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 4, © Pearson Education 2005
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
Network address 2:60:8c:2:b0:5a file Socket Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 © Addison-Wesley Publishers 2000 Web server
Figure 9.2
Iterative navigation NS2 Client 2 1 3 NS1 Name servers 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 client 1 4 NS1 2 3 NS2 NS3 client 1 5 NS1 2 4 NS2 3 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
Note
: Name server names are in italics, and the corresponding domains are in parentheses. Arrows denote name server entries
ns1.nic.uk
(uk) co.uk
ac.uk
a.root-servers.net
(root) uk purdue.edu
yahoo.com
ns0.ja.net
(ac.uk) ic.ac.uk
qmw.ac.uk
ns.purdue.edu
* .purdue.edu
dcs.qmw.ac.uk
*.qmw.ac.uk
alpha.qmw.ac.uk
(qmw.ac.uk) *.dcs.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 (purdue.edu)
Figure 9.5
DNS resource records
Record type Meaning
A NS CNAME SOA WKS PTR HINFO MX TXT
Main contents
A computer address An authoritative name server The canonical name for an alias IP number Domain name for server Domain name for alias Marks the start of data for a zone Parameters governing the zone A well-known service description List of service names and protocols Domain name pointer (reverse lookups) Host information Mail exchange Domain name Machine architecture and operating system List of <
preference, host
> pairs Text string Arbitrary text Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 © Addison-Wesley Publishers 2000
Figure 9.6
DNS zone data records
domain name time to live
1D 1D 1D 1D 1D
class
IN IN IN IN IN
type
NS NS NS MX MX
value
dns0 dns1 cancer.ucs.ed.ac.uk
1 mail1.qmul.ac.uk
2 mail2.qmul.ac.uk
domain name time to live
www apricot 1D 1D dcs dns0.dcs
dcs dns1.dcs
dcs
class
IN IN
type
CNAME A
value
apricot 138.37.88.248
1D 1D 1D 1D 1D IN IN IN IN IN NS A NS A NS dns0.dcs
138.37.88.249
dns1.dcs
138.37.94.248
cancer.ucs.ed.ac.uk
Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 © Addison-Wesley Publishers 2000
Figure 9.7
GNS directory tree and value tree for user Peter.Smith
DI: 599 (EC) DI: 543 UK FR DI: 574 DI: 437 AC DI: 322 QMW mailboxes Peter.Smith
password Alpha Beta 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 DI: 599 DI: 543 EC UK FR DI: 574 DI: 732 NORTH AMERICA DI: 642 US CANADA DI: 457 Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 © Addison-Wesley Publishers 2000
Figure 9.9
Restructuring the directory DI: 633 (WORLD) Well-known directories: #599 = #633/EC #642 = #633/NORTH AMERICA DI: 599 DI: 543 UK FR EC NORTH AMERICA DI: 642 DI: 574 US 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 DUA DSA DSA DSA DSA 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) ...
...
...
Computing Service (organizationalUnit) Department of Computer Science (organizationalUnit) ...
Departmental Staff (organizationalUnit) ely (applicationProcess) ...
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
roomNumber
Z42
userClass
Research Fellow Instructor’s Guide for Coulouris, Dollimore and Kindberg Distributed Systems: Concepts and Design Edn. 3 © Addison-Wesley Publishers 2000