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Showing posts from January, 2011

What is HyperGraphDB?

HyperGraphDB (http://www.hypergraphdb.org/) is a storage framework based on generalized hypergraphs as its underlying data model. Borislav Iordanov is a creator for HyperGraphDB. It originated from an AI project (http://www.opencog.org) and its power is partly in its data model and in its open-architecture framework.

Two unique features of HyperGraphDB:
Higher-order, n-ary relations are unique to HyperGraphDBOpen-architecture: there’s a very strong “frameworky” aspect to HyperGraphDB, it’s not a black box with fixed, restrictive data-model. The storage layout is open and documented. One can plugin customized indexing, customized type handling, customized back-end storage, customized distribution algorithms etc.A HyperGraphDB database is a generalized graph of entities. The generalization is two-fold:
Links/edges "point to" an arbitrary number of elements instead of just two as in regular graphs. Links can be pointed to by other links as well. Feature Summary:
Powerful data mode…

Getting Started with MongoDB

Introduction:
The name MongoDB comes from "humongous". Its most notable key-features are: FLOSS (Free/Libre Open Source Software), horizontally scalable, very fast, schema-less, document-oriented, written in C++ with native drivers to most programming languages out there e.g. C, C++, C# & .NET, ColdFusion, Erlang, Factor, Java, JavaScript, PHP, Python, Ruby, Perl, etc. belongs into the so called NoSQL category of DBMSs. The way it works is so that it manages collections (the equivalent to tables in RDBMSs) of JSON (JavaScript Object Notation) documents (the equivalent to rows in RDBMSs) which are stored in a binary format referred to as BSON (Binary JSON).

Following is a comparison of MySQL, Oracle, PostgreSQL (DBMSs) with MongoDB (NoSQL):

MySQL, PostgreSQL,...
----------------------
Server:Port
- Database(s)
- Table(s)
- Row(s)
- Column(s)

- Index
- Join

MongoDB
--------
Server:Port
- Database(s)
- Collection(s)
- Document(s)
- Field(s)

- Index
- embedding and linking

BlackBerry Application Development

BlackBerry is a fun mobile platform to start with and it is based on J2ME. Don't think of mobile app development as something new. Till now you might have deployed web apps on web servers and now you will deploy on black berry simulator. As you are a Java developer you will feel at home with BlackBerry too.

First, decide for which OS or mobile model you are going to development. If not sure then avoid working on latest version of OS (OS 6 is the latest). Reason being whatever is developed in OS 6 will only work with latest compatible phones. Few latest APIs may not work in older phones so make sure you start development using OS 4.7 or 5.0 version.

To start BlackBerry app development you need to do following:

1. Download and install BlackBerry eclipse plug-in and its free. Link: http://us.blackberry.com/developers/javaappdev/javaupdate.jsp (If you have done already, run sample and see if simulator is working properly)

2. To deploy app on real device you need to pay onetime fee of …

Upload file using servlet

I was looking for easy way to upload excel file from JSP. I came across very good link which contains working example. I had to make few changes in servlet code but thanks a lot for the information provided at the link. See following link for more information.

Title: Servlet File Upload Example
Link: http://www.jsptube.com/servlet-tutorials/servlet-file-upload-example.html