checking temporal business rules kåre jelling kristoffersen it univ. of copenhagen joint work with...

Checking Temporal Business Rules

Kåre Jelling KristoffersenIT Univ. Of Copenhagen

Joint work with Christian Pedersen and Henrik Andersen

- Part of Next generation?

Kåre J. Kristoffersen 2

Profile:1989 - 1994: MSc. Computer Science, Aalborg University.

1995 – 1998: PhD Thesis, Aalborg Univ., Formal Tools for software test and Verification.

1998 – 2000: Post Doc, Aalborg Univ.

2000 – 2001: ORACLE PL/SQL developer WM-Data/SONOFON: Number Portability, Sonofon Clearing House.

2001 - 2004: Assistant Professor, ITU Copenhagen.

- Softwaretest and Verification.

- Computer Networking.


Business Rules: What do we need?

Current Development platforms only offer very primitive means to specify business rules:

• ”Check constraints” on database tables asserts that single pieces of data are valid.

• assert(condition) checks validity of condition at chosen places, e.g. in C.

• Using triggers we can check a simple boolean property upon each insert, update and delete.

• Using workflow descriptions (and implementation) we can assert that the computer system is used to apply tasks i a correct order!

BUT, we do not have any generic way of expressing or monitoring that the data in the system evolves correctly as time passes! (Of course this can be programmed in each individual system, but this is not a feasible solution.)


What we provide:1. Provide a Language (timed logic) for

expressing legal state sequences for the data in a DBMS.

2. This language enables a non-tecnical domain expert to specify temporal business rules for a DBMS or a REA Model.

3. Provide a verification server for checking such rules at runtime.

4. Currently, we run server against my.ITU, an ORACLE Database for courses, student projects etc. at the IT University.


Outline:• Motivation

• Time sequences and Timed Logic.

• Temporal Business Rules.

• Verification Server.

• Internal Server Representation.

• J2EE Server Implementation.

• Demo


Temporal Rules, example 1Whenever Account.Balance goes below Treshold it gets back to Treshold+100 after no more than 10 time units!

P: Account.Balance < Treshold

q: Account.Balance >= Treshold+100

Time

t0

p

t1

q

<= 10

t0

p

t1

q

<= 10

Always( p => Eventually(10) q )


Temporal Rules,example 2Before 20 time units the Balance on Account should reach level high and remain for at least 5 time units.

Time

0 20

>= 5

Low

High

Eventually(20)(Acc.Bal=High AND Always(5)(Acc.Bal=High))


Temporal Rule + Feedback = Temporal Business Rule

If Temporal Rule r succeds give Feedback1

else give Feedback2Possible Feedbacks:

• Send an Email, SMS, Letter, other message.

• Close an Account.

• Execute an event?

• Other?

Temporal Business Rules:


Using Verification Server

DBMS/REA

Database

Verification Server

State information

Feedback

Algorithm:

{Yes, No, Wait}

TemporalBusiness Rules


Internal Rule Representation

The formula:

Always(Acc.Bal<0 => Eventually(10)(Acc.Bal >= 100))

Becomes:

X = ((Acc.Bal >= 0) AND NextTime(X)) OR

( Acc.Bal < 0) and NextTime(X) and NextTime(Y(CurrentTime))

Y(t) = (Acc.Bal >= 100 AND CurrentTime < t+10) OR

NextTime(Y(t))


J2EE Server implementation

public String stateChange(State state){1. Find corresponding residualformula2. Find corresponding FS3. RT with state as argument4. Replace old RF with new RF5. Return satisfaction value

}

public int newConstraint(String constraint){1. Transform constraint into a FS2. Insert FS in the FS-Container3. Create ResidualFormulea for all involved processes4. return FS-number

}

public procesInfo newProces(State state){1. Find corresponding FS.2. Create a new residualFormula only consisting of the topidentifier.3. RT with state.4. Insert Residual Formula in FS-container.5. Return procesInfo containing

process number + status.}

public RF procesFormula(RF rf, DNF dnf, State state){1. Process the whole thing2. Return new Residual formula3. Register rf in TimeObserver}

public int insertnewRF(RF rf){1. Give RF a number.2. insert the RF.3. Return number}

public replaceRF(RF rf){1. replace rf.number with rf}

public void remove(int i){1. remove RF nummer i}

public RF getRF(int i){1. Return objekt representing formulanumber i}

public int insertnewFS(FS fs){1. Give fs a number.2. Insert fs.3. Return number}

public void remove(int i){1. Remove Fs number i2. Remove al processescorresponding to FS nr i}

public FS getFS(int i){1. Return object representation ofFS number i}

Stateless Session BeanResidual Transformer

public DNF buildFormula(String s){1. Transform s into a formula system.2. Return FS.}

Stateless Session BeanDNF-Builder

Entity BeanResidualFormulaContainer

Entity BeanFS-Container

public void regRF(RF rf){1. Registrer rf in rf.SIT}

Statefull SessionBean

TimeObserver


Current Activities:

1. Syntax directed editor that allows a domain expert to easily type in Temporal Rules and Feedback Rules.

2. Use Verification Server to check temporal Business Rules for my.ITU, an ORACLE Administrative Database at the ITU.


Demo:x y z

0 0 0

0 0 0

0 0 0

Assume a Table t with tree columns x, y and z.

Temporal property: Whenever x is greater than 50 then y is less than 10 before 6 time units have passed. (This must hold for any row in table t !!)


Demo:Let p= x>50 and let q= y<10

Always( p => Eventually(6) q )

Written as: Always(p => x.(t<x+6 UNTIL q))

Typed in as: [] ( p => ( x . ( t<x+6 UNTIL q ) ) )


3. Build Initial Residuals

Monitored ProgramVerification Server

Equation System

Collection of Residual Formulas

Instrumentation

Temporal Property: . 0

( .( ( 30)))

k Konto saldo

k x k t x

Navn nr. saldoKåre 1 500Christian 2 -600

Konto

K:=Konto.saldo<0Proces := 1


2. Build Equation System


Equation System Instrumentation


( .( ( 30)))

k Konto saldo

k x k t x


Konto


4. Runtime Verification


State Changes

Verification Results

Equation System

Collection of Residual Formulas

Instrumentation


( .( ( 30)))

k Konto saldo

k x k t x


Konto

K:=Konto.saldo<0Proces := 1


Residual formulas

1 1 2 1

2 1 4

3 1 1 2 4

( (2) (5)) ( (4))

( (4)) ( (7))

( (1) (2) (5)) ( (7))

R X X X

R X X

R X X X X

2 51 2 1 4

1 4 4 7

2 51 21 1 4 7


Residual formulas

1 1 2 1

2 1 4

3 1 1 2 4

( (2) (5)) ( (4))

( (4)) ( (7))

( (1) (2) (5)) ( (7))

R X X X

R X X

R X X X X

2 51 2 1 4

4 7

1 1


Residual formulas 2Dis

Con Dis

Con Conid

1

pa2

id

2

pa

5

id

1

pa4

1 1 2 1( (2) (5)) ( (4))R X X X


Dis

Con Dis

Con Conid

1

pa2

id

2

pa

5

id

1

pa

4

1 2 1(( (2)) ( (5))) (( (4)))X X X

1(( (4)))X1 2( (2)) ( (5))X X

1( (4))X

1(4)X

4

1(2)X

2

2( (5))X

2 (5)X

5

Residual formulas 3

checking temporal business rules kåre jelling kristoffersen it univ. of copenhagen joint work with...

Documents

high slide

kristoffersen7 temporal

kristoffersen6 temporal

feedback rules

kristoffersen3 business

nexttimeyt slide

time units

demo slide