Clients - Cassandra: The Definitive Guide - page 173

"response": "null",
"errors": ["InvalidRequestException", "UnavailableException",
"TimedOutException"]

},
//etc...

The JSON format is concise and easy to read. You can see, for example, that there are at least
two kinds of messages, one representing a get request and the other representing an insert re-
quest. The exceptions possible for each type are packaged with their messages.

NOTE
The meaning of each exception is discussed earlier in Thrift .

Avro Ant Targets
The Cassandra build.xmlile defines two Ant targets that are executed when Cassandra is com-
piled from source, which is made possible by avro-1.2.0-dev.jarin the Cassandra libdirectory.
These targets are shown in the following listing:

<!--
Generate avro code

-->
<target name=" check-avro-generate ">
<uptodate property="avroUpToDate"
srcfile="${interface.dir}/cassandra.avpr"
targetfile="${interface.avro.dir}/org/apache/cassandra/avro/

Cassandra.java" />
<taskdef name="protocol"
classname="org.apache.avro.specific.ProtocolTask">
<classpath refid="cassandra.classpath" />
</taskdef>
<taskdef name=" schema " classname="org.apache.avro.specific.SchemaTask">
<classpath refid="cassandra.classpath" />
</taskdef>
<taskdef name=" paranamer "
classname="com.thoughtworks.paranamer.ant.ParanamerGeneratorTask">
<classpath refid="cassandra.classpath" />
</taskdef>
</target>

<target name=" avro-generate " unless="avroUpToDate"
depends="init,check-avro-generate">
<echo>Generating avro code...</echo>