Globule: A collaborative Globule: A collaborative Content Delivery - - PDF document

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Globule: A collaborative Globule: A collaborative Content Delivery Network Content Delivery Network

Guillaume Pierre Maarten van Steen

Presented By: Marwa K. Elteir

Outline Outline

Introduction Introduction Related work Related work Collaborative Content Delivery Network Collaborative Content Delivery Network

• Requirements

Requirements

• Model

Model

• Content Distribution

Content Distribution

• Management

Management

Handling dynamic content Handling dynamic content Comments Comments

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Introduction Introduction

For a user or an organization to be able to For a user or an organization to be able to publish a web site publish a web site, they either do that , they either do that through paying a monthly fees to a hosting through paying a monthly fees to a hosting servers or deploying their own servers. servers or deploying their own servers. Problems appear when the web sites Problems appear when the web sites

• wners requires some sort of guarantees
• wners requires some sort of guarantees

about the about the availability availability and and performance performance of

• f

their web sites. their web sites.

Introduction Introduction

One solution is to use a One solution is to use a commercial commercial Content Delivery Network Content Delivery Network (CDN) which (CDN) which provides resources to be allocated provides resources to be allocated dynamically to serve certain web sites. dynamically to serve certain web sites. Another solution is to build a Another solution is to build a personal personal CDN CDN composed of the resources available composed of the resources available locally in the user's side. locally in the user's side.

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Introduction Introduction

The work of this paper extends the idea of The work of this paper extends the idea of personal CDN into what is called personal CDN into what is called Collaborative CDN (CCDN). Collaborative CDN (CCDN). In CCDN, an overlay network of end In CCDN, an overlay network of end-

• user

user machines cooperate through a wide area machines cooperate through a wide area network in a peer network in a peer-

• to

to-

• peer fashion

peer fashion. . They provide some of their resources and They provide some of their resources and in return be able to replicate their web in return be able to replicate their web content across the CCDN which guarantee content across the CCDN which guarantee the required performance. the required performance.

Related Work Related Work

Kazaa and BitTorrent Coral- CoDeeN

Replicas Reasonable performance No efficient replica placement scheme No efficient handle for dynamic content

ACDN

Dynamic content Assume no data modification

DotSlash

Dynamic content Assume the database is not bottleneck

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CCDN Requirements CCDN Requirements

Transparency to the clients. Transparency to the clients. Automatic redirection to the target replica. Automatic redirection to the target replica. Network proximity between clients and Network proximity between clients and their replicas should by used as a factor to their replicas should by used as a factor to distribute the distribute the replicas. replicas. Consistency management. Consistency management.

CCDN Model CCDN Model

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CCDN Content Distribution(1/6) CCDN Content Distribution(1/6)

Measuring proximity Measuring proximity The locations of replicas are determined The locations of replicas are determined based on their proximity to the clients. based on their proximity to the clients. They chose They chose internode internode latency latency as their as their proximity measure. proximity measure. This measure is also used to redirect the This measure is also used to redirect the client to the most appropriate replica. client to the most appropriate replica.

CCDN Content Distribution(2/6) CCDN Content Distribution(2/6)

Measuring proximity Measuring proximity Estimating the distance between every Estimating the distance between every client machine to the replica servers is client machine to the replica servers is impossible. impossible. An alternative is to assume that the nodes An alternative is to assume that the nodes are placed in M are placed in M-

• dimensional geometry

dimensional geometry

• space. (M =6)
• space. (M =6)

The coordinates of a node X is calculated The coordinates of a node X is calculated based on the latency between this node based on the latency between this node and m and m landmark landmark nodes nodes

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CCDN Content Distribution(3/6) CCDN Content Distribution(3/6)

Measuring proximity Measuring proximity 90 % of the latency estimation fall in the interval [2/3 L, 3/2L], where L is the actual latency between two nodes.

CCDN Content Distribution(4/6) CCDN Content Distribution(4/6)

Replica Placement Replica Placement

The clients are localized. (Dynamic process?) The clients are localized. (Dynamic process?) The M The M-

• dimensional space is partitioned into cells

dimensional space is partitioned into cells

• f equal size.
• f equal size.

Each cell is ranked according to the number of Each cell is ranked according to the number of clients located in this cell. clients located in this cell. Put the replica servers in the k highest ranked Put the replica servers in the k highest ranked cells. cells. The results of this algorithm is near optimal. In The results of this algorithm is near optimal. In addition, its computational complexity is lower addition, its computational complexity is lower than the optimal alternative. than the optimal alternative.

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CCDN Content Distribution(5/6) CCDN Content Distribution(5/6)

Client Redirection Client Redirection

HTTP based redirection HTTP based redirection

• Per

Per-

• page basis decision

page basis decision

• No transparency .. URL is returned

No transparency .. URL is returned

DNS based redirection DNS based redirection

• Per

Per-

• site basis decision

site basis decision

• Transparent .. IP is returned

Transparent .. IP is returned

Another redirection policy can be used other Another redirection policy can be used other than the estimated latency like for example the than the estimated latency like for example the average load average load in each replica server. in each replica server.

CCDN Content Distribution(6/6) CCDN Content Distribution(6/6)

Content availability Content availability

Redirector availability Redirector availability: DNS protocol allows : DNS protocol allows multiple redundant servers to be registered for multiple redundant servers to be registered for the same name. the same name. Replica server availability Replica server availability: Redirector server : Redirector server should periodically check the availability of should periodically check the availability of replica servers. replica servers. Fresh copy availability Fresh copy availability: Every replica server : Every replica server should be able to contact the origin server or the should be able to contact the origin server or the backup server to retrieve the up backup server to retrieve the up-

• to

to-

• date

date documents. documents.

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CCDN Management CCDN Management

Security Security

• Malicious content .. Sandboxing technique

Malicious content .. Sandboxing technique

• Malicious replica server .. Client solution or

Malicious replica server .. Client solution or Origin server solution Origin server solution

Brokerage Brokerage

• Allows any server to perform automatic

Allows any server to perform automatic resource discovery and allocation. resource discovery and allocation.

• Important especially during the registration

Important especially during the registration process. process.

Supporting Web Applications (1/2) Supporting Web Applications (1/2)

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Supporting Web Applications (2/2) Supporting Web Applications (2/2)

Comments Comments

The main idea is based on deploying a peer The main idea is based on deploying a peer-

• to

to-

• peer overlay network. It is adopted a lot as a

peer overlay network. It is adopted a lot as a solution to several problems in distributed solution to several problems in distributed systems arena. systems arena. How they handle the dynamic nature of the web How they handle the dynamic nature of the web clients and replicas? clients and replicas? How the assignments of the different servers to How the assignments of the different servers to the participating nodes are achieved? the participating nodes are achieved? Performance evaluation Performance evaluation

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Thank you Thank you