Network Protocol Design and Evaluation 04 - Protocol Specification, - - PowerPoint PPT Presentation
Network Protocol Design and Evaluation 04 - Protocol Specification, Part II Stefan Rhrup University of Freiburg Computer Networks and Telematics Summer 2009 Overview In Part I of this chapter: Modeling with state machines and
University of Freiburg Computer Networks and Telematics Summer 2009
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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(asynchronous communication)
states & transitions
message queues
in
states & transitions
message queues
in
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
(asynchronous communication)
(here called action), but not by both
not coupled
5 [Holzmann 1991]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
[Holzmann 1991]
alternating bit, indicated by msg0 and msg1.
using the alternating bit, indicated by ack0 and ack1.
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Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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?msg1 !ack0 !ack1 ?msg0 !ack1 ?msg1 ?msg0 !ack0 Sender
?ack1 !msg0 ?ack0 !msg1 ?ack1 ?ack0 Receiver
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
8 State In Out Next state q0 msg1
q0 msg0
q1
q3 q2
q0 q3 msg0
q3 msg1
q4
q0 q5
q3
?msg1 !ack0 !ack1 ?msg0 !ack1 ?msg1 ?msg0 !ack0 Receiver
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
where A is the set of actions (input, output, or ε)
9 [Holzmann 1991]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
successor state.
example: T(q0, !msg) = q1
10 [Holzmann 1991]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
where A is the set of actions (input, output, boolean conditions, assignments, or ε)
13 [Holzmann 1991]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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in?x,y x<y y==0
x>y [cf. Holzmann 1991] x=x-y y=y-x
asssignments and conditions input channel
channel (assume x≠0)
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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the minimum number of states
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
Define an boolean array E of dimension |Q| × |Q|, init = false for all entries E[i,j] if the states i and j are defined for the same actions, set E[i,j] := true (regardless of the next state) end for repeat for all true entries E[i,j] Check, if their next states are equivalent for all actions,
end for until the number of false entries is not increased
16 [Holzmann 1991]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
17 State In Out Next state q0 msg1
q0 msg0
q1
q3 q2
q0 q3 msg0
q3 msg1
q4
q0 q5
q3 q0 1 q1 1 q2 1 q3 1 1 q4 1 1 q5 1 1 q0 q1 q2 q3 q4 q5
Equivalence table E State transition table T
Step 1: for all entries E[i,j] if the states i and j are defined for the same actions, set E[i,j] := true (regardless of the next state)
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
18 State In Out Next state q0 msg1
q0 msg0
q1
q3 q2
q0 q3 msg0
q3 msg1
q4
q0 q5
q3 q0 1 q1 1 q2 1 q3 1 1 q4 1 1 q5 1 1 q0 q1 q2 q3 q4 q5
Equivalence table E State transition table T
Step 2: for all true entries E[i,j] Check, if their next states are equivalent for all actions, i.e. ∀ a E[T(i,a),T(j,a)], otherwise set E[i,j] := false
Action a T(q0,a) T(q3,a) msg1 q1 q5 E[q1,q5] = 1 msg0 q2 q4 E[q2,q4] = 1
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
19 State In Out Next state q0 msg1
q0 msg0
q1
q3 q2
q0 q3 msg0
q3 msg1
q4
q0 q5
q3 q0 1 q1 1 q2 1 q3 1 1 q4 1 1 q5 1 1 q0 q1 q2 q3 q4 q5
Equivalence table E State transition table T
Step 2: for all true entries E[i,j] Check, if their next states are equivalent for all actions, i.e. ∀ a E[T(i,a),T(j,a)], otherwise set E[i,j] := false
Action a T(q2,a) T(q4,a) ack1 q0 q0 E[q0,q0] = 1
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
20 State In Out Next state q0 msg1
q0 msg0
q1
q3 q2
q0 q3 msg0
q3 msg1
q4
q0 q5
q3 q0 1 q1 1 q2 1 q3 1 1 q4 1 1 q5 1 1 q0 q1 q2 q3 q4 q5
Equivalence table E State transition table T
Step 2: for all true entries E[i,j] Check, if their next states are equivalent for all actions, i.e. ∀ a E[T(i,a),T(j,a)], otherwise set E[i,j] := false
Action a T(q1,a) T(q5,a) ack1 q3 q3 E[q3,q3] = 1
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
21 State In Out Next state new q0 msg1
q0 msg0
q1
q3 q0 q2
q0 q0 q3 msg0
(q2) q3 msg1
(q3) q4
q0 q5
q3 q0 1 q1 1 q2 1 q3 1 1 q4 1 1 q5 1 1 q0 q1 q2 q3 q4 q5
Equivalence table E State transition table T
Result:
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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?msg1 !ack0 !ack1 ?msg0 !ack1 ?msg1 ?msg0 !ack0 Receiver
Result:
State In Out Next state new q0 msg1
q0 msg0
q1
q3 q0 q2
q0 q3 msg0
(q2) q3 msg1
(q3) q4
q0 q5
q3
State transition table T
!ack1
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
∀ a: T(q1q2,a) = T1(q1,a) ∪ T2(q2,a)
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Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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?msg1 ?msg0 !ack0 !ack1 Sender
?ack1 !msg0 ?ack0 !msg1 ?ack1 ?ack0 Receiver
msg0 ack0 msg1 ack1
Synchronous coupling
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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?msg1 !ack1 !msg0 ?ack0 ?msg1,!msg1 !ack1,?ack1
Synchronous coupling, 2nd example
Terminal 1 Terminal 2
?msg0 !ack0 !msg1 ?ack1
!msg0,?msg0 ?ack0,!ack0
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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?msg1 !ack1 !msg0 ?ack0
Asynchronous coupling
Terminal 1 Terminal 2
?msg0 !ack0 !msg1 ?ack1
msg1 msg0
input queue input queue
?ack0,--
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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?msg1 !ack1 !msg0 ?ack0
Asynchronous coupling
Terminal 1 Terminal 2
?msg0 !ack0 !msg1 ?ack1
!msg0,--
?msg1,--
!msg0,-- ...T2 cannot send ack0 in q2 ...T1 cannot send ack1 in q2
Specification incomplete!
The protocol blocks here, because...
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
based on Extended FSMs
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Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
(SDL) [ITU-T Recommendation Z.100]
telecommunication systems (esp. telephone exchanges)
Source: http://www.itu.int/ITU-T/studygroups/com10/languages/
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process transceive
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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receive send process start procedure call state
SDL process diagram for Lynch’s protocol
get next char get next char ERR NACK ACK receive
ACK ACK
next state = previous state
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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block process
Extended FSM
process
Extended FSM
system
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
33 block
process
EFSM
process
EFSM
block
system
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
34 block
process
EFSM
process
EFSM
block
that interfaces the environment
blocks and processes (agents)
They can contain other blocks and/or processes
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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[R. Reed, SDL-2000 Presentation, sdl-forum.org/sdl2000present/]
b11
extended finite state machine
signals.
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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[R. Reed, SDL-2000 Presentation, sdl-forum.org/sdl2000present/]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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b11
diagram heading page number block channel signal gates channel name process (reference to)
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
(distinction between channels and signal routes in SDL-88)
38 bidirectional, without delay bidirectional, without delay bidirectional, with delay uniderectional, with delay channel types: ch1 [msg,ack] channel name signals
block
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
39 diagram heading page number state start state connector (for splitting diagrams) procedure (reference to) procedure call input
p2
appearance of p2 inside a block:
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
40 diagram heading page number state procedure start return symbol create process input
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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[R. Reed, SDL-2000 Presentation, sdl-forum.org/sdl2000present/]
b11
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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[sdl-forum.org/sdl88tutorial/]
S1 start symbol
(only one per agent)
task
c:=0;
proc
state procedure call termination
procedure insertion (reference)
* (S1,S2)
all states
(except those listed)
descr. text extension
previous state
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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BREAK label
label
(outcome) ELSE
expr. decision (branch) join parts can be separated by BREAK and connectors connector
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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[sdl-forum.org/sdl88tutorial/]
(0) (1)
x
(true) (false)
x = y
length(header)
(>0) (<0)
x - y
(“A”)
TYPE
ELSE (“B”) (“ERR”)
(=0) (0) ELSE (16)
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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are added to the queue
empty and there are signals associated with transitions from that state, then the signal is removed from the queue and the transition is triggered.
consumed without any action (implicit transition)
[sdl-forum.org/sdl88tutorial/]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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b a a b process1 a a process2
input queue input queue
a
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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B
save signal (msg.
remains in queue, no
abort
continuous signal with enabling condition B priority input save all other signals B A input signal
SIGNAL A,B; signal declaration SIGNALLIST sl1 = A,B; SIGNALLIST sl2 = sl1,C;
A
TO Dest
Dest: Process ID
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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A
TO SELF
A
TO SENDER
A
VIA ch1
Sending to a specific receiver: sending via a channel sending back to the sender sending a self-message
PARENT OFFSPRING
Further addresses: the creating instance last created instance by this instance
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
Input and Output in layered protocols (Notation used in IEEE Standards, not official part of Z.100)
50
in_pkt
in_frame
signals from or to processes logically above or parallel to this process pointer or wedge to the right pointer or wedge to the left signals from or to processes logically below this process
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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S3 b c S2 a S1 a b a
c
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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S3 c S2 S1 a b a
c
b a
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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S3 b S2 a S1
c
c a b a
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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S3 S2 S1
c
c b a
S2 c S3 b a
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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b a S3 c b S4 S3
triggering this transition is effectively discarded.
S2 c S3
A
TO Dest
Dest: Process ID
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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A
TO SELF
A
TO SENDER
A
VIA ch1
Sending to a specific receiver: sending via a channel sending back to the sender sending a self-message
PARENT OFFSPRING
Further addresses: the creating instance last created instance by this instance
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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block example
p2 p1
ch1 ch2 process p1
S1 S2
A VIA ch2
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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[sdl-forum.org/sdl88tutorial/]
DCL counter Integer := 0, increment Integer :=1;
Declare keyword Variable name Type Initial value
counter := counter + increment;
Task symbol Text symbol comma-separated list
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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[sdl-forum.org/sdl88tutorial/]
TIMER T; SET(now+50, T) RESET(T)
T Timer definition Timer setting
(predefined function)
Timer activation (self-message) Timer reset
(predefined function)
b a a b process1
Timer signals are added to the input queue
T
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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[sdl-forum.org/sdl88tutorial/]
DCL expirytime Time := 0.0; DCL period Duration := 13; TIMER T; expirytime := expirytime + period; SET (expirytime, T)
T Wait
Wait4Timer PeriodAction Declaration in-connector
Alternative: expirytime := NOW + period;
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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Block b1
[sdl-forum.org/sdl88tutorial/]
SIGNAL A(Integer,Boolean);
[A] ch
Process P2
DCL V1 Integer, V2 Boolean;
Process P1
A(v1,v2) A_recvd A(4,True)
S S
A_sent
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
a process and imported by another process
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[sdl-forum.org/sdl88tutorial/]
DCL EXPORTED sum Integer; EXPORT(sum) IMPORT(sum, exporterID)
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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[sdl-forum.org/sdl88tutorial/]
Block Example [A]
p1 p1
Process P1 S2 A S1 P2(4,True) Process P2 FPAR V1 Integer, V2 Boolean
create symbol create line
A S1
process terminates
B Dynamic process creation
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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process type Agent 2 (2)
Yes via retry
No retry busy failure Clear
release idle
state open 1 (4) retry
busy waitch
init
req(ch)
tidy
cong announ cong busy waitch
composite state
[R. Reed, SDL-2000 Presentation, sdl-forum.org/sdl2000present/]
substate definition return symbol
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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EXCEPTION someError;
someError
eh
S
someError
eh
Exception definition Raising the exception Exception handler State with associated exception handler Handle
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
Duration, Time, Bitstring, Octet, Octetstring, Pid
Structures, Choice, Powerset, Bag
Value types, Object types, Syntypes (with range check)
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[R. Reed, SDL-2000 Presentation, sdl-forum.org/sdl2000present/]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
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<type Elementsort> struct prev, next this Linkedlist; data Elementsort;
"in" (Elementsort, Linkedlist)
methods delete (Elementsort);
method delete referenced; endobject type Linkedlist;
inherits Linkedlist <Natural> endobject type Natlist; dcl primes Natlist := (. Null, Null, 1 .);
[R. Reed, SDL-2000 Presentation, sdl-forum.org/sdl2000present/]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
type implicitly
68 block type B block type B2 inherits B adding block type C
B2 c b:B2
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
69
system convert; signal s,t; channel c_out nodelay from B to env with t; endchannel c_in; channel c_in nodelay from env to B with s; endchannelc_out; block B referenced; endsystem convert; block B; channel rin nodelay from env to P with s; endchannel rin; channel rout nodelay from P to env with t; endchannel rout; process P referenced; connect c_out and rout; connect c_in and rin; endblock B; process P; start; nextstate idle; state idle; input s;
nextstate idle; endstate idle; endprocess P;
signal s,t; t s B
1(1)
system convert c_in c_out
[R. Reed, SDL-2000 Presentation, sdl-forum.org/sdl2000present/]
SDL/PR phrase representation SDL/GR graphical representation
Activity information flow set of documents Analysis classified information Draft Design SDL+ Methodology Requirements capture Documentation draft designs product descriptions Test Specification Validation Test Execution test results Implementation product validation result formal SDL+ description tests c
l e c t e d r e q u i r e m e n t s Formalization
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
70
[ITU-T Z.100 Supplement 1]
Scope of SDL+ (SDL and MSC with ASN.1) and recommended methodology
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Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
71 [IEEE Std. 802.11-2007]
System specification (part)
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Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
72 [IEEE Std. 802.11-2007]
Transmission block specification (part)
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`KA*,*B(F %,B0&=*'&1B> ;)*C(B(%,>(0? )&1%'(_J )(B0(%A =+-O$_J>%1( P,Y(*$O0*.%&= %(a1()>*>&*1)( ,)*,00%*&.*D&B(? (G<&%> 4=+-O$6 'B> )L&>SB>_J*',LL \,B0&=4'F6 S:&&)(*%,B0&= 2,'-&..*'&1B> ;.*'B>*J*E3? S:,BB(L/+1)H T>*)>,%>*,))1=(*>:,>*>:(*MN ;)*21)H*1B>;L*%('(;Y;BC*,*);CB,L F:;':*;B0;',>()*>:(*MN*;)*;0L(? O0L( 9%,B);>;&B)*>& S:,BB(L/O0L( ,L)&*,L;CB*>:( +,'-&..*);CB,L ,%%;Y,L*>;=(*>& )L&>*2&1B0,%H 4N56*>;=;BC? PL&> PL&>*&BLH*)(B> +1)H S,B'(L )B0/ )L&>SB>_J*'B> \()1=(*F;>:*'&1B> .%&=*',B'(LL(0 2,'-&..*;.*'B>IJK? **4`K6 **4IJK6
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
73 [IEEE Std. 802.11-2007]
Backoff process specification (part)
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
(SPC) systems (telephone exchanges)
interaction, specification and description, and programming
graphical language
data elements, graphical and textual notation
74
[R. Reed, “Notes on SDL-2000 for the new millennium, Computer Networks (35), 2001]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
and semantics consolidated. SDL-88 is the foundation of all subsequent versions. [sdl-forum.org/sdl88tutorial/]
75
[R. Reed, “Notes on SDL-2000 for the new millennium, Computer Networks (35), 2001]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
76
SDL-88 SDL-92 SDL-2000 SDL-76 UML 2.0
(2005)
MSC-92
Harel’s state charts (’87)
MSC-2000 UML 1.1
(1997)
UML draft
(1995)
SysML 1.0
(2007)
UML 2.2
(2009)
state machines Booch, OMT SDL UML Profile
2000 1990 1980 2010
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
77
UML SDL
collection of notations for describing different views of a system, including structure, state machine, interaction, collaboration etc. weak semantics with many variation points formal language focusing on structural and state machine views interactions are modeled by MSC complete semantics mapping of subsets UMLSDL ↔ SDLUML defined in [ITU Z.109]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
78 [B. Møller-Pedersen: “SDL combined with UML”, Telektronikk 4.2000]
Mapping subsets of UML and SDL
Use Cases Collaborations Interactions Activity Deployment Action Language Object/Class Instance/Type State Machine State Machine
UMLSDL UML SDLUML SDL
UML-SDL Profile
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
model concurrent and communicating processes such as network protocols.
were introduced
SDL has the stronger semantics
79
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
Source: http://www.itu.int/ITU-T/studygroups/com10/languages/
specific executions (scenarios, traces)
80
msc cs_operation
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
81
client server
time instance name instance head instance axis instance end instance
request(sid) response(data,status)
message name message parameters
input
msc cs_operation
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
82
client server
self-message
req data1
transmission delay
data2 m
lost message with intended target
req
server client
found message with supposed source
init
message from the environment
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
83
(send before receive, partial ordering)
msc cs_operation
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
84
client server
parameters
(p1,p2)
stop symbol
confirm stop confirm
createline symbol
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
85
inst1
timer name (required), timer instance name (optional)
t1 t2,ti1 t2 [10,15] t2 [2] t3
timer start duration (optional) with duration [min,max] restart timeout timer stop
t3 t1
timeout duration = [0,infinity] unless
msc cs_operation client server req
guarding condition
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
86
when connected response
setting condition
disconnected process request
action
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
labels associated with the covered instances
the labels associated with the covered instances
instance (only one instance can be active)
87
msc cs_operation client server req
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
88
response
MSC reference
dispatcher ds_operation
MSC reference name
g1 g2
gate
msc ds_operation server dispatcher
req response conn reply(state) ack data
msc cs_operation client server req
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
89
ack
MSC reference
dispatcher conn_establishment
MSC reference name
g1 g2
gate
loop<2,4> ds_operation
executed 2 - 4 times
disconnect fin
further execution
exc
exception
par
parallel
seq
sequential
msc setupChannel msc exchangeData msc disconnect
msc connection
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
90
[Grabowski, Reed: “ ASN.1, MSC, SDL and TTCN Today”, Tutorial, WITUL 2004] Infrastr. connected idle
disconnect setupChannel exchangeData
Base Mobile ConnReq Ready SyncAck Sync Close Ack
Confirm RserveCh ChDown Unlock DataReq
Base Mobile Base Mobile Base Mobile
Locked Lock DataAck Confirm CfAck Lookup Data Response Ack
when idle
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
91 msc example alt Two alternatives Inline expression separator Inst1 Inst2
t1 t1
conn_reset data_ack conn_req conn_ack data
t1
msc inline_example_2 loop<0,inf>
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
92 alt when conn_established Inst1 Inst2
t1 t1
conn_reset data_ack conn_req conn_ack data
t1
Nested inline expression Guard
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
93
[Ø. Haugen: “MSC-2000 Interaction for the new Millenium”, sdl-forum.org/MSC2000present]
Absolute Time Relative Time
?r2 @a1 call openConnection(port) call requestAccess(uid,pwd) response reply
msc time_example
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
94
[Ø. Haugen: “MSC-2000 Interaction for the new Millenium”, sdl-forum.org/MSC2000present]
Relative time constraint for execution Relative time constraint for msg duration Relative measurement of msg duration Inst1 Inst2
call proc1(x) proc1(x)
Inst3
msg1 time &t msg2 time (0,2*t]
disconnect
[1,2*t)
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
95 msc call_example Inst1 Inst2
call p3 p3
Inst3
call p2(x,y) p2(x,y)
Reply Reply gate Method call gate Suspension area Method area
call p1 p1
Method call
msc systemOverview
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
96
[Ø. Haugen: “MSC-2000 Interaction for the new Millenium”, sdl-forum.org/MSC2000present]
MSC Reference Loop Connection point HMSC start Restrictive condition Alternative User rejected User accepted Idle Unlocked timeout Unlocked reset Unlocked unclosed unlocked
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
sequences
(message transmissions) are hidden
97
4HJGKAHLHM$& 6H?>A$&NAJLH& 4.4",& 46"7/65*BM%& 4.4",& 46"7/65*AHO& 4.4", 46"7/65*PNL& 4.4",& 4"1#=6"*PNL& 4HJGKAHLHM$& 6HOKHG$&NAJLH& 4.4", 46"<="#5*BM%& 4.4",& 4"1#=6"*AHO& 4.4", 46"<="#5*AHO& 4.4", 46"<="#5*PNL&
!"# "$"# %###&'()*++&!,-& "$"# !"# %###&'()*++&!,-
3HPBGB>M&$>&AHOKHG$& LHJGKAHLHM$&NA>L&?HHA& #51& 3HPBGB>M&$>&JPPH?$& LHJGKAHLHM$&AHOKHG$& NA>L&?HHA3& 4HJGKAHLHM$& ?A>PHGG& 0>L?BFH& LHJGKAHLHM$& AH?>A$& 4HJGKAHLHM$& AHOKHG$& P>L?FH$H%&
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
98 [IEEE Std. 802.11-2007]
station management entity MAC sublayer management entity
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
documenting test cases etc.
99
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
but not liveness (something will eventually happen)
MSC-2000
100
[M. Brill, W. Damm, J. Klose, B. Westphal, H. Wittke: Live Sequence Charts: An Introduction to Lines, Arrows, and Strange Boxes in the Context of Formal Verification. SoftSpez Final Report 2004]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
components specified in the MSC?
... or are there other message sequences allowed?
101
[I. Krüger, R. Grosu, P . Scholz, and M. Broy, “From MSCs to Statecharts”, DIPES’98]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
102
[I. Krüger, R. Grosu, P . Scholz, and M. Broy, “From MSCs to Statecharts”, DIPES’98]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
1. Projection of MSCs onto the component 2. Normalization 3. Transformation into an MSC automaton 4. Transformation into an automaton 5. Optimization (minimization etc.)
103
[I. Krüger, R. Grosu, P . Scholz, and M. Broy, “From MSCs to Statecharts”, DIPES’98]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
door motor
control (signals: “lock” and “unlock”)
finished their action and sent a “ready” message
104
[I. Krüger, R. Grosu, P . Scholz, and M. Broy, “From MSCs to Statecharts”, DIPES’98]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
105
msc locking
KeyControl LeftMotor RightMotor unlocked lock
locked lm_down down down rm_down rm_ready lm_ready
msc unlocking
KeyControl LeftMotor RightMotor locked unlock
unlocked lm_up up up rm_up rm_ready lm_ready
[I. Krüger, R. Grosu, P . Scholz, and M. Broy, “From MSCs to Statecharts”, DIPES’98]
msc locking
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
106
which the state machine should be derived
and all messages that are neither sent nor received by C
[I. Krüger, R. Grosu, P . Scholz, and M. Broy, “From MSCs to Statecharts”, DIPES’98]
KeyControl LeftMotor RightMotor unlocked lock
locked lm_down down down rm_down rm_ready lm_ready
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
107
msc lockSeq
KeyControl unlocked lock locked lm_down rm_down rm_ready lm_ready
msc locking
KeyControl LeftMotor RightMotor unlocked lock
locked lm_down down down rm_down rm_ready lm_ready
[I. Krüger, R. Grosu, P . Scholz, and M. Broy, “From MSCs to Statecharts”, DIPES’98]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
108
with a condition symbol.
a (empty or non-empty) sequence of messages in between
are split (the example MSC is alread normalized)
msc lockSeq
KeyControl unlocked lock locked lm_down rm_down rm_ready lm_ready
[I. Krüger, R. Grosu, P . Scholz, and M. Broy, “From MSCs to Statecharts”, DIPES’98]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
109
msc lockSeq
KeyControl unlocked lock locked lm_down rm_down rm_ready lm_ready
msc unlockSeq
KeyControl locked unlock unlocked lm_up rm_up rm_ready lm_ready
locked unlocked
lockSeq unlockSeq
[I. Krüger, R. Grosu, P . Scholz, and M. Broy, “From MSCs to Statecharts”, DIPES’98]
States = conditions Transitions = MSCs beginning and ending with the respective conditions
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
110
locked unlocked
lockSeq unlockSeq ?lock !lm_down !rm_down ?rm_ready ?lm_ready ?unlock !lm_up !rm_up ?rm_ready ?lm_ready
locked unlocked u1 u2 u3 u4 l4 l3 l2 l1
[I. Krüger, R. Grosu, P . Scholz, and M. Broy, “From MSCs to Statecharts”, DIPES’98]
expand transitions
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
111 ?lock !lm_down !rm_down ?rm_ready ?lm_ready ?unlock !lm_up !rm_up ?rm_ready ?lm_ready
locked unlocked u1 u2 u3 u4 l4 l3 l2 l1 locked unlocked u l
?lock/ !lm_down, !rm_down ?unlock/ !lm_up, !rm_up ?lm_ready, ?rm_ready ?lm_ready, ?rm_ready
[I. Krüger, R. Grosu, P . Scholz, and M. Broy, “From MSCs to Statecharts”, DIPES’98]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
(Extension of MSC-96)
112 [W. Damm, D. Harel: “LSCs: Breathing Life into Message Sequence Charts”, Formal Methods in System Design, 19, 45–80, 2001]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
113 mandatory condition asynchronous message instantaneous message LSC: Example1a AC: Act AM: Invariant activation mode
∈ {initial, invariant, iterative}
activation condition sync1 Inst1 Inst2 Env Inst3 sync1r condition1 sync2r sync2 sync3r sync3 async1 async2
[M. Brill, W. Damm, J. Klose, B. Westphal, H. Wittke: Live Sequence Charts: An Introduction to Lines, Arrows, and Strange Boxes in the Context of Formal Verification. SoftSpez Final Report 2004]
universal chart
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
114 LSC: Example1b AC: Act AM: Invariant sync1 Inst1 Inst2 Env Inst3 sync1r invariant1 sync2r sync2 sync3r sync3 mandatory invariant async1 async2
[M. Brill, W. Damm, J. Klose, B. Westphal, H. Wittke: Live Sequence Charts: An Introduction to Lines, Arrows, and Strange Boxes in the Context of Formal Verification. SoftSpez Final Report 2004]
hot location
(progress enforced, solid line)
cold location
(dashed line)
existential chart
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
115
Mandatory (notation: solid line) Provisional (notation: dashed line) Chart universal must be fulfilled by all runs existential describes a possible run Locations hot progress is enforced cold staying without progress is allowed Messages hot has to be delivered cold may be lost Conditions hot must hold, otherwise abort cold exit current chart if not met
[W. Damm, D. Harel: “LSCs: Breathing Life into Message Sequence Charts”, Formal Methods in System Design, 19, 45–80, 2001]
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
116 min,max delay LSC: Example2 AC: Act AM: Invariant Inst2 Inst3
msg1 msg3 msg4
timer reset
[M. Brill, W. Damm, J. Klose, B. Westphal, H. Wittke: Live Sequence Charts: An Introduction to Lines, Arrows, and Strange Boxes in the Context of Formal Verification. SoftSpez Final Report 2004]
Inst1
T1(10) [1,5) T2(2) msg2[2,3] T2
timer set
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
that describes valid message sequences (unwinding)
required that time is non-decreasing and progressing
117
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
sending and receiving messages, conditions) and the borderline between processed and unprocessed elements is called a cut.
been processed
are enabled
118
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
119 LSC: Example2 AC: Act AM: Invariant c a b d e Inst1 Inst2 Inst3 Inst4 Cut Cold cut c0 c1 c2 c3 c4 c5
Moving a cut from top to bottom through the LSC:
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
120
cuts (successor relation reflects the partial order)
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
121
q1 q2
¬a ∧ ¬b a ∧ b
q3 q4 q5 q0
¬c ∧ ¬d c ∧ d c d c d ¬d ¬c e true
LSC: Example2 AC: Act AM: Invariant c a b d e Inst1 Inst2 Inst3 Inst4
Cut Cold cut
c0 c1 c2 c3 c4 c5
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
122
describes valid message sequences: {(a,b,d,c,e), (a,b,c,d,e),...}
machine as an implementation model
q1 q2
¬a ∧ ¬b a ∧ b
q3 q4 q5 q0
¬c ∧ ¬d c ∧ d c d c d ¬d ¬c e true
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
123
LSC, MSC
State machine(s)
transformation
Require- ments
code generation
descriptive view constructive view Implemen- tation
code generation
Implemen- tation
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
124
LSC
State machine(s)
manual design
Require- ments
Symbolic Automaton
verification/ consistency check
descriptive view constructive view
transformation
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
125
UML 2.0
(2005)
MSC-92 MSC-2000 UML 1.1
(1997)
2000 1990 2010
MSC-96 LSC
Network Protocol Design and Evaluation Stefan Rührup, Summer 2009 Computer Networks and Telematics University of Freiburg
describing scenarios
additonal semantic model
semantic.
state machines
single process or define valid message sequenes
126