Blueriq provides IExternalFlowStore interface which can be used to interact with a generic datastore. A default implementation is already provided in the Blueriq External Flow Component. If other datastore implementation is desired the following have to be done:

<project ...>
  ...  
  <dependencies>
    ...
    <dependency>
	  <groupId>com.blueriq</groupId>
	  <artifactId>blueriq-component-api</artifactId>
	  <version>${blueriq.version}</version>
    </dependency>
    ...
  </dependencies>
  ...
</project>
package ...;

import com.blueriq.component.api.store.externalflow.IExternalFlowStore;
// other imports ...

@Component
public class CustomExternalFlowStore implements IExternalFlowStore {

  @Override
  public void delete(String key) 
    throws ExternalFlowStoreException, IllegalArgumentException {
    // add implementation here
  }

  @Override
  public <T extends Serializable> T get(String key, Class<T> valueType) 
    throws ExternalFlowStoreException,    IllegalArgumentException {   
    // add implementation here
    return null; 
  }

  @Override
  public boolean hasKey(String key) 
    throws ExternalFlowStoreException, IllegalArgumentException {    
    // add implementation here
    return false;
  }

  @Override
  public void set(String key, Serializable value) 
    throws ExternalFlowStoreException, IllegalArgumentException {
    // add implementation here
  }
}

Example Hazelcast Datastore

Here is a example Hazelcast implementation of the datastore.

Adding the dependencies

The following dependencies are required in the pom.xml

<project ...>
  ...
  <dependencies>
    ...
    <dependency>
      <groupId>com.hazelcast</groupId>
      <artifactId>hazelcast-all</artifactId>
      <version>${hazelcast.version}</version>
    </dependency>
    <dependency>
      <groupId>com.blueriq</groupId>
      <artifactId>blueriq-component-api</artifactId>
      <version>${blueriq.version}</version>
    </dependency>
    ...
  <dependencies>
  ...
</project>

Implementing the IExternalFlowStore Interface

Please make sure that HazelcastExternalFlowStore component is scanned by Spring.

package ...;

import com.blueriq.component.api.store.externalflow.IExternalFlowStore;
// other imports ...

@Component
public class HazelcastExternalFlowStore implements IExternalFlowStore {

  private final IMap<String, Serializable> map;

  public HazelcastExternalFlowStore() {
    ClientConfig config = new ClientConfig();
    // configure Hazelcast properties here
    HazelcastInstance hazelcastInstance
      = HazelcastClient.newHazelcastClient(config);
    map = hazelcastInstance.getMap("blueriq");
  }

  @Override
  public void delete(String key) 
    throws ExternalFlowStoreException, IllegalArgumentException {
    if (isInvalid(key)) {
      throw new IllegalArgumentException("Invalid key.");
    }

    try {
      map.delete(key);
    } catch (Exception e) {
      throw new ExternalFlowStoreException("Something went wrong", e);
    }
  }

  @Override
  public <T extends Serializable> T get(String key, Class<T> valueType)
      throws ExternalFlowStoreException, IllegalArgumentException {
    if (isInvalid(key)) {
      throw new IllegalArgumentException("Invalid key.");
    }

    try {
      Serializable storedValue = map.get(key);
      if (storedValue == null) {
        return null;
      }

      if (valueType.isInstance(storedValue)) {
        return valueType.cast(storedValue);
      }

      throw new IllegalArgumentException(
          String.format("Cannot cast from %s to %s.", 
            storedValue.getClass(), valueType));
    } catch (Exception e) {
      throw new ExternalFlowStoreException("Something went wrong", e);
    }
  }

  @Override
  public boolean hasKey(String key) 
    throws ExternalFlowStoreException, IllegalArgumentException {
    if (isInvalid(key)) {
      throw new IllegalArgumentException("Invalid key.");
    }

    try {
      return map.get(key) != null;
    } catch (Exception e) {
      throw new ExternalFlowStoreException("Something went wrong", e);
    }
  }

  @Override
  public void set(String key, Serializable value) 
    throws ExternalFlowStoreException, IllegalArgumentException {
    if (isInvalid(key)) {
      throw new IllegalArgumentException("Invalid key.");
    }

    try {
      map.set(key, value, 1, TimeUnit.MINUTES);
    } catch (Exception e) {
      throw new ExternalFlowStoreException("Something went wrong", e);
    }

  }

  private boolean isInvalid(String key) {
    // define what an invalid key means
    return false;
  }

}