Spring Memcache Sample

A small working out of the box sample to demo the use of Spring's @Cache annotations on a Spring MVC powered REST API.

Used libraries

The following is a list of most important libraries used in the demo:

library	version	comment
springframework	4.1.2.RELEASE	Spring Core
spring-data-jpa	1.7.1.RELEASE	Persistency FW
spring-hateoas	0.16.0.RELEASE	REST HATEOAS support
hibernate	4.3.7.Final	ORM
jackson	2.4.4	JSON support
h2	1.4.182	Embedded in memory DB
simple-spring-memcached	3.5.1-SNAPSHOT	Annotational Memcached Caching
ehcache	2.9.0	In JVM cache
jetty-runner	9.2.5.v20141112	Jetty webrunner
webapp-runner	7.0.40.1	Tomcat webrunner

##Caching backends##

The sample shows the use of 3 different caching backends:

• EHCache an in JVM caching solution
• SpyMemcached single threaded memcached based solution
• XMemcached multi threaded memcahced based solution

A three caching backend are configured using the Spring Java based @Configuration method. Since only one backend is supported at a time, you will need to comment out the others to switch between backends (spymemcached is defaulted).

Make sure you have memcached installed on your system before experimenting with the memcached based solutions:

sudo apt-get install memcached

The memcached server address is configured using a property file cache.properties:

cache.server=127.0.0.1:11211

##The sample##

The demo sample provides two REST endpoints, to demonstrate the difference with or without caching:

• http://localhost:9090/rest/persons (none cached list of person)
• http://localhost:9090/rest/persons/3 (none cached person)
• http://localhost:9090/rest/cache-persons (cached list of person)
• http://localhost:9090/rest/cache-persons/3 (cached person)

Caching is applied on the service methods used by the REST controllers, which are delayed (sleep 2000) in purpose the accentuate the difference. Debugging is enabled in log4j.xml to show cache hits/misses:

INFO  SSMCache - Cache miss. Get by key 3 from cache defaultCache
Hibernate: select cacheperso0_.id as id1_0_0_, cacheperso0_.first_name as first_na2_0_0_, cacheperso0_.last_name as last_nam3_0_0_, cacheperso0_.version as version4_0_0_ from person cacheperso0_ where cacheperso0_.id=?
INFO  CachePersonServiceImpl - Found cachePerson CachePerson{id=3, firstName='Donald', lastName='Duck', version=0} with id 3
INFO  SSMCache - Put 'CachePerson{id=3, firstName='Donald', lastName='Duck', version=0}' under key 3 to cache defaultCache

INFO  SSMCache - Cache hit. Get by key 3 from cache defaultCache value 'CachePerson{id=3, firstName='Donald', lastName='Duck', version=0}'

Corresponding JSON responses:

{
  "firstName" : "Donald",
  "lastName" : "Duck",
  "fetchTime" : 2009,
  "version" : 0,
  "cachePersonId" : 3,
  "links" : [ {
	"rel" : "self",
	"href" : "http://localhost:9090/rest/cache-persons/3"
  } ],
  "id" : 3
}


{
  "firstName" : "Donald",
  "lastName" : "Duck",
  "fetchTime" : 1,
  "version" : 0,
  "cachePersonId" : 3,
  "links" : [ {
	"rel" : "self",
	"href" : "http://localhost:9090/rest/cache-persons/3"
  } ],
  "id" : 3
}

##Building and running the sample##

Build the sample using maven:

mvn clean install

In the root of the project a run.sh script is provided which start the Spring based web archive (war) using Jetty or Tomcat webrunners, on port 9090. Edit the file to tweak this behavior or execute the java commands directly providing the proper arguments.

java -jar target/dependency/jetty-runner.jar --port 9090 target/*.war
java -jar target/dependency/webapp-runner.jar --port 9090 --expand-war target/*.war

##External References##

• simple-spring-memcached
• spymemcached
• xmemcached

Thanks a lot to ragnor for his support on getting the memcached backends properly configured using the Spring Java @Configuration approach!