Editing Client–server model (section)

==Comparison with peer-to-peer architecture==
In addition to the client-server model, [[distributed computing]] applications often use the [[peer-to-peer]] (P2P) application architecture.

In the client-server model, the server is often designed to operate as a centralized system that serves many clients. The computing power, memory and storage requirements of a server must be scaled appropriately to the expected workload. [[Load balancing (computing)|Load-balancing]] and [[failover]] systems are often employed to scale the server beyond a single physical machine.<ref name="Cardellini Colajanni Yu 1999 pp. 28–39">{{cite journal | last1=Cardellini | first1=V. | last2=Colajanni | first2=M. | last3=Yu | first3=P.S. | title=Dynamic load balancing on Web-server systems | journal=IEEE Internet Computing | publisher=Institute of Electrical and Electronics Engineers (IEEE) | volume=3 | issue=3 | year=1999 | issn=1089-7801 | doi=10.1109/4236.769420 | pages=28–39}}</ref><ref name="NGINX 2014">{{cite web | title=What Is Load Balancing? How Load Balancers Work | website=NGINX | date=June 1, 2014 | url=https://www.nginx.com/resources/glossary/load-balancing/ | access-date=January 21, 2020}}</ref>

Load balancing is defined as the methodical and efficient distribution of network or application traffic across multiple servers in a server farm. Each load balancer sits between client devices and backend servers, receiving and then distributing incoming requests to any available server capable of fulfilling them.

In a [[peer-to-peer]] network, two or more computers (''peers'') pool their resources and communicate in a [[decentralized system]]. Peers are coequal, or equipotent [[Node (networking)|nodes]] in a non-hierarchical network. Unlike clients in a client-server or [[client-queue-client]] network, peers communicate with each other directly. <ref>{{Cite journal | last1 = Alharbi | first1 = A. | last2 = Aljaedi | first2 = A. | title = Peer-to-Peer Network Security Issues and Analysis: Review | journal = IJCSNS International Journal of Computer Science and Network Security | DOI = 10.1007/978-3-540-45172-3_6 | year = 2004 }}</ref> In peer-to-peer networking, an [[algorithm]] in the peer-to-peer communications protocol balances [[Load (computing)|load]], and even peers with modest resources can help to share the load.<ref>{{Cite journal | last1 = Rao | first1 = A. | last2 = Lakshminarayanan | first2 = K. | last3 = Surana | first3 = S.| last4 = Manning Karp | first4 = R. | title = Load Balancing in Structured P2P Systems | journal = IJCSNS International Journal of Computer Science and Network Security | volume = 20 | pages = 74–88 | year = 2020 }}</ref> If a node becomes unavailable, its shared resources remain available as long as other peers offer it. Ideally, a peer does not need to achieve [[high availability]] because other, [[Redundancy (engineering)|redundant]] peers make up for any resource [[downtime]]; as the availability and load capacity of peers change, the protocol reroutes requests.

Both client-server and [[Master/slave (technology)|master-slave]] are regarded as sub-categories of distributed peer-to-peer systems.<ref>
{{cite book
| last1 = Varma
| first1 = Vasudeva
| chapter = 1: Software Architecture Primer
| title = Software Architecture: A Case Based Approach
| chapter-url = https://books.google.com/books?id=jOMYtrJ6r_0C
| location = Delhi
| publisher = Pearson Education India
| date = 2009
| page = 29
| isbn = 9788131707494
| access-date = 2017-07-04
| quote = Distributed Peer-to-Peer Systems [...] This is a generic style of which popular styles are the client-server and master-slave styles.
}}
</ref>