SCI-Flex and Open Source

When planning SCI-Flex, we had to decide on one major factor. That is the development model that we are going to use. We chose Open Source as we believe that it would benefit a larger audience. The SOA and CEP combination being a novel idea is another fact that we believe Open Source will be the best possible way to unleash it's true potential.

The level of research we are expecting to put into this project is immense. However, this doesn't guarantee that the SOA+CEP combination is a true success and does not confirm whether it meets the requirements of a potential user. The Open Source approach gives the SCI-Flex project the ability to be used and utilized in an efficient manner to uncover the true power of CEP systems in the presence of a well organized SOA environment.

Still at the beginning of the project, we have not yet planned about distributions and deployment alternates. Thus, the prime focus remains still in rather What should be done? rather than How should it be done?. As a starting point we've made the source code for SCI-Flex available @ Google Code. You are free to go ahead and give it a try. Further involvement with the project development activities are made possible through the project's mailing lists. Discussions are welcome on the SCI-Flex developer mailing list.

Several Open Source projects such as Apache HTTP Server, Linux Kernel, and Mozilla Firefox have made it the forefront as globally renowned software. We the SCI-Flex project team would like to see someday, our project being a globally renowned software in the SOA+CEP sphere.

Open Source Licensing

Yesterday we had a meeting with Dr. Sanjiva Weerawarana founder/CEO of WSO2 where we were in a position to know lot about open source licensing. We happened to know lot about how a particular license would obtain and how to donate to a particular project having different license like Apache2 and GPL V3 etc. With having GPL license a particular project is like a gift from the inventors to the community which serves for further improvement. If they add new stuff or modify some code they have to give it back the inventor. Those are the main stuff we focused yesterday.

I will explain bit about open source licensing a bit further. An open source license is a copyright license for computer software that makes the source code available under terms that allow for modification and redistribution without having to pay the original author. Such licenses may have additional restrictions such as a requirement to preserve the name of the authors and the copyright statement within the code. One popular (and sometimes considered normative) set of open source software licenses are those approved by the Open Source Initiative (OSI) based on their Open Source Definition (OSD).

Licensing is more critical for developers. The beauty of the open source license is its assignment of copyright (and patents, if held by the author) to the end user and re-distributor without compensation. Thus, for example, the Web professional can leverage an application at no cost, use it in the course of commercial business, and profit by it in interactions with their customers.

Often, in the course of their work, developers discover that the software doesn't quite meet their needs: it lacks a given capability. To resolve the problem, the developers may decide to build new functionality. This is the epitome of the open source license: there are no strings attached! The new, modified solution can be redistributed under the original license (or separate from it, as we will see shortly) depending on the license selection. The result of this exercise is that hundreds of new open source software packages are available at large.

Why we chose Esper

Esper, is an open source CEP implementation, developed by EsperTech. Prior to building an SOA infrastructure that would utilize the true power of CEP systems in an SOA environment, we did a great deal of research into existing products. We identified two streams of possible candidates,

1. Commercial
2. Open Source

When talking about Open Source CEP systems, Esper and Nesper are two popular projects that outrun many others by both capability and portability. The portability of Esper was a major concern since the CEP system itself will be worthless if it can't easily be ported into an SOA environment. Our decision to use the Apache Synapse ESB was another reason to what made us consider Esper the most likely candidate for the CEP system that we are going to use in our project.

Paul Fremantle, who's one of the mentors of this project has done some initial research on connecting Synapse and Esper which was perhaps one of the major reasons behind our choice.

AXIOM support
AXIOM or Axis Object Model is an object oriented mechanism of handling XML which is proven to be much faster than the traditional marshelling of textual data. Esper's support for AXIOM and especially capabilities in processing AXIOM based events is another fact that makes Esper one of the very likely candidates to work in an environment driven by the Apache Axis2 architecture.

Java APIs
Esper's Java APIs have been well tailored making portability very easy and least complicated. This makes it easier for us to use it in our venture of creating an SOA infrastructure which exposes a CEP system.

Popularity
Our decison to go ahead with an Open Source project was another reason to why we chose Esper, since it is perhaps the most popular Open Source CEP system which is available as of today. Popularity introduces many plus points as our target audience will be more familiar with Esper and it's API compared to another Open Source CEP implementation.