Web Scale Discovery Service Vs Federated Search NIKESH NARAYANAN

Web Scale Discovery Service Vs Federated Search Both facilitate Single Search Box for searching from Multiple resources Federated Search is fairly old technology which allows users to submit a real-time search in parallel to multiple information sources and retrieve results. Web Scale Discovery services is the state of the art technology which is basically based on pre-harvested metadata from vast collection of resources. Some of the features are – Unified platform to search all the resources including licensed, open and local collections including Library Catalog and Institutional Repository – Pre-harvested central index of metadata – Google like single search box – Single results list for all collections – Relevancy ranking across entire results – Full featured user interface – Facets and tools for narrowing results – Connections to full text

Federated Search Softwares Search: Search Results Real-time query and responses

Search: Search Results Pre-built harvesting and indexing Meta Search Index Local Index Digital Collections Discovery Services

Federated SearchDiscovery Service IndexNo IndexOne unified index SourcesNo limit, but it effect the speed when more number of connectors Must have agreements Information CurrencyReal-time returnDepends on index update PreparationConnector DevelopmentIndex Development ControlSelect sourcesSome Discovery services provides publisher facets ( EBSCO discovery Basic Differences

It is too slow Connectors break Brings back too few results from each source Difficult to rank results well (meta-data differences, lack of info) Federated Search - Drawbacks

Discovery ServiceFederated Search Engines Search is very fast as retrieval is done in pre- harvested index Slow (longer time for search completion) – Federated searching is performing the meta search on the fly from different resources Standardized unified IndexMany indexes: Individual indexes and different database structures of various publishers makes it difficult for metadata retrieval. Robust Relevancy Ranking as retrieval is from Unified index Testing has proven that relevancy ranking is a major issue in retrieval of quality data. Metadata Enhancement is possibleMetadata enhancement is not possible Comprehensive resultsShallow results -and eventually users will miss much relevant content. Performance quality is very highMany times important information from relevant resources are missed out due to connection error. Can cover all the single subscription journals from small publishers. Single titles may not have federated search connectors ( Assume you have 150 single titles). Also, if you put more than 5 connectors, speed would considerably down. Advantages of Discovery service compared to Federated Search Engine