Twitter ising imodel idance itrain5/7/2023 Therefore, iTwin.js includes ECSQL to form queries of iModels in terms of classes and property names, rather than table and column names. However, due to the mapping of BIS classes to database tables, direct use of SQL with iModels is not straightforward. SQLite has extensive support for SQL, including indexing and comprehensive query planning. ECSQL is the query language of iModelsĪn iModel is an SQLite database. JavaScript was chosen as the language for iTwin.js due to its ubiquitous nature and the vast body of open source tools and frameworks available for it. It provides ways to create, modify, query, display, and analyze iModels. The purpose of the iTwin.js library is to make iModels accessible to everyone, everywhere, for any purpose that is approved by the iModel's owner. iTwin.js makes iModels accessible anywhere Only GeometricElements, held in GeometricModels, are visible in Views. There are many types of Elements, corresponding to the type of information they contain. A Model is comprised of many ElementsĮlements are the smallest independently addressable building block in BIS.Įvery Element is owned by (i.e. spatial, functional, drawing, etc.) There can be many instances of each type of Model in the same iModel. There are many types of Models, corresponding to the type of information they hold (e.g. Within an iModel, logical subdivisions of information are defined by Models. All information held in an iModel is an instance of some class defined in BIS, inserted using the iTwin.js API. The Base Infrastructure Schemas are a family of domain-specific class definitions that define the properties and relationships of entities within an iModel. The format of information in an iModel is defined by BIS All geometry in the spatial coordinate system of an iModel must be contained inside this volume. IModels have a property called Project Extents that describes the volume of interest they occupy. In this manner multiple iModels can be oriented relative to oneĪnother, and relative to external reality models, cartographic and geographic information systems, etc. An iModel occupies physical space on the earthĮvery iModel has a single spatial coordinate system that may be positioned and oriented somewhere on the earth. Each Briefcase maintains the GUID of its iModel soĪccess to it can be controlled by its owner. They are each uniquely identified with a Globally Unique Identifier, so they can be tracked and secured by iModelHub. Every iModel has a GUIDĪn iModel holds information about a single infrastructure asset. In the same manner that every programmer has a full copy of a source code repository, with iModels every user has a full copy of the database. For programmers, a helpful analogy is Git and GitHub. Many copies of an iModel may be extant simultaneously, each held in a briefcase and synchronized via ChangeSets from iModelHub. iModels may contain physical and functional models, drawings, specifications, analytical models, etc. An iModel holds information about a single infrastructure asset. An iModel is a distributed relational database, based on SQLite, with a schema defined by BIS.
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