Virtual entity is a custom entity that has fields containing data read from an external data source, a feature released in Dynamics 365 version 9.
With virtual entities you connect directly to external data source, and data is displayed at runtime, rather than stored in CRM database, as with “normal” entities.
Virtual Entity cloud web-service is a service that converts data from SQL database and from Excel spreadsheet to formatted ODATA v4 endpoint, which makes CRM integration to external databases, a breeze.
GUID is a unique identifying number of any CRM record. The important property of a GUID is that each value is globally unique. GUID has 32 characters with 4 dashes in format like: 1B752291-DAD0-E711-A959-000D3A81EDE3.
When records in the data source have unique GUID, the records in the virtual entity are created with same GUID. Although virtual entity retrieves records from external database every time the list is refreshed, the GUID ensures that what is linked to the record of the virtual entity, is always associated with the same record in the external database. The GUID ensures one-to-one link between a virtual entity record and the matching record in the data source.
When creating Virtual Entity you can enable Notes and Activities. You can also create relationships with other entities. If there is no GUID to the virtual entity records attachment, notes and activity disappear once the CRM session is completed. Having GUID in data source and in the virtual entity records provides CRM a way to save and associate the Notes, Activities and attachments to the records, a feature that further enhance virtual entities’ capability and usage.