Application Deployment Simplified

Data-tier Applications (DACs), a new feature of SQL Server 2008 R2, aim to simplify the process of deploying and upgrading databases. The functionality is integrated into SQL Server and Visual Studio (VS) 2010 management tools, bridging the technical and procedural gap between application developers and database administrators (DBAs) that can add complexity to database deployment, version control, upgrading, and migration. Due to limitations in the database types supported, it may not be appropriate for all databases, but some may want to evaluate the feature, especially those deploying applications to SQL Azure.

Deploying and Managing Database Applications

The term data tier comes from the three-tier application architecture, which comprises three components: a data tier that manages data storage, a business logic tier that processes data according to an application’s process rules, and a presentation tier that presents an interface to users.

The data tier usually includes tables, schemas, stored procedures, and other database elements that need to be deployed on database servers, which are typically owned by a database specialist. Historically, this process involves a manual or semiautomated transfer of one or more SQL build scripts from application developers to the DBA. These scripts are composed of SQL statements that update database schemas. For example, they might create databases and tables, install database code such as stored procedures, and migrate existing data from the old schema to the new one. However, the scripting method is very fragile: one incorrect or out-of-order step can result in a deployment that might not work as the developer intended.