A Real-Life Example - Getting Started with Storm - page 50

...
}
As mentioned earlier, use the ProductsReader helper class to read the product specific
information.
package storm . analytics . utilities ;
...
public class ProductsReader {
...
public Product readItem ( String id ) throws Exception {
String content = jedis . get ( id );
if ( content == null || ( "nil" . equals ( content )))
return null ;
Object obj = JSONValue . parse ( content );
JSONObject product =( JSONObject ) obj ;
Product i = new Product (( Long ) product . get ( "id" ),
( String ) product . get ( "title" ),
( Long ) product . get ( "price" ),
( String ) product . get ( "category" ));
return i ;
}
...
}
UserHistoryBolt
The UserHistoryBolt is the core of the application. It's responsible for keeping track of
the products navigated by each user and determining the result pairs that should be
incremented.
You'll use the Redis server to store product history by user, and you'll also keep a local
copy for performance reasons. You hid the data access details in the methods getUser
NavigationHistory( user ) and addProductToHistory( user , prodKey ) for read and write
access, respectively.
package storm . analytics ;
...
public class UserHistoryBolt extends BaseRichBolt {
@Override
public void execute ( Tuple input ) {
String user = input . getString ( 0 );
String prod1 = input . getString ( 1 );
String cat1 = input . getString ( 2 );
// Product key will have category information embedded.
String prodKey = prod1 + ":" + cat1 ;
Set < String > productsNavigated = getUserNavigationHistory ( user );
// If the user previously navigated this item -> ignore it
if (! productsNavigated . contains ( prodKey )) {
// Otherwise update related items