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The document proposes a technique called CrossTalk to interconnect IM networks through bypass gateways. This avoids the scalability issues of standard gateways and prevents vendor lock-in for users. The approach was implemented in a prototype using unmodified IM clients that connects to bypass gateways. Evaluation shows the gateways can support a large enterprise workload and introduces minimal latency. Future work is discussed to handle encryption and develop a more generalized architecture.
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- 1. CrossTalk: Scalably Interconnecting IM Networks Marti Motoyama George Varghese UC San Diego
- 2. Problem Growth of social sites relying onnetwork effect Consequences of the network effect: Quality does not necessarily drive adoption Popularity within social circles matters most Users subject to vendor lock-in for social apps? Mechanisms to mitigate vendor lock-inin social apps
- 3. Introduction/Motivation Case Study: IM Networks Simple social application, provides insight Scalably interconnects IM networks while allowing users to continue utilizing the client of their choice Benefits: Allows users to switch to new innovative clients Permits smaller IM networks to interoperate with larger IM services May rekindle interest in 3rd party applications by allowing inter-IM network message exchanges Examples include Chat Translator, Twitter Synch, etc
- 4. Outline Existing Approaches New Idea: Bypass Gateways Implementation Evaluation Future Work: Encryption General Architecture
- 5. Approach 1: Ignore Problem AIM Server Yahoo Server AIM Yahoo hello hello Alice Dan Claire Bob o Cannot communicate across boundaries
- 6. Approach 2: Client Consolidation AIM Server Yahoo Server AIM Yahoo Reverse engineered protocols, features lost hello in translation Alice Dan/Dizzle Claire Bob o Main problem: Feature Subtraction o Multiple identities
- 7. Client Consolidation Limitations Feature subtraction Never worked for ..unable to use transfer me either files using Trillian Multiple Identities Software/Network Overhead 13.7 MB vs 1.3 MB
- 8. Approach 3: Standard Gateway AIM Server Alice and Yahoo Server Gateway 1 MUST be AIM buddies Yahoo hello Gateway 1 Gateway 2 hello Alice Bob o Main problem: Scalability o Server can easily detect/disable
- 9. Standard Gateway Limitations Gateways subject to user restrictions: Limits on buddy list size (e.g. < 512) Limits on concurrent sessions (e.g. 1 for Skype) Suppose IM network with 50 million users: If maximum size of buddy list 500: 100k Gateways to cover all users Need massive gateway replication to interconnect millions of users Thus, standard gateways do not scale Gateways employ awkward semantics: Ex: IM gtalk:user@domain.com hello
- 10. Outline Existing Approaches New Idea: Bypass Gateways Implementation Evaluation Future Work
- 11. Bypass Gateways Traffic flow through server causes scalability problems Gateway to Gateway Network AIM Server Yahoo Server AIM Yahoo Gateway 1 Gateway 2 Alice Bob
- 12. Bypass Gateways G2G Network AIM Yahoo AIM Server Yahoo Server Hello Gateway 1 Gateway 2 Hello Scalable and no feature subtraction (in base network) Hello oBut, both Alice must be behind gatewayBob ends
- 13. Outline Existing Approaches Our New Idea: Bypass Gateways Implementation Evaluation Future Work
- 14. Crosstalk Components Unmodified clients Each user must have the ability to specify a proxy Simple naming convention ex: AOL user alice identified as alice@aol Bypass gateways Interpose between clients and servers Gateway-to-Gateway network Logical network Gateways connected via DHT
- 15. CrossTalk Architecture 3 major functions: Translation between AIM, MSN, Yahoo, Jabber Bifurcating Presence Information Merging Buddy Information
- 16. Gateway Processing Steps For each user: 1. Identify protocol, wait for user to authenticate to base server 2. Update users state in DHT 3. Retrieve foreign buddy list from DHT 4. Repeatedly : pass-through or intercept & translate
- 17. Lessons Learned Can use protocol version numbers to allow time for reverse engineering Must merge protocol packets carefully Ex: AOL embeds sequence numbers in messages that must be modified to merge information Must scale to many TCP connections per user Ex: MSN creates per conversation TCP connection
- 18. Applications Built on CrossTalk Built 2 example applications: IP geolocation Last.fm information Suppose AOL user A wants to know Yahoo user Ys location or listening habits: User A types /music or /location as an IM User Ys client responds with Shakira or San Diego Works because bypass gateways allows IMs to reach other networks
- 19. Outline Existing Approaches New Idea: Bypass Gateways Implementation Evaluation Future Work
- 20. Evaluation Questions Two metrics 1. Latency: How much delay for translation? Baseline delays vary from 5msec 230msec 2. Throughput: What size enterprise can a single Bypass Gateway support? Latency: < 25 msec Throughput: 1 desktop PC, greater than 4000 person workload
- 21. IM Traffic Model Guo et. al monitored MSN, AIM traffic in an enterprise network with > 4000 employees Heaviest load usage characteristics: ~130 online users per protocol ~20 concurrent conversations per user Message length of ~150 characters ~1 second interval between successive chat messages
- 22. Evaluation Methodology Modeled cross/same-to-same IM traffic using market shares Implemented mock IM servers to handle same-to-same traffic Spread clients/servers across local VMs Gateway run on P4 3.2 Ghz, 1Gb
- 23. Translation Latency Results Latency experienced by Yahoo receiver AIM JABBER MSN YAHOO SENDER PROTOCOL Max cross traffic latency < 25 msec
- 24. Outline Existing Approaches Our New Idea: Bypass Gateways Implementation Evaluation Future Work
- 25. Future Work: Handling Encryption G2G Network Skype SIP Gateway Box Skype Binary SIP Binary Gateway Shim Gateway Shim Skype UI bob dial: skype user SIP UI alice bob
- 26. Future Work: General Architecture Migrate to a new abstract client layer Ask for services using abstract calls Send IM, Dial Call, Get File Insulate users from changes in technology Protocol intelligence in the cloud Make use of bypass gateways or shim layers to achieve interconnectivity for unmodified clients Use a DHT to store mappings on behalf of all applications Enable service composition by modeling services as nodes in graph
- 27. Conclusion Introduced new technique (bypass gateways) that overcomes vendor lock-in and avoids scaling limits of standard gateways May foster third-party innovation Larger providers cannot easily hinder and smaller providers have incentives to join IM gateway prototype can support throughput for enterprise IM benchmark