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* 'master' of https://github.com/iluwatar/java-design-patterns: (27 commits) Remove use of coveralls-maven-plugin (sonarqube.com covers this) Add SonarQube.com badge Fix environment variable Add Travis instructions for SonarQube.com analysis Adds more criticism to Singleton pattern. Event Based Asynchronous pattern: Add missing license header and puml diagram Changed config to non-interactive Moved config into a separate dir Unused import removed. End process logic clause has been corrected. Caching pattern: Documentation and diagram Fixes #437. Adds criticism to Singleton pattern. Alter JUnit tests to run in lesser time. Updated version snapshot to 1.14.0 Changes based on review feedback. Closes #436. Adds criticism to service locator pattern. Caching pattern: Implementation of Cache-Aside pattern Caching pattern: Style fix for null check Caching pattern: Refactor LRU cache to avoid NPE and unnecessary cache lookup Caching pattern: Refactor shutdown hook to use method reference ...
layout, title, folder, permalink, pumlid, categories, tags
| layout | title | folder | permalink | pumlid | categories | tags | |||
|---|---|---|---|---|---|---|---|---|---|
| pattern | Service Locator | service-locator | /patterns/service-locator/ | NSjB3iCm203HgxG7iDdtDeIWX0fZYqzo_MRTtUX9ynOZhPtBzNLchlW0EDxza3nhgs2dQScMdUO0qRenqU6B5xQTGmvh2pFPBM1WF07FSmbnqqcOqu6J_gsNZxvgw0y0 | Structural |
|
Intent
Encapsulate the processes involved in obtaining a service with a strong abstraction layer.
Applicability
The service locator pattern is applicable whenever we want to locate/fetch various services using JNDI which, typically, is a redundant and expensive lookup. The service Locator pattern addresses this expensive lookup by making use of caching techniques ie. for the very first time a particular service is requested, the service Locator looks up in JNDI, fetched the relevant service and then finally caches this service object. Now, further lookups of the same service via Service Locator is done in its cache which improves the performance of application to great extent.
Typical Use Case
- when network hits are expensive and time consuming
- lookups of services are done quite frequently
- large number of services are being used
Consequences
- Violates Interface Segregation Principle (ISP) by providing pattern consumers with an access to a number of services that they don't potentially need.
- Creates hidden dependencies that can break the clients at runtime.