A Mechanically Proved and an Incremental Development of the Session Initiation Protocol INVITE Transaction

Algorithm 3

Events of second refinement.

  Exipre_B 

REFINES

   client_final_state

WHEN

   grd3: r1xx cl_got

   grd1: B = 64 ∗ cst

   grd4: c_st = Calling

THEN

   act1: c_st    Terminated

   act2: B 0

   act3: Temp_B FALSE

END

  Expire_H 

REFINES

   server_final_state

WHEN

   grd3: ACK sr_got

   grd1: H = 64 ∗ cst

   grd2: s_st = Completed

THEN

   act1: s_st     Terminated

   act2: H 0

   act3: Temp_H FALSE

END

  Expire_D 

REFINES

   client_final_state

WHEN

   grd1: Temp_D = TRUE

   grd2: c_st = Completed

THEN

   act1: c_st     Terminated

   act2: Temp_D FALSE

END

  Expire_I 

REFINES

   Server_final_state

WHEN

   grd2: Temp_I = TRUE

   grd1: s_st = Confirmed

THEN

   act1: s_st     Terminated

   act2: Temp_I FALSE

END

  Expire_M 

REFINES

   Client_final_state

WHEN

   grd2: Temp_M = TRUE

   grd1: c_st = Accepted

THEN

   act1: c_st     Terminated

   act2: Temp_M FALSE

END

  Expire_L 

REFINES

   Server_final_state

WHEN

   grd2: Temp_L = TRUE

   grd1: s_st = Accepted

THEN

   act1: s_st     Terminated

   act2: Temp_L FALSE

END