |
route a packet with destination IP 1 across switch A and B:
(match(switch=A) & (match(dstip='1'))>>fwd(6)) +
(match(switch=B) & (match(dstip='1'))>>fwd(7))
use predicate policies (match, &) to disambiguate between
packets based on their location in the network as well as their
contents; use modification policies (fwd) to change the
header content or location of packets.