Archive for January, 2009

Social Networks APIs

January 26th, 2009
Comments Off

Report on the presentation of Alban Galland, January 26th, 2009
See slides for more details.
Warning : this report outlines the understanding of the post author (Alban Galland) and nothing more.

Some existing APIs

There is different kind of APIs for Social Networks : micro-formats, ontologies, query interaction with social sites and application definition for social sites… These different kind of APIs give different level of details of how to represent a social graph and how to query it.


xfn (XHTML Friends networks) is a mirco-format which is use to tag the hyperlink with predefined friendship concepts. There are plenty of other micro-formats which are also linked to Social Networks. These micro-formats are easy to use and naturally distributed, but it is hard to have a global view of the network and to query it.


FOAF (Friend Of A Friend) is an ontology in RDF and OWL which describes a social network. It contains in particular a large number of way of identification. Because ontologies are hard to design, this one is still unstable. It is also hard to have a global view of the network and it could also lead to too much complexity in description. Nevertheless, some tools as Google Social Graph APIs add a layer to query both XFN and FOAF information on the web as a whole.

Interaction with social sites

Open Social is an example of APIs which allows application to interact with social sites. It is a package of three APIs (Javascript, REST and RPC). Using one of these APIs, a couple (viewer,application) can query a social site (container) about the social informations of a distinct user (owner). For example, the CoolApplication application could use my credential of logged user on Orkut to query it about some of my friends. The readable data are the profile of the users (corresponding to the Orkut profile) and their lists of friends. There are also some discovery capabilities of an unstructured table of data. This feature was probably designed for containers which are not owned by Google, but would like to use the API. That is, of course, the limit of the approach “one designs for himself and tries then to convince others”. The container can implement its own security policy to filter what is readable, but there is no way to specify such a policy and no clue about what should be the default policy. The application could also write two kinds of information : a log of activities and some persistent couples attribute-value. The FBJS, Rest-Like and Connect APIs of Facebook are designed with the same spirit.
These APIs allow some transfer of the data from social site to applications, which make the former more useful and the latter usable on more container. They are nevertheless designed in a centralized way (with a container) and privacy is largely under-specified.

Application specification

FBML is an example of application specification (or at least about rendering a user interface using embedded service calls to Facebook). The principle is relatively different of the interaction specification, since the evaluation of FBML is done by Facebook and the data are not transfered to the application server. FBML could access data using FQL or complex tags which are wrapping of FQL queries. FQL is an SQL-like language and the Facebook Social Network is described as table with indexability constraints which restrict the queries. This kind of APIs limits the expressiveness of the applications, but it protects more the privacy since it did not transfer any data to the applications.

Some clues about design of SN APIs

To summarize, a good API should be easy to use, distributed, easy to query as a whole and allow data transfer with privacy control.

Such APIs must rely on a model of social networks with :

  • People, which could be identified, authenticated and have a profile
  • Relationships, which could be of different type
  • Applications, which could be identified, authenticated, are described by a code and could write some part of the profile of a user.

They must also allow queries with right access. We believe that a good model of Social Network is a distributed knowledge base with right access. We are currently defining such a model.

News , , ,

Serge Abiteboul elected to the French Academy of Sciences.

January 16th, 2009
Comments Off

The Academy of Science of the Institut de France is a select group of French scholars joined by foreign scholars, all chosen from among the most eminent in their fields. Serge Abiteboul is one of eleven newly elected members.

The Academy of Science has various roles, from examining the standing worldwide of research carried out in France, to how research is organized and its interface with the public, seeking to ensure that scientific culture and the advancement of knowledge are accessible to everyone. It also plays an active part in the development of international relations between researchers and institutions, especially in Europe. Lastly, the Academy of Science, thanks to its multi-disciplinary approach and its interactions with other branches of knowledge, contributes, as part of the Institut de France, to the life and livelihood of science.


Incentives for Users of Social Software

January 14th, 2009
Comments Off

Report on the presentation of Panayotis Antoniadis, January 14th, 2009
See slides for more details.
Warning : this report outlines the understanding of the post author (Alban Galland) and nothing more.


The presentation was focused on how to understand and model users behavior in P2P systems. The design of incentive mechanisms must indeed take into account not only economics but also social behavior.

The social networks are directly connected to the notion of self organized communities. P2P systems are going more slowly social than centralized systems, because of legal reasons or because they are less open to participation (friend-to-friend networks control their access). Web-based communities are efficient but sometimes they already are using P2P for content distribution. Some may argue that this content distribution could be used to manage all the community and that the web-access layer is then useless. This layer also leads to privacy and censorship problems which encourage systems enabling independence. Other reason to use P2P systems may also come from applications using distribution features. Actually, benefit is still not totally obvious : web-based and P2P seem in fact complementary. For example, web-based systems could be used to meet people and P2P systems to interact with friends (in a private way).


There are two kinds of challenges :

  • Technical issues : content distribution, information integrity, different privacy/security issues. In general, identity matters in social system and some data should not be shared
  • Incentives issues : participation, resource sharing, trust

The presentation is focused on the latter one.

Example of Wireless Neighborhood communities

Hybrid on-line communities are both physical and virtual communities. The notion is connected to P2P systems and ad-hoc networks. They are used to provide Internet for everybody avoiding hotspots, but it is also fun to have a private network and it is a means to organize something in a neighborhood. There are already localized communities (lifeAt, i-neighbors,, Facebook neighborhoods, meetup…) These services usually allow users to exchange services and information with their neighborhood, but are web based (not physical). There are also grassroots communities of wireless networks (seattle wireless net, awmn). The idea is to bring both components together to create incentives.

About incentives

Economics vision : the users share resources through market or reciprocity (token, reputation…). The goal is to design markets such as when they reach equilibrium, users have the targeted behavior. Modeling the optimization process is possible knowing utility and cost. But there is a problem of information because utility and cost are usually unknown, even by the users themselves which are then hard to predict.

Social vision : Even without economic reasons, P2P systems are still working : people make efforts without direct economics incentives. Some reasons are spirit, value/cost ratio, self-efficacy, altruism or in general social incentives…

In general, incentives cover a wide range from extrinsic to intrinsic motivations : payments, reciprocity, long term benefit, popularity, status, self-image, sense of efficacy, community vision, interest, fun…

The economics vision could be difficult to apply on the resources layer. For example, FON let you share a bit of your wifi with other Foneros, based on global reciprocity. But there is a deep problem of symmetry of resources usage since fewer people will try to access wifi of people living in an isolated place. There is other models as the yellow chair project or the wifi-thank-you site where incentives are purely social. In general, incentives are not additive : the more you control (extrinsic incentives), the less people are self-motivated (intrinsic incentives).

An interesting idea is to use a cross-layer incentive : sharing low-level resources is rewarded at the level of the community and reciprocally the good members of the community get more low-level resources.

Application to social-software design

The key features of a social-software are

  • the general vision or promise
  • the community outcome
  • the personal image of the user
  • the local activity : the user must feel that somebody has seen her profil or interacts with her
  • what the user see about the rest of the world
  • the types of relations and interactions…

On-going work

After studying at the Computer Science Department of University of Crete and at the Department of Informatics of Athens University of Economics and Business, Panayotis is now a post-doc researcher at LIP6 Laboratory (University of Pierre and Marie Curie, Paris) working on the design of incentive mechanisms for network shared testbeds (like Planetlab) and virtual communities (on the Internet and wireless networks). Panayotis is collaborating with Benedicte Le Grand, Marcelo Dias De Amorim, Ileana Apostol and Tridib Banerjee. He is member of the wip project.

Updated 01/20/2009 thanks to P. Amtoniadis helpful comments

News , , ,

01/09/2009 : Webdam kickoff meeting

January 7th, 2009
Comments Off

When : Friday January 9th

Who : By invitation only

Where : Ecole Normale Supérieure, Cachan, LSV Library

Agenda :

  • 12:00-14:00 : lunch
  • 14:00-15:00 : presentation of Webdam (Serge)
  • 15:00-16:00 : brainstorming

Summary : slides of the presentation.