Company Confidential 1 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials Towards a mobile...
-
date post
19-Dec-2015 -
Category
Documents
-
view
215 -
download
2
Transcript of Company Confidential 1 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials Towards a mobile...
1 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials
Company Confidential
Towards a mobile content delivery network with a P2P architectureCarlos Quiroz
2 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials
Company Confidential
Overview
• Analysis of P2P architecture for a mobile oriented content delivery system
• Open Questions• Is there value on using P2P instead of traditional techniques for large scale
delivery systems
• What characteristics of a delivery system for mobile devices make using P2P techniques appealing
• How to measure those benefits
• Hypothesis: A P2P architecture would enable certain scenarios involving mobile terminals not support by current architectures
3 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials
Company Confidential
Content Sharing and Delivery Service
• Content Delivery network for both mobile and web based clients
• Content is created mostly in the mobile nodes, e.g. pictures, movies, etc.
• Differences to traditional CDN• Clients are mobile and have unreliable
connections• Most of the content is produced at the
edges
• In normal operation content is uploaded automatically
• Service also acts a backup service
• Sharing (Content Delivery) is enable among users or to everybody
Storage systemMetadata DB
Web server
Web serverMobile server
Mobile server
Mobile server
4 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials
Company Confidential
Life cycle of a media item
• Objects are created in the device (e.g. picture)
• They are automatically uploaded to the service and a unique ID is generated
• On the service side they are stored and entries into a metadata DB are created
• Files made public or set as shared can be requested based on the ID (Security restrictions apply)
• What is the best way to store and distribute those files in a scalable way?
Storage systemMetadata DB
Web server
Web serverMobile server
Mobile server
Mobile server
5 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials
Company Confidential
Deferred uploading
• In some cases automatic uploading is not optimal• While roaming
• Low battery situations
• Very slow connections
• In those cases media is not uploaded completely:• Metadata is sent to the service (Searches are enabled)
• Possible a low-resolution object is uploaded
• But we still want to allow for publication
6 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials
Company Confidential
Content Delivery Networks
• Classical client-server architecture (Normally in the form of large clusters)
• Storage in the form of Storage Area Networks (SAN) or distributed file systems
• Content Delivery Networks:• Complement client-servers for the delivery of static content• They are composed of several large clusters distributed globally• Each cluster has its own replica stored locally
• Peer-to-peer CDNs• Unstructured networks (Gnutella, BitTorrent) are not adequate for
interactive operation• But, research structured delivery networks are available
• Most of them are DHT based• Not yet proven as better alternative than existing system
7 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials
Company Confidential
Supporting storage systems
• SANs• Well known and robust
• Expensive to buy and operate
• Distributed file systems (Google FS)• Cheaper
• Robustness given by software
• Both are easy to use from the point of view of applications
• P2P file systems (PAST, Ivy)• Require a structured network for reliably locating files
• Keeping the structure is expensive, especially for mobile devices
8 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials
Company Confidential
Architectures
SAN
Metadata DB
Metadata DB
Architecture with centralized storage Architecture with P2P storage
9 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials
Company Confidential
Issues on current architectures
• Centralized file systems cannot easily deliver content still in the mobile devices
• Solutions through e.g. mobile web servers are possible
• Structured P2P networks create overhead on keeping the structure
• Direct P2P delivery is not feasible for web based interactive applications
10 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials
Company Confidential
Proposal for a hybrid architecture
• Delivery and queries to/from web based clients are done in the traditional way
• Use a P2P storage system based on DHT (Like Chord or PAST)• Each node has a set of items stored locally and it knows its IDs
• Make the devices part of the P2P storage system• Allows to access item still in the phone
• This is only used if needed
• The set of IDs in a node are augment with those of the devices connected to
• Metadata is still kept centrally to enable queries and use when the device is out of range
11 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials
Company Confidential
High-level view
Metadata DB
Query
Item found inthe cluster
Item found inthe device
ObjectID
Retrieve Object
Chord style network
12 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials
Company Confidential
Open issues
• Validate the concept through simulation and/or implementation
• Are existing DHT-based routing protocols enough to make this workable
• Creations of metrics to compare different systems
• Security is an issue since mobile clients become part of the storage system
• Is it worth the effort? Are there other subsidiary benefits
13 © 2005 Nokia V1-Filename.ppt / yyyy-mm-dd / Initials
Company Confidential
Q&A