[OpenDHT-Users] Re: Transaction like capability in openDHT

[Sean Rhea]

Zahir,

Do you know that OpenDHT will store multiple values per key?  I think
you can solve your problem like this: when a node A registers with a
gateway G, that gateway does

  put_removable(A, G, SHA1(S))

where S is a secret chosen by G.  When A subsequently registers with a
different gateway H, that gateway in turn does

  put_removable(A, H, SHA1(T))

where T is a secret chosen by H.  When a node B wants to route a
message to A, it does

  get(A)

which returns [G, H].  B then picks one of G or H and contacts A
through that gateway.

If A later unregisters with G, then G does

  remove(A, SHA(G), S)

so that subsequent calls to

  get(A)

will return only [H].

Does that not work for some reason?

Sean



On 8/22/06, Zahir Koradia <zahir.koradia at gmail.com> wrote:
> I am working with the Tetherless Computing group at university of
> Waterloo and am working on a routing protocol for Delay Tolerant
> Networks. What I need is that when a Node registers its existence this
> registeration message reaches multiple "gateways". All these gateways
> will try to register this node in the DHT by making an entry in it. If
> an entry for the node is already there then the gateway simply appends
> its id to the entry. The entry will basically indicate the list of
> gateways through which the node is reachable. Now if two gateways read
> an entry together and then update it without knowing that the otehr is
> working with it then only one of the two updates will be present
> leading to incorrectness. What I want is that when a gateway plans to
> update an entry it must be able to tell the otehr gateways that it is
> working on that entry and that no one else touch it. If two people
> send out the same message then a "collision" occurs and they need to
> agree upon who among the two should go ahead. Currently I am trying to
> use a group communication toolkit for the purpose but want to know my
> options before I go ahead.
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