Functionality, Challenges and Architecture of Social Networks

Transcription

1 Functionality, Challenges and Architecture of Social Networks INF 5370 Outline Social Network Services Functionality Business Model Current Architecture and Scalability Challenges Conclusion 1

2 Social Network Services Social Structure o made up of individuals that are connected by one or more specific types of relationships friendships common interests Social Network Services o focuses on building and reflecting social networks or social relations among people Which services should we call as "Social Network Services"? Allows users to create data Provides representation for o users o links between users Provides personalized services Allows users to form communities o long-term or short-termterm o explicit or implicit 2

3 Top Global Web Sites* * Feb 2011 What Are Social Networks Used For? Connecting with friends o Facebook Social news, bookmark o Delicious, reddit, digg Recommend o StumbleUpon, LinkedIn Broadcast o Twitter Data sharing o Youtube, Blogger, Flickr, LiveJournal Estimating trends o twitter, StumbleUpon, digg Forming communities o Facebook Collaborative Editing o Google Docs Streaming o Justin.tv, Skype Building Relationships o eharmony Search o StumbleUpon Virtual Reality o Online games, SecondLife 3

4 Outline Social Network Services Functionality Business Model Current Architecture and Scalability Challenges Conclusion Functionality Functional Requirement o "system shall do <requirement>" o drives application architecture of a system Non-functional Requirement o "system shall be <requirement>" o drives technical architecture of a system o e.g. availability, real-time guarantees 4

5 Functionality provided by OSNs Create and persist data o user profiles (facebook) o user interests explictly (facebook) based on tagging behavior (delicious) o blog (blogger) o bookmarks (delicious) o tweets (twitter) o participating i in discussionsi o data generated through collaboration document editing / sharing multi-player online games Functionality provided by OSNs... Establish links with other users o links may represent different relationships friendship (facebook) professional acquaintance (LinkedIn) o links can be of different directionality directional (twitter) bi-directional (facebook) o links may be valid for either short duration (participants in an online game), or long duration (friends in facebook) 5

6 Functionality provided by OSNs... Establish links with other users... o provides mechanism to discover interesting users manual search based on names, -ids (searching for friend) keywords (searching for an expert in area) automated suggestions for friends (facebook) people to follow (twitter) o creation of links may be explicit (twitter, facebook) implicit based on interests (StumbleUpon) Functionality provided by OSNs... Disseminate data between users o users receive updates within a reasonable amount of time about their social network or interests o if number of updates are more than a given threshold, it sorts the updates according to receiver's interest shows only threshold number of most interesting data examples also include real time information streams such as o examples also include real-time information streams such as Twitter timeline Facebook live feed LinkedIn activity feeds 6

7 Functionality provided by OSNs... Personalized recommendations o for bookmarks, photos, jobs, interests, search o e.g. for a potential job opportunity LinkedIn recommends people who can refer you for a job people on shortest-paths between the employer and the user Form communities o allows platform for collaboration on some niche topic Establishing expertise o allows much faster peer-review Functionality provided by OSNs... Provides indexing infrastructure based on behavior of large number of users o automates the "word-of-mouth" referral of peer-approved web sites o helps in finding highly relevant articles o helps in estimating global trends o real-time like behavior can also lead to faster discovery e.g. monitor twitter streams to detect flash crowd 7

8 Functionality provided by OSNs... Enforcing user's privacy settings o e.g. Why Twitter Engineers Hate The Replies Feature* Default "only see replies by people you follow to people you follow" 3% of users " see replies to people they don't follow" Caused performance degradation "Even though only 3% of all Twitter accounts ever changed this setting away from the default, it was causing a strain and impacting other parts of the system" o On the other hand data is owned by companies and they can sell it to others #@ * # Evolving Social Graphs 8

9 Evolving Social Graphs... User's social graphs evolves with time o to provide more personalized experience Users initially create social graphs Features provided by the OSNs help extend user's social graph into virtual social graph depending on o user's current interests and behavior o system receives a feedback from users and evolves the virtual social graph Outline Social Network Services Functionality Business Model Current Architecture and Scalability Challenges Conclusion 9

10 Business Model Sponsored advertisements (content ads) o e.g. twitter, LinkedIn, Facebook, Stumbleupon Subscriptions o provides extra features o e.g. flickr, skype, LinkedIn Promoted profiles, tweets, topics o e.g. LinkedIn, Facebook, digg, reddit, twitter Service provider for business transactions o allow users to buy photos from other user e.g. flickr o allow users to follow other user's streams by paying e.g. justin.tv Targeted Advertisements Uses knowledge of user's interest to deliver targeted advertising Estimate user's interest based on o tagging behavior o data-disseminated o likes / bookmarks o recommendations 10

11 Outline Social Network Services Functionality Business Model Current Architecture and Scalability Challenges Conclusion Scalability Challenges GoogleTalk Architecture Challenges o handling small low latency messages o messages must be delivered in-order o handling user presence indications dominate the design (non-linear growth) * ConnectedUsers x BuddyListSize x OnlineStateChanges What characterizes OSN services different from the traditional web-sites? Real-time Social Graphs * 11

12 "Real-time Social Graphs" Traditional web-sites o User's personalized page is based on person's data less amount of data needs to be fetched o Less number of users at the same time all data can be cached in memory Online Social Networking services o queries proportional to the number of friends compute results need to merged and ranked o data is active all the time users continuously create and update data o difficult to partition database because of high-degree of connectivity Architecture Pull on Demand o compute and fetch updates on a request o Issues harder to scale Facebook has a limit of 5,000 friends/user* * 12

13 Architecture... Push on Change o changes are pushed out to all the relevant users o changes (in some form) are stored with each user o issues duplication consistency permissions and security should permission be consulted when data is produced d or consumed? what if the data is deleted after it has already been copied around? Outline Social Network Services Functionality Business Model Current Architecture and Scalability Challenges Conclusion 13

14 Conclusion Social networks services provides personalized views Evolving social networks o users start with a manually constructed social graph o features provided my the OSNs help evolve the social graph Type of functionality supported by an OSN and its implementation ti architecture t can lead to scalability issues 14