Chapter 38. Data Interoperability
38.1. Protocol Interoperability
38.1.1. Protocol 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.
Compatibility mode supports only strings and primitives. Objects are not supported.
38.1.2. Enabling Compatibility Mode
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>38.1.3. Marshallers
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:
| Marshaller | Description |
|---|---|
|
| Uses the JBoss marshaller to serialize and deserialize strings and primitives as byte arrays. This is the default marshaller for JDG. |
|
| Uses the ProtoStream library to serialize and deserialize strings and primitives as byte arrays. |
|
| Serializes and deserializes strings and primitives as UTF8 byte arrays. |
JBoss Data Grid does not currently support custom marshallers.
38.1.4. Setting the Marshaller
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>38.1.5. Protocol Interoperability Over Memcached
When using memcached in compatibility mode, you must explicitly set the default marshaller, GenericJBossMarshaller, in the configuration as follows:
Memcached Marshaller Configuration
<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>
38.1.5.1. Transcoder for Java Clients
Java clients must use a transcoder to perform read and write operations in compatibility mode. The transcoder enables memcached clients written in Java to convert between byte arrays and strings or primitives.
38.1.6. Protocol Interoperability Over REST
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.
