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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 SoftwaresSearch:
Search Results
Real-time query and responses
Search:
Search Results
Pre-built harvesting and indexing
Meta Search Index
Local Index
Local Index
Digital Collections
Discovery Services
Federated Search Discovery Service
Index No Index One unified index
Sources No limit, but it effect the speed when more number of connectors
Must have agreements
Information Currency Real-time return Depends on index update
Preparation Connector Development Index Development
Control Select sources Some 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 Service Federated 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 Index Many 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 possible Metadata enhancement is not possible
Comprehensive results Shallow results -and eventually users will miss much relevant content.
Performance quality is very high Many 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
