The architecture of Microsoft MSSQL Server is mainly divided into three components:
1. SQLOS: which implements the basic services required by MS SQL Server, including thread scheduling, I/O stat management and memory management.
2. Relational Engine: which implements the relational database components including support for databases, tables, queries and stored procedures as well as implementing the type system.
3. Protocol Layer: which exposes the MS SQL Server functionality.
SQLOS



