Browsing is a way of finding documents in a large amount of data which is complementary to querying and which is particularly suitable for multimedia documents. Locating particular documents in a very large collection of multimedia documents such as the ones available in peer to peer networks is a difficult task. However, current peer to peer systems do not allow to do this by browsing. In this report, we show how one can build a peer to peer system supporting a kind of browsing. In our proposal, one must extend an existing distributed hash table system with a few features : handling partial hashkeys and providing appropriate routing mechanisms for these hash-keys. We give such an algorithm for the particular case of the Tapestry distributed hash table. This is a work in progress as no proper validation has been done yet.
The work of Loisant @cite_6 @cite_3 is a good representative of the state of the art in multimedia browsing systems. It is based on a clustering of the documents that is done before the browsing process. This pre-analysis allows to build classes which are more relevant than the ones we use. However, in order to build that clustering, the system needs to have access to all the descriptors. For this reason, that system cannot be easily used in a peer to peer framework. Moreover, when new documents are added to the system, the clustering may have to be modified, which raises new difficulties. Another difficulty in using such a system is the mapping between clusters and logical addresses. In our system this mapping is canonical. With dynamical or ad hoc clusters, another DHT layer would be necessary to make the translation.
@cite_3 @cite_6
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We divide image querying paradigms into three categories: formal querying, interactive search, and browsing. The first two paradigms have been largely investigated in the literature, whereas the last one has not been as much studied. We propose a browsing technique based on concept lattices. The result is a kind of hypertext of images that mixes classification and visualisation issues in a high-dimensionnality space. Les donnees dites multimedia (images, videos) se distinguent des donnees classique par une densite variable d'information et l'impossibilite de normaliser ces donnees. Du fait de ces particularites, de nouvelles techniques d'indexation et de recherche d'information ont du etre etudiees. Il y a principalement deux problemes a resoudre pour la recherche d'information dans les collections multimedia (ou les bases de donnees multimedia) : (1) la representation des donnees et (2) le processus de recherche du point de vue de l'utilisateur. Dans le cas des bases de donnees, l'indexation est fortement liee a ces deux problemes. Dans le cas particulier des images, on distingue trois grandes classes: – la recherche par requetes formelles, heritee des bases de donnees classiques ; – la recherche avec boucle de retour, ou l'utilisateur fait partie integrante du processus de recherche ; – la navigation ou les images sont organisees en une structure preparee a l'avance, utilisee comme index et comme structure de recherche. C'est sur cette troisieme approche que nos travaux se sont portes ; nous nous sommes en effet interesses au treillis de Galois, une structure de graphe permettant d'organiser les elements d'une relation binaire. Une telle structure de navigation a plusieurs avantages sur une approche classique basee sur des requetes : en particulier, elle permet d'affranchir l'utilisateur d'une phase de redaction de requete.