Directory UMM :Data Elmu:jurnal:E:Environmental Management and Health:Vol09.Issue1.1998:

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Enviro nme ntal Manage me nt and He alth

9 / 1 [1998] 2 2 –2 6

System architecture and the catalogue of data

sources

ir. Gerrit van Barneveld

Sys te m Engine e ring Manage r, Ins titute fo r Inland Wate r Manage me nt and Was te Wate r Tre atme nt, RIZ A, The Ne the rlands

The article describes the system architecture concept applied in the REMSSBOT project, focusing especially on the use of the Catalogue of Data Sources (CDS). The design approach is explained, taking into account the exist-ing situation and the general requirements for environmen-tal information in the REMSS-BOT participating regions. The REMSSBOT meta-information system is pre-sented, together with a description of the EEA ETC/CDS and Thesaurus, on which the REMSSBOT CDS datamodel was based. The functionality of the CDS is also shown, as well as the search and navigation approach. Last, the standards and components used for the implementation of the system architecture are given, together with a short descrip-tion of the implementadescrip-tion, design and process itself.

T h e d esign of t h e sy st em a r ch it ect u r e of t h e RE MSSBOT-sy st em w a s a gen er a l t a sk w it h in t h e RE MSSBOT p r oject : t o d esign on e sy st em a r ch it ect u r e for t h r ee com p u t er sy st em s w it h d iffer en t fr on t - a n d b a ck -en d s in t h e At t ica , P iem on t e a n d t h e Sch eld t r e gion .

Design approach

T h e m a in ob ject ive is sh a r in g en v ir on m en t a l in for m a t ion by k ee p in g t h e d a t a a t t h eir or igin a l loca t ioigin a igin d by coigin igin ect iigin g t h e loca l d a t a -b a se sy st em s in ea ch r e gion t o t h e RE MSS-BOT-sy st em . We d id n ot con sid er bu ild in g a cen t r a lised d a t a w a r eh ou se a s a solu t ion . In t h a t la st ca se, cop ies h ave t o b e m a d e of t h e or igin a l d a t a a n d t h ese cop ied d a t a h ave t o b e st or ed in a n ew d a t a b a se sy st em . A n ew cen -t r a lised d a -t a b a se sy s-t em h a s -t o b e d esign ed a n d bu ilt , a ll ava ila ble in for m a t ion n eed s t o b e cop ied a n d la st , bu t n ot lea st , t h e con t en t s of t h e n ew d a t a b a se sy st em h ave t o b e m a in -t a in ed . If -t h e or igin a l d a -t a a r e ch a n ged , -t h e cop ied d a t a h ave t o b e ch a n ged in t h e sa m e w ay. Wit h in t h e RE MSSBOT p r oject we h ave ch osen t h e ot h er solu t ion : k ee p in g t h e d a t a a t t h eir or igin a l loca t ion . Th e r eq u ir em en t s for su ch a sy st em w ill b e sp ecified b elow.

General requirements

In t h e t h r ee p a r t icip a t in g r e gion s t h e RE MSSBOTsyst em w ill b e u sed t o exch a n ge in for m a -t ion con cer n in g d iffer en -t en v ir on m en -t a l t op ics, su ch a s solid w a st e, w a t er p ollu t ion , a ir p ollu t ion , r isk m a n a gem en t a n d ecologica l m a n a gem en t of a r iver b a sin . Th e d esign of t h e sy st em a r ch it ect u r e h a d t o b e u sefu l for a ll of t h ese d iffer en t t op ics; t h er efor e t h e d esign h a d t o b e ver y gen er a l or, in ot h er wor d s, t op ic-in d ep en d en t .

T h e t ech n ica l en v ir on m en t a n d t h e com m u -n ica t io-n i-n fr a st r u ct u r e i-n t h e t h r ee r e gio-n s a r e n ot eq u a l. In t h e exist in g en v ir on m en t s we fi n d a ll k in d s of d iffer en t com p u t er p la t -for m s, t h e in -for m a t ion ca n b e st or ed in ever y p ossible w ay, u sin g d iffer en t k in d of fi le-sy s-t em s a n d d a s-t a b a ses. T h e d a s-t a com m u n ica s-t ion n et wor k s va r y fr om d ia l-u p -lin es t o st a t e-of-t h e-a r e-of-t d a e-of-t a com m u n ica e-of-t ion n ee-of-t wor k s. In e-of-t h is d iver sit y we h ave t o d esign a sy st em wor k a ble t o exch a n ge t h e ava ila ble in for m a t ion .

T h e r a n ge of u ser s of t h e sy st em ca n b e ver y w id e, for exa m p le: p olicy m a k er s, en v ir on -m en t a l -m a n a ger s, p r ofession a l u ser s,

d a t a -p r ov id er s, t ech n ica l sp ecia list s, r ela t ed a d m in ist r a t ion s, u n iver sit ies, gen er a l p u blic, et c. In gen er a l, we ca n n ot exp ect t h is w id e r a n ge of u ser s t o h ave sp ecia l k n ow led ge of d a t a com m u n ica t ion . Th er efor e, t h e d a t a com m u n ica t ion p a r t of t h e n ew sy st em h a s t o b e t r a n sp a r en t for t h e u ser s.

Ad d it ion a lly, in t h is r esea r ch a n d d evelop -m en t p r oject t h e p r oject p a r t n er s p r efer t o u se n ew t ech n ologies a n d t ools t o r ea lise t h e sy s-t em , s-t o con s-t r ibu s-t e m a k in g in n ova s-t ion s in s-t h e t h r ee r e gion s a n d t o bu ild u p exp er ien ces a n d k n ow led ge.

The existing and prospective situation

Cu r r en t ly, t h e p r osp ect ive RE MSSBOT u ser s (en v ir on m en t a l in for m a t ion con su m er s) gen er a lly h ave d ir ect a ccess t o t h e in for m a -t ion of -t h eir ow n or ga n isa -t ion on ly. In m a n y ca ses t h ey d o n ot k n ow wh ich in for m a t ion , r eleva n t for t h eir wor k , is ava ila ble in ot h er or ga n isa t ion s a n d if t h ey d o k n ow wh ich in for m a t ion is ava ila ble, t h ey ca n n ot a ccess t h a t in for m a t ion d ir ect ly.

Da t a -p r ov id er s h ave com p a r a ble p r oblem s. T h ey p r ov id e in for m a t ion t o con su m er s in t h eir ow n or ga n isa t ion . Ou t sid e t h eir ow n or ga n isa t ion t h ey d o n ot u su a lly k n ow t h e p r osp ect ive con su m er s. If t h ey d o k n ow t h e ext er n a l con su m er s a n d if t h ey p r ov id e in for -m a t ion on ly on ce, t h ey d o n ot k n ow wh en t h ey h ave t o p r ov id e t h e u p d a t es of t h e in for m a -t ion .

Tod ay, m or e a n d m or e or ga n isa t ion s n eed t o su p p ly t h e p u blic w it h cu r r en t in for m a t ion .

In t h e p r osp ect ive sit u a t ion t h e u ser s h ave d ir ect a ccess t o a ll t h e ava ila ble in for m a t ion st or ed in t h e d a t a b a ses con n ect ed by t h e RE MSSBOT-sy st em (F igu r es 1 a n d 2).

T h e u ser ca n b e a n em p loyee of on e of t h e in for m a t ion p r ov id in g or ga n isa t ion s or of a r ela t ed a d m in ist r a t ion , bu t h e or sh e ca n a lso b e a n ext er n a l p er son , for exa m p le a n in t er -est ed In t er n et -u ser.

T h e u ser w a n t s t o b e a ble t o id en t ify wh a t in for m a t ion is ava ila ble a n d w a n t s t o m a k e a select ion of t h e ava ila ble in for m a t ion . Aft er t h a t h e or sh e w a n t s t o a ccess a n d r et r ieve t h e select ed in for m a t ion w it h ou t t h e n eed for a ll k in d s of sp ecia l t ech n ica l k n ow led ge t o ca r r y ou t t h ese p r ocesses. F in a lly t h e u ser w a n t s t o k n ow wh er e t h e in for m a t ion com es fr om .

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ir. Ge rrit van Barne ve ld Syste m arc hite c ture and the c atalo gue o f data so urc e s

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T h is p r osp ect ive sit u a t ion d efi n es a lot of t ech n ica l fu n ct ion s: Th e sy st em n eed s a u ser in t er fa ce (a clien t p r ogr a m m e or a Web in t er -fa ce), a m et a -in for m a t ion sy st em (a sy st em t o st or e wh ich in for m a t ion is ava ila ble), sea r ch fu n ct ion s t o select t h e m et a -in for m a t ion , com m u n ica t ion fu n ct ion s (t o a ch ieve a con -n ect io-n t o o-n e or m or e d a t a -p r ov id er s, t r a -n s-p a r en t ly for t h e u ser ), a ccess a n d r et r ieve fu n ct ion s a n d fu n ct ion s t o p r esen t t h e select ed in for m a t ion .

Meta-information systems

Wit h in t h e RE MSSBOT p r oject we h ave a n a ly sed t wo m a in gr ou p s of m et a in for m a -t ion sy s-t em s:

• sy st em s b a sed on sy n t a x (t ext sea r ch sy s-t em s);

• sy st em s b a sed on sem a n t ics (a b st r a ct s a n d k ey wor d s sy st em s).

Sea r ch en gin es (fa m ilia r w it h In t er n et u ser s) b elon g t o t h e fi r st gr ou p (exa m p les: Alt a Vist a , E xcit e, In foseek , Lycos, Ma gella n , Ya h oo, et c.). T h ese sy st em s a r e fa st , t h e m a in t en a n ce effor t is lim it ed , t h ey a r e n on -select ive (for exa m p le: “t h is d ocu m en t d escr ib es t h e sy st em a r ch it ect u r e” a n d “t h is d ocu m en t d oes n ot d escr ib e t h e sy st em a r ch it ect u r e” a r e b ot h h it s if you sea r ch for “sy st em a r ch it ect u r e” even t h ou gh you wer e n ot look in g for t h e secon d on e) a n d t h ey h ave b een sp ecia lly d evelop ed for d igit a l d ocu m en t s ava ila ble on ser ver s.

T h e ca t a logu es (well-k n ow n of t h e lib r a r ies) b elon g t o t h e secon d gr ou p, t h ey con t a in a b st r a ct s, in d exed by k ey wor d s. T h ese sy s-t em s n eed a los-t of m a in s-t en a n ce effor s-t , s-t h ey a r e select ive a n d u sa ble for a ll k in d of in for m a -t ion (d igi-t a l a n d n on -d igi-t a l in for m a -t ion , st r u ct u r ed a n d n on -st r u ct u r ed in for m a t ion ).

T h e RE MSSBOT-sy st em u ses a ca t a logu e. T h e ca t a logu e is b a sed on t h e gu id elin es of t h e Ca t a logu e of Da t a Sou r ces (CDS) a n d Th e-sa u r u s d evelop ed by or d er of t h e E u r op ea n E n v ir on m en t Agen cy (E E A) in Cop en h a gen by t h e E u r op ea n Top ic Cen t r e on Ca t a logu e of Da t a Sou r ces a n d Th esa u r u s (E TC/ CDS a n d T h esa u r u s).

The Catalogue of Data Sources and Thesaurus

T h e Ca t a logu e of Da t a Sou r ces is d evelop ed by t h e CDS Top ic Cen t r e of t h e E E A. In 1996 t h ey p r od u ced t h e fi r st ver sion of t h e CDS. To p r o-d u ce t h is ver sion t h ey u seo-d t h e exp er ien ces of ot h er d a t a m od els of m et a -in for m a t ion sy s-t em s or ss-t a n d a r d s. For exa m p le: s-t h e CORIN E CDS p ilot p r od u ct , UDK (Um welt d a t en k a t a -log), DIF (Dir ect or y In t er ch a n ge For m a t ), IF E N, N or d ic, et c.). In t h e la st ver sion of t h e CDS (Se p t em b er 1997, ver sion 2.0) t h e st a n d a r d elem en t set GE LOS (Glob a l E n v ir on m en -t a l In for m a -t ion Loca -t or Ser v ices), p r op osed by t h e MITWG (Met a -In for m a t ion Top ic Wor k in g Gr ou p ) of t h e G7 E N RM p r oject , is a n in t e gr a t ed p a r t of t h e CDS.

In t h e RE MSSBOT-sy st em we u se t h e E TC/ CDS ver sion 1.0, Sep t em b er 1996. Th e CDS con t a in s t h e m et a -in for m a t ion of t h e en v ir on m en t a l d a t a -ob ject s (a b st r a ct s, a d d r esses of in st it u t ion s a n d p er son s a n d ot h er a d d it ion a l sp ecifica t ion s of t h e d a t a -ob ject s).

In or d er t o in d ex, r et r ieve a n d select t h e a b st r a ct s of t h e d a t a -ob ject s a t h esa u r u s is u sed . A t h esa u r u s is a st r u ct u r ed list of t er m s. T h e E TC/ CDS u ses t h e GE ME T (Gen er a l E u r op ea n Mu lt ilin gu a l E nv ir on m en t Th e-sa u r u s). Th e fi r st ver sion con t a in ed a b ou t 4,000 t er m s in E n glish , w it h cla ssifi ca t ion , u p p er h ier a r ch y a n d p a r t ia l eq u iva len ce in Du t ch , F r en ch , Ger m a n , It a lia n a n d Sp a n ish . existing database 1

existing database 2

webserver existing database 3

existing database 4 user 1

user 2

user 3

user 4

user 5

internet

Figure 1

Exis ting s ituatio n

existing database 1

existing database 2

we bs e rve r e xis ting databas e 3

existing database 4 us e r 1

us e r 2

us e r 3

us e r 4

us e r 5

REMSSBOT

me ta-info rmatio n

we b-inte rfac e us e r-inte rfac e

data c o mmunic atio n

func tio ns

we b-bro ws e r

inte rne t Figure 2

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9 / 1 [1 9 9 8 ] 2 2 –2 6

It w a s t h e r esu lt of m er gin g t h e follow in g m u lt ilin gu a l d ocu m en t s:

• Um welt Th esa u r u s of Um welt bu n d esa m t , Ber lin ;

• T h esa u r u s q u a d r ilin gu e p er l’Am b ien t e of CN R, Rom e;

• CN R/ E E A Cla ssifi ca t ion Sch em e; • Mu lt ilin gu a l E n v ir on m en t Th esa u r u s of

N BOI, Am st er d a m ;

• E n Voc UN E P In fot er r a T h esa u r u s, N a ir ob i;

• T h esa u r u s of Med io Am b ien t e, Ma d r id ; • Lexiq u e E n v ir on n em en t P la n èt e, P a r is. T h e la st ver sion of t h e GE ME T (ver sion 1.0, Se p t em b er 1997) h a s t wo a r r a n gem en t s: a cla ssifi ca t ion sch em e (fou r su p er gr ou p s, 34 gr ou p s: t op -t er m s, sign ifi ca n t d escr ip t or s, t er m s) a n d a t h em a t ic or d er (40 t h em es).

T h e GE ME T h a s a t r ee st r u ct u r e of d escr ip-t or s: b r oa d er ip-t er m s, ip-t er m s a n d n a r r ower t er m s.

In t h e RE MSSBOT-sy st em we d o n ot n eed t h e com p let e con t en t s of t h e GE ME T. We u se a soca lled m icr ot h esa u r u s con t a in in g a n u m -b er of select ed t er m s of t h e GE ME T, su p p lied w it h sp ecia l t er m s, con cer n in g t h e en v ir on -m en t a l t op ic of t h e RE MSSBOT-sy st e-m . We u se t h e t r ee st r u ct u r e of t er m s, n ot lim it ed t o t h r ee levels.

T h is t r ee st r u ct u r e is ver y efficien t for sea r ch in g, t h er efor e we u se m or e m icr o-t h esa u r i: on e for t h em a t ic sea r ch (wh a t d escr ip -t or s), a n o-t h er for sp a -t ia l sea r ch (wh er ed escr ip t or s) a n ed t h e t h ir ed for sea r ch for ed a t a -ow n er s (wh o-d escr ip t or s).

Ad d it ion a l in for m a t ion for t h e E E A a n d t h e E TC/ CDS a n d Th esa u r u s ca n b e fou n d fr om t h e a d d r esses sh ow n in F igu r e 3.

The search and selection approach

T h e RE MSSBOT a p p r oa ch for select in g d a t a -ob ject s is b a sed on fou r m a in k ey wor d s: w w w w (wh a t , wh er e, wh o a n d wh en ).

Wit h t h e w h a t -k eywor d t h e u ser specifi es t h e t h em a t ic cover a ge of t h e r equ ir ed da t a -object . He/ sh e is sea r ch in g t h e (t h em a t ic) t h esa u r u s a n d select s on e or m or e descr ipt or s.

Wit h t h e wh er e-k ey wor d t h e u ser sp ecifies t h e sp a t ia l cover a ge. In t h e RE MSSBOT-sy st em h e or sh e is sea r ch in g a geogr a p h ica l-m icr o-t h esa u r u s a n d select s on e or l-m or e geogr a p h ica l d escr ip t or s.

Wit h t h e wh o-k ey wor d t h e u ser sp ecifies t h e ow n er (a u t h or, d a t a -p r ov id er, et c.). He is sea r ch in g t h e a d d r ess in for m a t ion of in st it u t ion s a n d p er son s (or a n a d m in ist r a t ion -m icr o-t h esa u r u s) a n d select s on e or -m or e it em s.

Wit h t h e wh en -k ey wor d t h e u ser sp ecifies t h e t im e cover a ge of t h e r eq u ir ed d a t a -ob ject . T h is in p u t is a select ion cr it er ion a n d is r ela t ed t o t h e t im e sp ecifica t ion of t h e d a t a -ob ject .

Aft er t h is in p u t t h e u ser get s a n over v iew of a ll a b st r a ct s com p ly in g w it h t h e r eq u ir ed w w w w -sp ecifi ca t ion s.

The functionality of the CDS

T h e m a in fu n ct ion a lit y of t h e E TC/ CDS is t o p r ov id e m et a -in for m a t ion of en v ir on m en t a l d a t a ob ject s a n d t o p r ov id e t h e cu r r en t in for -m a t ion ava ila ble by t h e URL (Un iver sa l Resou r ce Loca t or ; for exa m p le:

h t t p :/ / w w w.n et or. gr / r em ssb ot ).

To r ea lise t h is fu n ct ion a lit y, a d d r ess in for m a t ion , in d exed by t h e GE ME T, a n d m et a -in for m a t ion of d a t a -ob ject s, a lso -in d exed by t h e GE ME T, a r e st or ed in t h e CDS-d a t a b a se. T h e RE MSSBOT-sy st em h a s t h e sa m e fu n c-t ion a lic-t y a s c-t h e E TC/ CDS su p p lied w ic-t h c-t h e fu n ct ion a lit y t o a ccess a n d t o r et r ieve a ct u a l in for m a t ion a n d st r u ct u r ed d a t a ava ila ble on ot h er ser ver s (n ot by URL).

T h e RE MSSBOT-sy st em d ist in gu ish es in p r in cip le t h r ee t y p es of d a t a p r ov ision (t h r ee t y p es of ser v ices) t o t h e u ser s:

1 To p r ov id e m et a -in for m a t ion a n d t h e a d d r ess wh er e t o fi n d t h e r ea l in for m a t ion . T h e in for m a t ion is n ot ava ila ble in d igit a l for m a t .

2 To p r ov id e m et a -in for m a t ion a n d t h e m a t ch in g r ea l in for m a t ion , ava ila ble m or e or less in a fi xed for m a t , cop ied fr om a ser ver (for exa m p le: by URL).

3 To p r ov id e m et a -in for m a t ion a n d t h e r ea l in for m a t ion by ca r r y in g ou t of select ion s on d a t a b a ses. T h is ser v ice is a n ext en sion t o t h e E TC/ CDS.

T h ese t h r ee t y p es of ser v ices a r e ca lled RE MSSBOT-ser v ices (ser v ices): in fo, R-p r od u ct a n d R-R-p r ocess.

European Environment Agency

Ko nge ns Nyto rv 6 , DK-1 0 5 0 Ko pe nhage n K, De nmark

Pro je c t manage r CDS: Sigfús Bjarnas o n e -mail: s igfus .bjarnas o n@ e e a.dk

URL: http:/ / www.e e a.dk

European Topic Centre on Catalogue of Data Sources & Thesaurus

Pro je c t le ade r: Ste fan Je ns e n Minis try o f Enviro nme nt o f Lo we r Saxo ny Arc hivs tras s e 2 , D-3 0 1 6 9 Hanno ve r, Ge rmany

e -mail: re fe rat6 0 6 @ mu.rrzn-s e rv.de URL: http:/ / www.mu.nie de rs ac hs e n.de / c ds Figure 3

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To r ea lise t h e ext en sion t o t h e E TC/ CDS-sy st em we n eed m or e t ech n ica l in for m a t ion a b ou t d a t a -ob ject s a n d we h ave t o st or e t h is t ech n ica l in for m a t ion in a n ext en sion t o t h e E TC/ CDS-d a t a b a se.

The datamodel of the CDS and Thesaurus

T h e E TC/ CDS a n d Th esa u r u s con sist s of t h r ee m a in com p on en t s: a collect ion of

k ey wor d s (t er m s or d escr ip t or s), a collect ion of a d d r esses of in st it u t ion s a n d p er son s a n d a collect ion of a b st r a ct s of d a t a -ob ject s a n d sp ecifi ca t ion s (F igu r e 4).

E n v ir on m en t a l in for m a t ion (a n d t h u s m et a -in for m a t ion ) ca n b e cla ssifi ed -in a n u m b er of ca t e gor ies: a ct iv it ies, d a t a set s, d a t a , st a t ion s a n d sit es, m a p s, t ools a n d a p p lica t ion s a n d d ocu m en t s.

An a ct iv it y or a d a t a set con sist s of a collect ion of m iscella n eou s env ir on m en collect a l in for m a -t ion . An a c-t iv i-t y d escr ib es a p r ojec-t or a p r o-gr a m m e; w it h in a p r oject d iffer en t k in d s of d a t a a r e gen er a t ed or collect ed . Th e d a t a col-lect ion a n d d ocu m en t a t ion a r e d escr ib ed by a d a t a set . Th e d a t a collect ion con sist s of d iffer -en t ob ject s d ea lin g w it h a cer t a in issu e or r ela t ed t o a com m on sp a t ia l r efer en ce. Ob ject s m ay t a k e t h e for m of m a p s, m ea su r em en t d a t a (e.g. in a fi le or d a t a b a se), r e p or t s, et c.

In gen er a l, t h is m ea n s we h ave d iffer en t cla sses of d a t a -ob ject s a n d on e d a t a -ob ject ca n h ave on e or m or e r ela t ed d a t a -ob ject s. In t h a t ca se we sp ea k of p a r en t a n d ch ild d a t a -ob ject s.

Ad d r esses fr om in st it u t ion s a n d p er son s p lay a m a jor r ole in t h e E TC/ CDS, b eca u se a n y m et a -in for m a t ion is a ffilia t ed t o a n in st i-t u i-t ion or i-t o on e or m or e p er son s a n d ca n b e loca lised by t h ese a d d r esses. F u r t h er m or e, p er son s a r e r ela t ed t o a n in st it u t ion .

T h is m ea n s on e d a t a -ob ject is r ela t ed t o on e or m or e a d d r esses. Of cou r se on e p er son or in st it u t ion ca n a lso b e r ela t ed t o m or e d a t a -ob ject s; a n d on e a dd r ess ca n h ave on e or m or e r ela t ed a d d r esses. In t h a t ca se we sp ea k of p a r en t a n d ch ild a d d r esses.

T h e m u lt ilin gu a l t h esa u r u s (GE ME T) is a st r u ct u r ed list of a u t h or ised t er m s, gr ou p ed in logica l ca t e gor ies a n d su b -ca t e gor ies: fou r su p er gr ou p s, gr ou p s, t op -t er m s, sign ifi ca n t d escr ip t or s, t er m s. T h e t op -t er m s, sign ifi ca n t d escr ip t or s a n d t er m s a r e u sed a s k ey wor d s for in d exin g a d d r esses a n d d a t a -ob ject s.

T h e RE MSSBOT d a t a m od el h a s t wo ext en -sion s t o t h e E TC/ CDS-d a t a m od el (F igu r e 5): 1 To sp ecify u ser s a n d u ser gr ou p s a n d t o

sp ecify u ser p r iv ile ges som e t a bles a r e a d d ed t o t h e E TC/ CDS-d a t a m od el, r ela t ed t o a d d r esses. T h is fu n ct ion a lit y is op t ion a l. T h e secu r it y level a n d t h e a ccess con t r ol ca n b e d iffer en t in t h e At t ica , P iem on t e or Sch eld t r e gion .

2 To ca r r y ou t t h e RE MSSBOT-ser v ices (R-p r od u ct a n d R-p r ocess) som e t a bles t o st or e t ech n ica l in for m a t ion a r e a d d ed t o t h e E TC/ CDSd a t a m od el, r ela t ed t o d a t a -ob ject s.

Wit h in t h e RE MSSBOT-sy st em t h e R-p r ocess is ca r r ied by t h e E ser v ice (E lem en t a r y ser -v ice). Th e E -ser -v ice sen d s a q u er y a n d r et u r n s sin gle or m u lt ip le va lu es, st r u ct u r ed d a t a , a m a p or a p ict u r e fr om a RE DP (r e gion a l en v i-r on m en t a l d a t a -p i-r ov id ei-r ).

Supe r gro up

Gro ups

To p-te rms

Sign. de s c ripto rs

Te rms the saurus

Ins titutio ns addre sse s

Pe rs o ns

Do c ume nts data-o bje c ts

To o ls & Applic atio ns Maps

Statio n & Site s

Data

Datas e ts

Ac tivitie s Figure 4

Lo gic al datamo de l o f the ETC/ CDS (ve rs io n 1 .0 ) and The s aurus

Supe r gro up

Gro ups

To p-te rms

Sign. de s c ripto rs

Te rms s to re d in the the saurus table s

Ins titutio ns

Pe rs o ns

Do c ume nts s to re d in the Datao bje c t table

To o ls & Applic atio ns Maps

Statio n & Site s

Data

Datas e ts

Ac tivitie s

s to re d in DatThe sRe l table s to re d in DatRe l table sto re d in AdrDatRelation table

s to re d in AdrRe l table

REMSSBOT-us e rs and us e rgro ups

s pe c ific atio ns

R-info REMSSBOT-s e rvic e s

R-pro duc t

Ele me ntary-s e rvic e s s to re d in AdrThe sRe l table

s to re d in the Addre ss table

R-pro c e s s Figure 5

(5)

9 / 1 [1 9 9 8 ] 2 2 –2 6

Standards and components of the

system architecture

T h e sy st em a r ch it ect u r e is r ea lised w it h t h e follow in g st a n d a r d s a n d com p on en t s: • op en in d u st r y st a n d a r d s;

• ob ject t ech n ology ; • Web t ech n ology ;

• CORBA (Com m on Ob ject Req u est Br ok er -in g Ar ch it ect u r e);

• Visu a lWave/ Visu a lWor k s a n d Dist r ibu t ed Sm a llt a lk (At t ica / Sch eld t );

• For t é en v ir on m en t (P iem on t e);

• A m et a -in for m a t ion sy st em b a sed on t h e E E A E TC/ CDS a n d Th esa u r u s d a t a m od el; • Clien t : P C (Win d ow s 3.11 + Win d ow s 95) ,

wor k st a t ion (Win d ow s N T + Un ix); • Ser ver -p la t for m : Win d ow s N T , Un ix, Aix.

Design and implementation

process

T h e d esign a n d d evelop m en t t ea m for t h e sy st em a r ch it ect u r e, com p osed of exp er t s of

t h e su b con t r a ct or E DS-Belgiu m (E lect r on ic Da t a Sy st em s), p r od u ced t h r ee d ocu m en t s: 1 “Su r vey a n d im p a ct of CDS sit u a t ion a n d

r esea r ch of t h e t ech n ica l sit u a t ion .” T h is d ocu m en t h elp s t o select t h e gen er a l p u r -p ose ser ver -in d e-p en d en t t ech n ology for u se in d evelop in g d ist r ibu t ed a p p lica t ion s a n d gives exa m p les of t ech n ica l a r ch it ec-t u r es.

2 “Gu id elin es for t h e Sy st em Ar ch it ect u r e” d ocu m en t s t h e t ech n ica l bu ild in g block s a n d t h e gu id elin es for t h e a r ch it ect u r e, b a sed on a r esea r ch of t h e t ech n ica l a lt er -n a t ives a -n d a su r vey of t h e i-n fr a st r u ct u r e in t h e t h r ee r e gion s (F igu r e 6).

3 “Tech n ica l Gu id elin es for t h e Sy st em Ar ch it ect u r e” d escr ib es t h e im p lem en t a -t ion of -t h e sy s-t em a r ch i-t ec-t u r e in m or e d et a il.

At t h e sa m e t im e a p r ot ot y p e of t h e a r ch it ec-t u r e w a s bu ilec-t ec-t o p r ove ec-t h a ec-t ec-t h e d esign a n d ec-t h e ch osen d evelop m en t en v ir on m en t is a r ea l wor k in g solu t ion . Th e p r ot ot y p e w a s p r o-d u ceo-d in close co-op er a t ion w it h t h e t h r ee d evelop m en t t ea m s in t h e At t ica , P iem on t e a n d Sch eld t r e gion s.

T h e t ech n ica l gu id elin es a n d t h e p r ot ot y p e of t h e sy st em a r ch it ect u r e (in clu d in g a CDSd a t a b a se, a fu n ct ion a l fr on t en CDSd clien t a p p lica -t ion a n d a b a ck -en d ser ver ) fu n c-t ion a l for a lim it ed n u m b er of d a t a t y p es, w a s t h e st a r t in g p oin t for t h e “im p lem en t a t ion -p h a se” of t h e d em on st r a t or s in t h e t h r ee r e gion s.

Directory UMM :Data Elmu:jurnal:E:Environmental Management and Health:Vol09.Issue1.1998:

System architecture and the catalogue of data

sources

ir. Gerrit van Barneveld

Design approach

Meta-information systems

The search and selection approach

The functionality of the CDS

Standards and components of the

system architecture

Design and implementation

process

Further reading