Examples of com.hmsonline.storm.cassandra.bolt.mapper.ValuelessColumnsMapper

com.hmsonline.storm.cassandra.bolt.mapper.ValuelessColumnsMapper

A mapper implementation that emits tuples based on a combination of cassandra rowkey, collumnkey, and delimiter.

When this bolt receives a tuple, it will attempt the following:

Look up a value in the tuple using rowKeyField
Fetch the corresponding row from cassandra
Fetch the column columnKeyField value from the row.
Split the column value into an array based on delimiter
For each value, emit a tuple with {emitIdFieldName}={value}

For example, given the following cassandra row:

 RowKey: mike => (column=followers, value=john:bob, timestamp=1328848653055000)

and the following bolt setup:

 rowKeyField = "rowKey" columnKeyField = "followers" delimiter = ":" emitIdFieldName = "rowKey" emitValueFieldName = "follower"

if the following tuple were received by the bolt:

 {rowKey:mike}

The following tuples would be emitted:

 {rowKey:mike, follower:john} {rowKey:mike, follower:bob}

        // "followers", ":", "rowKey", "follower", true);


        // cf = "tweeters", rowkey = tuple["url"]
        TupleMapper<String, String, String> tweetersTupleMapper = new DefaultTupleMapper("stormks", "tweeters", "url");
        // cf (url -> tweeters) -> emit(url, follower)
        ColumnMapper<String, String, String> tweetersColumnsMapper = new ValuelessColumnsMapper("url", "tweeter", true);
        CassandraLookupBolt<String, String, String> tweetersBolt = new CassandraLookupBolt<String, String, String>(configKey,
                tweetersTupleMapper, tweetersColumnsMapper);


        // cf = "followers", rowkey = tuple["tweeter"]
        TupleMapper<String, String, String> followersTupleMapper = new DefaultTupleMapper("stormks", "followers", "tweeter");
        // cf (tweeter -> followers) ==> emit(url, follower)
        ValuelessColumnsMapper followersColumnsMapper = new ValuelessColumnsMapper("url", "follower", true);
        CassandraLookupBolt<String, String, String> followersBolt = new CassandraLookupBolt<String, String, String>(configKey,
                followersTupleMapper, followersColumnsMapper);


        builder.addBolt(new InitBolt());
        builder.addBolt(tweetersBolt).shuffleGrouping();

Examples of com.hmsonline.storm.cassandra.bolt.mapper.ValuelessColumnsMapper

Related Classes of com.hmsonline.storm.cassandra.bolt.mapper.ValuelessColumnsMapper