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

Algorithm 4

Events of third refienement.

  Resend_INVITE 

WHEN

  grd1: c_st = Calling

  grd2: A = T1

THEN

  act1: T1 2 ∗ T1

  act2: cl_sent cl_sent   {INVITE}

  act3: c_st Calling

  act4: A 0

END

  Resend_3xx-699 

ANY

  data

WHERE

  grd1: data = T1

  grd2: G = min ({data, T2})

  grd3: s_st = Completed

THEN

   act1: sr_sent sr_sent   {r3xx_r699}

   act2: s_st Completed

   act3: T1 2 ∗ T1

   act4: G 0

END