[alto] Unified properties salient design points

["Y. Richard Yang" <[e-mail]>]

Dear all,

As multiple discussions, we feel that the unified properties draft (),
although not a working group draft, can be an important piece to help
finish several remaining working items.

For those who are not tracking the document, the design might appear to be
simple: it is after all just a simple key-value map. When conducting a real
design, many issues, many quite general, however, appear. Hence the design
can benefit from good feedback from the good talents of this group. The
objective of this email is to make clear the salient points of the current
design. We will go over and discuss them Friday during the WG session.

D1. The goal is to provide properties to entities.

D2. Each entity must have an entity name to be identified. An entity name
is a typed (domained) string, in a format of <domain>:<name>, e.g.,
"ipv4:192.1.1.1", "pid:myid1", "ane:myane111". The <domain> provides
essentially the type of the name.

D3. There are essentially three types of domains: global, per-resource,
per-query (dynamic):

D3.1 ipv4 and ipv6 are global, in that they are not dependent on particular
resources;

D3.2 pid depends on a particular network map resource;

D3.3 ane (abstract network element) may depend on a particular query of an
ALTO resource. So far we cannot handle such case well. There can be
multiple design options, but each adds more complexity.

D4. Aggregation of entities is allowed, to improve scalability. Hence, an
entity name may be either an individual entity or a set. An example is an
IP prefix.

D4.1 An implication of 4. is that we need to handle property inheritance.
Multi-inheritance is tricky, as OOP multi-inheritance demonstrated. So far
longest prefix matching (LPM) avoids the problem. But we need to decide if
we want to have a spec on future design of this aspect.

D5. Property names are in a global namespace, to enforce global, consistent
usage of property names.

It is not a long list but contains many interesting design points.

Looking forward to good discussions soon!

Richard