Transcript Figure 15.1 A distributed multimedia system

Slides for Chapter 9:
Name Services
From Coulouris, Dollimore and Kindberg
Distributed Systems:
Concepts and Design
Edition 3, © Addison-Wesley 2001
Figure 9.1
Composed naming domains used to access a resource from a UR
URL
http://www.cdk3.net:8888/WebExamples/earth.html
DNS lookup
Resource ID (IP number, port number, pathname)
55.55.55.55
8888
WebExamples/earth.html
Web server
Network address
file
2:60:8c:2:b0:5a
Socket
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 9.2
Iterative navigation
NS2
2
Client
1
NS1
Name
servers
3
NS3
A client iteratively contacts name servers NS1–NS3 in order to resolve a name
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 9.3
Non-recursive and recursive server-controlled navigation
NS2
NS2
2
2
1
1
NS1
client
4
client
3
4
3
NS1
5
NS3
NS3
Non-recursive
server-controlled
Recursive
server-controlled
A name server NS1 communicates with other name servers on behalf of a client
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 9.4
DNS name servers
a.root-servers.net
(root)
Note: Name server names are
in italics, and the corresponding
domains are in parentheses.
Arrows denote name server entries
ns1.nic.uk
(uk)
uk
purdue.edu
yahoo.com
ns.purdue.edu
(purdue.edu)
co.uk
ac.uk
ns0.ja.net
(ac.uk)
* .purdue.edu
ic.ac.uk
qmw.ac.uk
dcs.qmw.ac.uk
*.qmw.ac.uk
*.dcs.qmw.ac.uk
alpha.qmw.ac.uk
(qmw.ac.uk)
dns0.dcs.qmw.ac.uk
(dcs.qmw.ac.uk)
*.ic.ac.uk
dns0-doc.ic.ac.uk
(ic.ac.uk)
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 9.5
DNS resource records
Record type Meaning
Main contents
A
NS
CNAME
SOA
WKS
PTR
IP number
Domain name for server
Domain name for alias
Parameters governing the zone
List of service names and protocols
Domain name
HINFO
A computer address
An authoritative name server
The canonical name for an alias
Marks the start of data for a zone
A well-known service description
Domain name pointer (reverse
lookups)
Host information
MX
TXT
Mail exchange
Text string
Machine architecture and operating
system
List of <preference, host > pairs
Arbitrary text
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 9.6
Service discovery in Jini
admin
Client
Printing
service
1. ‘finance’
lookup service?
admin
Client
Lookup
service
Network
2. Here I am: .....
4. Use printing
service
Corporate
infoservice
admin, finance
Printing
service
3. Request
printing
finance
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Lookup
service
Figure 9.7
GNS directory tree and value tree for user Peter.Smith
DI: 599 (EC)
DI: 543
FR
DI: 574
AC
DI: 437
DI: 322
UK
QMW
Peter.Smith
mailboxes
Alpha
Beta
password
Gamma
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 9.8
Merging trees under a new root
DI: 633 (WORLD)
Well-known directories:
#599 = #633/EC
#642 = #633/NORTH AMERICA
NORTH AMERICA
EC
DI: 599
DI: 543
DI: 642
UK
FR
DI: 574
DI: 732
US
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
CANADA
DI: 457
Figure 9.9
Restructuring the directory
DI: 633 (WORLD)
Well-known directories:
#599 = #633/EC
#642 = #633/NORTH AMERICA
EC
DI: 599
DI: 543
UK
NORTH AMERICA
DI: 642
FR
US
DI: 574
DI: 732
US
CANADA
DI: 457
#633/EC/US
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 9.10
X.500 service architecture
DUA
DUA
DSA
DSA
DSA
DSA
DUA
DSA
DSA
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
Figure 9.11
Part of the X.500 Directory Information Tree
X.500 Service (root)
...
France (country) Great Britain (country) Greece (country)...
...
BT Plc (organization) University of Gormenghast (organization)
...
... Computing Service (organizationalUnit)
Department of Computer Science (organizationalUnit)
Engineering Department (organizationalUnit)
...
... Departmental Staff (organizationalUnit)
ely (applicationProcess)
Research Students (organizationalUnit)
...
... Alice Flintstone (person) ... Pat King (person) James Healey (person) Janet Papworth (person)
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000
...
Figure 9.12
An X.500 DIB Entry
info
Alice Flintstone, Departmental Staff, Department of Computer Science,
University of Gormenghast, GB
commonName
Alice.L.Flintstone
Alice.Flintstone
Alice Flintstone
A. Flintstone
surname
Flintstone
telephoneNumber
+44 986 33 4604
uid
alf
mail
[email protected]
[email protected]
roomNumber
Z42
userClass
Research Fellow
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3
© Addison-Wesley Publishers 2000