I would like to use Cassandra NoSQL server with an RDBMS in Play 2.3.0!
Started to build it up using Kundera, according to this tutorial:
http://recipes4geeks.com/2013/07/06/play-nosql-building-nosql-applications-with-play-framework/
It works fine, and I can use it with pure mysql-jdbc connection, and it also works if I use jdbc for Cassandra connection and JPA for MySQL..
.. but the goal is to use a persistence framework, without handling basic JDBC stuffs!
It looks, this problem was mentioned in the link above:
Caution: javaJdbc app dependency downloads hibernate-entitymanager jar file that interferes with Kundera. Make sure you remove this app dependency which is by default present.
If I remove the hibernate-entitymanager from the dependencies, the project runs, but when it wants to call the Persistence.createEntityManagerFactory("mysql") method, Play says: No Persistence provider... as it was expected.
If I keep the hibernate-entitymanager in the dependencies list, beside the kundera client, the Play server simply shuts down.
Is there a possibility to make it work or I have to replace Kundera?
DataNucleus JPA supports persistence to all RDBMS around (via JDBC), as well as to Cassandra, MongoDB, Neo4j, LDAP, HBase and many others. It's Cassandra support seems to be for all latest versions and uses the native Cassandra driver (not JDBC) and so no chance of conflicts like above. You can read up on it at
http://www.datanucleus.org
Caution: javaJdbc app dependency downloads hibernate-entitymanager jar file that interferes with Kundera. Make sure you remove this app dependency which is by default present.
This should not be an issue with latest Kundera releases. Also you can email sample project at kundera#impetus.co.in in case looking for quick support.
Related
I am on Sling 11, which uses Jackrabbit Oak as content repository. I was wondering how to set up Sling to store the JCR repo on an RDBMS (DB2 to be specific).
I found this link on Jackrabbit Persistence, but looks like it does not apply to Oak and Oak documentation is mostly about MongoDB.
Also found an implementation of a Cassandra Resource Provider, although that seems designed to access specific paths mapped to Cassandra without using Oak.
Thanks,
Answering here but credit goes to Sling user's mailing list
Package the DB driver in an OSGi bundle
Download Sling's starter project
In boot.txt add a new running mode (in my case oak_db2)
[settings]
sling.run.mode.install.options=oak_tar,oak_mongo,oak_db2
Download Sling's datasource project and compile it.
In oak.txt configure the running mode (this will load the bundles for you in Felix):
[artifacts startLevel=15 runModes=oak_db2]
com.h2database/h2-mvstore/1.4.196
com.ibm.db2/jcc4/11.1
org.apache.sling/org.apache.sling.datasource/1.0.3-SNAPSHOT
And set-up the services that will manage persistence:
[configurations runModes=oak_db2]
org.apache.jackrabbit.oak.plugins.document.DocumentNodeStoreService
documentStoreType="RDB"
org.apache.sling.datasource.DataSourceFactory
url="jdbc:db2://10.1.2.3:50000/sling"
driverClassName="com.ibm.db2.jcc.DB2Driver"
username="****"
password="****"
datasource.name="oak"
Create a 'sling' named database.
run with java -jar -Dsling.run.modes=oak_db2 sling-starter.jar
I am looking for someone that can explain me in simple terms with written instructions how to create a JDBC in PostgreSQL (I am losing my mind with this). I found other answers in this page and others but I couldn't follow them.
I am no programmer, so I didn't undertand any of the instructions of how to do it in webpages and forums -the method mentioned was configuring the classpath environment variable in the command prompt but I got stuck in the command prompt, I think I have to configure the Java console or something.
I am learning some data mining and I wish to connect to some databases in order to practice. I suppose that for someone knowledgeable in this area this should be an easy job.
I prefer to install a driver in postgresql and not using a bridge.
Thanks a lot!
The phrase “how to create a JDBC” makes no sense.
You need to learn some basics first. Be clear on what JDBC is (a standard for connecting or mediating between a database and a Java app), what a JDBC driver is (a particular implementation of JDBC for a specific database.
There are four types of JDBC drivers, the Type 4 (pure Java) being most common in my experience.
For any particular database, you may find there are zero, one or more drivers implemented and available. Some are free-of-cost and open-source, some are not. For example, in Postgres there are two open source drivers, the classic one and a newer rewrite-from-scratch one, as well as some commercial products.
A JDBC driver is only useful when trying to connect a Java app to your database. That may be your own app you are writing, or a finished app you obtained such as a database-administration tool.
You must have a Java implementation installed on your computer, such as one from Oracle or from the OpenJDK project, or from another vendor such as Azul (Zing & Zulu).
You need to learn about the Java Classpath, the list of all the folders where the JVM will be looking for Java classes and JAR files. Read the Oracle Tutorial. The easiest way to go is to drop your JDBC driver JAR into an already existing folder on the Classpath, so you do not need to twiddle with setting the Classpath. For example, on a Mac you could drop your driver into /Library/Java/Extensions.
The JDBC driver sits between the database engine and the Java app. You do not install the JDBC driver into the database engine, such as your Questions mentioned, “install a driver in postgresql”.
[Postgres] ↔ [JDBC driver] ↔ [JVM] ↔ [Java app]
We have a webapp that is currently running on one instance of Apache Tomcat with one database instance, but the increase in traffic will soon (probably) force us to resort to load-balancing several webapp instances, and we've run into a problem that seems to have no easy answer.
Currently our JDBC DataSource is configured as Resource-local, rather than Transactional, and after some searching, everyone recommends to use Transactional, which requires the use of a JTA provider. No real justification is used for why I don't just stick with the current scenario where we have a servlet filter catch any unhandled exceptions and rollback the active transaction. Besides that the only one I've found that is just a JTA provider (not with 5 more JEE technologies combined) and is still maintained is Bitronix. The other alternative is to move out of Tomcat and use Glassfish, since it is a full Java EE platform, and we also use JavaMail, JPA and JAX-RS.
Only one transaction scenario uses Serializable isolation level.
As for the database, we may be looking too far ahead to think of distributed storage like Postgres-XL or pgpool, but if we make the wrong choice now it will be harder to fix later.
My questions are as follows:
Do synchronous database replication tools and JTA complete each-other, hinder each-other or just perform the same consistency checks twice?
Do we need JTA if we only have one database, but multiple webapp instances?
Do we need JTA if we have multiple database and multiple webapp instances?
Should we just switch to Glassfish or something like TomEE?
Supposedly there are ways we can keep using Hibernate as our JPA under both. It would be tedious to have to rewrite all our native queries to use positional parameters because EclipseLink and OpenJPA don't support them. That little extra feature makes Hibernate worth choosing above all other JPAs for me.
Pardon if I can't give more pointers, but I'm really a noob at wildfly. I'm using version 9.0.2.
I have deployed jbpm-console, drools, and dashboard - no problems here. I restart wildfly using the jboss CLI, and when I login again, the repositories won't appear in the web interface or on disk (atleast nothing that grepping or find will show).
I'm using the H2 database. I'm not even sure where to look, does anyone have any idea?
Thanks in advance!
After enough reading through the docs, it would seem that it's necessary to configure jBPM to persist. From the docs:
"By default, the engine does not save runtime data persistently. This means you can use the engine completely without persistence (so not even requiring an in memory database) if necessary, for example for performance reasons, or when you would like to manage persistence yourself. It is, however, possible to configure the engine to do use persistence by configuring it to do so. This usually requires adding the necessary dependencies, configuring a datasource and creating the engine with persistence configured."
https://docs.jboss.org/jbpm/v5.3/userguide/ch.core-persistence.html
Can I expect that I replace the Java .jar files and client-side .js files of version 2.4 or 2.5 of CometD in an existing software that is running fine, with the same files in 2.9.1 and it all runs the same?
1- Are the API of CometD exactly the same on all 2.x versions?
2- Is there an upgrade guide that I can use?
Also, I noticed that on the client side, CometD 2.4/2.5 is not AMD and is a single file, but on 2.9.1 it is AMD-based. Is there a single .js file that contains all client-side CometD code?
You can expect upgrades from 2.4/2.5 to 2.9.x to be either without problems, or requiring very little changes, so yes, it should be typically be a drop-in replacement.
While you're upgrading, I suggest to move to CometD 3. You can find here the migration guide from CometD 2.x.
CometD 2.9.x is AMD compliant, and the single file you should include in your HTML is typically org/cometd.js along with a binding for a toolkit (either jquery or dojo).
If you use extensions, you should add also those, see for example http://docs.cometd.org/3/reference/#_primer, or if you don't want to use Maven, this other section.
Follow also the tutorials, that should get you going.
Full documentation link.