Hi Ralph,
A session is intended to be a long-lived, i.e., application-scoped object.
You only need one session per cluster. I think what you are doing with
the @Singleton is fine. In my opinion though, EJB really does not offer
much value when working with Cassandra. I would be inclined to just use CDI.
Cheers
John
On Tue, Jun 11, 2019 at 5:38 PM Ralph Soika <ralph.so...@imixs.com> wrote:
> Hi,
>
> I have a question concerning the Cassandra DataStax Java Driver in
> combination with Java EE and EJBs.
>
> I have implemented a Rest Service API based on Java EE8. In my application
> I have for example a jax-rs rest resource to write data into cassandra
> cluster. My first approach was to create in each method call
>
> 1. a new Casssandra Cluster and Session object,
> 2. write my data into cassandra
> 3. and finally close the session and the cluster object.
>
> This works but it takes a lot of time (2-3 seconds) until the cluster
> object / session is opened for each request.
>
> So my second approach is now a @Singleton EJB providing the session
> object for my jax-rs resources. My service implementation to hold the
> Session object looks something like this:
>
>
> *@Singleton*
> *public class* ClusterService {
> private Cluster cluster;
> private Session session;
>
> @PostConstruct
> *private void* init() throws ArchiveException {
> cluster=initCluster();
> session = initArchiveSession();
> }
>
> @PreDestroy
> *private* void tearDown() throws ArchiveException {
> // close session and cluster object
> if (session != null) {
> session.close();
> }
> if (cluster != null) {
> cluster.close();
> }
> }
>
> *public* Session getSession() {
> if (session==null) {
> try {
> init();
> } catch (ArchiveException e) {
> logger.warning("unable to get falid session: " +
> e.getMessage());
> e.printStackTrace();
> }
> }
> *return* session;
> }
>
> .....
>
> }
>
>
> And my rest service calls now looking like this:
>
>
> @Path("/archive")
> @Stateless
> *public class* ArchiveRestService {
>
> @EJB
> ClusterService clusterService;
>
> @POST
> @Consumes({ MediaType.APPLICATION_XML, MediaType.TEXT_XML })
> *public* Response postData(XMLDocument xmlDocument) {
> Session session = clusterService.getSession();
> session.execute(....);
> ...
> }
> ...
> }
>
>
> The result is now a super-fast behavior! Seems to be clear because my
> rest service no longer need to open a new session for each request.
>
> My question is: Is this approach with a @Singleton ClusterService EJB
> valid or is there something I should avoid?
> As far as I can see this works pretty fine and is really fast. I am
> running the application on a Wildfly 15 server which is Java EE8.
>
> Thanks for your comments
>
> Ralph
>
>
>
>
> --
>
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--
- John
