EMF Search provides the fundamental infrastructure and components for search queries on EMF based models. A particular focus is made on integration with the Eclipse Core Search API for end user tight integration.
EMF Search is an Ecore meta-model based extensible search engine which purpose is to provide users query launching services against Ecore based models.
Meta-model based search is basically being able to take advantage of a meta-model structure to run generic search queries onto it. This means that a meta-model structure, defining a minimal modeling "organization", contains information enough to get operations applied to it, and by extension having same operations applied to any inheriting model compliant with this meta-model structure. Ecore based search is in fact a particular case of meta-model based treatment, a typical approach also known as Model Driven Architecture.
In other words, this allows to develop meta-model based generic algorithms, valid across any user defined model extending elements & structure of a given meta-model. Such method are usually employed as part of a code generation development process also known as Model Driven Development, allowing developers to code things once, setting up templates based code generation getting its data from the particular valuation of an instance of a given meta-model (eg: An actual user defined model or domain model populated with pertinent data).
For model search explanatory purposes, we need to introduce some terminology. First of all, let's keep in mind that a model search query always needs to deal with entities such as a scope of model resource(s)/element(s) onto which a search query will apply, a set of participant meta-elements which the search query will consider, and finally a search query, whether textual, scriptical or programmatic, which an associated model search engine will evaluate against a scope and participants. This evaluation obviously having the role to produce Model Search Results.
This brief explanation just made main concepts appearing : Model Search Scope, Model Search Participants, Model Search Query, Model Search Engine, and Model Search Results.
Model Search Engine
EMF Search has an extension point allowing a user to contribute custom model search engines
org.eclipse.emf.search.modelSearchEngine extension point definition).
A model search engine has responsibility, given a model resource scope, to evaluate a model search query applying only on a set of selected meta-elements (called meta-element participants).
Model Search Query
EMF Search offers an extensible mechanism for model search queries.
Users can contribute model search queries potentially combined with any number of different element participants.
(eg. given the fact that different user defined elements extend Ecore meta-elements). As a result, users can register to
org.eclipse.emf.search.modelSearchID extension their own model search queries (plus the way to handle it from the UI point of view) and then, associate it to an existing model search engine.
Model Search Participants
EMF Search offers extensible model search participants elements mechanism.
Users can contribute model search participants potentially combined with any numbers of different model search queries.
As a result, users can register to
org.eclipse.emf.search.modelSearchParticipantTab extension their own model search participant elements (plus the way to handle it from the UI point of view), and associate it to an existing model search engine.
Model Search Scope
Model Search Scope stands for a set of ecore resources to be considered by the search query.
We can make a comparison with platform search concepts from the scope point of view. As in the text search or java search, a user can search into the whole workspace or reduce its scope to selected resources, selected projects or even a given working set.
Model Search Result
Query evaluation produces matches, being collected in a result object or each resource evaluated. Matches can be considered as result entries of top level result object. These matches are considered as Model Search Result and will populate the Eclipse Search View.