SOA Enabled DAL

Introduction

Traditional applications using relational data sources such as Oracle, SQL Server and DB2 to expose their business logic to external world in a tightly coupled manner. This tightly coupled approach leads to the performancescalability issues. This post discusses the Designing a SOA enabled DAL with example.

Traditional Service Data Access

Above figure shows the set of web services accessing the same relational database. Every request from the client requires data access which creates the performance issue when multiple concurrent users are trying to access the database.

Traditional applications having their own databases and when we migrate to the SOA data integrity issues will arise.

SOA Model Data Access

SOA model represents the loosely coupled architecture where business logic and Data access logic are no longer integrated. We are using LINQ-SQL as an interface for the SOA DAL.

SOA DAL only exposes the DTO’s[Data Transfer Objects] to the services

DTO representing the Employee looks like the following

Data Transfer Objects

This DAL is a provider independent and can be pluggable to different databases by reading the provider from the configuration file.

The Data provider using LINQ to SQL looks as follows

Data Provider

The DataService that exposed through service layer looks like

Now You can call the above service in windows or web application. We have seen how we decoupled the application from data access logic.

More information on building the SOA data access at http://msdn.microsoft.com/en-gb/magazine/dd263098.aspx.