The Use of OO-Modelling Principles (OOM) and UML Notation to Define Signalling Requirements Raphael...

The Use of

OO-Modelling Principles

(OOM) and

UML Notation to

Define Signalling

RequirementsRaphael J. Schumacher, Rapporteur Q.8/11Swisscom AG, Switzerland

ITUWorkshop

"Use of Description Techniques"

Geneva,23. Nov. 2002

“Use of OOM and UML to define Signalling Requirements”

2ITU Workshop on "Use of Description Techniques"Geneva, 23 November 2002

A little story about a personal experience in...

attempting to motivate the use ofobject-oriented modelling techniques in SG11

...

advocating the advantages for the experts’ work

...

the attention achieved in the process

...

observations and conclusions



Contents

1 Introduction– Preamble

– About Signalling Requirements

– The OOM Story in SG11

2 Why OO-Modelling & UML

– OO-Analysis & -Design (OOA/D)

– OO-Modelling (OOM)

– Telecom vs. Computing

3 OOM for BICC Requirements

– Purpose and Benefits

– Existing BICC CS2 Signalling Requirements

– Supplementing BICC Signalling Requirements

4 Results & Conclusion– Reception by the meetings

– Personal observations

– Long-term view

Intro

OOM

BICC

Results




– About Signalling Requirements

– The OOM Story in SG11











– Long-term view

Intro

OOM

BICC

Results



SG11 Signalling Requirements - what’s this? Question to be answered before protocol development

starts:“What do we expect the particular signalling protocol to do?”

A collection of functional requirements on a signalling protocol that is destined for specific purposes and applications:

– That is, signalling requirements need to identify...– The context of usage (= equal to an applicability statement?)– All the scenarios that need to be applicable

– Hence signalling requirements would contain– Signalling [network] architecture and functional elements– Description of network functions that are needed– Functional elements to be implemented ( != physical elements)

Ideally...Intro

OOM

BICC

Results



The Proposal for SG11

BICC Capability Set 3 (Bearer Independent Call Control)– BICC is a framework for providing ISDN services over

transport technologies beyond simply TDM: ATM AAL1, AAL2, IP, MPLS.

– In the light of the starting BICC CS3 activity, further ways to improve the modelling techniques for envisaged signalling architecture were seeked.

– This resulted in a contribution brought into WP 2/11 at the SG11 meeting in Mai 2001:

Delayed Contribution D.229 – 2/11Aim: to propagate the idea of using OOM and UML for the development of signalling requirements

Intro

OOM

BICC

Results




– Story line

– About myself and SG11











– Long-term view

Intro

OOM

BICC

Results



Object-Oriented Analysis & Design (OOA/D) A very, very little history:

– late 1980s: OO programming languages (Smalltalk, C++)

– early 1990s: OOA/D techniques (Booch, Rumbaugh, Jacobson, ...)

– late 1990s: joint effort to develop the UML standard; adopted by OMG

OOA&D as conceptual tool was originally directly associated with software development:

– OOA:Analysing a system and its environment, as well as the requirements on the system, seen from a user’s perspective

– OOD:Documentation on the concept, and the design of the implementation (== the inside of the system)

– UML: UML as notation standard; UML tools with the purpose to automatically create program code out of the object-oriented models.

Intro

OOM

BICC

Results



Object-Oriented Modelling (OOM)

Simply going beyond the purpose of developing software :– OOA, OOD & UML are description techniques, thus probably

also applicable for other things than software development.

– Meanwhile, modelling is used in many areas, e.g.:– Business engineering: modelling of enterprises in terms of

purpose, processes and organisational entities– Service development: service components and their

associations amongst themselves as well to network capabilities– Database design & data warehouses: data structures,

specifications for data mining and information exchange (XML/DTD)

– Telecom Operations Map (TOM): a framework for a process architecture suitable to telecommunications service providers

– Network Management Systems: managed objects (MIBs)

Why not make profit from OOM & UML in ITU efforts as well?

Intro

OOM

BICC

Results



Telecommunication vs. Computing

Telecommunication & computing industry is converging– How will the demarcation line look like in - let’s say - 5 years?

A grey area by best...

– Who will be faced to communication standards in future?– SW developers incorporating telecom modules into vertical

products– Integrators struggling with service convergence telecommunication services won’t remain stand-alone products

– As a consequence, the dominant customers of ITU standards will more and more be...

– software engineers for whom OOM has become everyday practise– service providers which need to cope with the increased

complexity

Telecom services convergence, a long-term business needconsolidating portfolios require clean concepts, interfaces & APIs

Intro

OOM

BICC

Results




– Story line












– Long-term view

Intro

OOM

BICC

Results



OOM @ BICC: Purpose and Benefits

OOM can be used to:

define processes and information flows

identify relationships between processes and information

increase the degree of reuse (protocol) requirements and components

Benefits:

further refine the scope of BICC capabilities and their protocols

improve the common understanding of terminology

improved documentation of BICC and its evolution (CS1..CS3)

improve quality control and consistency check on protocol designs

trace protocol standardisation (from req’s to test specifications)

Intro

OOM

BICC

Results



Existing BICC CS2 Signalling Requirements

Intro

OOM

BICC

Results

Scope of Signalling Requirements

Call ControlSignalling

Bearer ControlSignalling

Signalling Transport Network

BCF-JBCF-RSWN-2

BCF-RSWN-3

CSF-N

ISN-B

BCF-N(z)

Backbone Network

Connection Link

Backbone Network ConnectionsNetwork Bearer Connection (end to end)

CSF-N

BCF-N(v)

ISN-A

BearerInter-working

Function(BIWF)

BCF-RSWN-1

CSF-T

BCF-T(w)

TSN-x

CSF-G

BCF-G(x)

GSN-xCSF-G

BCF-G(y)

GSN-yCSF-C

CMN-x

TE

TE

TE TE

ACN-E

Joint DomainBearer Inter-working

Function (BIWF)

Access Network

BCF-RACN-w

Otherservicesuppliernetworks

CSF-R

BCF-A(a)

Access ControlSignalling

Otherservicesuppliernetworks

Call & Bear Control(CBC) Signalling



Supplementing BICC Signalling Requirements

1/6Overall Requirements

Use Cases -> helps to refine scopeIntro

OOM

BICC

Results

BICC Network

ISDN service

Multimedia service?

ISDN Network

ISDN Access

(ISDN DSS1 access)

(ISUP)

SIP Network

H.323 Network

??????




2/6Information Flows

Use Case -> overview of scenariosIntro

OOM

BICC

Results

BICC Network

Release ISDNcall/connection

SetupMultimediaconnection

ISDN Network

ISDN Access

(e.g. DSS1)

(ISUP)

SIP Network H.323 Network

???

???

Setup ISDNcall/connection

ReleaseMultimediaconnection

(ISUP)

(e.g. DSS1)

???

???

??????




3/6

BearerNetwork

Call ServiceFunction

(CSF)

BearerInterworking

Function(B-IWF)

0..*1..* 1

ATM BearerNetwork

AAL2 BearerNetwork

IP BearerNetwork

(MPLSBearer

Network)future

0..*

Intro

OOM

BICC

Results

Information Model

Class diagrams -> improve understanding the principle idea of BICC




4/6

Intro

OOM

BICC

Results

Information Model

further

refined

class

diagrams

BearerNetwork

Call ServiceFunction

(CSF)

BearerInterworking

Function(B-IWF)

BICCProtocol

0..*

1..*

1

ATM BearerNetwork

AAL2 BearerNetwork

IP BearerNetwork

MPLSBearer

Network(future)

H.248Protocol

BCP

0..*

Q.2931(ATM BCP)

Q.2630(AAL2 BCP)

IP BCPMPLS BCP

(future)




5/6

Intro

OOM

BICC

Results

Zooming into individual BICC components

“Play it again Sam!”, and:

Bearer Control Function(BICC side only)

Modify Bearer

Release Bearer

BICC Bearer Network

Request BICCBearer

Call Service Function ? BCP ?

BCP

BCPCBC

CBC

? CBC ?



EndPoint C

EndPoint B

EndPoint A

External

External

External

O-CSMA

T-CSMB

T-CSMC

CBC

Internal

Internal

Internal

CSF

BIWF

Local Call Instance

TerminationA1

Logical Port-A

TerminationC1

Logical Port-C

TerminationB1

Logical Port-B

CCA

CCA

CCA

BNCBNC

BNC

ContextConnection

BIWF Contr ol Por t

CCU C ontrol Port

(3) (3)

(3)

(2) (2) (2)

(1)

(1)(1)(4)

(4)

(5)

(5)(5)

BearerS ign all in g(optional )

BearerS ign all in g(optional )

Termination States- Null- Loop Back External Signal (loopback)- Loop Back Internal Signal

- Cut-Through Towards Context (Receive)- Cut-Through From Context (Send)- Cut-Through Both (Send / Receive)

Stream Mode

SLP-A SLP-CSLP-BSCF


5/6

Intro

OOM

BICC

Results

BIWF (X)

Termination(f)

Termination(h)

Connection(2 party)

Context(3)

Termination(g)

Context(4)

Connection(Hold)

Configuration 3

BIWF-Addr=(Y):BNC-ID=(3)

BIWF-Addr=(W):BNC-ID=(4)

BIWF-Addr=(X):BNC-ID=(5)

BNC

BNC

BNC

Termination(c)

Termination(d)

Termination(e)

Connection(3 party)

Context(2)Configuration 2

BIWF-Addr=(Y):BNC-ID=(2)

BIWF-Addr=(Z):BNC-ID=(4)

BIWF-Addr=(X):BNC-ID=(4)

BNC

BNC

BNC

Termination(a) Termination(b)

Connection(2 party)

Context(1)Configuration 1

BIWF-Addr=(Y):BNC-ID=(1) BIWF-Addr=(Y):BNC-ID=(4)

BNCBNC

Local Call Instance

Local Call Instance

Local Call Instance

And there’d be much more to be modelled!




– Story line












– Long-term view

Intro

OOM

BICC

Results



Reception by the Meeting (of WP 2/11)Achieved Interest

Remarkable interest shown by SG11 management

Moderate interest seen from participants progressing work

Gap between S.P. and Suppliers

Statement of Scepticism

Nice, but do we really need this?

Learning curve steep enough?

Return on investment?

UML not a bit too formal?

Possible Reasons for Spectisism

(Past) Experiences with Notations

SDL:Widely adopted within SG11 (protocol standards, typically specifying the state machines), but applied in the right way?

TTCN:ratio of sophistication vs. value was not perceived to be very promising to individuals

Little popularity of concept work

“With IP, everything is easier”

Intro

OOM

BICC

Results



Personal Observations

“Contemporary” factors

Time pressure->get out standards fast

Little resources available->reduce efforts to the

minimum

Increased Fluctuation->people change,

know-how changes...

Current quality control system-> iterative approach: changes

to standards as implementers discover imperfect parts

“Hidden” factors

Conceptual work– generally having a hard time

– benefits not convincing enough

ITU “hidden law”:A playground for different parties with particular interests. Lobbying e.g. to...

– advocate a specific solution

– slow down progress of work?

->often, full transparency is not necessarily desired

->poisons top down approaches

Intro

OOM

BICC

Results



Personal Long-term Views

Think positive!

Complexity in telecom will continue to increase

->a common understanding of technical and conceptual issues is indispensable

Parties with particular interest in transparency:

– Governments:regulation, lawful interception

– Service Providers:service convergence challenge, cope with network complexity

Summing up

Need for conceptual work– still an indisputable necessity

– adoption of new techniques takes a lot of time-> patience with optimism

Factors for success/failure:– on actual participation

(parties)

– market pressures (competition)

– the mood of telecom business

Better days will be coming

again

Intro

OOM

BICC

Results



Thank you!

...and enjoy your stay in Switzerland

...despite the *?+!%ç&*/ weather!

coffee breaknow?

psst!



Supplemental

BACKUP



Links & Book References 1/2

OOA/D http://www.sdmagazine.com/articles/1999/0006/0006a/0006a.htm “Building Object Applications That Work: Your Step-By-Step

Handbook for Developing Robust Systems with Object Technology” by Scott W. Ambler (Cambridge University Press, 1998)

OOM http://www.ambysoft.com/eCommerceArchitecture.html http://www.sdmagazine.com/articles/1999/0004/0004o/0004o.htm “Business Engineering With Object Technology” by David Taylor

(John Wiley and Sons, 1995) “Enterprise Modelling with UML” by Chris Marshall (Addison-

Wesley, Object Technology series, 1999)Intro

OOM

BICC

Results



Links & Book References 2/2

UML

http://www.omg.org/uml

http://www.rational.com/uml

“The Unified Modeling Language Reference Manual” by Grady Booch, James Rumbaugh, and Ivar Jacobson (Addison-Wesley, Object Technology Series, 1999)

“The Unified Modeling Language User Guide” by Grady Booch, James Rumbaugh, and Ivar Jacobson (Addison-Wesley, Object Technology Series, 1999)

Intro

OOM

BICC

Results

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