Chapter 38. Data Interoperability

Protocol interoperability enables clients that are written in different programming languages to read and write cache entries from any Red Hat JBoss Data Grid endpoint, such as REST, Memcached, or Hot Rod.

Each endpoint stores data in a suitable format so that data transformation is not required to retrieve entries from the cache. However, when accessing data from multiple protocols, Red Hat JBoss Data Grid must convert data between the formats for each endpoint.

To access data in a cache from multiple protocols, you must enable compatibility mode on that cache.

To enable compatibility mode, add enabled=true to the compatibility element as follows:

<cache-container name="local" default-cache="default" statistics="true">
    <local-cache name="default" statistics="true">
        <compatibility enabled="true">
    </local-cache>
</cache-container>

<cache-container name="local" default-cache="default" statistics="true">
    <local-cache name="default" statistics="true">
        <compatibility enabled="true">
    </local-cache>
</cache-container>

Marshallers enable JDG to serialize and deserialize raw bytes into strings and primitives. The following table describes the marshallers that you can use with JBoss Data Grid in compatibility mode:

By default JBoss Data Grid uses the GenericJBossMarshaller when in compatibility mode. To use a different marshaller, you must set it with the marshaller parameter as in the following example:

<cache-container name="local" default-cache="default" statistics="true">
    <local-cache name="default" statistics="true">
    	<compatibility enabled="true" marshaller="org.infinispan.commons.marshall.UTF8StringMarshaller"/>
    </local-cache>
</cache-container>

<cache-container name="local" default-cache="default" statistics="true">
    <local-cache name="default" statistics="true">
    	<compatibility enabled="true" marshaller="org.infinispan.commons.marshall.UTF8StringMarshaller"/>
    </local-cache>
</cache-container>

When using memcached in compatibility mode, you must explicitly set the default marshaller, GenericJBossMarshaller, in the configuration as follows:

<cache-container name="local" default-cache="default" statistics="true">
    <local-cache name="default" statistics="true">
        <compatibility enabled="true" marshaller="org.infinispan.commons.marshall.jboss.GenericJBossMarshaller"/>
    </local-cache>
</cache-container>

<cache-container name="local" default-cache="default" statistics="true">
    <local-cache name="default" statistics="true">
        <compatibility enabled="true" marshaller="org.infinispan.commons.marshall.jboss.GenericJBossMarshaller"/>
    </local-cache>
</cache-container>

When data is stored via the REST interface the values are interpreted by Hot Rod or Memcached clients as a sequence of bytes. Meaning is given to this byte-sequence using the MIME type specified via the "Content-Type" HTTP header, but the content type information is only available to REST clients. No specific interoperability configuration is required for this to occur.

When retrieving data via REST, primitive types stored are read in their primitive format. If a UTF-8 String has been stored via Hot Rod or Memcached, it will be retrieved as a String from REST. If custom objects have been serialized and stored via the remote cache, these can be retrieved as application/x-java-serialized-object, application/xml, or application/json. Any other byte arrays are treated as application/octet-stream.