1 .PS 3.5

2 arrowhead = 18

3

4 define disk {

5 Disk: [

6 ellipsewid=ellipsewid/2

7 ellipseht=ellipseht/2

8 ellipse

9 spline down ellipseht*4/3 from last ellipse.w \

10 then right ellipsewid \

11 then up ellipseht*4/3 to last ellipse.e

12 ]

13 }

14

15 define machine {

16 box wid $1.wid+.3 ht $1.ht+.3 dashed at $1

17 }

18

19 up

20 Sender: [

21 ellipse "\fBMUA\fP"

22 ellipse "MSA"

23 ]

24 machine(Sender)

25

26 arrow 3*linewid from Sender.n

27

28 right

29 Server1: [

30 ellipse "MTA"

31 ] with .s at last arrow.end

32 machine(Server1)

33

34 arrow 2*linewid from Server1.e

35 box invis ". . ."

36 arrow 2*linewid

37

38 Server2: [

39 ellipse "MTA"

40 ellipse "MDA"

41 arrow linewid/2

42 disk

43 move to Disk.s - (0,.05)

44 ]

45 machine(Server2)

46

47 down

48 arrow <- 3*linewid dashed from Server2.s+(.86,0)

49 arrow 3*linewid from Server2.s+(.9,0)

50

51 Recipient: [

52 ellipse "MRA"

53 ellipse "MDA"

54 move to last ellipse.w

55 left

56 arrow linewid/2

57 disk

58 arrow <-> linewid/2

59 #arrow <-> linewid/2 from Disk.w+(0,.03)

60 #arrow linewid/2 from Disk.w+(0,-.03)

61 ellipse "\fBMUA\fP"

62 ] with .n at last arrow.end-(.8,0)

63 machine(Recipient)

64

65 line from .5 <Sender.nw,Server1.sw> to .5 <Server2.se,Recipient.ne> dotted

66 .PE