Transcript en-us/library/ms978496.aspx

Position Paper
How should the business logic be developed? As middle-tier
application? or as a DBMS stored procedures?
Akash Sharma
Hiren Nagar
Introduction
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Presentation logic: The front end logic for data access
(viewable to users) that resides on the client side
Business Logic: Algorithms that translates the request
for data and retrieves it that resides on the application
server
Data Logic: The set of iterative algorithms, which
maintains data and its security that resides on the
Database Server
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There are two approaches on placing business logic in
architecture, in a separate tier called middle-tier, or as
stored procedure in relational database.
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PCs contain the presentation logic and perform simple
validation, the business logic executes on the business
servers, and centralized data stores and legacy
functionality reside on traditional servers. The three
separate logic areas use abstract interfaces to
communicate.
Argument
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Presentation tier
 Business logic tier
 Data tier
Technology support
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Three tier architectures readily allow different tiers to be
developed in different languages, such as a graphical user
interface language or light internet clients (HTML, applets)
for the top tier; C, C++, Smalltalk, Basic, Ada 83, or Ada
95 for the middle tier; and SQL for much of the database
tier
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Can be easily reused without affecting the other two levels
of the architecture.
Each tier has a separate interface and work in different
environments, thus giving each tier the flexibility of
updating, renewing (upgrading) or replacing independently
without affecting the other two tiers. This improves
scalability and flexiblity .
The three tier architecture can support the website’s
database on the data tier with the web-pages on the
presentation tier.
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It is even easier to manage the security and control the
access limits of different users, with all the data stored in
the data tier. It is notable that recently, “mainframes have
been combined as servers in distributed architectures to
provide massive storage and improve security. Migrating a
legacy system to three tier architecture can be done in a
manner that is low-risk and cost-effective.
The middle tier server improves performance, flexibility,
maintainability, reusability, and scalability by centralizing
process logic.
Supporting documents
http://csdl.computer.org/dl/mags/it/2000/
03/f3058.pdf
 http://www.sei.cmu.edu/str/descriptions/t
hreetier_body.html
 http://csdl.computer.org/dl/proceedings/t
ools/2001/1251/00/12510083.pdf
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Counter Argument
Stored procedure is a subroutine available to the presentation
layer to access database.
The business logic should be developed as stored procedure in
the database server.
Counterclaims
• Reduce Network Traffic
- Direct control over data being accessed, reduces
communication
• Faster Execution (Pre-compiled SQL statements)
- Stored pre-compiled SQL Statements, produces faster
response
• Security
- Security features are implemented in stored procedure,
restricts unauthorized access to the database
Weaknesses with the approach
Scalability
- Not a good idea to implement stored procedures for
applications requiring intensive processing
- This will put excessive load on data server hence, affects
efficiency of database server
- lacks scalability
Maintenance and Agility
- If business logic changes, application needs to undergo a
major change
- This approach lacks portability
Business logic as separate layer
-Business logic as stored procedure in the database impacts
the performance of the database server
-Security is at risk with stored procedures in database tier.
Supporting Documents
• Carpentiere Christa. (2004, March). An Evaluation of Stored Procedures for the .NET
Developer. URL: http://msdn2.microsoft.com/en-us/library/ms973918.aspx , Microsoft
Corporation, Last Accessed: Feb 19, 2007
• Crocker Angela, Olsen Andy, Jezierski Edward. (2002, August). Designing Data
Tier Components and Passing Data through Tiers. URL: http://msdn2.microsoft.com/
en-us/library/ms978496.aspx
•SQL Stored Procedures. URL: http://msdn2.microsoft.com/en-us/library/aa174792
%28SQL.80%29.aspx
Conclusion
Although there are some advantages with implementing
business logic as stored procedures but those advantages are
also offered by middle-tier along with other
features(discussed in the counter arguments) which stored
procedures fail to offer.
Thereby, we support deploying business logic in middle tier.