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Closed 10 years ago.
I'm looking for a message-queue api/library for managing queues locally in java. What do you suggest to me?
I don't want to use a Client/Server architecture, I'd rather do it locally to do not add a failure point. Also, scaling out isn't a necessary for now.
[EDITED]
Is there a Message-Queue API/Library for managing queries locally in java?
Features: 1) Persistent Queues; 2) Queue management; 3) Thread-safe
Once upon a time, I looked for persistent queues and could not find good implementation. I think you have 2 options:
use a JMS implementation
use an embedded key-value database with a Map implementation, like JDBM3. Emulate a queue as a Map, where id is assigned at the moment of put as previous max id +1, and take/poll/get reads the value with minimal id.
Related
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Closed 9 years ago.
I'm looking for a database which would allow me to store most of the objects in the memory. Basically I want to store in the memory everything except some rarely used data (history of changes, etc).
I'm looking for:
simple API for java, preferably non-ORM
ACID is not required (well, D is)
some support for queries, but nothing fancy
The idea is to operate on a model in memory, store any "command" mutating the model in the database, periodically synchronize model to database (like prevayler does)
Which database matches my needs? (I'll use postgres or H2 if there isn't anything simpler).
You need one of object databases: http://en.wikipedia.org/wiki/Comparison_of_object_database_management_systems
You should use Terracotta. It is usually used for caching, but its exactly what you are asking for, except that it's "querying" abilities are sparse.
Update:
The previous link was to their "enterprise" edition, but they have the open source project Ehcache which fits your needs, and their enterprise product is based on.
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Closed 9 years ago.
I am looking for a website where I could practice Java coding assignments that you often get on job interviews. I mean those tasks where you need to calculate primitive numbers, implement some sorting, or do something with an Array, List or a Map. I'm quite experienced java developer, but such tasks can sometimes be tricky :)
Do you know any free websites that could help?
Thanks.
Go to interviewstreet. Companies often use it as first technical screen
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Closed 10 years ago.
I was wondering if there is any api or library available that provides a taxonomy for a given term in jSON.
For instance, if the argument is Shoes, it should return a data structure consisting of all the synonmys or types of shoes like Boots, Flip-flops, Slippers, Stilettos, and so on..
Thanks :)
Your best bet is to use the Java API for WordNet
http://lyle.smu.edu/~tspell/jaws/index.html
You can wrap this inside a servlet and call it via jquery in your application.
JSON is not typed by itself, you have to use another notation to add type to the data encoded in JSON. JSON-LD for example allows to add the concepts of linked data/semantic web to the json data. Using this information it is possible to query the taxonomy that defines the structure of the data.
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Closed 10 years ago.
I need to represent quite some data for which a cube grid would just make perfect sense. Does such a thing exist for Swing?
A "cube grid" looks like this (and it's really darn impressive):
http://www.smartclient.com/smartgwtee/showcase/#cube_analytics
You can try JIDE Pivot table. I think it is pretty close to what you need.
More info at http://www.jidesoft.com/products/pivot.htm
Try out the free and simple Java swing component https://github.com/aristsoft/jpivot to visualize the data in multidimentional view.
It designed just to show the data, so it don't doing the data aggregation any kind itself.
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Closed 10 years ago.
I'm going to develop my own message queue implementation in Java and I need to distribute the queue content across multiple servers so that it would provide reliability and redundancy.
In addition to that I need to persist the queue content into the file system.
Can somebody tell me what is the most suitable distributed data structure implementation to hold my queue content?
Note: That data structure must provide me the message ordering facility. That means I need to receive messages according to the order they arrived. Also while reading a message, it should be in a 'locked' state so that other consumers cant read it until the first consumer completes the reading process
Have you looked at any of the many existing message queue implementations for java? Wikipedia lists many open source implementations. It seems to me that an existing, thoroughly tested message queue is the best place to hold your queue content :)
If you absolutely want to write your own, then starting with the open source solution that most fits your needs would probably answer most of your questions about what data structures work well.