TRl/OfNG DAI HOC AN GIANG
..

KHOA KITHUAT - CONG NGHE & MOI TRU*6fNG

TRI/ONG QUANG PH^C

KHOA LUAN TOT NGHIEP HAI HOC NGANH Ctf NHAN TIN HOC

^l HOC
AN GIANG

THl/VIEN

GV. Huong din:
ThS.Doan Thanh Nghi

An Giang, 05/2009


LCJI CAM ON
Toi xin giii ldi cam on chan thanh den:
-ThS. Doan Thanh Nghi, pho khoa KT thuat - Cong nghe & Moi trudng

ngudi da true tiep hudng din, gop y rat nhieu trong qua trinh thuc hien
luan van.

-Cac thay co bo mon KT thuat - Cong nghe & Moi trudng da cung cap cho
toi nhung kien thuc quy bau, de toi co dupe nen tang kien thuc va phuong
phap nghien cuu thuc hien luan van.
-Cac can bo UBND Phuong My Xuyen, Can bo Phong Cong tac Sinh vien

da ho trp trong qua trinh suu tam dtt lieu thuc hien luan van.
-Cac ngudi than trong gia dinh, ban be da gitip do, khuyen khich va dong
vien trong suot qua trinh hoc va lam luan van.


tomtAtdetai
Ten de tai:
Sir dung cong nghe WebGIS - Xay dung ban do so Thanh pho Long Xuyen.

Sinh vien thuc Men: TRlfONG QUANG PHUC
Giao vien huong din: DOAN THANH NGHJ
Mo ta so1 luuc:
GIS ra doi va dugc phat trien manh trong nhQng nam gan day. Ciing voi su biing no
ve cong nghe cua Internet, GIS ciing da phat trien cong nghe cho phep chia se thong
tin thong qua mang toan cau bang each ket hop GIS va Web hay con goi la
WebGIS. Vi the, viec nghien cuu ling dung WebGIS se mang lai kha nang chia se
thong tin dia Iy rong rai cho cac nganh.

Noi dung chinh cua d^ tai la nghien ciiu ve WebGIS, kha nang xay dung ling dung
WebGIS tren nen tang .NET thong qua cong nghe Map Suite, tren ca so do ling dung

xay dung WebGIS phuc vu du lich thanh ph6 Long Xuyen.
Yeucau:
-Tim hiSu each xay dung ban do true tuyen thong qua cac website
www.diadiem.com ...

-Thu thap du lieu thuc tk
-Xay dung ban do blng Maplnfo.
-Phan tich, thi^t kg he thong.
-Cai dat, thu nghiem.

Moi truong phat trien:
-Cong cq xay dung ban do Maplnfo Professional 9.0.
-Moi truong Visual Stuio 2008
-Ngon ngft: ASP .NET, C#.


MUC LUC
PhlnA^MODAU'....'.1

I.Tinh cap thiit:1
II.Muc tieu:1
III.Ljch sir nghien cini:2
IV.Djnh huong cong nghe:3

PHAN B. WEBGIS - CONG NGHE GIS QUA MANG4
I.WebGIS la gi?4
II.Tilm nang cua WebGIS4
III.M6 hinh xfr ly va kien true trien khai Webgis5
1 Kien true Webgis va cac butfc xfr lj>:,5

2Cackiin true triln khai:7
3. Chiin thuat xfr ly:8
4 Phan loai WebGis13
PHAN C. MAP SUITE WEB EDITION17
I - Gioi thieu17
II. Cac dac tinh cua Map Suite Web Edition17
l.'Map Suite 3.0 : mot the he phan mim GIS m^i17
2.Cai tien kha nang hrong tac cua Ajax18
3.H tro nhiu loai du-lieu18
III - Cau true va each thu-e hoat dong cua Map Suite Web Edition20

l.Ajax'..'21

2.Map Suite Engine25

3.Map Suite Web Edition31
Phan D. XAY DITNG WEBSITE BAN DO LONG XUYEN S& DUNG MAP SUITE WEB.

:48
I.

Phantich:48
1.Hien trang nhu cau thong tin:48

2.; Ph^n loai thong tin:48
3.; Phan tich he thong va d|nh hnotig cong nghe:49

H. Thiit ke:49
LI Thiit ki kiin true:49
2.Thiit ki co set dir liu50
Phan E. KET LUAN70
I.Kit qua dat diroc:70
II.KitLuan:•.70

III.Hu^ng phat triin de tai::70
Tai lieu tham khao:71


MUC LUC HINH
Hinh 1: Kin true WebGis6
5 vHinh 2: Cac dang yeu cau tir phia client7

Hinh 3: CSu hinh server side9
Hinh 4: Cau hinh Client-side10

Hinh 5: Tich hap xu ly GIS vao trinh duyet11
Hinh 6: Ket hap Client-side va Server-side,12

Hinh 7: Mo hinh hoat dong21
Hinh 8: Tao project mai trong Visual Studio .NET26
Hinh 9: Them reference vao project26

Hinh 10: Hiin thi ban d8 bang PictureBox27
Hinh 11: Ban do dan gian29
Hinh 12: ThiSt lap project mdi trong moi trucmg Visual Studio 200831
Hinh 13: Add reference vao project32

Hinh 14:Map Control32
Hinh 15: Keo Map Control vao project33
Hinh 16: Du lieu dugc stir dung trong vi du35

Hinh
Hinh
Hinh
Hinh
Hinh
Hinh

17: Ban do Chau Au dan gian37
18: Ban d6 chau Au vdi hai lop39
19: Du lieu cho vi du39
20: Sir dung TextStyle41

21: Trudc khi zoom43
22: Sau khi Zoom44

Hinh 23: Them marker vao ban do45
"Hinh 24: Tinh-toa do ban d8 trong he tpa do Descartes vuong goc52

Hinh
Hinh
Hinh
Hinh
Hinh
Hinh
Hinh

25: Hop thoai tao di8m di8u khiSn53
26: Thu thap du lieu tren duangNgo Gia Tir (1)55
27: Thu thap du lieu tren duang Ngo Gia Tu (2)56
28: Giao dien chinh66
29: Ve tren ban d866
30: Chp hi6n thi cac layer67
31: Hien thi nai tim kiem67

Hinh 32: K6t qua nhan xet68

Hinh 33:G6i hosting Start Plan cua M^t Bao68


MUC LUC BANG
Bang 1: Chign thuat Server - side10


Bang 2: Chign thuat Client-side12
B^ng 3: Cac chuc nang ciia cac loai djch vu15
Bang 4: Mo ta cac loai dQ" lieu ma may khach nhan dugc15

Bang
Bang
Bang
Bang
Bang
Bang
Bang

5: Lap du lieu khong gian ca ban57
6: Mo ta chi tigt vg thuc the Phuong58
7: Mo ta chi tigt vg thuc thg Duong58
8: Mo ta chi tiet vg thuc thg Song58
9: Mo ta chi tigt vg thuc the C3u58
10: Mo ta chi tiet vg thuc the Quan an59
11: Mo ta chi tigt vg thuc thg Bac sT - Tiem thu6c59

Bang 12: Mo ta chi tiet vg thuc the Benh vien59

Bng 13: Mo ta chi tigt vg thuc thg Cho,59
Bang 14: Mo ta chi tigt ve thuc the Nha tho - Chua59
Bang 15: Mo ta chi tiet vg thuc thg Co quan60
Bang 16: Mo ta chi tiet ve thuc the Cira hang xe may - Tiem sira xe60

Bang 17: Mo ta chi tigt vg thuc thg Cua hang dien thoai di dong60
Bdng 18: Mo ta chi tigt vg thuc thg Cua hang dien may60
Bang 19: Mo ta chi tigt vg thuc thg Trubng hoc61

Bang 20: Mo ta chi tigt vg thuc the Tiem vang - Cim dg61
Bang 21: Mo.ta chi tigt ve thuc thg Cua hang thai trang'.61
Bang 22: Mo ta chi tiet vg thuc thg Cua hang trang tri noi that61

Bang 23: Mo t^ chi tigt vg thuc thg Nha hang - Khach san61
Bang 24: Mo ta chi tigt vg thuc thg Ciia hang mit kinh62
Bang 25: Mo ta chi tigt vg thuc thg Khac62
Bang 26: Mo ta chi tigt vg thuc the Sinh vign62
Bang 27: Mo ta chi tigt vg thuc thg Nha tro63
Bang 28: Ket qua thu nghiem69


Danh muc cac tir viet tat.

Viet t^t

Nguyen van

Y nghla
He thbng thong tin dja Iy.

GIS

Geographic Information

ADF

Application Development
Framework


Framework cua Oracle.

COM

Component Object Mode

La mot dac ta, mpt tap hop cac dich vu.

NASA

National Aeronautics and
Space Administration

Cue quan trj hang khong va khong gian quoc

API

Application Programming

Systems

HTML
MAPI

gia Hoa ky.
Mot tap hop cac qui trdc goi ten dung di dinh

Interface

nghTa each thirc mot djch vu duoc goi ra

thong qua mot goi phan mem.

HyperText Markup

Ngon ngu danh dau duoc thiet ke de tao nen

Language

cac trang web.

Messaging Application

Giao dien lap trinh thong diep.

Program Interface

DBMS

Database Management

He qu4n trj co so dd lieu.

System

CGI

Common Gateway Interface

ISAPI


Internet Server Application

Cung nhu CGI, ISAPI la mot chuln giao dien

Programing Interface

cho phep mo rang kha nang khai thac co so

Chuan de ket noi chtrong trinh ung dung voi
Web server.

dCf lieu cua Web Server.

OGC

Open Geospatial Consortium

Mot t6 chuc phi lpi nhuan, din dlu tren the
gidi ve phat trien cac chuan dO lieu dja Iy va
cac dich vu.

WMS
SLD

Web Map Service

Dich vu cung cap ban do so tren Web.

Styled Layer Descriptor


Mot ma hoa cho dac ta WMS co the mo rong

d^ cho phep ky hieu hoa du lieu theo yeu clu
ngucri su dung.

WFS

Web Feature Service

Dich vu doi ttrong dja Iy. Cung cap cac doi
ttrong dja Iy cho cac client.

WCS

Web Coverage Services

Day la giao dien mo rong cua WMS cho
phep truy cap den cac dir lieu kieu "phu
tritm" the hien cac gia trj va thuoc tinh cua
cac vi tri khong gian hon la chi don thuan the

hien ban d6 da duoc t6ng hop (dang hinh
anh, pictures).

XML

Extensible Markup Languge

.


La ngon ng& xay dung cau true tai lieu van
ban.

UI

User Interface

Giao dien de ngudi sir dung tuong tac voi
phan mem.

GDI
AJAX

Graphics Device Interface

Tap cac ham va cac doi tuong do hoa.

Asynchronous JavaScript

La mot nhom cac cong nghe phat trien
web duoc su dung de tao cac ung dung web

and XML

dong hay cac ung dung giau tinh Internet.

.


Danh myc cac thuat ngfr tieng Anh

Thuat ngu tieng Anh
Y nghia
Cong
nghe
GIS
qua
mang.
WebGIS
MapServer

La mot moi trirong phat trien Open Source doi voi viec xay
dung cac ling dung internet cd yeu to khong gian.

ESR1

Cong ty di dau trong cong nghe GIS.

Geospatial data

Du lieu dja ly khong gian

Clearing house

Noi luu trii va duy tri cac d& lieu khong gian.
May phuc vu Web - May tinh ma tren do cai dat phln m^m

Web Server

phuc vu Web, doi khi nguoi ta cung gqi chinh phan m&n do la
Web Server.

Application server

Phan mem may chii ling dung: la mot phan mem trong cung cap
ling dung phan mem cho cac may tram hoac thiSt bj, thong
thubmg la qua mang Internet sii dung giao thiic HTML.

Data exchange server

May chii trao doi du lieu.

Data server

May chii chiia dfr lieu.

ActiveX

La mot doan ma tang them cho cac trang Web tinh nang
Multimedia.

Java Applet

La chuong trinh duoc viet fren ngon ngit Java, va duac kich
hoat nha cac trinh duyet mang.

Mainframe

He thong may vi tinh Ion.

Plug-in


La nhimg chucmg trinh nho, co the fr dang kha thi .exe hay dang
file .dll. Plugin dugc viet ra nham bo sung chiic nang cho cac
chuong trinh chinh, Ion hem.

Coverage

La loai dii lieu bieu dien cac hien tuong thay d6i theo khong
gian.

Zoom

Che do di chuyen tren ban do
Phong to, thu nho ban d6.

Marker

Ghi dau.

Popup

Cac cua so tu dong hien ra.

Pan

Spatial queries

Truy van du lieu khong gian.

Regular Expression
rendering


Bieu dien bang cac menh de chung.

Chart/graph rendering

Bieu dien b^n do/do thi.

Projections

BiSu diln Trai d^t tren bh mat 2D.

IntelliSense

Trinh cam ling thong minh.

Track shape

Ve hinh.

Post-back

Yeu cau load lai toan bo trang web.

Custom event

Sir kien do nguoi dung chi djnh.

Data grid

Ludd du lieu. Dung de bieu dien dfr lieu dang bang.


Map control

Dieu khien b^n do.

Refresh image

Lam mdi hinh ^nh cua ban do.

Reference

Dung de chi dinh cac thu vien.

Binary

Dang nhi phan.

Shapeftle

La mot dang dtt lieu ciia Map Suite de chiing ta ve ban do.


Layer

Lap dir lieu bdn do. Duac hi^n thi theo thO ttr "d^n trudc n5m
dudi".

Map

Ban do.


MapEngine

La lap ca sd chOa tat ca cac ddi tuang cho viec trinh diln ban
do.

Style

Kieu hien thi

UpdatePanel

NhOng gi dtrac dat trong UpdatePanel se dirge cap nhat khi qua
trang.


Sir dung cong nghe WebGIS - Xay dung ban do so TP Long Xuyen

Ph^nA. MdDAU
I.Tinh cap thiit:
-GIS da dugc ung dung ttr vai th^p nien trudc day, nhung dudng nhu GIS van chira den
dirge vdi moi ngudi. Ly do la, trudc nay cac ung dung GIS hau het chay tren may tinh
don. Vai cac may nay can thiet phai cai dat cac module xir ly GIS, deu nay can trd kha
nang ling dyng GIS rong rai.
-Vi du: Khi mot ngiccri can biet chuyen xe buyt de di chuyen thi ngoai trie anh ta trang bi
mot Pocket PC cai img dung tim duong xe buyt, con khong anh taphdi ve nha hay den co
quan lim dimg may tinh duoc cai img dung nay de fun kiem thong tin.
-Til vi du nay cho thay cac ung dung GIS mang tinh cong dong hoac khi can co the sir
dung bit cur nai dau, thi mo hinh ling dyng chay tren may don la khong dap ling dugc.
Nhu da bilt, Internet ra dai va da thu ngln khoang each giua moi ngudi, va cho phep tim

kilm thong tin moi liic moi nai. Mo hinh ling dung GIS chay tren nen Internet cho phe^
moi ngufri dung bit ky cong cu nao (may PC, may Laptop, mobile, Pocket PC ...) co the
truy cap Internet tim kiem thong tin minh can.
-Du lich la mot trong nhung thu vui mang lai su hung phln cho con ngugi, lam giam
stress, nhat la trong thai dai cong nghiep nhu hien nay. Be co mot chuyen du ljch thuan
lgi, thoai mai thi nhung thong tin lien quan den dja diem du lich, cac thong tin ve djch vu
do cac cong ty du lich cung cap la dieu ma bat cu nguai di du lich nao cung can phai biet
trudc. Hien nay, ngudi di du lich co the co cac thong tin bang viec truy cap cac trang web
thong qua mang internet. Tuy nhien, cac trang web hien nay chi dung lai d viec cung cap
cac thong tin mo ta ma chua ket hgp cung clp cac ban dd dong ve cac dia diem du lich.
-Trong nhung nam gan day, GIS da dugc ling dung rat nhieu trong cac nganh khoa hoc co
lien quan den du lieu khong gian. Vdi kha nang quan ly, chia s^ cac ling dyng thong tin
dia ly qua mang internet/intranet. B5ng viec ket hop GIS va web de tao thanh WebGIS,
ngudi di du lich se truy cap dugc cac thong tin du lich kit hgp vdi cac ban d6 dong de cd
dugc cai nhin true quan ve cac dja diem ma minh se din thong qua trinh duyet web ma
khong can phai hgc sii dung cac phan mem GIS. Ben canh do, neu ket hgp xay dung
WebGIS tr^n cong nghe .NET se cd dugc cac lgi ich do cong nghe .NET mang lai.
-Vi vay, dl tai dat ra vln dl nghien ciiu xay dung WebGIS phyc vu du lich, gdp phln tao
thuan lgi va cung cap da dang thdng tin cho ngudi di du ljch.
II.Muctieu:
Hien nay tai nude ta cong nghe GIS khong phai la mot cong nghe mdi. Nhung hien chi cd
mot so it vien nghien ctru, cac ca quan va vai cong ty la cd nghien cuu va sir dung GIS. Ve
WebGIS so lugng ngudi nghien cuu thi con it han.
Myc tieu cua de tai dugc chia thanh hai phan chinh nhu sau:

? Cong nghe WebGIS:
-Nghien cuu ve cong nghe WebGIS.
-Tim hilu Map Suite mot triln khai cong nghe WebGIS tren nln tang .NET.

Trang 1



Sir dung cong nghe WebGIS - Xay dung ban do so TP Long Xuyen

? Xay dung ban dd du ljch thanh ph6 Long Xuyen:
-Phan tich hien trang
-Khao sat cac yeu cau.

-Xay dung du lieu ban do.
-Viet ung dung.
III. Ljch sfr nghien cihi:
Hien nay co rat nhieu cong nghe dupe sir dung de xay dung WebGIS, mot trong so do co the
ke den nhu:
-MapServer: Theo nguon chinh thuc tir website MapServer: MapServer la mot moi trudng
phat trien Open Source doi vdi viec xay dung cac ung dung internet co yeu to khong gian.
MapServer khong la mot he thong GIS tron ven. Thay vao do, MapServer rit than thien
vdi du lieu khong gian (maps, images, va vector data) cho moi trucmg web. Ljch sir
•MapServer dupe phat triin bed dai hoc Minnesota(UMN) va Minnesota Department of
Natural Resources (MNDNR). Hien tai, du dn MapServer true thuoc du an TerraSIP, mot
du an dupe NASA tai trp doi vdi trucmg dai hoc UMN va nhung ngufri thuc hien trong
lTnh vuc quan ly dat dai. Phan mem dupe viet bdi mot nhdm gan 20 lap trinh vien va co
xu hudng tang len khap the gidi va dupe ho trp bed nhieu nhom va cac quy to chuc khac
nhau.

-ESRI webgis: ArcGIS Server co kha nang ho tro cac irng dung ldn nhu xay dung Web
GIS, chay tren nhiSu may chu, h5 tro da ngudi diing. Cong nghe ADF (Application
Development Framework) khong gidi han ban quyen. Dieu nay cho phep cac ung dung
server cd th^ chay tren nhiSu may chu Web, do do lam giam gia thanh, chi phu thuoc vao
s6 Iuong ngudi dimg. ArcGIS Server cung cap mot bo cac Web controls. Cac Web
controls nay lam don gian di cac cong doan xay dung tich hop ban do vao cac ung dung

Web, giup cho cac lap trinh vien tap trung vao xay dung cac chuc nang GIS theo muc
dich cua minh. ArcGIS Server ho tro nhieu ngon ngu lap trinh, bao gom ca .NET va Java
di phat triin cac ung dung, dich vu Web. Sir dung COM(Component Object Mode) va
.NET cho phep md rang ArcGIS Server cac tinh nang theo yeu ciu rieng, ngoai ra COM,
.NET, Java, va C++ con dupe dung di xay dung cac ung dung Desktop client. Dieu nay
cho phep cac dii tupng dupe lap trinh bang nhieu cong cu va cac lap trinh vien khong

nhit thiit phai biit nhiiu ngon ngu lap trinh.
-Cong nghe WebGIS Google: Ndi vi GIS tin chic ngoai trir NASA wordwin (nguin md)
ra thi google phai ndi la mot dai gia vi GIS ma cu the la web GIS
va ung dung gooleEarth. Google Maps dua ban do len web bang each cat ban do theo
tung dp phdng to, thu nhd (dp zoom) khac nhau. Va khi dua dnh len web chi can rap
nhiing tim anh nay theo do zoom, pan ma ngudi dung thao tac.
-Cong nghe Map Suite: la mot cong nghe mdi, Map Suite Web Edition cua hang ThinkGeo
la mot GIS control ciia nin tang .NET cho phep tao ra cac ban di tuomg tac true tuyin
mot each de dang. Co thi ndi day la mot ung dung manh nhat hien nay de phat trien
WebGIS. No ho trp nhieu loai du lieu, giao dien API don gian giiip viec viet code de dang
hem...

Trang 2


Sd dung cong nghe WebGIS - Xay dung ban do so TP Long Xuyen
IV.Djnh hudng cong nghe:
-Theo nhu da gidi thieu nhu tren thihien nay co rat nhieu cong nghe trong viec phat trien
WebGIS. Trong pham vi de tai nay se chi tint hieu ve mot cong nghe cd the coi la rat mdi
trong viec phat trien cic ung dung GIS qua mang, do la Map Suite cua hang ThinkGeo.
Day la mot cong nghe dua tren nen t^ng .NET. Tieu bieu trong do la Map Suite Web
Edition, mot map control ho trp dac lire trong viec phit trien cac ung dung GIS qua mang.
-D6i vdi viec phat trien mot WebGIS phuc vu du lich nhu de tai nay thi chien thuat xtr ly

tot nhat la ket hop ca hai chien thuat Client va Server, Map Suite co the dap ung dupe

dieu nay. Do WebGIS du lich khong doi hoi ngudi dimg cac hieu biet ve he thong GIS ma
van co th^ van hanh mot each tron tru, va cac chuc nang tuong tic vdi bin do phii thuc
hien mot each nhanh chdng. Vdi viec tich hop Ajax trong cong nghe Map Suite thi viec
nay se dupe thuc hien mot cich de dang. Day cung la diem manh nhit cua Map Suite so
vdi cac cong nghf khic.
-Dac di6m noi bat nua cua Map Suite la do dupe xay dung tren n^n tang .NET nen viec lap

trinh se tuong d6i de dang vdi nhung ngudi da lam viec vdi .NET trudc do (lap trinh ASP
.NET, C#, Visual Basic...).

-Tom lai, viec ung dung cong nghe Map Suite trong xay dung WebGIS du lich thanh phd
Long Xuyen se mang lai nhieu thuan lpi: moi trudng lam viec quen thupc, chien thuat hop
ly, cic chdc nang tren bin do dupe thuc hien nhanh hon so vdi cac cong nghe khic...

Trang 3


Sir dung cong nghe WebGIS - Xay dung ban do so TP Long Xuyen

PHAN B. WEBGIS - CONG NGHE GIS QUA MANG
Khai niem GIS (Geographic Information System) ra dcri tit nhilng nam d^u cua thap ky 60. Mot
trong nhung he thdng GIS dau tien la CGIS (Center for Geographic Information Science). Co
nhidu d|nh nghTa vd GIS, tuy nhidn co mot dinh nghTa cua ESRI nhu sau: GIS la mot he thong
gdm 5 thanh phan: phan ctrng, phan mem, dd lieu, quy trinh va to chuc - con ngucri.

Ngay nay, GIS con dugc hieu theo nhieu nghTa khac nhau: GIS (GISolution), GIS (GIService).
GIS thuc hien 4 chuc nang co ban:
•Thu thap

•Luu tru
•Phan ti'ch

•

Hidn thi

I.WebGIS la gi?
-Theo dinh nghTa do Cartography dua ra: WebGIS dugc xem nhu la mot he thong thong tin
dja ly dugc phan bo qua moi trudng mang may tinh dd tich hgp, phan phoi va truydn t^i
thong tin dja ^^ true dien tren WWW thong qua Internet.
II.Tiim nang cua WebGIS
-Kha nang phan phoi thong tin dja ly rang rai tren toan cau.
-Ngucri diing Internet co thd truy cap ddn cac ung dung GIS ma khong phdi mua ph^n mem.

Bieu nay giup cho chung ta tidt kiem dugc chi phi doi voi mot he thong GIS bdi cac phan
mem GIS hien nay co gia thanh rat cao.
-Boi voi ph^n Ion ngucri dung khong co kinh nghiem ve GIS thi viec su dung WebGIS se
don gian hon viec sir dung cac ung dung GIS loai khac.
-WebGIS cho phep them cac chuc nang GIS trong cac ung dung chay tren co sir mang nhu
thuong mai, chinh phu, giao due. Nhieu ung dung loai nay chay tren mang cue bo nhu mot
phuong tien phan phoi va sir dung du lieu dia ly khong gian (geospatial data).
-Mot trong nhung uu the noi troi cua WebGIS la kha nang tai sir dung nguon d& lieu da co,

ti'ch hgp dd xay dung thanh nhifng ling dung rieng cua minh ma khong phai t6n chi phi cho
dtt lieu ndn.
-WebGIS thoa man dugc mot trong nhung yeu cau khat khe cua bai toan tich hgp trong mot

he th6ng GIS la dap dug theo thcri gian thuc.
WebGIS la mot dng dung truy xuat thong tin dia ly chay tren trinh duyet, ho trg day du cac

tinh nang cua mot dng dung thong tin dia ly va co the tuy bidn cho nhieu ngu6n thong tin
khac nhau, cho nhieu muc dich khac nhau.
-Voi WebGIS, cac ban co thd xem va thao tac tren ban do cua ca thanh pho voi nhi^u chuc
nang da dang (phong to, thu nho, keo tha, them xoa cac cong trinh, in ban do ...). Hon nira,
cac ban co thd tim kidm nhanh va xem cac don vj hanh chinh quan huyen, thong tin cac dja

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Sir dung cong nghe WebGIS - Xay dung ban d6 s6 TP Long Xuyen
danh, danh lam thdng canh n6i ti^ng cung vdi cac di tich licit su van hoa, cac cong trinh
kien true...

Hien nay, tren the gidi co rat nhieu cong nghe ve WebGIS nhu cong nghe MapServer,
GeoServer, ESRI, Maplnfo, Map Suite Web Edition...
III. Mo hinh xu ly va kien true trien khai Webgis.
1 Kien true Webgis va cac biroc xir ly:
1.1 Kien true Webgis
-Kien true xuat ban web cua he thong thong tin du lieu khong gian cung g^n gidng nhu
kien true danh cho mot he thdng tin web co ban khac, ngoai trir co ung dung GIS sir
dung cac ky thuat khac. Co nhieu dang cua viec xuat ban web cho thong tin khong

gian, d day se trinh bay phln phirc tap nh^t d^ cd cai nhin tdng quat hon vh kiSn true
cua chiing.
-Co sd d& lieu khong gian se duoc dimg de qu^n ly va truy xuat d& lieu khong gian,
duoc dat tren data server. Nha kho hay noi luu tru (clearing house) duoc diing d^ luu
tr^ va duy tri nhung sieu du lieu (dS lieu ve du lieu - metadata) ve du lieu khong gian
tai nhung data server khac nhau. Dua tren nhung thanh ph^n quan ly du lieu, ung
dung server va mo hinh server duqc dimg cho ung dung he thdng de tinh toan thong
tin khong gian thong qua cac ham cu the. Tat cd ket qua tinh toan ciia dng dung cua

server se dugc gui den web server de them vao cac gdi HTML, gui cho phia client va
hiln thi noi trinh duyet web.
-Xem hinh minh hoa dudi day. Luu y la tat ca cac thanh phan deu duoc ket n6i nhau
thong qua Internet.

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Sir dung cong nghe WebGIS — Xay dung ban do so TP Long Xuyen

"Web Browser: HTML (ActiveX, Plugio. Applet, Script Language).

er

Web Server: IIS (C.QI, IS API, ASP
Server. MAPI).

Application Server: Model Server,
Method server.

Clearing house: catalog server, meta
data server.

er
Data server: SDBMS (SDE,
SpatialWare, SQL...)

Hinh I:Ki6ntri)c WebGis
1.2Cacbuocxfrly:
Qua trinh lam viec voi hf thong web xii ly thong tin khong gian duoc minh hoa nhtr tren

hinh ve tren.

Nguwi dung sii dung trinh duyet web d phia client (thuong la giao dien d6 hoa).
-Client gui yeu cau cua ngiroi str dung thong qua giao thuc HTTP den web server.
-Web server nhan yeu cau cua ngubi dung gtjri den tir phia client, x^ ly va chuyen tiSp
yeu cau den utig dung tren server co lien quan.

-Application Server (chinh la cac irng dung GIS) nhan eac yeu clu cu th^ d6i vdi irng
dung va goi cac ham co lien quan de tinh toan xu ly. Neu co yeu cau d5 lieu no se gtri
yeu cau dtt lieu den data exchange server (server trao doi du lieu)...
-Data exchange server nhan yeu cau d& lieu va tim kiem vj tri cua nhirng dO lieu nay
sau do gtri yeu cau du lieu den server chura du lieu (data server) tuong ling c^n tim.
-Data server du lieu tien hanh truy vln lay ra du lieu c^n thiet va tra du lieu nay vh cho
data exchange server.

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Sir dung cong nghe WebGIS - Xay dung ban do s6 TP Long Xuyen
Data exchange server nhan dir lieu nhieu nguon tir data server khac nhau nam rai rac
tren mang. Sap xep dtt lieu lai theo logic cua yeu cau dir lieu, sau do guri tra dir lieu ve
cho application server.
Application server nhan dtt lieu tra ve tir cac data exchange server va dtra chung dSn
cac ham can sir dung, xtr ly chung tai day va ket quii dugc tra ve cho web server.
Web server nhan ve k^t qua xir ly, them vao cac ngir canh web (HTML, PHP,
Javascript, ASP ...) de co the hien thi dirge tren trinh duyet va cuoi ciing giri tra ket
qua ve cho trinh duyet dtroi dang cac trang web.

Hinh 2: Cac dang yeu cau tir phia client.
2 Cac kien true tricn khai:

Trong mo hinh hoat dong cua WebGis dugc chia ra hai phan: cac hoat dgng a phia client
(client side) va cac hoat dong d phia server (server side).

?Client side:
-Client side dugc dung de hien thi ket qua den cho nguai dung, nhan cac dieu khien
true tiep tir ngucri dimg va tuong tac vdi web server thong qua trinh duyet web.
-Cac trinh duyet web sir dung chu yeu HTML de dinh dang trang web. Them vao do
mot vai plugin, ActiveX va cac ma Applet dugc nhung vao trinh duyet de tang tinh
tuong tac vdi ngudi dimg.
?Server side:
Gom co: Web server, Application server, Data server va Clearinghouse...

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Sir dung cong nghe WebGIS — Xay dung ban do so TP Long Xuyen
Server side co nhiem vu luu trCr dir lieu khong gian, xd ly tinh toan va tra ve ket qua (dudi
dang hien thi cho client side).
-Web server:

o Dirge dung de phuc vu cho cac irng dung web, web server sir diing nghi thdc HTTP
de giao tiep vdi trinh duyet web d phia client. Tat ca cac yeu cau tCr phia client doi
vdi irng dung web deu dirge web server nhan va thong dich va sau do goi cac chirc
nang cua irng dung thong qua cac giao tiep mang nhu MAPI, Winsock, namped pipe

-Application server:
o Day la phan chirong trinh goi cac ham xtr ly GIS, gdi yeu cau lay dir lieu dS
clearinghouse.
-Data server:


o Data server la phan ca ban cua hau het cac he thong thong tin vdi nhiem vu quan ly
va dieu khien truy cap dG lieu.
o Ban dau, da so GIS sir dung File System d quan lydG lieu khong gian va DBMS
(Database Management System) de quan ly dir lieu thuoc tinh. Ngay nay cd nhieu
san pham va giai phap phan mem thay the d& quan ly dir lieu khong gian va quan ly
mot each chung nhat.
o Nhin chung cac ca sd dir lieu sir dung deu la ca sd dir lieu quan he.
-Clearinghouse:
o Clearinghouse dirge sir dung de chira dir lieu khong gian dirge quan ly bdi cac data
server. Clearinghouse ddng vai trd nhir mot cudn catalog, clearinghouse tim kiem
trong catalog nay d^ tim dir lieu can.
3. Chienthuatxfrly:
Cd hai kieu chien thuat Iua chon, tucrng irng vdi hai kieu trien khai, kieu thG nh^t tap trung
cong viec chu yeu cho phia server, kieu kia ngirgc lai tap trung cho phia client.
3.1 Chien thuat server side:
Nhung chien thuat nay tap trung vao viec cung c^p dir lieu GIS va phan tich theo "yeu
cau" bdi mot server du manh, server nay se truy cap dir lieu va ph^n mem can thidt dd xd
ly dir lieu.
Chien thuat server side cd the so sanh vdi mo hinh sd dung may mainframe de chay GIS
trong mot mang cue bo. Trong do, may client cau hinh khong doi hdi cao, chi can chay
chirang trinh de gdi cac yeu cau va hien thi dugc cac tra ldi td server.
Cac budc xd ly nhir hinh ve:

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Sis dung cdng nghe WebGIS - Xay dung ban do so TP Long Xuyen
Csiu hinh Server-side

jt)(3) SERVER

1 .Client g^ri yfiu ciiu U6n server
2.Sorvor xCr ^? y^^u chu vA Q&\ c*ic thprig tin d&n cftc sc^^pt CGI
3.K^t qua ducrc tra v6 server
4.K^I qua ptian h^t y^u cau duxyc gS.Trlnh duy^t Ohio client hin thi th6nq tin

Hinh 3: Cau hinh server side.
Trong WebGIS doi khi thuat ngd "map server" duqc diing de chi ra rang chien thuat ap
dung la server-side. Ma trong do khi ngudi dung gui yeu cau "map" de hien thj, thi se
duoc phuc vu bbi server.
Chien thuat server-side dua tren kha nang trinh duyet web cua nguoi dung co the gui cac
yeu cau den cac ph^n mem GIS tren server thong qua Internet.
Cac chucmg trinh duqc diing de nhan va xu ly cac yeu ciu cua nguai diing co th duac
viet bang cac ngon ngtt nhu: Perl, Visual Basic, C#... Cac chucmg trinh nay cung co the
mua tu" nha san xuat de tao kh^ nang ket noi tot hem den cac he xu ly GIS da ton tai.
Be co the giao tiep vdi cac ung dung WebGIS dat tren server, web server co th^ sir dung
cac chuan giao tiep pho bien nhu CGI (Common Gateway Interface), Java, ISAPI
(Internet Server Application Programming Interface)...
Cac thuan loi va kho khan cua chien thuat nay:
-Thuan loi:
o Vdi server co c^u hinh manh duoc sir dung, nguai dung co thi truy xuat tren tap
dCb lieu ldn hon va phuc tap ldn. Thay vi phai xir ly tren may client, hlu hit khong
duac cau hinh manh va viec truyen dif lieu ldn qua mang Internet se gay nhilu kho
khan.

o Cung vdi server manh viec phan tich, xu ly cac chiic nang GIS, se duqc tien hanh
nhanh va khong doi hoi qua nhieu d ngudi dung su am hieu.
o Kiem soat duqc cac thao tac cua ngudi dung (chu yeu la don gian) tren du lieu va
luon dam bao ngudi dung nhan ket qua dung tr dd lieu (do phia client khong phai xd
ly nhieu).

-Kho khan:

o Vdi chiln thuat nay thi dii yeu clu la nhd (client hoan toan xu ly duqc) hay ldn, tit
ca deu gdi vl phia server, va server xu ly xong lai gdi tra ve cho client thong qua
dudng truyen tren mang.
o Hieu nang cua hf thong WebGIS se bi anh hudng bdi bang thong va dudng truyen
mang Internet gida server va client. Nhat la khi ma kit qua tra vl phai mang chuyln
nhung file ldn.

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Sir dung cong nghe WebGIS - Xay dung ban dd s6 TP Long Xuyen
o He thing WebGIS su dung chien thuat nay khong tan dung dupe kha nang xii ly
tren may client. Chu yeu client chi xir ly gdi yeu clu va hien thj k^t qua dap ung.
Nhin chung chien thuat nay ap d^ng tot nhat cho cac ung dung WebGIS thuong mai
hay cong ding vdi so lupng Idn ngudi dung ma khong quan tam den kha nang xii ly
GIS tren cac may nguoi diing.
Bang 1: Chiln thuat Server - side.

Chien thuat Server - side
NhiSm vu phia server

Nhiem vu phia client

Duyet ban d6

Hiln thi

Truy van

Phan tich
Ve ban d6
3.2 Chien thuat Client-side:
Thay vi de server lam qua nhieu viec, mot so chuc nSng xu ly GIS se duqc dua ve phia
may nguoi dung va tai day se co mot ph^n du lieu dupe xu ly.
Co 2 dang trien khai chien thuat Client-side nhu sau:
? GIS Applet duac phan phoi den Client khi co yeu edit:
Trong each trien khai chien thuat nay cac xir ly GIS se dupe server cung cap cho phia
client dudi dang cac chuong trinh thuc thi nho hoac la cac Applet de co the chay dupe a
phia client. Nh5ng applet nhu vay dupe phan phoi den client khi client can no de xu ly.

'

Hinh 4: C^u hinh Client-side.
Cac budrc xu ly:
-Ngudi dung tao ra mot yeu cau tir trinh duyet.
Yeu cau dupe chuyen qua Internet den server.
Server xu ly cac yeu cau.

-Kit qua phan hli tra vl bao gom du lieu va cac applet cln thilt dl ngudi diing co thi
lam viec tren dU lieu nay.

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Sir dung cong nghe WebGIS - Xay dung ban do so TP Long Xuyen
Cac applet co the dirge viSt bang Java, JavaScript, hoac d dang cac ActiveX. Nhu vay
trinh duyet can tich hop cac compiler de xii ly cac applet nay.
? G1S Applet va Plug-in co djnh a Client.

Cac trien khai tren can them cac chuc nang xir ly GIS vao trinh duyet. Tuy nhien viec
chuy^n dS lieu va cac applet can thiet qua mang Internet mat nhieu thai gian nhat la khi
ma ling dung it dirge dung den.
Giai phap cho v^n de nay la each chuy^n khai sau day:
-Chuy^n cac GIS applet den cac client mot each co dinh va khong phai chuy^n d^n moi
khi can ntra.

-Download va cai dat c6 djnh cac plug-in vao trinh duyet web cua client.
-Xay dung mot trinh duyet web co tich hop san phan mem xii ly GIS de chay tren
client.
-Tich hgp cac link den nguon tai nguyen du lieu khac tren mang trong moi goi dii lieu
tai \'e.

-Server chi dugc goi khi client yeu cau d5 lieu mdi hoac dQ" lieu cho mot ung dung
mdi.
-Nguoi dung dugc toan quyen thao tc tren dS lieu ho dung va phan tich chiing.

Tich h^p cho trinh duy^l
kha nang x& ly GIS

CLIENT

SERVER
1 .Tich hep cac link l^y dii 1^11 cho cSc yau cSu
?.Di> li^n rTircm nh^^n nh^i khi cAn

Hinh 5: Tich hgp xir ly GIS vao trinh duyet.
Cac thuan lgi va kho khan cua chien thuat nay:
-Thuan lgi:
o Tan dung sire manh xu iy tren may ngucri diing.

o Ngucri diing dugc quyen dieu khien trong qua trinh phan tich du lif u.
o Khi server gdi du lieu can thi^t ve, ngucri diing co thi lam viec vcri du lieu nay ma
khong phai gdi di hay nhan ve cai gi khac tir mang.
-Kho khan:

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Sir dung cong nghe WebGIS - Xay dung ban dd s6 TP Long Xuyen
o Cac hoi dap tCr server co the bao gdm lupng Ion du lieu cung nhu cac applet (cho
Ian dau tien khi trinh duyet tai may sir dung chay ung dung WebGIS) co the dan
den sir tri hoan.

o Du lieu GIS thuong Ion va phirc tap din ddn se khd xu ly ndu client khdng dupe
cau hinh manh.
o Ngudi diing co the chua dupe huan Iuyen day du de thuc hien cac chirc nang phan
tich du lieu mot each diing dan -> khong danh cho nguoi dung binh thuong.
Bang 2: Chien thuat Client-side.

Chien thuat Client-side
Nhiem vu phia Server

Nhiem vu phia Client

Phan tich

Hien thi

Ve ban d6

Duyet ban do
Truy vln

3.3 Kit hop hai chiin thuat:
-Ap dung thuan tuy hai chiin thuat tren deu co nhung han chi nhit dinh. Doi vdi chien
thuat Server-side chat lugng dubng truyen se anh huong den toe do va thai gian
truyen giCra yeu cau va doi dap. Trong khi do vdi Client-side lai phu thuoc vao ciu
hinh may client. Mot vai thao tac cd the cham do doi hoi bp xii Iy manh khong duoc
dap ling.
-Ket hop hai chien thuat cho ta mot giai phap "lai", tan dung dupe uu diim cua hai
chien thuat tren. Nhiing cong viec doi hdi du lieu Idn, tinh toan phiic tap giao cho
server xd ly. Nhung cong viec doi hdi ngudi dung cd quyen dieu khien cao (thao tac
ban do ...) dupe giao cho client. Nhu vay ddi hdi thong tin ve cau hinh cua server va
client cln dupe chia se cho nhau.
-Giai phap nay to ra hieu qua khi ma client thinh thoang mdi can lien lac vdi server de
lay du lieu.
Kdt hop 2 chi^n Ihu^t Client - Server

CLIENT

SERVER
1 Cic yCu c^u du- liu
2.DQ' li^u vi cic applet du^c tri vi
3.Tt^p tpc duy trl va trao dfii

Hinh 6: Ket hop Client-side va Server-side.

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Sir dung cong nghe WebGIS - Xay dung ban do so TP Long Xuyen

4 Phan lo^i WcbGis
4.1 Theo kien true
Internet theo triet ly dtra tren kiln true khach/chii (Client/Server). Sir ket hop giira
Client/Server se cho ra cac trang WebGIS co cac chirc nang khac nhau.
-Thuan Server: May chii (Server) se dam nhiem tat ca cac cong viec bao gom Itru
dd lieu va phan tfch dtf lieu.
-Thuan Client: May khach dugc cung cap cac chirc nang de xir ly cac yeu cau ma
khong can phai gCri ve cho may chii xir ly.
-Ket hop Server va Client: Co the ket hop bang each dif lieu ltru tren may chu, cac
;chirc nang xir ly dat tai may khach. Cung co the ket hop bang each may chu cung
cap cac chirc nang, dd lieu ltru of may khach. Hoac cung co the ket hop theo each
do lieu va chirc nang vira liru cr may chu, vira cung dp cac chirc nang xir ly don
gian cho may khach,...

4.2 Theo ky thuat

?Thu^n HTML (Pure HTML)
-Thuat ngd "thuln HTML" dimg dl chi nhdng trang WebGIS dugc tao ra biing
each sir dung cac kha nang ciia HTML, loai trir viec dung cac phan mcr rpng tir
phia may chu (Server side extensions) hoSc cac Scripts. Cac phan tir ciia no chi sir
dung cac lien ket don gian (simple link) va cac hinh anh. Cac chirc nang ciia no
dugc thgc hien thong qua cau true lien ket. HTML chi cho phep dung cac hinh rinh
dang raster, vi vay chi co nhihig ban do raster moi dugc phan phoi tren no. Uu
diem cua ky thu^t nay la thu nh^t chi c^n diing cac Server thrip de xir ly, vi Server
a day lam viec nhu la mot Webserver dung phan phoi cac trang HTML va cac
hinh anh. Thu hai, khong can ph^n mem GIS nao chay trong luc thuc thi cac yeu
ciu crJa nguoi diing. Thu ba, phia may kh^eh chi can dung trinh duyet Web chuan.
-Nhugc diem : chi dirng cho cac nhiem vu co cau true don gian.

?HTML vdi cac chuong trinh thuc thi tren Server (HTML with Server Programs)
-Trai ngugc \a\ giai phap "thuan HTML", day la giai phap tao ra m^t trang HTML
WebGIS do mot chuong trinh dang chay tren Server, chuong trinh nay co kha
nang dap ling day du cac yeu cau. May khach giiri mot yu cau den Webserver,
chuong trinh tren may chii se nh^n dugc yeu cau nay va tao ra ket qua rieng, ket
qua nay co the la mot ban d6 (raster) hoac la mot trang HTML. Cac tham s6 co th^
dugc gui kern din chuong trinh, cac tham so nay dugc lay tir cac thanh phan ciia
trang HTML nhu text boxs, combo boxs, radio button,..
-Khi chuyen den may chii, toa do ciia diem kich tren ban d6 curig dugc chuyen kem
theo. Vi vay cac chuong trinh tren may chii se xu ly cac hanh dong tuong ling voi
diem kich. Do do co the phong to, thu nho, dich chuyen hoac thuc hien cac hanh
dong tai cac diem kich tr6n ban do chinh xac.

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Sfir dung cong nghe WebGIS - Xay dung ban d6 s6 TP Long Xuyen
-Kit noi giifa Webserver va cac chuong trinh tra ldi co the thuc hien thong qua
CGI (Common Gateway Interface) hoac bat cu giao dien nao dugc cung cap ma
giao tiep dugc vdi Webserver.

?Cac giai phap dua tren JAVA (JAVA based solutions)
-Java la ngon ngit lap trinh doc lap co the dugc phien djch bdi trinh duyet Web.
Chuong trinh Java se dugc tai ve trinh duyet, cua may khach khi can thiet. Chuong
trinh Java (applets) se khdi dong va co the yeu cau dCr lieu can thiet tir may chu.
Noi chung gi^i phap dua tren Java rat uyen chuyen bdi no tranh dugc nhung giai
han cua HTML thu^n. U'u dim cua viec dung Java la cong viec co the thuc thi
tren may khach ma khong cn phai truyen ve may chu. Nhugc diem la viec sii
dung Java d^ giai quyet cong viec hien nay tren mang la rat cham, vai ung dung
Java khong hoat dong sau buc tuong lua.

4.3 Theo djch vu
Theo Claus R1NNER (nghien cuu sinh cua hoc vien tin hoc GMD - Germany National
Research Center for Information Technology) thi co 5 loai djch vu WebGIS sau :
?Geodata Server
-Chi Iuu tru du lieu dia ly va cung cap du lieu cho may khach khi co yu cau thong
qua Internet. May khach download du lieu ve va diing cac chuong trinh G1S tren
may khach de xir ly dir lieu. U'u diem cua djch vu nay la du lieu co san ma khong
can phai so hoa.
?J* Map Server
Luu tru du lieu va cung cap cac b^n do thong qua WWW, kem theo mot so chirc
nang nhu Zoom, Pan va mot so tham so nhu hien thj lap, lira chon mau sac. C) day
may chu xu ly toan bo, may khach chi hien thj cac ban do do may chu cung cap.
^Online Retrieval System
-Phan phoi cac ban do chuyen de va mot so ham phan tich. Khi sii dung cac ham
nay, kit qua se tra v6 cho may khach, dir lieu tra ve cr day la du lieu da dugc phan
tich.

?Online GIS
-Lorn hem Online Retrieval System vi no c6 klia nang thuc hien cac chuc nang phan
tich thuc (real analysis functions) tren cac tien trinh cua dir lifu dua vao.
?GIS Function Server
-Gi6ng nhu Online GIS nhung chi khac la GIS Function Server khong chua du
lieu, neu Online GIS chi tra ve du lieu thi GIS Function Server tra ve dir lieu, cac
chuong trinh phan tich nho de may khach co the xu ly. GIS Function Server cung
cap cac chuc nang GIS giai quyet tren dir lieu do nguoi dung Upload len hoac
cung dp cac ham phan tich cho may khach download vg. Nhu vay viec phan tich
khong gian khong con gidi han d viec du lieu luu tren may chu.
-C6 the quan sat de han cac chuc nang cua cac loai djch vu qua bang sau:

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Sir dung cong nghe WebGIS - Xay dung ban 66 so TP Long Xuy&i
Bang 3: Cac chirc nang cua cac loai djch vu

Quan ly

HiSn thj

du lieu

Phan tich va

Phan

tra dir lieu

GIS

Geodata Sever

X

Map Sever

X

X

Online Retrieval System

X

X

X

Online G1S

X

X

X

X

X

X

X

GIS Function Server

tich

Nhitng chirc nang tren thuoc ve may chu, vay may khach se nhan dugc nhitng gi?
Bang 4: Mo ta cac loai dir lieu ma may khach nhan dugc.

Du lieu kliong

Bdhoa

Bao cao

gian (tho)
Geodata Sever

Cac ham

xuly

X

Map Sever

X

Online Retrieval System

X

X

X

Online GIS

X

X

X

X

GIS Function Server

(X)

(X)

(X)

X

Theo OGC (Open Geospatial Consortium) mot to chirc phi lgi nhuan, dan dau tren the
gidi ve phat trien cac chuan dir lieu dia ly va cac djch vu, da dua ra cac dac ta ve cac
loai dich vu sau:

? Web Map Service (WMS)
WMS la mot trong cac chuan pho bien nhat cua OGC. WMS tao ra cac ban do dudi
dang anh. Cac ban do nay tu ban than chung khong chira dir lieu. Mot WMS co b^n
cho phep Client ket noi va lay ban do thong qua cac phuong thirc:
- GetMap (bat buoc): Yeu cau GetMap trk ve mot ban do dudi dang anh (anh b^n
do) trong mot pham vi dia ly va theo cac tham so dugc d|nh nghTa cu the. GetMap
dugc trieu ggi bdi mot client de nhan ve mot tap hgp cac pixels. Cac pixels nay
chira mot anh cua mot ban do trong mot viing dia ly (khong gian) hoac mot tap c^c
doi tugng d6 hoa nSm trong viing dia ly cu the. Yeu cau GetMap cho phep c^c

WMS client chi ra mot Idp thdng tin cu th^, he quy chi^u khong gian, khu vuc dia
ly, va cac tham so khac quy dinh djnh dang du" lieu tra ve. Tren co sd cac yeu cau
GetMap, mot WMS server se tra v6 cac ket qua hoac nem mot biet le theo cac chi
dan biet le trong yeu cau GetMap;

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Sir dung cong nghe WebGIS - Xay dung ban do so TP Long Xuyen
GetCapabilities (bat buoc): Yeu cau GetCapabilities tra ve cac sieu dir lieu mo ta
WMS server. Cac mo ta bao g6m noi dung thong tin ma WMS server co th^ phuc
vu, cac tham so ma WMS server co the nhan.
-GetFeaturelnfo (tuy chon): Yeu cau GetFeaturelnfo tra ve thong tin ve doi tuong
dia ly cu the duoc hien thj tren ban do. Neu mot WMS server ho tro djch vu nay
thi ban d6 ma no tra v^ duoc goi la ban d6 co kha nang truy v^n thong tin va mot
WMS client co thi yeu cku thong tin v6 d6i tuong tren mot ban do bang each them
vao URL cac tham s6 chi ra mpt v| tri (X,Y) va s6 doi tuong co thg tra ve thong
tin.

Ngoai ra, WMS con cung cap cho Client kiem soat cac kieu hien thi ban do thong qua

Styled Layer Desrciptor (SLD).
?Web Feature Service (WFS)
WFS cung ctip cac d6i tuong dir lieu dudi dang dinh dang thong nhat GML
(Geography Markup Languge). Dit lieu ma Client nhan duoc la mot dac ta ve dir lieu
khong gian va thong tin thuoc tinh kem theo. Mpt WFS co ban cho phep Client ket
noi va lay d& lieu ve theo cac phuong thirc:
-GetCapabilities: tra ve tai lieu XML mo ta chuc nang cua WFS.
-DescribeFeatureType: tr^ ve mot luoc do XML djnh nghTa cac lap doi tuang.
-GetFeature: tr^ vg mot tap cac doi tuong da lieu thoa man cac rang buoc duoc mo

ta trong yeu cau.

Ngoai ra, WFS con cho phep Client thuc hien cac giao tac tao, xoa, sua cac doi tuong.

?Web Coverage Service (WCS)
WCS cung cip dir lieu dudi dang Coverage. Coverage la loai du lieu bieu dien cac
hien tuong thay doi theo khong gian. WCS cung cap cac phuong thuc dS Client truy
cap va lay d& lieu ve:
-GetCapabilities: tra vi mot tai lieu XML (Extensible Markup Languge) mo ta
chirc nang cua WCS.
-DescribeCoverage: tra ve mot tai lieu XML mo ta cac Coverage ma WCS Server
co the cung cap.
-GetCoverage: tra ve mot Coverage thoa man cac dieu kien ma Client cung cap.

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