I should start off by saying that a lot of this code is in flux right
now. As KK mentioned, I recently checked in some significant changes
to authenticator that will hopefully make retrieving exactly the type
of information Te-Yuan is looking for much more efficient by not
requiring a call to the database and thus not requiring the
asynchronous callback interface. That being said, only the back-end
of these changes has been checked in, and the improved interface +
documentation to go with it has yet to be completed. Thus in the
meantime, bindings_storage is the correct way to retrieve this
information.
All calls to bindings_storage take a callback as an argument because
they require a query to the database. Assuming you're querying from
python (the required callback prototypes for C++ can be inferred from
bindings_storage.hh), there are two high-level types of queries:
get_names_by_* and get_entities_by_name.
get_name_by_* (e.g. get_names_by_mac, get_names_by_ip etc) will
retrieve all names associated with a given network identifier. The
callback passed in will be called with a list of (name, name_type)
tuples (e.g. [ ("host1", Name.HOST), ("user1", Name.USER) ]).
get_entities_by_name meanwhile will retrieve all network identifiers
associated with a particular name. In particular, the callback passed
in will be called with of a list of (dpid, port, ethernet addr, ip
addr) tuples. The values returned however are in their integer format
so you'll likely want to create datapathid/ethernetaddr/ipaddr objects
out of them.
bindings_directory.py wraps some of the bindings_storage code for
specific uses, but I'm not sure how easy the code is to follow as
example uses. For example, get_interfaces_for_host(hostname) returns
the information get_entities_by_name does but with a location name and
also with the mac/ip addresses in their typed forms.
In regards to the specific query for the switch a host is connected
to, you'll probably want to use get_entities_by_name("host1",
Name.HOST, cb)
In general all of this code isn't nearly as clean/documented as we'd
like it to be, but we're working on it and will hopefully be able to
get it out there soon.
Natasha
On Feb 16, 2009, at 1:00 PM, kk yap wrote:
HI All,
Below is a question about location binding. The new upgraded version
from Natasha looks very useful, and we would love some help in getting
to use it.
Thanks.
Regards
KK
---------- Forwarded message ----------
From: Te-Yuan Huang <[email protected]>
Date: 2009/2/16
Subject: Questions on Location Binding
To: [email protected]
Cc: kk yap <[email protected]>, Nikhil Handigol
<[email protected]>, Michael Chan <[email protected]>,
Masayoshi Kobayashi <[email protected]>
Hi all,
I am trying to use Bindings_Storage to retrieve information
about which datapath(switch) a host is connected to.
Questions:
1. Which function should I look into?
I did found that "get_location_by_name" might be helpful,
but I would like to confirm the functionality of it.
Or would love to know where can I find documentations about
functions inside Bindings_Storage.
2. In order to use get_location_by_name, I need to supply a name for
host in string format.
There is a get_name_by_ip() function, but there is no return value.
I guess the information is passed by reference through callback
functions.
But I have no clue about which function I should pass into the
get_name_by_ip() function.
Is there any sample code that I can take a look at ?
Best,
Te-Yuan
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