The Horizontal Internet CS241, Internet Services © 1999-2001 Armando Fox [email protected] Outline The horizontal Internet Internet service composition (intro) Implications for software structure (intro) A few words about the Project Early Internet Services: “Vertical” TWA reservations, CIRRUS banking network Proprietary, closed systems (Tandem NonStop hardware) America Online (pre-Web) PC and Mac proprietary client S/W Proprietary mainframe-based back end Modem banks connect directly to terminal concentrators Early WWW Portals: “Diagonal” Commodity protocols & software... HTTP, TCP/IP, SSL, off-the-shelf client (Navigator, MSIE) Farms of off-the-shelf servers …augmented with proprietary “secret sauce” Web-based email (Hotmail, Yahoo, …) Industrial-scale homebuilt email servers (EarthLink) Search engine portals (AltaVista, Infoseek, Lycos...) Customizable news (My Yahoo, Netcenter…) AOL is now a Web portal + world’s largest ISP Portal Evolution (1) All operations at server site Infrastructure vendor (e.g. Cisco) sells directly to destination sites (e.g. Yahoo.com) Client requests go to destination site operations center PortalCo InfraCo Content Advertisements Search User profiles Mobile-friendly pages Portal Evolution (2) Operations migrate to “server farms” (e.g. Exodus) Infrastructure vendors sell primarily to IDC’s All client traffic and peering handled via IDC Peering relationships between IDC’s (not operators) Data Center PortalCo InfraCo Data Center InfraCo Content Advertisements Search User profiles Mobile-friendly pages Data Center Administration, site updates InfraCo Portal Evolution (3) Services migrate to hosted application providers Typically paid per use or similar metering Client doesn’t visit arms merchants directly (still sees portal’s brand) Some portal Data services outsourced Center to “arms merchants” PortalCo InfraCo AdTarget Co Data Center Data Center InfraCo InfraCo Content User profiles Mobile-friendly pages SearchCo Portal Evolution (4) “Arms merchants” provide individual services to destination sites/brands Inktomi Traffic Server, Cisco Hosted Apps Initiative, others DevelopmentData platform for various Center services PortalCo InfraCo Data Center AdTarget Co Data Center AppDevCo InfraCo InfraCo Content User profiles Mobile-friendly pages SearchCo AppDevCo The Arms Merchants Model What Hosted Service Search Email Calendar Cache/mirror Shop Ads Thin access “Sensitive” info Notify on update Email CRM Inktomi CriticalPath When.com (AOL acq) Sandpiper/Inktomi Inktomi DoubleClick ProxiNet (Puma acq) VerticalOne NetMind (Puma acq) General Interactive Sell Iron (or S/W) Excite, Infoseek Software.com, NetApp Netscape Server Network Appliance, Cisco NetGravity Unwired Planet ?? ?? ?? The Food Chain Who’s at each level? Aggregators/Brands Value-Added Svcs Arms Arms Infrastructure Physical Plant Infrastructure Vendor Advantages of Large Hosted Services Amortization of infrastructure costs (at IDC’s) Physical plant, physical security & human monitoring Network connectivity Scale of 100’s of nodes requires serious infrastructure Large scale can increase service sophistication Inktomi search DB over 2x competitors’ Doubleclick ad selection uses large DB, cross-site history, compute-intensive selection algorithm Tracking usage/buying/etc. patterns of specific user populations (mobile users, leisure travelers, etc.) Direct-to-consumer wholesale-style e-commerce (Paul Allen, Mercata) aggregates buying power of many individuals Disadvantages... “In a society where knowledge is power, centralized knowledge is centralized power” --Richard Sobel, HLS Fellow, Berkman Center for Internet & Society Do you want your user profile, portfolio balances, etc. stored at one place or many? (VerticalOne) Business model highly dependent on partners Billing models being adopted slowly (pay per use, subscription, …) Shift of responsibility: HSP may have operations responsibility (wearing a pager vs. not) Other Arms To Be Marketed? Geographic/location services: maps, directions, POI’s Today: MapQuest, MapBlast, Yahoo Maps... Tomorrow: “Powered by” Extension to other platforms Today: Yahoo to your pager, Fidelity Instant Broker, … Tomorrow: “Powered by” User profiles Others Directories (yellow/white pages, mail/news, encyclopediae) Highly customized news feeds Toward Service Composition Services from building blocks Can think of a particular destination Web site as providing one or more autonomous “building block” MapQuest: given a pair of addresses, return directions and map Amazon: given keywords, return listing and price info for matching books IMDB: given movie title or other keywords, return movie reviews and production info Can we create new Internet services simply by composing these, without writing (much) new code? Programming Via Service Composition Remote invocation of several services in real time Example: “Find the most highly reviewed James Bond movie and locate the best price for it” Observations Typically services aren’t designed to be composed, and may have do quite different tasks “Compositor” only does remote invocation--not mobile code Potential for good fault isolation Potential for high availability through redundancy Can compose “meta-services” into higher-level ones management/heterogeneity issues in dealing with a collection of autonomous services Why Compose Web Services? Highly available building blocks We’ve learned to make heavily-used destination sites H/A Autonomous services Fault isolation through loose coupling “Self-sufficient” We don’t own or control them--so no control over their interfaces--but... Universally deployed open protocols Self-describing services No compile or link step needed for client (no issue of stale interface stubs) No mobile code: just “submit-and-scrape” invocation Related Work XML-RPC SOAP Idea: provide structural, programmatic-like interfaces to Web services Today: “fake” RPC using HTTP and HTML What aspects of it are “fake”? Composition Using Strong Types How do you know when it’s “safe” to compose A and B? Output semantics of A match input semantics of B Example: A maps keywords to movie titles and reviews; B maps movie titles to prices at online vendors The main problem is semantic mapping of arguments In most systems to date, this requires human level knowledge If system is purpose-built for composition, semantic mapping can be explicitly coded into service interfaces Otherwise, we can “wrap” each service with a shell that codes semantic mapping of that service Example: IMDB and Netflix A non-earth-shaking example... Consider services M and N M is IMDB: movie title --> critics’ reviews ranked by rating N is Netflix: movie title --> vendors ranked by price Example composition: (M,N) is “Identify highest-reviewed James Bond film, and find the best price” Common mundane problem… M’s movie title includes a year: Tomorrow Never Dies (1998) N’s doesn’t…must munge M’s movie title to feed to N Problem: where to capture this transformation? Composition and Appliance Computing How can you exploit service composition for… A TiVo box? Digital photography? Portable MP3 players? Home-control applications? etc. It will be a feature for your project to leverage this Composition Challenges Economics How is billing done? (Subscription? Per-use? Transactionbased? Subsidy?) Is there incentive to provide user choice? Technical challenges Type system and semantics Runtime system and error handling You’ll hear more about these in future classes Internet Evolution Clients and servers (today) S S S C S C S C C S Internet Evolution Clients, servers, and caches (to reduce client latency and backhaul congestion) S S S C $ C $ S $ S C C S Internet Evolution Add proxies and service compositors to provide various kinds of intelligent information delivery S S S P C CS P $ C P $ S $ S C C S A few words about the project Appliance computing (1/24) & composition (2/12) We will provide software infrastructure for both of these You can build either an application or more infrastructure (with a “toy” app to demonstrate it) It is a feature to leverage existing Web services via composition We have a (limited) hardware and software budget General project process Pre-proposal (~1 page) posted on Web: 1/31 Revised proposal forms basis for project & discussions with Advisors starting 2/5 No other explicit checkpoint/design review till end of qtr Today’s Travel Photo: Where Am I?
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