Analyzing the key constraints of a RESTful web architecture with respect to their impact on overall system performance and scalability

1. Impact of RESTful web architecture
on performance and scalability
Sanchit Gera
2B Computer Engineering
University of Waterloo

2. Overview
• Background
– Web Services
– Performance
– Scalability
• Introduction to REST
• Characteristics of RESTful design
• Summary
• Conclusion
2

3. Web Services
• Means of exposing functionality or data
• Analogous to web pages for machines
• Facilitate integration between applications
• Tend to be flexible and client agnostic
CLIENT SERVICE
Request
Response
3

4. Performance
• Driven by a number of factors, some of which
are impacted by architectural decisions
• Performance discussed in terms of
– Relates to issues such as network latency and
limited network bandwidth
– Minimizing data-trips between server and client
– Minimizing “message overheads”
4

5. Scalability
• Need to support large number of concurrent
instances or interactions
• Scaling up - increasing the capacity of
services, consumers, and network devices
(vertical scaling)
• Scaling out - distributing load across services
and programs (horizontal scaling)
5

6. Introduction to REST
• REpresentationalState Transfer
• An architectural style for web services
• Open ended specifications
• Utilizes the inherent design of the Web for
scalability and performance
6

7. Characteristics of REST
• Uniform interface
• Stateless system
• Client-server architecture
• Cacheable
• Layered System
• Code on Demand (Optional)
7

8. Stateless System
• Server does not store any context between
requests
• Each request should be independent and self
containing
– Self descriptive messages
• Any session state is held on the client
• Imposes restrictions on the communication
allowed between services and consumers
8

9. Stateless System
9

10. Stateless System
• Frees up service memory resources, allowing
the service to scale with the number of
concurrent requests
• Less complicated to design and distribute
across servers (horizontal scaling)
• Reduces network performance by increasing
transmission of repetitive data
10

11. Cacheable
• Service consumers can cache and reuse
response message data
• Responses from the service to consumers are
labeled as cacheable or non-cacheable
• Improves runtime efficiency and allows for
“lazy replication”
• Boosts system performance by reducing user
perceived latency
11

12. Cacheable
• Caches work mostly, but not exclusively with
GET requests
• Implemented either implicitly, explicitly or
through negotiation
• Better user perceived performance
• Lowers perceived network latency
• Reduces load on the database boosting
scalability
12

13. Layered System
• Solution can have multiple intermediary
architectural layers
• No one layer can see past another
• Request-response mechanism must be
transparent to end client
• Every layer has a single high level purpose,
boosting separation of concerns
• Allows us to add features like a gateway, a load
balancer, or a firewall to accommodate system
scaling.
13

14. Conclusion
• Brief overview of REST and its principles
• Analysis of REST principles based on scalability
and performance
– Statelessness : Performance (Negative), Scalability
(Positive)
– Cacheable : Performance (Positive), Scalability
(Positive)
– Layered System : Performance (Negative),
Scalability (Positive)
14