Building Web Reputation Systems- P4

Building Web Reputation Systems- P4:Today’s Web is the product of over a billion hands and minds. Around the clock andaround the globe, people are pumping out contributions small and large: full-lengthfeatures on Vimeo, video shorts on YouTube, comments on Blogger, discussions onYahoo! Groups, and tagged-and-titled Del.icio.us bookmarks. User-generated contentand robust crowd participation have become the hallmarks of Web 2.0.
Nội dung trích xuất từ tài liệu:
Building Web Reputation Systems- P4Molecules: Constructing Reputation Models Using Messagesand ProcessesJust as molecules are often made up of many different atoms in various combinationsto produce materials with unique and valuable qualities, what makes reputation modelsso powerful is that they aggregate reputation statements from many sources and oftenstatements of different types. Instead of concerning ourselves with valence and Van derWaals forces, in reputation models we bind the atomic units—the reputationstatements—together with messages and processes.In the simple reputation model presented in Figure 2-3, messages are represented byarrows and flow in the direction indicated. The boxes are the processes and containdescriptions of the processes that interpret the activating message to update a reputa-tion statement and/or send one or more messages onto other processes. As inchemistry, the entire process is simultaneous; messages may come in at any time, andmultiple messages may take different paths through a complex reputation model at thesame time.People often become confused about the limited scope of reputation, and where todraw the lines between multiple reputations, so we need a couple of definitions:Reputation model A reputation model describes all of the reputation statements, events, and pro- cesses for a particular context. Usually a model focuses on a single type of reputable entity. Yahoo! Local, Travel, Movies, TV, etc. are all examples of ratings-and-reviews reputation models. eBay’s Seller Feedback model, in which users’ ratings of trans- actions are reflected in sellers’ profiles, is a karma reputation model. The example in Figure 2-3 is one of the simplest possible models and was inspired by the Digg it vote-to-promote reputation model (see Chapter 6) made popular by Digg.com.Reputation Context A reputation context is the relevant category for a specific reputation. By definition, the reputation’s reuse is limited to related contexts. A high ranking for a user of Yahoo! Chess doesn’t really tell you whether you should buy something from that user on eBay, but it might tell you something about how committed the user is to board gaming tournaments. See the sections “Reputation Takes Place Within a Context” on page 4 and “FICO: A Study in Global Reputation and Its Chal- lenges” on page 10 for a deeper consideration of the limiting effects of context.Messages and ProcessesAgain, look at the simplest reputation model diagram shown in Figure 2-3. The inputreputation statement appears on the left and is delivered as a message to the reputation26 | Chapter 2: A (Graphical) Grammar for ReputationFigure 2-3. Users endorse articles, and the sum of their votes is displayed by that article.process box. Messages and processes make up the working mechanics of the reputationmodel:Reputation message Reputation messages, represented by the flow lines in reputation model diagrams, are information supplied to a reputation process for some sort of computational action. In this example, the input is a reputation statement delivered as a message to the Raw Sum of Votes process. These messages may come from other processes, explicit user action, or external autonomous software. Don’t confuse the party sending the messages with the reputation source; they are usually unrelated. For example, even when the source of a reputation input is a user, the message usually comes from an application—allowing the reputation system to take different ac- tions based on the sender’s identity.Input event (reputation message) In this book, we call initial messages—those that start the execution flow of a reputation model—input events; we show them at the start of a model diagram. Input events are said to be transient when the reputation message does not need to be undone or referenced in the future. Transient input events are not stored. If, on the other hand, an event may need to be displayed or reversed in the future (e.g., if a user abuses the reputation model), it is said to be reversible and must be stored either in an external file such as a log or as a reputation statement. Most rating-and-review models have reversible inputs. But for very large-scale systems, such as IP address reputations that identify mail spammers, it’s too costly to store a separate input event for every email received. For those reputation models, the transient input method is appropriate.Reputation process The large boxes represent one or more reputation processes. Using the message parameters, these processes normalize, transform, store, decide how to route new messages, or, most often, calculate a value. Although this book describes several common process types, the logic in these processes is usually customized to the ...