Information flow modelling within the transport telematics' system

4th INTERNATIONAL CONFERENCE_________

TRANSPORT SYSTEMS TELEM ATICS TST’04

P O LITEC H N IK I Ś LĄ SK IEJ 2004 TR A N SPO R T z.55, nr kol. 1657

telematics, telecommunication, transport, sea transport, safety, effectiveness, reliability, information flow, information overflow, modelling, CASE

W ojciech W A W R Z Y Ń S K I1 P rzem ysław D Z IU L A 2

IN F O R M A T IO N FL O W M O D E L L IN G W IT H IN T H E T R A N SP O R T T E L E M A T IC S ’ SY ST E M

T he thesis describes m eth o d s, cap ab le o f m o d ellin g o f in fo rm atio n flow w ithin the Transport T elem atics’ S ystem . In cre ased inform ation am o u n t

{the information overflow)

M O D E L O W A N IE P R Z E P Ł Y W U IN F O R M A C JI W SY ST E M IE T E L E M A T Y K I T R A N SP O R T U

R eferat przed staw ia m eto d y um ożliw iające m odelow anie przep ły w ó w zaso b ó w inform acyjnych w S y stem ie T elem atyki T ransportu. Z w ięk szo n a ilość inform acji (

nadmiar informacyjny

P o k azan o ró w n ież p rz y k ła d o w ą realizację m o d elu lo g iczn eg o system u inform acyjnego, m ającego za zad an ie zw iększenie bezp iecz eń stw a i efektyw ności M o rskiego S ystem u T ransportow ego. Jako podstawę przyjęto bardziej racjonalne w y k o rzy stan ie istniejącej ju ż in frastruktury teleinform atycznej transportu m orskiego.

1. IN T R O D U C T IO N

The transport is one o f industry’s sectors, w here the significant increase o f telem atics’

usage can be observed. The m ost popular solutions are G PS satellite system receivers, and applications for transport m e an s’ m onitoring and m anagem ent, basing on this system .

F ig .l is show ing sim plified schem e o f typical transport m e an s’ m onitoring and m anagem ent system , using elem ents o f transport telem atics’ system [6], These elem ents are:

positioning sy stem s’ receivers installed and w orking on transport m eans, telecom m unication

1 F acu lty o f T ran sp o rt, W arsaw U n iv ersity o f T echnology, K o szy k o w a 75, 00-662 W arsaw , P oland w w a@ it.pw .edu.pl

2 F acu lty o fN a v ig a tio n , G dynia M aritim e U n iv ersity , A l. Z jednoczenia 3, 81-345 G dynia, P oland p dz@ am .gdynia.pl

4 5 2 W o jc ie c h W A W R Z Y Ń S K I, P rz e m y s ła w D ZIU L A system s capable o f d ata transm ission, and applications for m onitoring and m anagem ent o f tran sp o rt m eans, b ased on digital chart system s.

Fig. 1. T h e sim plified schem e o f tran sp o rt m o n ito rin g an d m an ag em en t system

P ointed above elem ents o f transport system are also constantly im proved. System s E G N O S , W A A S , M S A S , supporting G PS system , are already functioning. T he start o f E uropean S atellite N avig atio n S ystem - G A L IL E O , is scheduled for 2008 [3]. This system is g oing to show quite n ew q uality and possibilities, in com parison to existing G PS and G L O N A S S system s.

A m ong „earth -b ased ” telecom m unication system s, the U M TS technology is slow ly appearing. T his technology w ill allow to achieve m uch m ore efficient data transfer, than GSM c om m only used now . W e observe also significant increase o f p ossibilities o f “ satellite-based”

teleco m m u n icatio n system s. F ig.2 presents p ossibilities o f successive standards o f IN M A R S A T , the m ost p o p u lar telecom m unication system w ithin sea and air transport.

Telecommunication system

F ig.2. P o ssib ilities o f successive IN M A R S A T standards

In fo rm a tio n flo w m o d e llin g w ith in th e tra n s p o rt te le m a tic s ’ sy ste m

A dvanced digital ch a rts’ system s, b eing the base for transport m e an s’ m onitoring and m anagem ent system s, are also developed. T here is an increasing coverage o f areas covered w ith electronic data base. The possibilities o f system s w orking w ith this data base also are still being im proved.

2. IN F O R M A T IO N O V ER FL O W

D escribed aspects o f telem atics’ usage evolution w ithin transport system s, cause fact o f existing o f increased inform ation am ount in these system s. This am ount can be specified as information overflow. The inform ation overflow is one kind o f an overflow, w hich, in general, is used for securing p ro p er level o f safety o f a system . Inform ation overflow is defined as existing o f exceeded information amount within the system, concerning essential elements and events [5]. Illustration o f inform ation overflow existing w ithin the system , has been illustrated on the Fig.3.

Fig.3. T h e illustration o f inform ation overflow

It is possible to prove, that increased am ount o f inform ation w ithin a system , is resulting increased safety o f this system [7], Flowever, phrase inform ation overflow , can have also negative m eaning. O verflow , m eaning too m uch inform ation, can cause disturbances in its processing, consequently - disturbances in p roper functionality o f the system .

It is then highly recom m ended to p u t existing increased am ount o f inform ation in the right order. O ne o f possible w ays for p u ttin g inform ation overflow in the right order is to use an information flo w modelling. F urther sections o f this thesis describe new m odelling techniques and tools - supported by Software Engineering.

3. IN F O R M A T IO N FLO W M O D E LL IN G - T E C H N IQ U E S A N D TO O LS

In the m iddle o f sixties o f the 2 0 th century, new field in the com puters’ related technology - softw are engineering - appeared [4]. The reason w as a com puter hardw are and program m ing to o ls’ evolution, capable o f advanced sy stem s’ projecting and producing.

4 5 4 W o jc ie c h W A W R Z Y Ń S K I, P rz e m y s ła w D ZIU LA O ne o f the m o st im portant stages o f softw are engineering (w hich, as a com plex process, can be d escribed like in F ig.4), is modelling,n am ed also the Analysis.

User Project frnpteme ntation Testing futairtenance

requirements

— \ 1

I N I N | N i V i I /

K r — I

Strategy Analysis Documentation Inflation

F ig.4. S u ccessiv e stages o f S oftw are E n g in e erin g as a p ro cess, the analysis a d d itio n ally m arked

T he m ain p urpose o f the m o delling is to describe the rules o f sy stem ’s functioning - to build the logical m odel illustrating realisatio n o f requirem ents set at the beginning. The analysis stage is covering p artly user requirem ents and p r o je c t stages. U ser requirem ents sta g e’s targ et is to form intended functionality o f a system , intended result o f the p roject stage is softw are layout - m eaning - the w ay o f im plem entation. T he m odelling is then including part o f task s covered b y u ser requirem ents stage, also, th e m o delling resu lt is th e base to start p roject o f the system .

T he achievem ents o f softw are engineering in field o f analysis, can successfully be used for inform ation flow m o delling [2]. It supports m any interesting, not fully form alised techniques and tools, capable o f in teresting illustration o f p rocessed problem s. A dditionally, softw are engineering is b asing on clear, giving an im pression o f reality, graphic diagram s.

3.1. C A S E - C O M P U T E R A ID E D S O F T W A R E E N G IN E E R IN G

From the beg in n in g o f eighties o f th e p ast century, n ew sector in com puter related techn o lo g y is co nnected to softw are en gineering — C A S E ( C om puter A id e d Softw are E ngineering). C A S E is a com plex o f tools capable o f successive softw are engineering stages realisation, and erro r detection. T hese tools are m ainly u sed for m aking o f graphic diagram s, describing functions realised b y p ro jec ted system .

T he m o st im portant ta sk o f C A S E tools at m od ellin g stage, is supporting o f graphic m odel representation edition process. C A S E graphic editors are specialised for creating of, and n avigation th rough graphic diagram s, and ensuring o f illustrated inform ation co­

existence. T hese tools are capable o f realisation o f w hole system building process, starting w ith u se r requirem ents, through m odelling and system projecting, ending at im plem entation.

In fo rm a tio n flo w m o d e llin g w ith in th e tr a n s p o rt te le m a tic s ’ sy stem

3.2. S T R U C T U R E D A N A L Y SIS

The m odelling m ethods can be divided into tw o m ain kinds: structured, and object- oriented [4]. S tructured m ethods are b eing developed for forty years already, together w ith d eveloping o f softw are engineering. T hey are b asing on selecting tw o m ain com ponents o f a system : non-active (data processed b y system ), and active (functions perform ed by system ).

S tructured m ethods are designated for circum stances, w hen there is significant difference betw een structures o f non-active and active com ponents w ithin the system , i.e. system p erform ing sim ple operations on com plicated data, o r com plicated operations on sim ple data.

F ig.5. M a in stages o f structured m odel bu ild in g process

S tructured m odel building process consists o f tw o m ain stages: data model com position, and processes modelbuilding (see Fig.5). D ata m odel is the description o f an inform ation stored and processed b y system . Processes m odel describes functionality p erform ed b y system . T w o above m entioned m odels are afterw ards (w ith the use o f CA SE tolls) integrated. Integration resu lt is Data Flow Model. T he integration o f data and processes m odels is com plicated, w h en system is going to perform com plicated functions on com plicated data, therefore, for such system s, object-oriented m ethods are recom m ended.

3.3. O B JE C T -O R IE N T E D A N A L Y S IS

O bject-oriented m ethods appeared around tw enty years ago. F undam ental difference from structured m ethods is perm ission to use o f sy stem ’s elem ents being capable o f both storing and processing o f data [4], T hese m ethods are m ore useful, w hen projected system is going to p erform com plicated operations on com plicated data.

O bject-oriented m odelling is n o t separating data (non-active com ponents), and p rocesses (active com ponents). H ow ever, follow ing m odel elem ents are specified:

• objects— system com ponents being able to be precisely selected - having their own unique identity,

• classes- tem plates o f o b ject’s groups - described by field s(attributes), and services (operations being able to be processed w ithin class fields),

• class and objects associations - m utual interactions betw een different classes’

objects, and different o b je c ts’ classes,

• interactions - scenarios o f messages flow betw een system ’s objects, and external system s,

• state transition - system elem ents able to present the dynam ic behaviour o f w hole system , classes groups, o r individual classes having com plicated dynam ic structure.

4 5 6 W o jc ie c h W A W R Z Y Ń S K I, P rz e m y s ła w D Z IU L A

O bject-oriented m odel build in g process consists o f follow ing stages: Classes M odel building, and S ta te T ra n sitio n M o d e l com position. C lasses m odel is including: objects and classes identification, cla sse s’ attributes id entification and definition, p lu s objects and classes’

associations identification. State transition m odel covers m essages and services identification and definition.

O bject-o rien ted m odel b uilding p ro cess is not linear, as it w as in case o f structured m odels. P articu lar stages can be interactively m ade (see Fig.6). The an aly ser can start w ith any o f stages illustrated in Fig.6, d epending on his ow n consideration.

Fig.6. Stages o f o b ject-o rien ted m odel b u ild in g pro cess

4. L O G IC A L M O D E L OF IN F O R M A T IO N F LO W SY ST E M F O R T H E SEA T R A N S P O R T SY STEM

F ollow ing p art o f th e thesis is introducing inform ation system m odel, p roposed in [2], as a solution capable o f increasing the safety and effectiveness o f sea transport. The m odel is show ing a concept o f enhancing currently functioning, w ithin the sea transport, inform ation exchange system , able to use inform ation overflow existing in the system . M odel is show ing new d ata flow s and th eir sources. P roposed solution is able to increase the safety and effectiveness o f sea transport, b asing on m o re efficient use o f existing already sea transport teleco m m u n icatio n infrastructure.

T he m odel is m ade by using o f structured m od ellin g m ethods. S tructured analysis has been considered as m ore useful for sy stem ’s data flow m odelling. S tructured m odel lets for detailed presen tatio n o f data, on w hich the sy stem ’s operation is based. A chieving o f this target is m ore d ifficult by the use o f o b je ct-oriented m ethods.

The m odel is illustrating th e perform ance o f system (nam ed as S & E S yste m ), realising three b ase p rocesses (see Fig.7):

1. R e a d data process: reading b y the shore service, data from system s and devices functioning o n board o f ships.

2. D e te rm in e sta tu s process: d eterm ining b y the shore service o f current condition o f ship (safety, em ergency o r distress).

In fo rm a tio n flo w m o d e llin g w ith in th e tr a n s p o rt te le m a tic s ’ sy s te m

3. G enerate in stru c tio n s process: issuing o f instructions for the sh ip ’s crew - designated ( if fulfilled) for increasing sh ip ’s safety and/ o r effectiveness.

T he S& E S ystem is controlled by F le e t M o n ito rin g S y s te m , by form ing and sending o f steerin g instructions. S& E S ystem can w o rk u nder tw o follow ing m odes:

D eterm ining o f current sh ip ’s condition, or

- Supporting o f actions u ndertaken for “reflecting” the em ergency, if appeared, or supporting o f activity designated for m axim izing o f effectiveness o f ship’s exploitation.

control

F ig.7. D ata flow diagram o f S& E system ; sym bols: square - external system , circle - process, arro w - data flow, tw o p arallel lines - d ata store

4 5 8 W o jc ie c h W A W R Z Y Ń S K I, P rz e m y s ła w D Z IU L A

Inform ation o n current ta sk (m ode), to be realised by the system , is carried by the steering instruction. F or the p urpose o f d eterm ining the current condition o f ship, process R ead data is read in g from ship set o f control p ara m ete rs’ values. B asing on this data, D eterm ine status process is determ ining current condition o f ship. Inform ation on current sh ip ’s condition is then han d led to Fleet M onitoring System.

F or the purpose o f th e second o f above m entioned S& E S y stem ’s m odes, R ead data process is to m axim ize the collection o f inform ation on sh ip ’s situation. This is to be done by reading from ship all possible d ata concerned w ith actual em ergency, o r ex ploitation task realised b y ship. B y the use o f this data, and External Expert System, Generate instructions process is issuing instructions for the sh ip ’s crew . F ulfilling o f the instructions, depending on current sh ip ’s condition, is to effect w ith increased safety, o r effectiveness o f her exploitation.

5. C O N C L U SIO N S

It is d ifficult to find articles, treating on transport sy stem ’s inform ation flow m odelling subject, am ong publicatio n s d escribing transport sy stem ’s m odelling. T hen, inform ation flow m odelling, can be poin ted as new direction w ith in transport sy stem ’s m o delling sector.

U n dertaking o f this subject is especially im portant because o f constantly increasing am ount o f inform ation w ith in tran sp o rt system s. F or data flow m odelling C A S E tools are highly recom m ended, as they support good graphic techniques and tools. The recom m endation on need o f C A S E tools usage, in now adays jo b s treating on tran sp o rt system s, can be found i.e.

in [1],

T here is a m odel o f sea transport inform ation flow system introduced in th e thesis. This m odel is capable o f bein g th e base fo r fully w o rk in g system . The m odel can be also proposed fo r o ther transport system s: rail, road and air. E xisting o f increased am ount o f inform ation, we face now adays, is com m on feature o f all m en tio n ed transport system s.

B IB L IO G R A PH Y

[1] A M B R O Z IA K T ., W sp ó łczesn e sp o jrzen ie n a teo rię sy stem ó w tran sp o rto w y ch , O ficy n a W ydaw nicza P o litech n ik i W arsz aw sk iej, W arsz aw a 2002.

[2] D Z IU L A P., M o d e le w y m ian y in fo rm acji p o m ięd zy statkam i a służbam i lądow ym i um ożliw iające zw ięk szen ie b ezp iecz eń stw a i efek ty w n o ści żeg lu g i, R o z p raw a dok to rsk a, W arszaw a 2003.

[3] E u ro p ean S atellite N av ig atio n S ystem G A L IL E O :

h ttp ://e u ro p a .e u .in t/co m m /d g s/e n erg y _ tran sp o rt/g alileo /in tro /in d ex _ en .h tm [4] JA S Z K IE W IC Z A. In ży n ieria op ro g ram o w an ia, H elion, G liw ice 1997.

[5] JA ŹW TN SK I J. W A Ż Y Ń S K A -F IO K K ., B e zp ieczeń stw o system ów , PW N , W arsz aw a 1993.

[6] W A W R Z Y Ń S K I W ., T elem atics tran sp o rt system , International S cientific C onference “ T he T ran sp o rt o f the 2 1 st cen tu ry ” , W arsa w 2004.

[7] W A W R Z Y Ń S K I W . D Z IU L A P ., R o la n ad m iaru in form acyjnego w p o p raw ie bezp iecz eń stw a statku, X X X II Z im o w a S zk o ła N iezaw o d n o ści, S zczy rk 2004.

R e v ie w e r: P h. D . J e rz y M ik u lsk i