Editing Multitier architecture (section)

{{Short description|Computing system architecture}}
{{redirect-several|Three-tier system|Tier 1|Tier 2|Tier 3|Tier 4}}
{{More citations needed|date=January 2008}}

In [[software engineering]], '''multitier architecture''' (often referred to as '''''n''-tier architecture''') is a [[client–server architecture]] in which presentation, application processing and [[data management]] functions are physically separated. The most widespread use of multitier architecture is the '''three-tier architecture''' (for example, Cisco's [[Hierarchical internetworking model]]).

''N''-tier [[Applications architecture|application architecture]] provides a [[model]] by which developers can create flexible and reusable applications. By segregating an application into tiers, developers acquire the option of modifying or adding a specific tier, instead of reworking the entire application. N-tier architecture is a good fit for small and simple applications because of its simplicity and low-cost. Also, it can be a good starting point when architectural requirements are not clear yet.<ref>{{Cite book |last=Richards |first=Mark |title=Fundamentals of Software Architecture: An Engineering Approach |publisher=O'Reilly Media |year=2020 |isbn=978-1492043454 |edition=1st}}</ref><ref>{{Cite book |last=Richards |first=Mark |title=Software Architecture Patterns |publisher=O'Reilly Media, Inc. |year=2022 |isbn=9781098134273}}</ref> A three-tier architecture is typically composed of a ''presentation'' tier, a ''[[Business logic|logic]]'' tier, and a ''[[Data access layer|data]]'' tier.

While the concepts of layer and tier are often used interchangeably, one fairly common point of view is that there is indeed a difference. This view holds that a ''layer'' is a logical structuring mechanism for the conceptual elements that make up the software solution, while a ''tier'' is a physical structuring mechanism for the hardware elements that make up the system infrastructure.<ref>[http://msdn.microsoft.com/en-us/library/ms998478.aspx Deployment Patterns (Microsoft Enterprise Architecture, Patterns, and Practices)]</ref><ref>Fowler, Martin "Patterns of Enterprise Application Architecture" (2002). Addison Wesley.</ref> For example, a three-layer solution could easily be deployed on a single tier, such in the case of an extreme [[database-centric architecture]] called '''RDBMS-only architecture'''<ref>{{Cite book|last1=Vicente|first1=Alfonso|last2=Etcheverry|first2=Lorena|last3=Sabiguero|first3=Ariel|title=2021 XLVII Latin American Computing Conference (CLEI) |chapter=An RDBMS-only architecture for web applications |date=2021|chapter-url=https://ieeexplore.ieee.org/document/9640017|pages=1–9|doi=10.1109/CLEI53233.2021.9640017|isbn=978-1-6654-9503-5 |s2cid=245387844 }}</ref> or in a personal workstation.<ref>[http://msdn.microsoft.com/en-us/library/ms998478.aspx Deployment Patterns (Microsoft Enterprise  Architecture, Patterns, and Practices)]</ref>