1. Introduction to Distributed Systems Revised - PG.docx
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Chapter-1
Introduction to Distributed Systems
Introduction:
Networks of computers are everywhere. The Internet is one, as are the many networks of which it is
composed. Mobile phone networks, corporate networks, factory networks, campus networks, home
networks, in-car networks – all of these, both separately and in combination, share the essential
characteristics that make them relevant subjects for study under the heading distributed systems.
Distributed systems are everywhere. The Internet enables users throughout the world to access its
services wherever they may be located. Each organization manages an intranet, which provides local
services and Internet services for local users and generally provides services to other users in the
Internet. Small distributed systems can be constructed from mobile computers and other small
computational devices that are attached to a wireless network.
Resource sharing is the main motivating factor for constructing distributed systems. Resources such as
printers, files, web pages or database records are managed by servers of the appropriate type. For
example, web servers manage web pages and other web resources. Resources are accessed by clients –
for example, the clients of web servers are generally called browsers.
We define a distributed system as one in which hardware or software components located at networked
computers communicate and coordinate their actions only by passing messages. This simple definition
covers the entire range of systems in which networked computers can usefully be deployed.
Boqonnaa-1
Seensa Sirna Raabsame
Seensa:
Neetworkiin kompiitaraa bakka hundatti argama. Intarneetiin tokko, akkuma networkii hedduun inni
irraa ijaarame. Neetworkiin bilbila harkaa, neetworkiin dhaabbilee, neetworkiin warshaa, neetworkiin
mooraa, neetworkiin manaa, neetworkiin konkolaataa keessaa – kun hundinuu, addaan baafamaniis ta’e
walitti makamuun, amala barbaachisoo mata duree sirna raabsame jalatti barnootaaf barbaachisoo isaan
taasisan qooddatu.
Sirnoonni raabsaman bakka hundatti argamu. Intarneetiin fayyadamtoonni addunyaa guutuu bakka
jiranitti tajaajila isaa akka argatan dandeessisa. Tokkoon tokkoon dhaabbataa intraaneetii kan bulchu
yoo ta’u, kunis fayyadamtoota biyya keessaatiif tajaajila naannoo fi tajaajila interneetii kan kennu yoo
ta’u, akka waliigalaatti fayyadamtoota biroo interneetii keessa jiraniif tajaajila kenna. Sirnoonni
raabsaman xixiqqoo kompiitara sochootuu fi meeshaalee shallaggii xixiqqoo biroo kanneen neetworkii
wayaa malee waliin hidhaman irraa ijaaramuu danda’u.
Qabeenya qooduun sirna raabsame ijaaruuf kaka’umsa ijoodha. Qabeenyi akka maxxantoota, faayilii,
fuula weeb ykn galmee kuusdeetaa sarvaroota gosa barbaachisaa ta'een bulfamu. Fakkeenyaaf,
sarvaroonni weeb fuula weebii fi qabeenya weeb biroo ni bulchu. Qabeenyi maamiltootaan argama –
fakkeenyaaf, maamiltoonni sarvaroota weeb akka waliigalaatti biraawzaroota jedhamu.
1
Introduction to Distributed Systems
Introduction:
Networks of computers are everywhere. The Internet is one, as are the many networks of which it is
composed. Mobile phone networks, corporate networks, factory networks, campus networks, home
networks, in-car networks – all of these, both separately and in combination, share the essential
characteristics that make them relevant subjects for study under the heading distributed systems.
Distributed systems are everywhere. The Internet enables users throughout the world to access its
services wherever they may be located. Each organization manages an intranet, which provides local
services and Internet services for local users and generally provides services to other users in the
Internet. Small distributed systems can be constructed from mobile computers and other small
computational devices that are attached to a wireless network.
Resource sharing is the main motivating factor for constructing distributed systems. Resources such as
printers, files, web pages or database records are managed by servers of the appropriate type. For
example, web servers manage web pages and other web resources. Resources are accessed by clients –
for example, the clients of web servers are generally called browsers.
We define a distributed system as one in which hardware or software components located at networked
computers communicate and coordinate their actions only by passing messages. This simple definition
covers the entire range of systems in which networked computers can usefully be deployed.
Boqonnaa-1
Seensa Sirna Raabsame
Seensa:
Neetworkiin kompiitaraa bakka hundatti argama. Intarneetiin tokko, akkuma networkii hedduun inni
irraa ijaarame. Neetworkiin bilbila harkaa, neetworkiin dhaabbilee, neetworkiin warshaa, neetworkiin
mooraa, neetworkiin manaa, neetworkiin konkolaataa keessaa – kun hundinuu, addaan baafamaniis ta’e
walitti makamuun, amala barbaachisoo mata duree sirna raabsame jalatti barnootaaf barbaachisoo isaan
taasisan qooddatu.
Sirnoonni raabsaman bakka hundatti argamu. Intarneetiin fayyadamtoonni addunyaa guutuu bakka
jiranitti tajaajila isaa akka argatan dandeessisa. Tokkoon tokkoon dhaabbataa intraaneetii kan bulchu
yoo ta’u, kunis fayyadamtoota biyya keessaatiif tajaajila naannoo fi tajaajila interneetii kan kennu yoo
ta’u, akka waliigalaatti fayyadamtoota biroo interneetii keessa jiraniif tajaajila kenna. Sirnoonni
raabsaman xixiqqoo kompiitara sochootuu fi meeshaalee shallaggii xixiqqoo biroo kanneen neetworkii
wayaa malee waliin hidhaman irraa ijaaramuu danda’u.
Qabeenya qooduun sirna raabsame ijaaruuf kaka’umsa ijoodha. Qabeenyi akka maxxantoota, faayilii,
fuula weeb ykn galmee kuusdeetaa sarvaroota gosa barbaachisaa ta'een bulfamu. Fakkeenyaaf,
sarvaroonni weeb fuula weebii fi qabeenya weeb biroo ni bulchu. Qabeenyi maamiltootaan argama –
fakkeenyaaf, maamiltoonni sarvaroota weeb akka waliigalaatti biraawzaroota jedhamu.
1
Sirna raabsame jechuun qaamolee haardwaarii ykn sooftiweerii kompitara neetworkii irratti argaman
ergaa dabarsuu qofaan walqunnamsiisuu fi gocha isaanii qindeessan jennee ibsina. Hiikni salphaan kun
sirnoota kompiitaroonni neetworkiin qaban faayidaan itti bobba’uu danda’an hunda kan hammatudha.
Definition: - A distributed system is a collection of independent computers that appear to the users of
the system as a single computer.
Fig. 1-1 shows four networked computers and three applications, of which application B is distributed
across computers 2 and 3. Each application is offered the same interface. The distributed system
provides the means for components of a single distributed application to communicate with each other,
but also to let different applications communicate. At the same time, it hides, as best and reasonable as
possible, the differences in hardware and operating systems from each application.
Examples:
A network of workstations allocated to users
A pool of processors in the machine room allocated dynamically
A single file system (all users access files with the same path name)
User command executed in the best place (user workstation, a workstation belonging to
someone else, or on an unassigned processor in the machine room)
Our definition of distributed systems has the following significant consequences:
Concurrency: In a network of computers, concurrent program execution is the norm. I can do my work
on my computer while you do your work on yours, sharing resources such as web pages or files when
necessary. The capacity of the system to handle shared resources can be increased by adding more
resources (for example. computers) to the network. We will describe ways in which this extra capacity
2
ergaa dabarsuu qofaan walqunnamsiisuu fi gocha isaanii qindeessan jennee ibsina. Hiikni salphaan kun
sirnoota kompiitaroonni neetworkiin qaban faayidaan itti bobba’uu danda’an hunda kan hammatudha.
Definition: - A distributed system is a collection of independent computers that appear to the users of
the system as a single computer.
Fig. 1-1 shows four networked computers and three applications, of which application B is distributed
across computers 2 and 3. Each application is offered the same interface. The distributed system
provides the means for components of a single distributed application to communicate with each other,
but also to let different applications communicate. At the same time, it hides, as best and reasonable as
possible, the differences in hardware and operating systems from each application.
Examples:
A network of workstations allocated to users
A pool of processors in the machine room allocated dynamically
A single file system (all users access files with the same path name)
User command executed in the best place (user workstation, a workstation belonging to
someone else, or on an unassigned processor in the machine room)
Our definition of distributed systems has the following significant consequences:
Concurrency: In a network of computers, concurrent program execution is the norm. I can do my work
on my computer while you do your work on yours, sharing resources such as web pages or files when
necessary. The capacity of the system to handle shared resources can be increased by adding more
resources (for example. computers) to the network. We will describe ways in which this extra capacity
2
can be usefully deployed at many points in this book. The coordination of concurrently executing
programs that share resources is also an important and recurring topic.
No global clock: When programs need to cooperate they coordinate their actions by exchanging
messages. Close coordination often depends on a shared idea of the time at which the programs’ actions
occur. But it turns out that there are limits to the accuracy with which the computers in a network can
synchronize their clocks – there is no single global notion of the correct time. This is a direct
consequence of the fact that the only communication is by sending messages through a network.
Independent failures: All computer systems can fail, and it is the responsibility of system designers to
plan for the consequences of possible failures. Distributed systems can fail in new ways. Faults in the
network result in the isolation of the computers that are connected to it, but that doesn’t mean that they
stop running. In fact, the programs on them may not be able to detect whether the network has failed or
has become unusually slow. Similarly, the failure of a computer, or the unexpected termination of a
program somewhere in the system (a crash), is not immediately made known to the other components
with which it communicates. Each component of the system can fail independently, leaving the others
still running. The consequences of this characteristic of distributed systems will be a recurring theme
throughout the book.
Hiika: - Sirni raabsame walitti qabama kompiitara of danda’ee fayyadamtoota sirnichaaf akka
kompiitara tokkootti mul’atudha.
Fakkiin 1-1 kompitara networkii afur fi aplikeeshinii sadii kan agarsiisu yoo ta’u, isaan keessaa
application B kompitara 2 fi 3 irratti kan raabsame yoo ta’u, tokkoon tokkoon application interfeesii
walfakkaataan dhiyaateera. Sirni raabsame qaamolee aplikeeshinii raabsame tokkoo akka waliin
walqunnaman, garuu aplikeeshiniiwwan adda addaa akka walqunnaman gochuuf mala ni kenna.
Kanuma waliin, hamma danda’ametti, hamma danda’ametti, garaagarummaa haardwaarii fi sirna hojii
tokkoon tokkoon application irraa dhoksa.
Fakkeenyota: 1.1.
• Neetworkii buufataalee hojii fayyadamtootaaf ramadaman
• Kuusaa piroosesaroota kutaa maashinii keessatti daayinamiikiin ramadaman
• Sirna faayilii tokko (fayyadamtoonni hundi faayilii maqaa daandii walfakkaataa qaban argatu) .
• Ajajni fayyadamaa bakka hundarra gaarii ta'etti raawwatame (buufata hojii fayyadamaa, buufata hojii
kan nama biraa, ykn piroosesara hin ramadamne kutaa maashinii keessatti) .
Hiikni keenya sirnoota raabsamaniif kenninu bu’aa gurguddoo armaan gadii qaba:
Walfakkaachuu: Neetworkii kompiitaraa keessatti sagantaa walfaana raawwachuun waanuma jiruudha.
Ani hojii koo kompiitara koo irratti hojjechuu nan danda’a, ati immoo hojii kee kan kee irratti hojjettu,
yeroo barbaachisaa ta’etti qabeenya akka fuula weeb ykn faayiloota qooduun danda’a. Dandeettiin
3
programs that share resources is also an important and recurring topic.
No global clock: When programs need to cooperate they coordinate their actions by exchanging
messages. Close coordination often depends on a shared idea of the time at which the programs’ actions
occur. But it turns out that there are limits to the accuracy with which the computers in a network can
synchronize their clocks – there is no single global notion of the correct time. This is a direct
consequence of the fact that the only communication is by sending messages through a network.
Independent failures: All computer systems can fail, and it is the responsibility of system designers to
plan for the consequences of possible failures. Distributed systems can fail in new ways. Faults in the
network result in the isolation of the computers that are connected to it, but that doesn’t mean that they
stop running. In fact, the programs on them may not be able to detect whether the network has failed or
has become unusually slow. Similarly, the failure of a computer, or the unexpected termination of a
program somewhere in the system (a crash), is not immediately made known to the other components
with which it communicates. Each component of the system can fail independently, leaving the others
still running. The consequences of this characteristic of distributed systems will be a recurring theme
throughout the book.
Hiika: - Sirni raabsame walitti qabama kompiitara of danda’ee fayyadamtoota sirnichaaf akka
kompiitara tokkootti mul’atudha.
Fakkiin 1-1 kompitara networkii afur fi aplikeeshinii sadii kan agarsiisu yoo ta’u, isaan keessaa
application B kompitara 2 fi 3 irratti kan raabsame yoo ta’u, tokkoon tokkoon application interfeesii
walfakkaataan dhiyaateera. Sirni raabsame qaamolee aplikeeshinii raabsame tokkoo akka waliin
walqunnaman, garuu aplikeeshiniiwwan adda addaa akka walqunnaman gochuuf mala ni kenna.
Kanuma waliin, hamma danda’ametti, hamma danda’ametti, garaagarummaa haardwaarii fi sirna hojii
tokkoon tokkoon application irraa dhoksa.
Fakkeenyota: 1.1.
• Neetworkii buufataalee hojii fayyadamtootaaf ramadaman
• Kuusaa piroosesaroota kutaa maashinii keessatti daayinamiikiin ramadaman
• Sirna faayilii tokko (fayyadamtoonni hundi faayilii maqaa daandii walfakkaataa qaban argatu) .
• Ajajni fayyadamaa bakka hundarra gaarii ta'etti raawwatame (buufata hojii fayyadamaa, buufata hojii
kan nama biraa, ykn piroosesara hin ramadamne kutaa maashinii keessatti) .
Hiikni keenya sirnoota raabsamaniif kenninu bu’aa gurguddoo armaan gadii qaba:
Walfakkaachuu: Neetworkii kompiitaraa keessatti sagantaa walfaana raawwachuun waanuma jiruudha.
Ani hojii koo kompiitara koo irratti hojjechuu nan danda’a, ati immoo hojii kee kan kee irratti hojjettu,
yeroo barbaachisaa ta’etti qabeenya akka fuula weeb ykn faayiloota qooduun danda’a. Dandeettiin
3
sirnichi qabeenya qooddame qabachuu danda’u qabeenya dabalataa (fakkeenyaaf. kompiitara)
networkii irratti dabaluudhaan guddisuun ni danda’ama. Karaalee dandeettiin dabalataa kun bakka
hedduutti kitaaba kana keessatti faayidaan itti bobbaafamuu danda’u ni ibsina. Qindoominni
sagantaalee qabeenya qooddatan yeroo tokkotti raawwatanis mata duree barbaachisaa fi irra
deddeebi’amee mul’atudha.
Sa’aatii addunyaa hin qabu: Yeroo sagantaaleen tumsuu barbaadanitti ergaa wal jijjiiruun gocha isaanii
qindeessu. Qindoominni dhiyeenyaa yeroo baay’ee yaada waliinii yeroo gochi sagantaalee itti
raawwatamu irratti hundaa’a. Garuu sirrii ta’uu kompiitaroonni neetworkii tokko keessa jiran sa’aatii
isaanii walsimsiisuu danda’an irratti daangaa akka qaban ni mul’ata – yeroo sirrii ta’e ilaalchisee
yaadni addunyaa tokko hin jiru. Kunis bu’aa kallatti kan ta’e qunnamtiin karaa networkii ergaa erguu
qofa ta’uu isaati.
Kufaatii of danda’e: Sirnoonni kompiitaraa hundi kufaatii kan danda’an yoo ta’u, bu’aa kufaatii ta’uu
danda’u karoorfachuun itti gaafatamummaa dizaayinarota sirnaati. Sirnoonni raabsaman karaa
haaraatiin kufaa ta’uu danda’u. Balaan networkii keessatti uumamu kompiitaroonni isa waliin
walqabatan adda baafamuu fida, garuu hojii dhaabu jechuu miti. Dhugaa dubbachuuf, sagantaaleen
isaan irra jiran neetworkiin sun kufe ykn haala hin baratamneen suuta jechuu isaa adda baasuu dhiisuu
danda u. Haaluma walfakkaatuun, kufaatiin kompiitara, ykn sagantaa tokko bakka tokkotti sirnicha
ʼ
keessa jirutti osoo hin eegin addaan cituun (kufaatiin) qaamolee biroo inni waliin walqunnamsiisu
battalumatti hin beeksifamu. Tokkoon tokkoon qaama sirnichaa of danda'ee kufaa ta'uu danda'a,
kanneen biroo ammallee hojjechuuf dhiisuu danda'a. Bu’aan amala sirnoota raabsaman kanaa
guutummaa kitaabichaa keessatti mata duree irra deddeebi’amee mul’atu ta’a.
Examples of Distributed Systems:
1.Network of workstations
Personal workstations + processors not assigned to specific users.
Single file system, with all files accessible from all machines in the same way and using the
same path name.
4
networkii irratti dabaluudhaan guddisuun ni danda’ama. Karaalee dandeettiin dabalataa kun bakka
hedduutti kitaaba kana keessatti faayidaan itti bobbaafamuu danda’u ni ibsina. Qindoominni
sagantaalee qabeenya qooddatan yeroo tokkotti raawwatanis mata duree barbaachisaa fi irra
deddeebi’amee mul’atudha.
Sa’aatii addunyaa hin qabu: Yeroo sagantaaleen tumsuu barbaadanitti ergaa wal jijjiiruun gocha isaanii
qindeessu. Qindoominni dhiyeenyaa yeroo baay’ee yaada waliinii yeroo gochi sagantaalee itti
raawwatamu irratti hundaa’a. Garuu sirrii ta’uu kompiitaroonni neetworkii tokko keessa jiran sa’aatii
isaanii walsimsiisuu danda’an irratti daangaa akka qaban ni mul’ata – yeroo sirrii ta’e ilaalchisee
yaadni addunyaa tokko hin jiru. Kunis bu’aa kallatti kan ta’e qunnamtiin karaa networkii ergaa erguu
qofa ta’uu isaati.
Kufaatii of danda’e: Sirnoonni kompiitaraa hundi kufaatii kan danda’an yoo ta’u, bu’aa kufaatii ta’uu
danda’u karoorfachuun itti gaafatamummaa dizaayinarota sirnaati. Sirnoonni raabsaman karaa
haaraatiin kufaa ta’uu danda’u. Balaan networkii keessatti uumamu kompiitaroonni isa waliin
walqabatan adda baafamuu fida, garuu hojii dhaabu jechuu miti. Dhugaa dubbachuuf, sagantaaleen
isaan irra jiran neetworkiin sun kufe ykn haala hin baratamneen suuta jechuu isaa adda baasuu dhiisuu
danda u. Haaluma walfakkaatuun, kufaatiin kompiitara, ykn sagantaa tokko bakka tokkotti sirnicha
ʼ
keessa jirutti osoo hin eegin addaan cituun (kufaatiin) qaamolee biroo inni waliin walqunnamsiisu
battalumatti hin beeksifamu. Tokkoon tokkoon qaama sirnichaa of danda'ee kufaa ta'uu danda'a,
kanneen biroo ammallee hojjechuuf dhiisuu danda'a. Bu’aan amala sirnoota raabsaman kanaa
guutummaa kitaabichaa keessatti mata duree irra deddeebi’amee mul’atu ta’a.
Examples of Distributed Systems:
1.Network of workstations
Personal workstations + processors not assigned to specific users.
Single file system, with all files accessible from all machines in the same way and using the
same path name.
4
For a certain command the system can look for the best place (workstation) to execute it.
2.Automatic banking (teller machine) system
Primary requirements: security and reliability.
Consistency of replicated data.
Concurrent transactions (operations which involve accounts in different banks; simultaneous
access from several users, etc).
Fault tolerance
3. The cloud
5
2.Automatic banking (teller machine) system
Primary requirements: security and reliability.
Consistency of replicated data.
Concurrent transactions (operations which involve accounts in different banks; simultaneous
access from several users, etc).
Fault tolerance
3. The cloud
5
0
Computing as a utility: application, storage, computing services; pay on per-usage basis.
Main concerns: scaling, performance, security/reliability.
Fakkeenyota Sirnoota Raabsaman: 1.1.
1. Neetworkii buufataalee hojii
• Buufata hojii dhuunfaa + piroosesaroota fayyadamtoota murtaa’aniif
hin ramadamne.
6
Computing as a utility: application, storage, computing services; pay on per-usage basis.
Main concerns: scaling, performance, security/reliability.
Fakkeenyota Sirnoota Raabsaman: 1.1.
1. Neetworkii buufataalee hojii
• Buufata hojii dhuunfaa + piroosesaroota fayyadamtoota murtaa’aniif
hin ramadamne.
6
• Sirna faayilii tokko, faayiloota hunda maashinii hunda irraa haala
walfakkaatuun dhaqqabamaa fi maqaa daandii walfakkaataa
fayyadamuun.
• Ajaja murtaa'eef sirnichi bakka (buufata hojii) isa hunda caalu
barbaaduu danda'a.
2. Sirna baankii ofumaan (teller machine) hojjetu
• Ulaagaalee jalqabaa: nageenyaafi amanamummaa.
• Walsimannaa daataa fakkeeffame.
• Daldala walfakkaatu (hojiilee herrega baankota adda addaa keessatti
hirmaachisu; fayyadamtoota hedduu irraa yeroo tokkotti argachuu fi
kkf).
• Badii dandamachuu
3. Duumessa
• Shallaggii akka faayidaatti: tajaajila application, storage, computing;
itti fayyadama tokkoon tokkoon kaffaltii.
• Yaaddoowwan gurguddoo: iskeelii, raawwii hojii,
nageenya/amanamummaa.
Advantages and Disadvantages of Distributed Systems:-
7
walfakkaatuun dhaqqabamaa fi maqaa daandii walfakkaataa
fayyadamuun.
• Ajaja murtaa'eef sirnichi bakka (buufata hojii) isa hunda caalu
barbaaduu danda'a.
2. Sirna baankii ofumaan (teller machine) hojjetu
• Ulaagaalee jalqabaa: nageenyaafi amanamummaa.
• Walsimannaa daataa fakkeeffame.
• Daldala walfakkaatu (hojiilee herrega baankota adda addaa keessatti
hirmaachisu; fayyadamtoota hedduu irraa yeroo tokkotti argachuu fi
kkf).
• Badii dandamachuu
3. Duumessa
• Shallaggii akka faayidaatti: tajaajila application, storage, computing;
itti fayyadama tokkoon tokkoon kaffaltii.
• Yaaddoowwan gurguddoo: iskeelii, raawwii hojii,
nageenya/amanamummaa.
Advantages and Disadvantages of Distributed Systems:-
7
Trends in distributed systems:
Distributed systems are undergoing a period of significant change and this can be traced back to a
number of influential trends:
8
Distributed systems are undergoing a period of significant change and this can be traced back to a
number of influential trends:
8
1.The emergence of pervasive networking technology.
The modern Internet is a vast interconnected collection of computer networks of many different
types, with the range of types increasing all the time and now including, for example, a wide range
of wireless communication technologies such as WiFi, WiMAX, Bluetooth and third-generation
mobile phone networks. The net result is that networking has become a pervasive resource and
devices can be connected (if desired) at any time and in any place.
Figure 1.3 illustrates a typical portion of the Internet. Programs running on the computers connected
to it interact by passing messages, employing a common means of communication. The design and
construction of the Internet communication mechanisms (the Internet protocols) is a major technical
achievement, enabling a program running anywhere to address messages to programs anywhere else
and abstracting over the myriad of technologies mentioned above.
The Internet is also a very large distributed system. It enables users, wherever they are, to make use
of services such as the World Wide Web, email and file transfer. The set of services is open-ended
– it can be extended by the addition of server computers and new types of service. The figure shows
a collection of intranets – sub networks operated by companies and other organizations and
typically protected by firewalls.
Internet Service Providers (ISPs) are companies that provide broadband links and other types of
connection to individual users and small organizations, enabling them to access services anywhere in
the Internet as well as providing local services such as email and web hosting. The intranets are
linked together by backbones. A backbone is a network link with a high transmission capacity,
employing satellite connections, fiber optic cables and other high-bandwidth circuits.
Adeemsa sirna raabsame keessatti:
9
The modern Internet is a vast interconnected collection of computer networks of many different
types, with the range of types increasing all the time and now including, for example, a wide range
of wireless communication technologies such as WiFi, WiMAX, Bluetooth and third-generation
mobile phone networks. The net result is that networking has become a pervasive resource and
devices can be connected (if desired) at any time and in any place.
Figure 1.3 illustrates a typical portion of the Internet. Programs running on the computers connected
to it interact by passing messages, employing a common means of communication. The design and
construction of the Internet communication mechanisms (the Internet protocols) is a major technical
achievement, enabling a program running anywhere to address messages to programs anywhere else
and abstracting over the myriad of technologies mentioned above.
The Internet is also a very large distributed system. It enables users, wherever they are, to make use
of services such as the World Wide Web, email and file transfer. The set of services is open-ended
– it can be extended by the addition of server computers and new types of service. The figure shows
a collection of intranets – sub networks operated by companies and other organizations and
typically protected by firewalls.
Internet Service Providers (ISPs) are companies that provide broadband links and other types of
connection to individual users and small organizations, enabling them to access services anywhere in
the Internet as well as providing local services such as email and web hosting. The intranets are
linked together by backbones. A backbone is a network link with a high transmission capacity,
employing satellite connections, fiber optic cables and other high-bandwidth circuits.
Adeemsa sirna raabsame keessatti:
9
Sirnoonni raabsaman yeroo jijjiirama guddaa keessa kan jiran yoo ta’u kunis adeemsa dhiibbaa uumuu
danda’an hedduu irraa hordofamuu danda’a:
1. Teeknooloojiin networking babal’ate uumamuu.
Intarneetiin ammayyaa walitti qabama bal’aa walitti hidhame kan networkii kompiitaraa gosa adda
addaa hedduu yoo ta’u, hammi gosoota isaa yeroo hunda dabalaa kan jiru yoo ta’u, amma fakkeenyaaf
teeknooloojiiwwan qunnamtii wayaa malee kanneen akka WiFi, WiMAX, Bluetooth fi networkii
bilbila harkaa dhaloota sadaffaa kan hammatedha. Bu’aan qulqulluun isaas, networking qabeenya
babal’ataa ta’ee meeshaaleen yeroo kamiyyuu fi bakka barbaadetti (yoo barbaadame) walitti hidhamuu
danda’uu isaati.
Fakkiin 1.3 kutaa interneetii idilee agarsiisa. Sagantaawwan kompitara isa waliin walqabatan irratti
hojjetan ergaa dabarsuudhaan walitti dhufeenya uumuun, mala qunnamtii waliigalaa fayyadamu.
Dizaayinii fi ijaarsi mala qunnamtii interneetii (pirootokoolota Intarneetii) bu’aa teeknikaa guddaa yoo
ta’u, sagantaa bakka kamiyyuu fiigu ergaa sagantaalee bakka biraatti akka erguu fi teeknooloojiiwwan
armaan olitti ibsaman hedduu ta’an irratti abstracting gochuu dandeessisa.
Intarneetiinis sirna raabsame baayyee guddaadha. Fayyadamtoonni bakka jiranitti tajaajiloota akka
World Wide Web, email fi file transfer akka fayyadaman dandeessisa. Tuutni tajaajiloota banaa dha –
kompiitara sarvarii fi gosoota tajaajilaa haaraa dabaluudhaan dheerachuu danda’a. Fakkiin kun walitti
qabama intraaneetii agarsiisa – neetworkii xiqqaa dhaabbilee fi dhaabbilee birootiin hojjetamuu fi
akkaataa idileetti dallaa ibiddaatiin eegamu.
Dhiyeessitoonni Tajaajila Intarneetii (ISP) dhaabbilee fayyadamtoota dhuunfaa fi dhaabbilee
xixiqqaadhaaf walitti hidhamiinsa broodbaandii fi gosoota qunnamtii biroo kan kennan yoo ta’u,
tajaajila interneetii bakka kamittuu akka argatan akkasumas tajaajila biyya keessaa kan akka email fi
web hosting kennan. Intraneetonni lafee dugdaadhaan walitti hidhamaniiru. Lafeen dugdaa jechuun
walitti hidhamiinsa neetworkii dandeettii dabarsuu olaanaa qabu yoo ta’u, walitti hidhamiinsa
saatalaayitii, keebilii faayibar optikii fi sarkiyuutii baandii ol’aanaa biroo kan qacarudha.
2.Mobile Computing and Ubiquitous computing in distributed systems.
Mobile computing is the performance of computing tasks while the user is on the move, or visiting
places other than their usual environment. In mobile computing, users who are away from their
‘home’ intranet (the intranet at work, or their residence) are still provided with access to resources via
10
danda’an hedduu irraa hordofamuu danda’a:
1. Teeknooloojiin networking babal’ate uumamuu.
Intarneetiin ammayyaa walitti qabama bal’aa walitti hidhame kan networkii kompiitaraa gosa adda
addaa hedduu yoo ta’u, hammi gosoota isaa yeroo hunda dabalaa kan jiru yoo ta’u, amma fakkeenyaaf
teeknooloojiiwwan qunnamtii wayaa malee kanneen akka WiFi, WiMAX, Bluetooth fi networkii
bilbila harkaa dhaloota sadaffaa kan hammatedha. Bu’aan qulqulluun isaas, networking qabeenya
babal’ataa ta’ee meeshaaleen yeroo kamiyyuu fi bakka barbaadetti (yoo barbaadame) walitti hidhamuu
danda’uu isaati.
Fakkiin 1.3 kutaa interneetii idilee agarsiisa. Sagantaawwan kompitara isa waliin walqabatan irratti
hojjetan ergaa dabarsuudhaan walitti dhufeenya uumuun, mala qunnamtii waliigalaa fayyadamu.
Dizaayinii fi ijaarsi mala qunnamtii interneetii (pirootokoolota Intarneetii) bu’aa teeknikaa guddaa yoo
ta’u, sagantaa bakka kamiyyuu fiigu ergaa sagantaalee bakka biraatti akka erguu fi teeknooloojiiwwan
armaan olitti ibsaman hedduu ta’an irratti abstracting gochuu dandeessisa.
Intarneetiinis sirna raabsame baayyee guddaadha. Fayyadamtoonni bakka jiranitti tajaajiloota akka
World Wide Web, email fi file transfer akka fayyadaman dandeessisa. Tuutni tajaajiloota banaa dha –
kompiitara sarvarii fi gosoota tajaajilaa haaraa dabaluudhaan dheerachuu danda’a. Fakkiin kun walitti
qabama intraaneetii agarsiisa – neetworkii xiqqaa dhaabbilee fi dhaabbilee birootiin hojjetamuu fi
akkaataa idileetti dallaa ibiddaatiin eegamu.
Dhiyeessitoonni Tajaajila Intarneetii (ISP) dhaabbilee fayyadamtoota dhuunfaa fi dhaabbilee
xixiqqaadhaaf walitti hidhamiinsa broodbaandii fi gosoota qunnamtii biroo kan kennan yoo ta’u,
tajaajila interneetii bakka kamittuu akka argatan akkasumas tajaajila biyya keessaa kan akka email fi
web hosting kennan. Intraneetonni lafee dugdaadhaan walitti hidhamaniiru. Lafeen dugdaa jechuun
walitti hidhamiinsa neetworkii dandeettii dabarsuu olaanaa qabu yoo ta’u, walitti hidhamiinsa
saatalaayitii, keebilii faayibar optikii fi sarkiyuutii baandii ol’aanaa biroo kan qacarudha.
2.Mobile Computing and Ubiquitous computing in distributed systems.
Mobile computing is the performance of computing tasks while the user is on the move, or visiting
places other than their usual environment. In mobile computing, users who are away from their
‘home’ intranet (the intranet at work, or their residence) are still provided with access to resources via
10
the devices they carry with them. They can continue to access the Internet; they can continue to
access resources in their home intranet; and there is increasing provision for users to utilize resources
such as printers or even sales points that are conveniently nearby as they move around. The latter is
also known as location-aware or context-aware computing. Mobility introduces a number of
challenges for distributed systems, including the need to deal with variable connectivity and indeed
disconnection, and the need to maintain operation in the face of device mobility.
Ubiquitous computing is the harnessing of many small, cheap computational devices that are present
in users’ physical environments, including the home, office and even natural settings. The term
‘ubiquitous’ is intended to suggest that small computing devices will eventually become so pervasive
in everyday objects that they are scarcely noticed. That is, their computational behavior will be
transparently and intimately tied up with their physical function.
Ubiquitous and mobile computing overlap, since the mobile user can in principle benefit from
computers that are everywhere. But they are distinct, in general. Ubiquitous computing could benefit
users while they remain in a single environment such as the home or a hospital. Similarly, mobile
computing has advantages even if it involves only conventional, discrete computers and devices such
as laptops and printers.
3.The increasing demand for multimedia services.
The benefits of distributed multimedia computing are considerable in that a wide range of new
(multimedia) services and applications can be provided on the desktop, including access to live or
pre-recorded television broadcasts, access to film libraries offering video-on-demand services, access
to music libraries, the provision of audio and video conferencing facilities and integrated telephony
features including IP telephony or related technologies such as Skype, a peer-to-peer alternative to IP
telephony.
Distributed multimedia applications such as webcasting place considerable demands on the
underlying distributed infrastructure in terms of:
Providing support for an (extensible) range of encoding and encryption formats, such as the
MPEG series of standards (including for example the popular MP3 standard otherwise known
as MPEG-1, Audio Layer 3) and HDTV.
Providing a range of mechanisms to ensure that the desired quality of service can be met.
Providing associated resource management strategies, including appropriate scheduling policies
to support the desired quality of service.
Providing adaptation strategies to deal with the inevitable situation in open systems where
quality of service cannot be met or sustained.
4.The view of distributed systems as a utility.
With the increasing maturity of distributed systems infrastructure, a number of companies are
promoting the view of distributed resources as a commodity or utility, drawing the analogy between
11
access resources in their home intranet; and there is increasing provision for users to utilize resources
such as printers or even sales points that are conveniently nearby as they move around. The latter is
also known as location-aware or context-aware computing. Mobility introduces a number of
challenges for distributed systems, including the need to deal with variable connectivity and indeed
disconnection, and the need to maintain operation in the face of device mobility.
Ubiquitous computing is the harnessing of many small, cheap computational devices that are present
in users’ physical environments, including the home, office and even natural settings. The term
‘ubiquitous’ is intended to suggest that small computing devices will eventually become so pervasive
in everyday objects that they are scarcely noticed. That is, their computational behavior will be
transparently and intimately tied up with their physical function.
Ubiquitous and mobile computing overlap, since the mobile user can in principle benefit from
computers that are everywhere. But they are distinct, in general. Ubiquitous computing could benefit
users while they remain in a single environment such as the home or a hospital. Similarly, mobile
computing has advantages even if it involves only conventional, discrete computers and devices such
as laptops and printers.
3.The increasing demand for multimedia services.
The benefits of distributed multimedia computing are considerable in that a wide range of new
(multimedia) services and applications can be provided on the desktop, including access to live or
pre-recorded television broadcasts, access to film libraries offering video-on-demand services, access
to music libraries, the provision of audio and video conferencing facilities and integrated telephony
features including IP telephony or related technologies such as Skype, a peer-to-peer alternative to IP
telephony.
Distributed multimedia applications such as webcasting place considerable demands on the
underlying distributed infrastructure in terms of:
Providing support for an (extensible) range of encoding and encryption formats, such as the
MPEG series of standards (including for example the popular MP3 standard otherwise known
as MPEG-1, Audio Layer 3) and HDTV.
Providing a range of mechanisms to ensure that the desired quality of service can be met.
Providing associated resource management strategies, including appropriate scheduling policies
to support the desired quality of service.
Providing adaptation strategies to deal with the inevitable situation in open systems where
quality of service cannot be met or sustained.
4.The view of distributed systems as a utility.
With the increasing maturity of distributed systems infrastructure, a number of companies are
promoting the view of distributed resources as a commodity or utility, drawing the analogy between
11
distributed resources and other utilities such as water or electricity. With this model, resources are
provided by appropriate service suppliers and effectively rented rather than owned by the end user.
For Example- The term cloud computing is used to capture this vision of computing as a utility. A
cloud is defined as a set of Internet-based application, storage and computing services sufficient to
support most users’ needs, thus enabling them to largely or totally dispense with local data storage
and application software (see Figure 1.5). The term also promotes a view of everything as a service,
from physical or virtual infrastructure through to software, often paid for on a per-usage basis rather
than purchased. Note that cloud computing reduces requirements on users’ devices, allowing very
simple desktop or portable devices to access a potentially wide range of resources and services.
Clouds are generally implemented on cluster computers to provide the necessary scale and
performance required by such services. A cluster computer is a set of interconnected computers that
cooperate closely to provide a single, integrated high performance computing capability.
2. Shallaggii Moobaayilaa fi shallaggii bakka hundatti argamu sirna raabsame keessatti.
Shallaggii sochootuu jechuun yeroo fayyadamaan sochiirra jiru, ykn naannoo isaanii isa barame
irraa kan hafe bakka biraa daawwachuu hojiiwwan shallaggii raawwachuudha. Shallaggii
moobaayilaa keessatti fayyadamtoonni intraaneetii ‘mana’ isaanii (intranet bakka hojiitti, ykn
bakka jireenyaa isaanii) irraa fagaatan ammallee karaa meeshaalee qabatanii deemaniin
qabeenya akka argatan ni taasifama. Intarneetii fayyadamuu itti fufuu danda’u; qabeenya
intranet mana isaanii keessatti argamu argachuu itti fufuu ni danda’u; akkasumas
fayyadamtoonni qabeenya akka maxxansaa ykn illee bakka gurgurtaa yeroo socho’an haala
mijataa ta’een dhihoo ta’etti akka fayyadaman tumaan dabalaa dhufeera. Inni lammaffaan
shallaggii bakka beeku ykn haala dubbii beeku jedhamuunis beekama. Sochiin sirnoota
raabsamaniif qormaata hedduu kan fidu yoo ta’u, isaanis barbaachisummaa walitti hidhamiinsa
12
provided by appropriate service suppliers and effectively rented rather than owned by the end user.
For Example- The term cloud computing is used to capture this vision of computing as a utility. A
cloud is defined as a set of Internet-based application, storage and computing services sufficient to
support most users’ needs, thus enabling them to largely or totally dispense with local data storage
and application software (see Figure 1.5). The term also promotes a view of everything as a service,
from physical or virtual infrastructure through to software, often paid for on a per-usage basis rather
than purchased. Note that cloud computing reduces requirements on users’ devices, allowing very
simple desktop or portable devices to access a potentially wide range of resources and services.
Clouds are generally implemented on cluster computers to provide the necessary scale and
performance required by such services. A cluster computer is a set of interconnected computers that
cooperate closely to provide a single, integrated high performance computing capability.
2. Shallaggii Moobaayilaa fi shallaggii bakka hundatti argamu sirna raabsame keessatti.
Shallaggii sochootuu jechuun yeroo fayyadamaan sochiirra jiru, ykn naannoo isaanii isa barame
irraa kan hafe bakka biraa daawwachuu hojiiwwan shallaggii raawwachuudha. Shallaggii
moobaayilaa keessatti fayyadamtoonni intraaneetii ‘mana’ isaanii (intranet bakka hojiitti, ykn
bakka jireenyaa isaanii) irraa fagaatan ammallee karaa meeshaalee qabatanii deemaniin
qabeenya akka argatan ni taasifama. Intarneetii fayyadamuu itti fufuu danda’u; qabeenya
intranet mana isaanii keessatti argamu argachuu itti fufuu ni danda’u; akkasumas
fayyadamtoonni qabeenya akka maxxansaa ykn illee bakka gurgurtaa yeroo socho’an haala
mijataa ta’een dhihoo ta’etti akka fayyadaman tumaan dabalaa dhufeera. Inni lammaffaan
shallaggii bakka beeku ykn haala dubbii beeku jedhamuunis beekama. Sochiin sirnoota
raabsamaniif qormaata hedduu kan fidu yoo ta’u, isaanis barbaachisummaa walitti hidhamiinsa
12
jijjiiramaa fi dhugumatti walitti hidhamiinsa addaan cituu wajjin wal’aansoo qabuu, fi sochii
meeshaalee fuulduratti hojii eeguu dabalatee.
Shallaggiin bakka hundatti argamu meeshaalee shallaggii xixiqqoo, gatii salphaa ta’an hedduu
kanneen naannoo fiizikaalaa fayyadamtootaa keessatti argaman, mana, waajjiraafi illee bakka
uumamaa dabalatee fayyadamuudha. Jechi ‘bakka hundatti argamu’ jedhu meeshaaleen
shallaggii xixiqqoo dhuma irratti wantoota guyyaa guyyaa keessatti baay’ee akka babal’atan
waan ta’eef baay’ee akka hin hubatamne agarsiisuuf yaadame. Kunis, amala shallaggii isaanii
iftoominaa fi walitti dhiyeenyaan dalagaa fiizikaalaa isaanii wajjin kan walqabatu ta’a.
Fayyadamaan moobaayilaa akka seeraatti kompiitara bakka hundatti argamu irraa fayyadamuu
waan danda’uuf, kompiitara bakka hundatti argamu fi moobaayilaa wal-irra bu’a. Garuu adda
adda, walumaa galatti. Shallaggiin bakka hundatti argamu fayyadamtoota naannoo tokko kan
akka manaa ykn hospitaala keessa osoo jiranii fayyadamoo taasisuu danda'a. Haaluma
walfakkaatuun kompiitara moobaayilaa kompiitara barame, addaan baafamee fi meeshaalee kan
akka laptop fi printer qofa yoo hirmaachisellee faayidaa qaba.
3. Fedhiin tajaajila maltimidiyaa dabalaa dhufuu isaa.
Faayidaan shallaggii maltimidiyaa raabsame baay’ee guddaa kan ta’e, tamsaasa televijiinii
kallattiin ykn dursanii waraabame argachuu, mana kitaabaa fiilmii tajaajila viidiyoo gaaffii
irratti hundaa’e kennan argachuu, mana kitaabaa muuziqaa argachuu, meeshaalee konfiraansii
sagalee fi viidiyoo fi amaloota bilbilaa walitti makaman kanneen akka bilbila IP ykn
teeknooloojiiwwan walqabatan kanneen akka Skype, a bilbila IP irraa filannoo peer-to-peer.
Appilikeeshiniiwwan maltimidiyaa raabsaman kan akka weebkaastiin bu’uuraalee raabsaman
bu’uuraa irratti gaaffii guddaa kaa’u gama:
• Deeggarsa (babal’ataa) bifa koodii fi icciitii kennuu, kan akka istaandaardii tartiiba MPEG
(fakkeenyaaf istaandaardii MP3 beekamaa karaa biraatiin MPEG-1, Audio Layer 3 jedhamuun
beekamu dabalatee) fi HDTV.
• Qulqullinni tajaajilaa barbaadamu guutamuu akka danda’u mala adda addaa kennuu.
13
meeshaalee fuulduratti hojii eeguu dabalatee.
Shallaggiin bakka hundatti argamu meeshaalee shallaggii xixiqqoo, gatii salphaa ta’an hedduu
kanneen naannoo fiizikaalaa fayyadamtootaa keessatti argaman, mana, waajjiraafi illee bakka
uumamaa dabalatee fayyadamuudha. Jechi ‘bakka hundatti argamu’ jedhu meeshaaleen
shallaggii xixiqqoo dhuma irratti wantoota guyyaa guyyaa keessatti baay’ee akka babal’atan
waan ta’eef baay’ee akka hin hubatamne agarsiisuuf yaadame. Kunis, amala shallaggii isaanii
iftoominaa fi walitti dhiyeenyaan dalagaa fiizikaalaa isaanii wajjin kan walqabatu ta’a.
Fayyadamaan moobaayilaa akka seeraatti kompiitara bakka hundatti argamu irraa fayyadamuu
waan danda’uuf, kompiitara bakka hundatti argamu fi moobaayilaa wal-irra bu’a. Garuu adda
adda, walumaa galatti. Shallaggiin bakka hundatti argamu fayyadamtoota naannoo tokko kan
akka manaa ykn hospitaala keessa osoo jiranii fayyadamoo taasisuu danda'a. Haaluma
walfakkaatuun kompiitara moobaayilaa kompiitara barame, addaan baafamee fi meeshaalee kan
akka laptop fi printer qofa yoo hirmaachisellee faayidaa qaba.
3. Fedhiin tajaajila maltimidiyaa dabalaa dhufuu isaa.
Faayidaan shallaggii maltimidiyaa raabsame baay’ee guddaa kan ta’e, tamsaasa televijiinii
kallattiin ykn dursanii waraabame argachuu, mana kitaabaa fiilmii tajaajila viidiyoo gaaffii
irratti hundaa’e kennan argachuu, mana kitaabaa muuziqaa argachuu, meeshaalee konfiraansii
sagalee fi viidiyoo fi amaloota bilbilaa walitti makaman kanneen akka bilbila IP ykn
teeknooloojiiwwan walqabatan kanneen akka Skype, a bilbila IP irraa filannoo peer-to-peer.
Appilikeeshiniiwwan maltimidiyaa raabsaman kan akka weebkaastiin bu’uuraalee raabsaman
bu’uuraa irratti gaaffii guddaa kaa’u gama:
• Deeggarsa (babal’ataa) bifa koodii fi icciitii kennuu, kan akka istaandaardii tartiiba MPEG
(fakkeenyaaf istaandaardii MP3 beekamaa karaa biraatiin MPEG-1, Audio Layer 3 jedhamuun
beekamu dabalatee) fi HDTV.
• Qulqullinni tajaajilaa barbaadamu guutamuu akka danda’u mala adda addaa kennuu.
13
• Qulqullina tajaajilaa barbaadamu deeggaruuf imaammata sagantaa sirrii ta’e dabalatee
tooftaalee bulchiinsa qabeenya walqabatan kennuu.
• Sirna banaa qulqullinni tajaajilaa guutamuu ykn itti fufuu hin dandeenye keessatti haala hin
oolle furuuf tooftaalee madaqsuu kennuu.
4. Ilaalcha sirnoota raabsaman akka faayidaatti.
Bilchina bu’uuraalee sirna raabsame dabalaa dhufuun dhaabbileen hedduun qabeenya raabsame
akka meeshaa ykn faayidaatti ilaaluu guddisuudhaan, qabeenya raabsamee fi faayidaa biroo kan
akka bishaanii ykn ibsaa gidduutti walfakkeessuudhaan. Moodeela kanaan qabeenyi
dhiyeessitoota tajaajila mijatoo ta’aniin kan kennamu yoo ta’u, fayyadamaa dhumaatiin osoo hin
taane haala bu’a qabeessa ta’een kan kireeffamudha.
Fakkeenyaaf- Jechi cloud computing jedhu mul’ata shallaggii kana akka faayidaa tokkootti
qabachuuf kan gargaarudha. Duumessi akka tuuta tajaajila aplikeeshinii, kuusaa fi shallaggii
interneetii irratti hundaa’ee fi fedhii fayyadamtoota baay’ee deeggaruuf gahaa ta’etti ibsama,
kanaanis baay’inaan ykn guutummaatti kuusaa deetaa naannoo fi sooftiweerii aplikeeshinii irraa
akka of qusatan isaan dandeessisa (fakkii 1.5 ilaali). Jechi kun akkasumas ilaalcha waan hunda
akka tajaajilaatti, bu’uuraalee fiizikaalaa ykn vaartuwalii irraa kaasee hanga sooftiweerii, yeroo
baay’ee bitamee osoo hin taane itti fayyadama tokkoon tokkoon kaffalamutti ilaaluu ni
jajjabeessa. Hubadhaa, shallaggiin duumessaa meeshaalee fayyadamtootaa irratti
barbaachisummaa hir’isa, meeshaaleen deeskitooppii ykn socho’oo baay’ee salphaa ta’an
qabeenyaafi tajaajila bal’aa ta’uu danda’u akka argatan taasisa.
Duumessi akka waliigalaatti kompitara kilaastara irratti hojiirra kan oolu yoo ta’u, kunis iskeelii
fi raawwii barbaachisaa tajaajiloonni akkasii barbaadan akka kennan ta’a. Kompiitarri
kilaastara tuuta kompiitara walitti hidhamanii fi dandeettii shallaggii ga’umsa olaanaa qabu
tokko, walitti makame kennuudhaaf walitti dhiyeenyaan tumsaniidha.
Types of Distributed Systems:
Distributed systems are classified as following types.
1.Distributed computing systems.
14
tooftaalee bulchiinsa qabeenya walqabatan kennuu.
• Sirna banaa qulqullinni tajaajilaa guutamuu ykn itti fufuu hin dandeenye keessatti haala hin
oolle furuuf tooftaalee madaqsuu kennuu.
4. Ilaalcha sirnoota raabsaman akka faayidaatti.
Bilchina bu’uuraalee sirna raabsame dabalaa dhufuun dhaabbileen hedduun qabeenya raabsame
akka meeshaa ykn faayidaatti ilaaluu guddisuudhaan, qabeenya raabsamee fi faayidaa biroo kan
akka bishaanii ykn ibsaa gidduutti walfakkeessuudhaan. Moodeela kanaan qabeenyi
dhiyeessitoota tajaajila mijatoo ta’aniin kan kennamu yoo ta’u, fayyadamaa dhumaatiin osoo hin
taane haala bu’a qabeessa ta’een kan kireeffamudha.
Fakkeenyaaf- Jechi cloud computing jedhu mul’ata shallaggii kana akka faayidaa tokkootti
qabachuuf kan gargaarudha. Duumessi akka tuuta tajaajila aplikeeshinii, kuusaa fi shallaggii
interneetii irratti hundaa’ee fi fedhii fayyadamtoota baay’ee deeggaruuf gahaa ta’etti ibsama,
kanaanis baay’inaan ykn guutummaatti kuusaa deetaa naannoo fi sooftiweerii aplikeeshinii irraa
akka of qusatan isaan dandeessisa (fakkii 1.5 ilaali). Jechi kun akkasumas ilaalcha waan hunda
akka tajaajilaatti, bu’uuraalee fiizikaalaa ykn vaartuwalii irraa kaasee hanga sooftiweerii, yeroo
baay’ee bitamee osoo hin taane itti fayyadama tokkoon tokkoon kaffalamutti ilaaluu ni
jajjabeessa. Hubadhaa, shallaggiin duumessaa meeshaalee fayyadamtootaa irratti
barbaachisummaa hir’isa, meeshaaleen deeskitooppii ykn socho’oo baay’ee salphaa ta’an
qabeenyaafi tajaajila bal’aa ta’uu danda’u akka argatan taasisa.
Duumessi akka waliigalaatti kompitara kilaastara irratti hojiirra kan oolu yoo ta’u, kunis iskeelii
fi raawwii barbaachisaa tajaajiloonni akkasii barbaadan akka kennan ta’a. Kompiitarri
kilaastara tuuta kompiitara walitti hidhamanii fi dandeettii shallaggii ga’umsa olaanaa qabu
tokko, walitti makame kennuudhaaf walitti dhiyeenyaan tumsaniidha.
Types of Distributed Systems:
Distributed systems are classified as following types.
1.Distributed computing systems.
14
2.Distributed information systems.
3.Distributed embedded systems.
1. Distributed Computing Systems:
An important class of distributed systems is the one used for high-performance computing tasks.
Roughly speaking, one can make a distinction between two subgroups. In cluster computing the
underlying hardware consists of a collection of similar workstations or PCs, closely connected by
means of a high speed local-area network. In addition, each node runs the same operating system.
The situation becomes quite different in the case of grid computing. This subgroup consists of
distributed systems that are often constructed as a federation of computer systems, where each system
may fall under a different administrative domain, and may be very different when it comes to hardware,
software, and deployed network technology.
Cluster Computing Systems
Computers communicating over a high speed network can be made to work and present itself as a
single computer to the users. A set of computers that are grouped together in such a manner that they
form a single resource pool is called a cluster. Any task that has been assigned to the cluster would run
on all the computers in the cluster in a parallel fashion by breaking the whole task into smaller self
contained tasks. Then, the result of the smaller tasks would be combined to form the final result.
Cluster computing helps organizations to increase their computing power using the standard and
commonly available technology. These hardware and software which are commonly known as
commodity items can be purchased from the market at relatively low cost. Cluster computing has seen
tremendous growth in the recent years. Around 80 percent of top 500 supercomputing centers in the
world are using clusters. Clusters are used primarily to run scientific, engineering, commercial, and
industrial applications that require high availability and high throughput processing. Protein sequencing
in biomedical applications, earth quake simulation in civil engineering, petroleum reservoir simulation
in earth resource and petroleum engineering and replicated and distributed storage and backup servers
for high demand web based business applications are a few examples for applications which primarily
run on clusters. Below figure shows a typical arrangement of computers in a Computing Cluster.
15
3.Distributed embedded systems.
1. Distributed Computing Systems:
An important class of distributed systems is the one used for high-performance computing tasks.
Roughly speaking, one can make a distinction between two subgroups. In cluster computing the
underlying hardware consists of a collection of similar workstations or PCs, closely connected by
means of a high speed local-area network. In addition, each node runs the same operating system.
The situation becomes quite different in the case of grid computing. This subgroup consists of
distributed systems that are often constructed as a federation of computer systems, where each system
may fall under a different administrative domain, and may be very different when it comes to hardware,
software, and deployed network technology.
Cluster Computing Systems
Computers communicating over a high speed network can be made to work and present itself as a
single computer to the users. A set of computers that are grouped together in such a manner that they
form a single resource pool is called a cluster. Any task that has been assigned to the cluster would run
on all the computers in the cluster in a parallel fashion by breaking the whole task into smaller self
contained tasks. Then, the result of the smaller tasks would be combined to form the final result.
Cluster computing helps organizations to increase their computing power using the standard and
commonly available technology. These hardware and software which are commonly known as
commodity items can be purchased from the market at relatively low cost. Cluster computing has seen
tremendous growth in the recent years. Around 80 percent of top 500 supercomputing centers in the
world are using clusters. Clusters are used primarily to run scientific, engineering, commercial, and
industrial applications that require high availability and high throughput processing. Protein sequencing
in biomedical applications, earth quake simulation in civil engineering, petroleum reservoir simulation
in earth resource and petroleum engineering and replicated and distributed storage and backup servers
for high demand web based business applications are a few examples for applications which primarily
run on clusters. Below figure shows a typical arrangement of computers in a Computing Cluster.
15
Figure - Computing cluster
Grid Computing Systems
Grid is a type of distributed computing system where a large number of small loosely
coupled computers are brought together to form a large virtual supercomputer. This virtual
super computer has to perform tasks that are large for any single computer to perform
within a reasonable time.
Grid is defined as a parallel and distributed system that is capable of selecting, sharing, and
aggregating geographically distributed resources dynamically at runtime based on their
availability, capability, performance, and cost meeting the users’ Quality of Service (QoS)
requirements. Grid computing combines computing resources distributed across a large
geographical area belonging to different persons and organization. The main purpose of the
grid system is to collaboratively work across multiple systems to solve single computing
task by dividing the task into smaller self contained tasks and distributing those tasks to
different computers.
The middleware used in grid computing is responsible for dividing and apportioning the
tasks. The size of a grid system can vary from few hundred computers within an
organization to large systems consisting of thousands of nodes across multiple
organizations. Small grids confined to a single organization is commonly known as intra-
node corporation while the larger wider system is referred to as inter node corporation.
Below figure shows Grid System distributed across heterogeneous computing platforms.
16
Grid Computing Systems
Grid is a type of distributed computing system where a large number of small loosely
coupled computers are brought together to form a large virtual supercomputer. This virtual
super computer has to perform tasks that are large for any single computer to perform
within a reasonable time.
Grid is defined as a parallel and distributed system that is capable of selecting, sharing, and
aggregating geographically distributed resources dynamically at runtime based on their
availability, capability, performance, and cost meeting the users’ Quality of Service (QoS)
requirements. Grid computing combines computing resources distributed across a large
geographical area belonging to different persons and organization. The main purpose of the
grid system is to collaboratively work across multiple systems to solve single computing
task by dividing the task into smaller self contained tasks and distributing those tasks to
different computers.
The middleware used in grid computing is responsible for dividing and apportioning the
tasks. The size of a grid system can vary from few hundred computers within an
organization to large systems consisting of thousands of nodes across multiple
organizations. Small grids confined to a single organization is commonly known as intra-
node corporation while the larger wider system is referred to as inter node corporation.
Below figure shows Grid System distributed across heterogeneous computing platforms.
16
Figure - Grid computing system
Grids have been used to perform computationally intensive scientific, mathematical, and
academic problems through volunteer computing. Drug discovery, economic forecasting,
seismic analysis, and back office data processing for e-commerce are a few of the tasks that are
commonly solved using grid computing.
Gosoota Sirna Raabsaman: 1.1.
Sirnoonni raabsaman gosoota armaan gadiitiin ramadamu.
1. Sirna shallaggii raabsame.
2. Sirna odeeffannoo raabsame.
3. Sirnoota ukkaamfame raabsame.
1. Sirna Shallaggii Raabsame: 1.1.
Gitni barbaachisaan sirnoota raabsaman kan hojiiwwan shallaggii ga’umsa olaanaa qabaniif
fayyadamudha. Gara tilmaamaatti yoo ilaalle, namni tokko garee xiqqaa lama gidduutti addaan
baasuu danda’a. Shallaggii kilaastara keessatti haardwaariin bu’uuraa walitti qabama
buufataalee hojii ykn PC walfakkaataa kan of keessaa qabu yoo ta’u, karaa neetworkii naannoo
naannoo saffisa guddaa qabuun walitti dhiyeenyaan kan walqabatudha. Dabalataanis, tokkoon
tokkoon noodiin sirna hojii walfakkaataa hojjeta.
Haalli jiru haala shallaggii giiridii keessatti baayyee adda ta’a. Gareen xiqqaan kun sirnoota
raabsaman kan of keessaa qabu yoo ta’u, yeroo baay’ee akka federeeshinii sirna kompiitaraatti
kan ijaaraman yoo ta’u, sirni tokkoon tokkoon isaa damee bulchiinsaa adda addaa jalatti kufuu
danda’a, akkasumas yeroo haardwaarii, sooftiweerii fi teeknooloojii neetworkii bobbaafame
ilaalchisee baay’ee adda ta’uu danda’a.
• Sirna Shallaggii Kilaastara
17
Grids have been used to perform computationally intensive scientific, mathematical, and
academic problems through volunteer computing. Drug discovery, economic forecasting,
seismic analysis, and back office data processing for e-commerce are a few of the tasks that are
commonly solved using grid computing.
Gosoota Sirna Raabsaman: 1.1.
Sirnoonni raabsaman gosoota armaan gadiitiin ramadamu.
1. Sirna shallaggii raabsame.
2. Sirna odeeffannoo raabsame.
3. Sirnoota ukkaamfame raabsame.
1. Sirna Shallaggii Raabsame: 1.1.
Gitni barbaachisaan sirnoota raabsaman kan hojiiwwan shallaggii ga’umsa olaanaa qabaniif
fayyadamudha. Gara tilmaamaatti yoo ilaalle, namni tokko garee xiqqaa lama gidduutti addaan
baasuu danda’a. Shallaggii kilaastara keessatti haardwaariin bu’uuraa walitti qabama
buufataalee hojii ykn PC walfakkaataa kan of keessaa qabu yoo ta’u, karaa neetworkii naannoo
naannoo saffisa guddaa qabuun walitti dhiyeenyaan kan walqabatudha. Dabalataanis, tokkoon
tokkoon noodiin sirna hojii walfakkaataa hojjeta.
Haalli jiru haala shallaggii giiridii keessatti baayyee adda ta’a. Gareen xiqqaan kun sirnoota
raabsaman kan of keessaa qabu yoo ta’u, yeroo baay’ee akka federeeshinii sirna kompiitaraatti
kan ijaaraman yoo ta’u, sirni tokkoon tokkoon isaa damee bulchiinsaa adda addaa jalatti kufuu
danda’a, akkasumas yeroo haardwaarii, sooftiweerii fi teeknooloojii neetworkii bobbaafame
ilaalchisee baay’ee adda ta’uu danda’a.
• Sirna Shallaggii Kilaastara
17
Kompiitaroonni networkii saffisa olaanaatiin walqunnaman akka hojjetaniifi akka kompiitara
tokkootti fayyadamtootaaf akka of dhiyeessu gochuun ni danda’ama. Tuutni kompiitaraa haala
isaan kuusa qabeenya tokko uumuun walitti gurmaa'an kilaastara jedhama. Hojiin kamiyyuu
kilaastaraaf ramadame hojii guutuu gara hojiiwwan xixiqqoo of keessaa qabanitti cabsuudhaan
kompitara kilaastara keessa jiran hunda irratti haala walfakkaatuun hojjeta ture. Sana booda,
bu’aan hojiiwwan xixiqqoo walitti makamee bu’aa dhumaa uuma ture.
Shallaggiin kilaastara dhaabbileen teeknooloojii istaandaardii fi yeroo baay’ee argamu
fayyadamuun humna shallaggii isaanii akka guddisan gargaara. Hardware fi software kanneen
yeroo baayyee meeshaalee gurgurtaa jedhamuun beekaman kun baasii xiqqaadhaan gabaa irraa
bitamuu danda’u. Waggoota dhiyoo asitti kompiitara kilaastaraa guddina guddaa agarsiiseera.
Addunyaa irratti wiirtuuwwan suppercomputing 500 ol’aanoo ta’an keessaa gara dhibbeentaa
80 ta’an kilaastara fayyadamaa jiru. Kilaastaroonni adda durummaan hojiiwwan saayinsii,
injinariingii, daldalaa fi industirii kanneen argama olaanaa fi adeemsa bu’aa olaanaa barbaadan
hojjechuuf fayyadamu. Tartiiba pirootiinii hojiiwwan baayoomeediikaalaa keessatti,
simulashinii kirkira lafaa siiviil injinariingii keessatti, fakkeenya kuufama boba’aa qabeenya
lafaa fi injinariingii boba’aa keessatti fi sarvaroota kuusaa fi duwwaa fakkeessanii fi raabsaman
kanneen fedhii olaanaa weeb irratti hundaa’aniif aplikeeshiniiwwan adda durummaan kilaastara
irratti hojjetaniif fakkeenya muraasa. Fakkiin armaan gadii qindeessaa idilee kompiitara
Kilaastara Kompiitaraa keessatti agarsiisa.
Fakkii - Kilaastara shallaggii
• Sirna Shallaggii Giriidii
Giriidiin gosa sirna shallaggii raabsame yoo ta’u, kompiitaroonni xixiqqoo laaftuudhaan
walqabsiifaman baay’inaan walitti fidamanii supparkoompitara guddaa vaartuwalii uumuudha.
Virtual super computer kun hojiiwwan gurguddoo kompiitarri tokko kamiyyuu yeroo
madaalawaa keessatti raawwachuu qaba.
Giriidiin sirna walfakkaatuu fi raabsame kan qabeenya teessuma lafaatiin raabsaman yeroo
gaggeeffamutti argamu, dandeettii, raawwii, fi baasii barbaachisummaa Qulqullina Tajaajila
(QoS) fayyadamtootaa guutuu irratti hundaa’uun daayinamiikiin filachuu, qooduu fi walitti
qabuu danda’u jedhamee ibsama. Shallaggiin giiridii qabeenya shallaggii naannoo teessuma
lafaa guddaa kan namootaa fi dhaabbata adda addaa irratti raabsame walitti fida. Kaayyoon inni
guddaan sirna giiridii hojii shallaggii tokko furuuf sirnoota hedduu keessatti walta’iinsaan
hojjechuun hojii sana hojiiwwan xixiqqoo of danda’an keessatti qooduun hojiiwwan sana
kompitara adda addaatti raabsuu dha.
Giddugaleessi shallaggii giiridii keessatti fayyadamu hojiiwwan qooduu fi qooduuf itti
gaafatamummaa qaba. Guddinni sirna giiridii kompiitara dhibba muraasa dhaabbata tokko
keessa jiran irraa kaasee hanga sirnoota gurguddoo dhaabbilee hedduu keessatti noodota
kumaatamaan lakkaa’aman of keessaa qabanitti garaagarummaa qabaachuu danda’a.
Giriidoonni xixiqqoo dhaabbata tokko keessatti daangeffaman yeroo baay’ee intra-node
corporation jedhamuun kan beekaman yoo ta’u sirni bal’aan guddaan ammoo inter node
corporation jedhamuun waama. Fakkiin armaan gadii Sirna Giriidii waltajjiiwwan shallaggii
adda addaa irratti raabsame agarsiisa.
18
tokkootti fayyadamtootaaf akka of dhiyeessu gochuun ni danda’ama. Tuutni kompiitaraa haala
isaan kuusa qabeenya tokko uumuun walitti gurmaa'an kilaastara jedhama. Hojiin kamiyyuu
kilaastaraaf ramadame hojii guutuu gara hojiiwwan xixiqqoo of keessaa qabanitti cabsuudhaan
kompitara kilaastara keessa jiran hunda irratti haala walfakkaatuun hojjeta ture. Sana booda,
bu’aan hojiiwwan xixiqqoo walitti makamee bu’aa dhumaa uuma ture.
Shallaggiin kilaastara dhaabbileen teeknooloojii istaandaardii fi yeroo baay’ee argamu
fayyadamuun humna shallaggii isaanii akka guddisan gargaara. Hardware fi software kanneen
yeroo baayyee meeshaalee gurgurtaa jedhamuun beekaman kun baasii xiqqaadhaan gabaa irraa
bitamuu danda’u. Waggoota dhiyoo asitti kompiitara kilaastaraa guddina guddaa agarsiiseera.
Addunyaa irratti wiirtuuwwan suppercomputing 500 ol’aanoo ta’an keessaa gara dhibbeentaa
80 ta’an kilaastara fayyadamaa jiru. Kilaastaroonni adda durummaan hojiiwwan saayinsii,
injinariingii, daldalaa fi industirii kanneen argama olaanaa fi adeemsa bu’aa olaanaa barbaadan
hojjechuuf fayyadamu. Tartiiba pirootiinii hojiiwwan baayoomeediikaalaa keessatti,
simulashinii kirkira lafaa siiviil injinariingii keessatti, fakkeenya kuufama boba’aa qabeenya
lafaa fi injinariingii boba’aa keessatti fi sarvaroota kuusaa fi duwwaa fakkeessanii fi raabsaman
kanneen fedhii olaanaa weeb irratti hundaa’aniif aplikeeshiniiwwan adda durummaan kilaastara
irratti hojjetaniif fakkeenya muraasa. Fakkiin armaan gadii qindeessaa idilee kompiitara
Kilaastara Kompiitaraa keessatti agarsiisa.
Fakkii - Kilaastara shallaggii
• Sirna Shallaggii Giriidii
Giriidiin gosa sirna shallaggii raabsame yoo ta’u, kompiitaroonni xixiqqoo laaftuudhaan
walqabsiifaman baay’inaan walitti fidamanii supparkoompitara guddaa vaartuwalii uumuudha.
Virtual super computer kun hojiiwwan gurguddoo kompiitarri tokko kamiyyuu yeroo
madaalawaa keessatti raawwachuu qaba.
Giriidiin sirna walfakkaatuu fi raabsame kan qabeenya teessuma lafaatiin raabsaman yeroo
gaggeeffamutti argamu, dandeettii, raawwii, fi baasii barbaachisummaa Qulqullina Tajaajila
(QoS) fayyadamtootaa guutuu irratti hundaa’uun daayinamiikiin filachuu, qooduu fi walitti
qabuu danda’u jedhamee ibsama. Shallaggiin giiridii qabeenya shallaggii naannoo teessuma
lafaa guddaa kan namootaa fi dhaabbata adda addaa irratti raabsame walitti fida. Kaayyoon inni
guddaan sirna giiridii hojii shallaggii tokko furuuf sirnoota hedduu keessatti walta’iinsaan
hojjechuun hojii sana hojiiwwan xixiqqoo of danda’an keessatti qooduun hojiiwwan sana
kompitara adda addaatti raabsuu dha.
Giddugaleessi shallaggii giiridii keessatti fayyadamu hojiiwwan qooduu fi qooduuf itti
gaafatamummaa qaba. Guddinni sirna giiridii kompiitara dhibba muraasa dhaabbata tokko
keessa jiran irraa kaasee hanga sirnoota gurguddoo dhaabbilee hedduu keessatti noodota
kumaatamaan lakkaa’aman of keessaa qabanitti garaagarummaa qabaachuu danda’a.
Giriidoonni xixiqqoo dhaabbata tokko keessatti daangeffaman yeroo baay’ee intra-node
corporation jedhamuun kan beekaman yoo ta’u sirni bal’aan guddaan ammoo inter node
corporation jedhamuun waama. Fakkiin armaan gadii Sirna Giriidii waltajjiiwwan shallaggii
adda addaa irratti raabsame agarsiisa.
18
Fakkii - Sirna shallaggii giiridii
Giriidiin rakkoolee saayinsii, herregaa fi barnootaa shallaggii cimaa ta’an karaa shallaggii tola
ooltummaatiin raawwachuuf itti fayyadamaniiru. Argannoon qoricha, tilmaama dinagdee,
xiinxala seesmiikii, fi adeemsi daataa waajjira duubaa daldala elektirooniksii hojiiwwan yeroo
baay’ee shallaggii giiridii fayyadamuun furmaata argatan keessaa muraasa.
Distributed Storage Systems
The rapid growth of storage volume, bandwidth and computation resources along with the reduction in
the cost of storage devices have fueled popularity of distributed storage systems. The main objective of
distributing storage across multiple devices is to protect the data in case of disk failure through
redundant storage in multiple devices and to make data available closer to the user in massively
distributed system. There are mainly four types of distributed storage systems. There are namely,
Server Attached Redundant Array of Independent Disks (RAID), centralized RAID, Network Attached
Storage (NAS) and Storage Area Network (SAN). NAS and SAN are the most popular distributed
storage techniques out of the four. Below figure shows the typical arrangement of distributed storage
system.
Figure - Distributed storage system
NAS and SAN have slight differences in techniques adopted for transferring data between devices and
the performance due to this difference. NAS mainly uses TCP/IP protocol to transfer data across
multiple devices whereas SAN uses SCSI setup on fiber channels. Hence NAS can be implemented on
any physical network supporting TCP/IP such as Ethernet, FDDI, or ATM. But SAN can be
implemented only fiber channel. SAN has better performance compared NAS as TCP has higher
overhead and SCSI faster than TCP/IP networks.
19
Giriidiin rakkoolee saayinsii, herregaa fi barnootaa shallaggii cimaa ta’an karaa shallaggii tola
ooltummaatiin raawwachuuf itti fayyadamaniiru. Argannoon qoricha, tilmaama dinagdee,
xiinxala seesmiikii, fi adeemsi daataa waajjira duubaa daldala elektirooniksii hojiiwwan yeroo
baay’ee shallaggii giiridii fayyadamuun furmaata argatan keessaa muraasa.
Distributed Storage Systems
The rapid growth of storage volume, bandwidth and computation resources along with the reduction in
the cost of storage devices have fueled popularity of distributed storage systems. The main objective of
distributing storage across multiple devices is to protect the data in case of disk failure through
redundant storage in multiple devices and to make data available closer to the user in massively
distributed system. There are mainly four types of distributed storage systems. There are namely,
Server Attached Redundant Array of Independent Disks (RAID), centralized RAID, Network Attached
Storage (NAS) and Storage Area Network (SAN). NAS and SAN are the most popular distributed
storage techniques out of the four. Below figure shows the typical arrangement of distributed storage
system.
Figure - Distributed storage system
NAS and SAN have slight differences in techniques adopted for transferring data between devices and
the performance due to this difference. NAS mainly uses TCP/IP protocol to transfer data across
multiple devices whereas SAN uses SCSI setup on fiber channels. Hence NAS can be implemented on
any physical network supporting TCP/IP such as Ethernet, FDDI, or ATM. But SAN can be
implemented only fiber channel. SAN has better performance compared NAS as TCP has higher
overhead and SCSI faster than TCP/IP networks.
19
Distributed Database Systems
Distributed database system is a collection of independent database systems distributed across multiple
computers that collaboratively store data in such a manner that a user can access data from anywhere as
if it has been stored locally irrespective of where the data is actually stored. Below figure shows an
arrangement of distributed database system across multiple network sites.
Figure - Distributed Database system
• Sirna Kuusaa Raabsame
Guddinni saffisaan heddummina kuusaa, baandii fi qabeenya shallaggii baasii meeshaalee
kuusaa hir’achuu waliin ta’uun jaalala sirna kuusaa raabsame boba’aa ta’eera. Kaayyoon inni
guddaan kuusaa meeshaalee hedduu irratti raabsuu yoo diskiin kufe deetaa karaa kuusaa
dabalataa meeshaalee hedduu keessatti eeguu fi sirna baay’inaan raabsame keessatti daataa
fayyadamaatti dhihoo ta’ee akka argamu gochuudha. Sirni kuusaa raabsame baay’inaan gosa
afur qaba. Isaanis, Server Attached Redundant Array of Independent Disks (RAID), RAID
giddugaleessaa, Kuusaa Network Attached (NAS) fi Neetwork Naannoo Kuusaa (SAN) ni
argamu. NAS fi SAN tooftaalee kuusaa raabsaman afran keessaa baay’ee beekamoodha.
Fakkiin armaan gadii qophii idilee sirna kuusaa raabsame agarsiisa.
Fakkii - Sirna kuusaa raabsame
NAS fi SAN tooftaalee meeshaalee gidduutti daataa dabarsuudhaaf fudhataman fi raawwii hojii
garaagarummaa kanaan kan ka’e garaagarummaa xiqqaa qabu. NAS irra caalaa pirootokoolii
TCP/IP fayyadamuun deetaa meeshaalee hedduu irratti dabarsuu yoo ta'u SAN ammoo SCSI
setup chaanaalii faayibaraa irratti fayyadama. Kanarraa ka’uun NAS networkii fiizikaalaa
TCP/IP deeggaru kamiyyuu kan akka Ethernet, FDDI, ykn ATM irratti hojiirra oolchuun ni
danda’ama. Garuu SAN hojiirra oolchuun kan danda'amu fiber channel qofa. TCPn overhead
ol'aanaa fi SCSI network TCP/IP caalaa saffisaa waan qabuuf SAN NAS waliin wal bira
qabamee yoo ilaalamu ga'umsa fooyya'aa qaba.
• Sirna Kuusaa Deetaa Raabsame
20
Distributed database system is a collection of independent database systems distributed across multiple
computers that collaboratively store data in such a manner that a user can access data from anywhere as
if it has been stored locally irrespective of where the data is actually stored. Below figure shows an
arrangement of distributed database system across multiple network sites.
Figure - Distributed Database system
• Sirna Kuusaa Raabsame
Guddinni saffisaan heddummina kuusaa, baandii fi qabeenya shallaggii baasii meeshaalee
kuusaa hir’achuu waliin ta’uun jaalala sirna kuusaa raabsame boba’aa ta’eera. Kaayyoon inni
guddaan kuusaa meeshaalee hedduu irratti raabsuu yoo diskiin kufe deetaa karaa kuusaa
dabalataa meeshaalee hedduu keessatti eeguu fi sirna baay’inaan raabsame keessatti daataa
fayyadamaatti dhihoo ta’ee akka argamu gochuudha. Sirni kuusaa raabsame baay’inaan gosa
afur qaba. Isaanis, Server Attached Redundant Array of Independent Disks (RAID), RAID
giddugaleessaa, Kuusaa Network Attached (NAS) fi Neetwork Naannoo Kuusaa (SAN) ni
argamu. NAS fi SAN tooftaalee kuusaa raabsaman afran keessaa baay’ee beekamoodha.
Fakkiin armaan gadii qophii idilee sirna kuusaa raabsame agarsiisa.
Fakkii - Sirna kuusaa raabsame
NAS fi SAN tooftaalee meeshaalee gidduutti daataa dabarsuudhaaf fudhataman fi raawwii hojii
garaagarummaa kanaan kan ka’e garaagarummaa xiqqaa qabu. NAS irra caalaa pirootokoolii
TCP/IP fayyadamuun deetaa meeshaalee hedduu irratti dabarsuu yoo ta'u SAN ammoo SCSI
setup chaanaalii faayibaraa irratti fayyadama. Kanarraa ka’uun NAS networkii fiizikaalaa
TCP/IP deeggaru kamiyyuu kan akka Ethernet, FDDI, ykn ATM irratti hojiirra oolchuun ni
danda’ama. Garuu SAN hojiirra oolchuun kan danda'amu fiber channel qofa. TCPn overhead
ol'aanaa fi SCSI network TCP/IP caalaa saffisaa waan qabuuf SAN NAS waliin wal bira
qabamee yoo ilaalamu ga'umsa fooyya'aa qaba.
• Sirna Kuusaa Deetaa Raabsame
20
Sirni kuusdeetaa raabsame walitti qabama sirnoota kuusaa deetaa of danda’anii kompitara
hedduu irratti raabsamanii fi walta’iinsaan deetaa haala fayyadamaan tokko bakka deetaan sun
qabatamaan kuufame osoo hin ilaalin bakka kamirraayyuu akka waan naannootti kuufameetti
argachuu danda’uun kuusudha. Fakkiin armaan gadii qophii sirna kuusdeetaa raabsame
marsariitiiwwan neetworkii hedduu irratti agarsiisa.
Fakkii - Sirna Kuusaa Deetaa Raabsame
Challenges:
The construction of distributed systems produces many challenges:
Heterogeneity: They must be constructed from a variety of different networks, operating systems,
computer hardware and programming languages. The Internet communication protocols mask the
difference in networks, and middleware can deal with the other differences. Heterogeneity (that is,
variety and difference) applies to all of the following:
• Networks;
• Computer Hardware;
• Operating Systems;
• Programming Languages;
• Implementations by different developers
Openness: Distributed systems should be extensible – the first step is to publish the interfaces of the
components, but the integration of components written by different programmers is a real challenge.
Security: Encryption can be used to provide adequate protection of shared resources and to keep
sensitive information secret when it is transmitted in messages over a network. Denial of service attacks
are still a problem.
Scalability: A distributed system is scalable if the cost of adding a user is a constant amount in terms of
the resources that must be added. The algorithms used to access shared data should avoid performance
bottlenecks and data should be structured hierarchically to get the best access times. Frequently
accessed data can be replicated.
Failure handling: Any process, computer or network may fail independently of the others. Therefore
each component needs to be aware of the possible ways in which the components it depends on may
fail and be designed to deal with each of those failures appropriately.
Concurrency: The presence of multiple users in a distributed system is a source of concurrent requests
to its resources. Each resource must be designed to be safe in a concurrent environment.
21
hedduu irratti raabsamanii fi walta’iinsaan deetaa haala fayyadamaan tokko bakka deetaan sun
qabatamaan kuufame osoo hin ilaalin bakka kamirraayyuu akka waan naannootti kuufameetti
argachuu danda’uun kuusudha. Fakkiin armaan gadii qophii sirna kuusdeetaa raabsame
marsariitiiwwan neetworkii hedduu irratti agarsiisa.
Fakkii - Sirna Kuusaa Deetaa Raabsame
Challenges:
The construction of distributed systems produces many challenges:
Heterogeneity: They must be constructed from a variety of different networks, operating systems,
computer hardware and programming languages. The Internet communication protocols mask the
difference in networks, and middleware can deal with the other differences. Heterogeneity (that is,
variety and difference) applies to all of the following:
• Networks;
• Computer Hardware;
• Operating Systems;
• Programming Languages;
• Implementations by different developers
Openness: Distributed systems should be extensible – the first step is to publish the interfaces of the
components, but the integration of components written by different programmers is a real challenge.
Security: Encryption can be used to provide adequate protection of shared resources and to keep
sensitive information secret when it is transmitted in messages over a network. Denial of service attacks
are still a problem.
Scalability: A distributed system is scalable if the cost of adding a user is a constant amount in terms of
the resources that must be added. The algorithms used to access shared data should avoid performance
bottlenecks and data should be structured hierarchically to get the best access times. Frequently
accessed data can be replicated.
Failure handling: Any process, computer or network may fail independently of the others. Therefore
each component needs to be aware of the possible ways in which the components it depends on may
fail and be designed to deal with each of those failures appropriately.
Concurrency: The presence of multiple users in a distributed system is a source of concurrent requests
to its resources. Each resource must be designed to be safe in a concurrent environment.
21
Transparency: The aim is to make certain aspects of distribution invisible to the application
programmer so that they need only be concerned with the design of their particular application. For
example, they need not be concerned with its location or the details of how its operations are accessed
by other components, or whether it will be replicated or migrated. Even failures of networks and
processes can be presented to application programmers in the form of exceptions – but they must be
handled.
Quality of service: It is not sufficient to provide access to services in distributed systems. In particular,
it is also important to provide guarantees regarding the qualities associated with such service access.
Examples of such qualities include parameters related to performance, security and reliability.
****THE END****
Qormaata: 1.1.
Ijaarsi sirna raabsame qormaata hedduu fida:
Heterogeneity: Isaanis networkii adda addaa, sirna hojii, haardwaara kompiitaraa fi afaanota
sagantaa adda addaa irraa ijaaramuu qabu. Pirootokooliin qunnamtii interneetii
garaagarummaa networkii kan haguugu yoo ta'u, middleware garaagarummaa biroo furuu
danda'a. Heterogeneity (jechuunis, adda addaa fi garaagarummaa) kanneen armaan gadii hunda
irratti raawwatiinsa qaba:
• Neetworkota;
• Hardware Kompiitaraa;
• Sirna Hojii;
• Afaanota Sagantaa;
• Hojiirra oolmaa misoomsitoota adda addaatiin
Banummaa: Sirnoonni raabsaman babal’achuu qabu – tarkaanfiin jalqabaa walqunnamsiistota
qaamolee maxxansuudha, garuu walitti makamuun qaamolee sagantaa adda addaatiin
barreeffaman qormaata dhugaa dha.
Nageenya: Icciitii qabeenya qooddatameef eegumsa gahaa kennuu fi odeeffannoon miira namaa
kakaasu yeroo ergaawwan karaa neetworkiin darbu dhoksaa ta’eef fayyadamuu ni danda’ama.
Haleellaan tajaajila dhorkuu ammallee rakkoodha.
Madaallii: Sirni raabsame kan guddachuu danda’u yoo baasii fayyadamaa dabaluu qabeenya
dabalamuu qabuun hamma dhaabbataa ta’edha. Algoritmoonni daataa qoodame argachuuf itti
fayyadaman rakkoo raawwii hojii irraa fagaachuu fi yeroo qaqqabummaa gaarii argachuuf
daataa sadarkaa sadarkaan caaseffamuu qaba. Daataan yeroo baayyee argamu fakkeessuun ni
danda’ama.
Kufaatii qabachuu: Adeemsi, kompiitara ykn neetworkiin kamiyyuu kanneen biroo irraa walaba
ta’ee kufaa ta’uu danda’a. Kanaafuu tokkoon tokkoon qaamaa karaalee qaamoleen inni irratti
hirkate itti kufaa ta’uu danda’an beekuu fi tokkoon tokkoon kufaatii sana haala sirrii ta’een
akka ilaaluuf qophaa’uu qaba.
Walfakkaachuu: Sirna raabsame keessatti fayyadamtoonni hedduun jiraachuun isaanii madda
gaaffii walfaana qabeenya isaati. Qabeenyi tokkoon tokkoon isaa naannoo walfakkaatu keessatti
nageenya akka qabaatutti qophaa’uu qaba.
22
programmer so that they need only be concerned with the design of their particular application. For
example, they need not be concerned with its location or the details of how its operations are accessed
by other components, or whether it will be replicated or migrated. Even failures of networks and
processes can be presented to application programmers in the form of exceptions – but they must be
handled.
Quality of service: It is not sufficient to provide access to services in distributed systems. In particular,
it is also important to provide guarantees regarding the qualities associated with such service access.
Examples of such qualities include parameters related to performance, security and reliability.
****THE END****
Qormaata: 1.1.
Ijaarsi sirna raabsame qormaata hedduu fida:
Heterogeneity: Isaanis networkii adda addaa, sirna hojii, haardwaara kompiitaraa fi afaanota
sagantaa adda addaa irraa ijaaramuu qabu. Pirootokooliin qunnamtii interneetii
garaagarummaa networkii kan haguugu yoo ta'u, middleware garaagarummaa biroo furuu
danda'a. Heterogeneity (jechuunis, adda addaa fi garaagarummaa) kanneen armaan gadii hunda
irratti raawwatiinsa qaba:
• Neetworkota;
• Hardware Kompiitaraa;
• Sirna Hojii;
• Afaanota Sagantaa;
• Hojiirra oolmaa misoomsitoota adda addaatiin
Banummaa: Sirnoonni raabsaman babal’achuu qabu – tarkaanfiin jalqabaa walqunnamsiistota
qaamolee maxxansuudha, garuu walitti makamuun qaamolee sagantaa adda addaatiin
barreeffaman qormaata dhugaa dha.
Nageenya: Icciitii qabeenya qooddatameef eegumsa gahaa kennuu fi odeeffannoon miira namaa
kakaasu yeroo ergaawwan karaa neetworkiin darbu dhoksaa ta’eef fayyadamuu ni danda’ama.
Haleellaan tajaajila dhorkuu ammallee rakkoodha.
Madaallii: Sirni raabsame kan guddachuu danda’u yoo baasii fayyadamaa dabaluu qabeenya
dabalamuu qabuun hamma dhaabbataa ta’edha. Algoritmoonni daataa qoodame argachuuf itti
fayyadaman rakkoo raawwii hojii irraa fagaachuu fi yeroo qaqqabummaa gaarii argachuuf
daataa sadarkaa sadarkaan caaseffamuu qaba. Daataan yeroo baayyee argamu fakkeessuun ni
danda’ama.
Kufaatii qabachuu: Adeemsi, kompiitara ykn neetworkiin kamiyyuu kanneen biroo irraa walaba
ta’ee kufaa ta’uu danda’a. Kanaafuu tokkoon tokkoon qaamaa karaalee qaamoleen inni irratti
hirkate itti kufaa ta’uu danda’an beekuu fi tokkoon tokkoon kufaatii sana haala sirrii ta’een
akka ilaaluuf qophaa’uu qaba.
Walfakkaachuu: Sirna raabsame keessatti fayyadamtoonni hedduun jiraachuun isaanii madda
gaaffii walfaana qabeenya isaati. Qabeenyi tokkoon tokkoon isaa naannoo walfakkaatu keessatti
nageenya akka qabaatutti qophaa’uu qaba.
22
Iftoomina: Kaayyoon isaas, dizaayinii application addaa isaanii qofa akka isaan ilaallatu
gochuuf, gama raabsaa murtaa’e sagantaa application’f akka hin mul’anne gochuudha.
Fakkeenyaaf, bakka inni itti argamu ykn bal'ina akkaataa hojiiwwan isaa qaamolee birootiin itti
dhaqqabaman, ykn akka fakkaachuu ykn godaanuu fi dhiisuu isaa ilaalchisee yaaddoo
qabaachuu hin qaban. Kufaatiin neetworkii fi adeemsa illee bifa ala ta’een sagantaalee
application’f dhiyaachuu danda’a – garuu qabamuu qabu.
Qulqullina tajaajilaa: Sirna raabsame keessatti tajaajila argachuun gahaa miti. Keessattuu,
amaloota qaqqabummaa tajaajila akkasii waliin walqabatan ilaalchisee wabii kennuunis
barbaachisaa dha. Fakkeenyonni amaloota akkasii paaraameetota raawwii hojii, nageenyaafi
amanamummaa wajjin walqabatan kan dabalatudha.
****DHUMARRAA****
23
gochuuf, gama raabsaa murtaa’e sagantaa application’f akka hin mul’anne gochuudha.
Fakkeenyaaf, bakka inni itti argamu ykn bal'ina akkaataa hojiiwwan isaa qaamolee birootiin itti
dhaqqabaman, ykn akka fakkaachuu ykn godaanuu fi dhiisuu isaa ilaalchisee yaaddoo
qabaachuu hin qaban. Kufaatiin neetworkii fi adeemsa illee bifa ala ta’een sagantaalee
application’f dhiyaachuu danda’a – garuu qabamuu qabu.
Qulqullina tajaajilaa: Sirna raabsame keessatti tajaajila argachuun gahaa miti. Keessattuu,
amaloota qaqqabummaa tajaajila akkasii waliin walqabatan ilaalchisee wabii kennuunis
barbaachisaa dha. Fakkeenyonni amaloota akkasii paaraameetota raawwii hojii, nageenyaafi
amanamummaa wajjin walqabatan kan dabalatudha.
****DHUMARRAA****
23
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