#kundera-azure-table

Kundera client module to support Azure Table.

Kundera is a JPA 2.0 compliant Object-Datastore Mapping Library for NoSQL Datastores and is available here.

For complete documentation see Kundera Wiki.

##Supported Features The following feature are supported by this extension:

• JPA relationships are supported as Kundera supports them
• @GeneratedValue only with strategy GenerationType.AUTO.
• @ElementCollection java Collection or Map are supported as types and are serialized when persisted into azure table.
• @Embedded embedded entities are supported but deeply serialized when persisted into azure table.
• @Enumerated java Enum types are supported and stored as strings.

For each feature see the relative JUnit test for usage examples.

##ID and Consistency In Azure Table strong consistency is guaranteed while entities are stored within the same partition key otherwise consistency will be eventual. IDs are supported only in field of type String (so only a String field can be annotated with @Id). User can define IDs both with or without partition key.

Please take as reference the naming constraints from Azure Table documentation.

###Define both row key and partition key This can be done in two ways:

• using AzureTableKey.asString method by passing both partition key and row key to obtain a string representation of the whole key and assign it to the entity ID field before persist.
• manually define the entity ID before persist the entity, the string must follow the pattern partitionKey_rowKey.

###Define only the row key If only the row key is defined, the partition key is implicitly the default one (which can be set in a datastore specific properties file).

There are three ways to do this:

• auto-generated IDs (the row key is a random java UUID)
• manually define the entity ID before persist the entity
• using AzureTableKey.asString passing as parameter the desired row key and assign its result to the entity ID field before persist.

##Query support JPQL queries are supported as Kundera supports them, the operator supported is resumed in the following table:

JPA-QL Clause	Azure Table
SELECT	✔
UPDATE	✔
DELETE	✔
ORDER BY	X
AND	✔
OR	✔
BETWEEN	✔
LIKE	X
IN	X
=	✔
>	✔
<	✔
>=	✔
<=	✔

Examples in use of queries can be found in the JUnit test.

More details on the operator supported by Azure Tables can be found in the official documentation.

##Configuration

###persistence.xml The configuration is done in the persistence.xml file, the properties to be specified inside the <properties> tag are:

• kundera.username required, the storage account name (from azure portal)
• kundera.password required, the storage account key (from azure portal)
• kundera.client.lookup.class required, it.polimi.kundera.client.azuretable.AzureTableClientFactory
• kundera.ddl.auto.prepare optional, possible values are:
  • create which creates the schema (if not already exists)
  • create-drop which drop the schema (if exists) and creates it
• kundera.client.property optional, the name of the xml file containing the datastore specific properties.

###Datastore specific properties A file with client specific properties can be created and placed inside the classpath, you need to specify its name in the persistence.xml file.

the skeleton of the file is the following:

<?xml version="1.0" encoding="UTF-8"?>
<clientProperties>
    <datastores>
        <dataStore>
            <name>azure-table</name>
            <connection>
                <properties>
                    <!-- list of properties -->
                    <property name="" value=""></property>
                </properties>
            </connection>
        </dataStore>
    </datastores>
</clientProperties>

for more information see kundera datastore specific properties.

The available properties are:

• table.emulator [true|false] default: false. If present (and set to true) storage emulator is used. When using dev server kundera.username and kundera.password in persistence xml are ignored.
• table.emulator.proxy default: localhost. If storage emulator is used set the value for the emulator proxy.
• table.protocol [http|https] default: https. Define the protocol to be used within requests.
• table.partition.default default: DEFAULT.
  The value for the default partition key, used when no one is specified by the user.