all index.md files renamed to README.md for more compatibility with github

service-locator/README.md

@@ -0,0 +1,37 @@
+---
+layout: pattern
+title: Service Locator
+folder: service-locator
+permalink: /patterns/service-locator/
+categories: Structural
+tags:
+ - Java
+ - Difficulty-Beginner
+ - Performance
+---
+
+## Intent
+Encapsulate the processes involved in obtaining a service with a
+strong abstraction layer.
+
+![alt text](./etc/service-locator.png "Service Locator")
+
+## 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
+
+## Credits
+
+* [J2EE Design Patterns](http://www.amazon.com/J2EE-Design-Patterns-William-Crawford/dp/0596004273/ref=sr_1_2)