From puramihai at gmail.com  Wed Mar 17 04:28:12 2010
From: puramihai at gmail.com (Pura Mihai)
Date: Wed, 17 Mar 2010 10:28:12 +0200
Subject: [Avispa-users] Sending a set
Message-ID: <b61346f11003170128r6d9ca451k9f1f216f3ab9f75e@mail.gmail.com>

Good day,

I want to model a protocol in witch agents add their identities to the
message they forward. Example:

S -> B: (S)
B -> C: (S, B)
C-> D: (S, B,C)

I modeled the coresponding information as a set (IDs : (agent) set). Each of
the roles will get as parameter a different IDs variable that was
initialized with {}. The problem is that I found out from the documentation
that sets are transmitted through reference. So when node B will modify its
IDs variable and sent it to C, IDs of S will be modified too.

How can I solve this problem?

Mihai Pura
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From puramihai at gmail.com  Wed Mar 17 04:40:26 2010
From: puramihai at gmail.com (Pura Mihai)
Date: Wed, 17 Mar 2010 10:40:26 +0200
Subject: [Avispa-users] Sending a set Example
Message-ID: <b61346f11003170140x406c4f4frba0326b5ac99bb24@mail.gmail.com>

Here is the code for the role

role node(N   : agent,
              RouteN : (agent) set,
              Snd, Rcv  : channel(dy))
played_by N def=
local State : nat,
      RP : text,
      T,I : agent,
      Ni : text
init State := 1
transition
forwardrdp. State = 1 /\ Rcv(RP'.I'.T'.Ni'.RouteN')
            =|> State' := 1 /\ RouteN' := cons(N,RouteN') /\
Snd(RP'.I'.T'.Ni'.RouteN')
end role

///////////////////////////////////////////
So the agent needs to extract the set, add its identity to its contents, and
then send the new set.
It is an intermediary node in DSR routing protocol.

Mihai Pura
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From puramihai at gmail.com  Wed Mar 17 04:59:02 2010
From: puramihai at gmail.com (Pura Mihai)
Date: Wed, 17 Mar 2010 10:59:02 +0200
Subject: [Avispa-users] Send a set over a channel
Message-ID: <b61346f11003170159u1190657em9f3eb7f03cfc57f3@mail.gmail.com>

I have just tested the approach suggested by Tigran S. Avanesov:

role node(N   : agent,
            RouteN : message,
            Snd, Rcv  : channel(dy))
played_by N def=
local State : nat,
    RP : text,
    T,I : agent,
    Ni : text
init State := 1
transition
forwardrdp. State = 1 /\ Rcv(RP'.I'.T'.Ni'.RouteN')
          =|> State' := 1 /\  Snd(RP'.I'.T'.Ni'.RouteN'.N)
end role

The problem is that in environment role I have several instances for the
role node. And all these instances should do the same thing: receive the
message, add their identities and then send the message to the next node.
Using the above approach the message format changes for each forwarding. So
the next node will not accept the forwarded message.

For example:
       node(U,S2,R2)
      /\node(K,S4,R4)
      /\target(V,S3,R3)

the second node will not accept de message

Mihai
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