Introduction to JCache JSR 107
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Introduction to JCache JSR 107...
billdigman
Fri Feb 08, 2013 01:55 PM

Resin has supported caching, session replication (another form of caching), and http proxy caching in cluster environments for over ten years. When you use Resin caching, you are using the same platform that has the speed and scalability of custom services written in C like NginX with the usability of Java, and the industry platform Java EE.  JCache JSR 107  is a distributed cache that has a similar interface to the HashMap that you know and love. To be more specific, the Cache object in JCache looks like a java.util.ConncurrentHashMap. In addition, JCache JSR 107 defines integration with CDI (as well as Spring and Guice). You can decorate services with interceptors that apply caching to the services just by defining annotations.

Resin 4 has support for JCache, and JCache support is required for Java EE 7.

Let's look at a small example to see how easy is to get started with JCache.

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print ?
01. package   hello.world;
02.  
03.  
04.  
05.  
06. import   javax.cache.Cache;
07. import   javax.cache.CacheBuilder;
08. import   javax.cache.CacheManager;
09. import   javax.cache.Caching;
10. ...
11.  
12.  
13.  
14.  
15. @WebServlet ( "/HelloServlet" )
16. public   class   HelloServlet  extends   HttpServlet {
17.  
18. Cache cache;
19.  
20. public   Cache cache() {
21. if   (cache ==  null ) {  //building a cache
22. CacheManager manager = Caching.getCacheManager( "cacheManagerHello" );
23. CacheBuilder builder = manager.createCacheBuilder( "a" );
24. cache = builder.build();
25. }
26. return   cache;
27. }
28.  
29.  
30.  
31.  
32. protected   void   doGet(HttpServletRequest request, HttpServletResponse response) 
33. throws ServletException, IOException {
34. response.setContentType( "text/html" );
35. response.getWriter().append("
36.  
37.  
38.  
39. <p>");
40.  
41.  
42.  
43.  
44. String helloMessage = cache().get( "hello message" );
45.  
46. if   (helloMessage ==  null ) {
47. helloMessage =  new   StringBuilder( 20 )
48. .append("Hello World !
49.  
50.  
51.  
52.  
53. ")
54. .append(System.currentTimeMillis()).toString();
55.  
56.  
57.  
58.  
59. cache().put( "hello message" , helloMessage);  // <-------------- putting results in the cache
60. }
61.  
62.  
63.  
64.  
65. response.getWriter().append(helloMessage);
66.  
67.  
68.  
69.  
70.  
71. response.getWriter().append("</p>
72.  
73.  
74.  
75. ");
76. }
77.  
78.  
79.  
80.  
81. }

The above works out fairly well, but what if we want to periodically change the helloMessage. Let's say we get 2,000 requests a second, but every 10 seconds or so we would like to regenerate the helloMessage.

The message might be:

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print ?
1. Hello World !
2. 1358979745996

Later we would want it to change.

If we wanted it to change every 10 seconds after it was last accessed, we would do this:

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print ?
1. cache = builder.setExpiry(ExpiryType.ACCESSED,  new Duration(TimeUnit.SECONDS,  10 )).build();

For this example, we want to change it every 10 seconds after is was last modified. We would set up the timeout on the creation as follows:

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print ?
1. cache = builder.setExpiry(ExpiryType.MODIFIED,  new Duration(TimeUnit.SECONDS,  10 )).build();

This would go right in the cache method we defined earlier.

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print ?
01. public   Cache<String, String> cache() {
02. if   (cache ==  null ) {
03. CacheManager manager = Caching.getCacheManager( "cacheManagerHello" );
04.  
05. CacheBuilder<String,String> builder = manager.createCacheBuilder( "b" );
06. cache = builder.setExpiry(ExpiryType.MODIFIED,  new Duration(TimeUnit.SECONDS,  10 )).build();
07. }
08. return   cache;
09. }

Resin's JCache implementation is built on top Resin distributed cache architecture. You get replication, and data redundancy built in.

Bill Digman  is a Java EE / Servlet enthusiast and Open Source enthusiast who loves working with Caucho's Resin Servlet Container, a Java EE Web Profile Servlet Container.

Caucho's Resin OpenSource Servlet Container

Java EE Web Profile Servlet Container

Caucho's Resin 4.0 JCache blog post

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