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I am building an centralized inventory system using java(swing and servlets). I have local data stored in desktop application which needs to be in sync with an server.
Requirement is:-
1) When local stores are online ,data must be synchronized with server in real time.
2) Local store will have access to their data even if they go offline, but when they go online all local changes must be reflected on server.
I got across microsoft sync framework which is exactly what I need. Is there something equivalent in java?
There are a number of Open Source Replication and Synchronization Tools Written in Java:
Of those listed the following might handle your "offline" requirement:
SymmetricDS – SymmetricDS is a web based, database independent, data synchronization system. Beyond replicating tables between relational databases the software incorporates functionality to handle a large number of databases, manage low-bandwidth connections and work within periods of network outage. The system supports two way replication, guaranteed delivery and multiple active schemas.
I'm sure the others are worth a quick look as well.
See also Strategy for Offline/Online data synchronization for some great discussion on things to think about/watch out for.
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I have an application that makes heavy use of JMS (OpenMQ at the moment). We need durable persistence on some of the messages in flight, and that needs to survive the database blowing up, so we've moved the broker's storage to JDBC as it means that we can replicate and back up a database cluster and know that both the relational and message stores are at the same point in time when restoring from a backup.
We're finding that OpenMQ's JDBC backed storage method is very slow (tens of messages/s). Are there any brokers out there that perform well using JDBC? We're ideally after thousands of messages/s, but can probably tolerate 100s/s.
Backing a messaging server with JDBC is never going to be as fast using an optimized message store. Most of the time, a broker simply writes messages to disk but do not read. A traditional database is often more optimized towards read performance and complex queries than maximum write performance.
ActiveMQ with replicated LevelDB seems to be a decent fit for your requirements. It will automatically replicate the message store to "slave" brokers while still allow high throughput.
Another option would be to dig into the database part rather than the broker part. You will probably notice similar patterns with other brokers as well, if you hook them up to JDBC. Is there a way to make your database work more efficient with write performance? SSD disks? Settings? etc. As I said, by default, most databases are tweaked towards read performance and performance of complex queries.
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Is there a way to find an online Hadoop database and practice on it using Java?
I found that you can practice on www.gethue.com, but I don't think you can do it using java.
Thank you
You can try Cloudera Live.
It's in beta, but seems to work pretty well.
I made a small list of free offers enabling you to manage your own hadoop cluster. It's not technically an available database, but you can fill these clusters with the data you want.
Here is the list :
Microsoft Azure HDInsight : they offer you 150€ to spend on their products. You can rent a Hadoop cluster and work on it.
Qubole : they give you preconfigured Hadoop clusters, you have 75 computing hours for free
Joyent : you can have one VM for free for a year.
You may also try amazon's Elastic Map Reduce, although I'm not sure this specific offer is included in their free trial. An advantage of using it is you can access free datasets more easily (for instance, this one).
Please also note that all these services (except Qubole) require a credit card for registration.
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My use case is to develop a telecom billing in Java. Knowing that i must calculate 60 000 bills per day, i need to distribute the load of the calculation on several(three or four) servers.
That is called Clustering ( correct me if it's wrong).
My Solution is to develop a middleware that will distribute for each server a list of client who should be charged, and then each server will calculate the bill and generate a PDF file.
Could you give me some more ideas, for example which Java class do i need, or which methods shall i use.
Thank you
if you use jms (maybe as part of using j2ee?) you could simply use a jms queue for this - have several consumers (mdbs in j2ee) on every node, and send the list of clients to process to the queue.
the queue will guarantee that every message (==client) will be handled by one and only one listener, and since each node will have a limited number of listeners you get work distribution this way.
try apache hadoop.
http://hadoop.apache.org/
It will be perfect for this kind of divide and conquer tasks.
Spring batch will be a good fit for that: http://projects.spring.io/spring-batch/
It has support for automatic restart of jobs and partitioning ( distribution over many machines ).
There is an entire chaptr in the docs dedicated to scaling/distribution: http://docs.spring.io/spring-batch/2.2.x/reference/html/scalability.html
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what is a better nosql database for creating a system to record advertisement data for about 50 to 200 millions insert per day, the aggregation of the data will be used to show the pattern of how users engage with the ads. I really like MongoDB but it seems that major industry players are picking Riak for the job. It seems that Mongo had to flush some caveats in last 2 releases and the current version seems to be pretty good for the job, any idea?
It seems mongodb with hadoop (http://docs.mongodb.org/ecosystem/tutorial/getting-started-with-hadoop/ ) fits your data requirements. You can store data in mongodb and run aggregation jobs (map/reduce) on hadoop cluster.
I'd use Java Berkeley DB from Oracle.
Very powerful and easy to use Open source but not free.
This is not a type of question that could be answered as Product1 or Product2. It is just too small amount of information given. There is no info about the environment, where the system will run, what type of information will be inserted, how are you going to aggregate it.
The best way is to try:
write a test using Product1,
write a the same thing with a Product2
start inserting the data which looks as close as possible to the
data you are assuming to get in real environment
make measurements of speed and whatever factors you need
and only based on that you will be able to determine what suits you
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I'm looking for a java framework for handling RDF data in a graph database. The main purpose is to manage several versions of a RDF graph and all versions must be accessible all the time. So version tracking is an important feature I need. Is there any tool that supports this out of the box without to develop it from scratch?
The only tool I found related to this topic is OpenAnzo, but the website is no longer available.
To add a timestamp to the nodes should not be the problem, but also an easy access via SPARQL or another query language should be possible.
You might be interested in the Alibaba Auditing Repository and Auditing SAIL, which are Sesame extensions for RDF data change tracking and provenance (disclosure: I'm on the Sesame development team).
I don't know of any existing database solutions which provide versioning out of the box. Your best bet is to work on a custom scheme for your application over an existing database. For example, you could put different versions of the data into named graphs and use those as the versioning structure, then using from/from named in your query be able to query some or all different versions of your data. You could also try and works something up with reification which would give similar results.