Discovery --- Vertical Search
There is more information about discovery services including useful links and resources on SCONUL's Higher Education Library Technology (HELibTech) wiki

Discovery/Vertical Search Specification

Requirements for a library Discovery/Vertical Search product.(Online editable version and WORD download)

Introduction

Vertical search is a relatively new tier in the Internet search industry

consisting of search engines that focus on specific
businesses or domains (e.g. libraries). The number of these search engines being introduced has greatly increased in recent years so it’s not surprising that the library vendors are adopting this approach. In the library domain the term 'Discovery Service' is widely adopted for these systems. Their key attribute is the unification search across multiple library (especially print and electronic) resources. It does this by 'harvesting' (meta) data from publishers and other sources (such as the library catalogue, institutional repository etc) and creating a unified index for all materials. This (Google-like) approach is fundamentally different from Metasearch products (such as MetaLib or 360Search) which make search requests (simultaneously) of many separate databases (indexes). Discovery services therefore overcome some of the performance issues inherent on a metasearch approach.

Discovery/vertical search products-


To link the user from the search results through to a journal article the vertical search system may provide a direct URL, or may rely on the institution's own OpenURL resolver. Sometimes an OpenURL resolver is included with the vertical search product.

Issues with Discovery services

A key issue is the coverage of resources in the unified index. A library will typically want to provide access to a wide range of licensed and also unlicensed (often free) resources. There may not be a 100 per cent match against the resources that the vertical search product includes in its unified index. These resources will either be neglected of may have to be accessible via metasearch, which may be integrated with the vertical search product or may be a separate product. This diminishes some of the value of a 'unified' search. The library will typically want the discovery service to also harvest and index local databases such as the library catalogue and institutional repository (IR). The harmonisation of metadata (eg variant forms of names or subject descriptors) across a diverse range of resources may also cause problems.

A good summary of the market and issues is provided in 'The Next Generation of Discovery. The stage is set for a simpler search for users, but choosing a product is much more complex.' By Judy Luther & Maureen C. Kelly Library Journal. 15th March 2011. Short extract below......
'A casual Google search may well be good enough for a daily task. But if you are a college student conducting his or her first search for peer-reviewed content, or an established scholar taking up a new line of inquiry, then the stakes are a lot higher. The challenge for academic libraries, caught in the seismic shift from print to electronic resources, is to offer an experience that has the simplicity of Google—which users expect—while searching the library’s rich digital and print collections—which users need. Increasingly, they are turning to a new generation of search tools, called discovery, for help'

Implementing a solution

Implementation and evaluation issues are usefully discussed in 'Simplifying resource discovery and access in academic libraries: implementing and evaluating Summon at Huddersfield and Northumbria Universities.By June Thoburn, Annette Coates and Graham Stone. [JISC] Project Report.2010