Open Source is the current rave of the software industry. It's making great progress because of Linux - an operating system that truly works. People are all a-bustle about Open Source and are beginning to look for an Open Source option appropriate to all their application needs. This raises questions: How can you take advantage of Open Source when you're building applications? Are there any dangers involved in using Open Source?

As often happens, people are taking the extreme route and want to do everything in Open Source because they don't have to pay for it. That's logical thinking. You can't beat free! But, are there other costs involved besides monetary ones? Certainly Open Source applications alleviate spending, but shouldn't there be a balance in everything we do? What's that optimal balance between Open Source and traditional proprietary software applications? The purpose of this article is to explore both Open Source and proprietary software, and then reveal effective tactics for building applications with Open Source software.

Open Source Versus Proprietary Software
Sometimes a price tag with the word "free in it is more than a good thing - a blessing in disguise. What a deal! Other times, what appears to be good, turns out to be quite problematic. Herein lie the dangers of Open Source software (OSS). As far as OSS is concerned, it's important to evaluate your needs and determine whether "free" will really be free, or if it's a better idea to invest in the stability and support of commercial software.

It's a reasonably wise and safe move to use OSS as a foundation. An infrastructure can be built on top of it. In fact, many companies do this with network servers and some of the DNS services. Linux is especially good as a foundation for such low-level utilities. We'll touch more on this later.

As you move to higher-level utilities, such as mail servers, it becomes more advantageous to go with commercial software. Why? Stability and flexibility. You could take the cheap route. But, your operation won't work well, which is why it's highly recommended - and worth the investment - to buy commercial software.

The same concept applies to application servers. When you build an application, sure, you can go with Open Source. But, if you really want the performance scalability of a big application, you have to go with a commercial application server. And when it comes to new applications, new languages, or coding in any new form, stick with proprietary software to avoid bugs.

If a line were to be drawn between when you should and shouldn't use free software, it would be this: use it for basic server operating systems, network support, and directory services. These are all utilities for which OSS is a safe, wise choice because many IT-related applications are well used and well tested. The programs that run on top of these utilities are what you should buy. Certainly, if you venture into the realm of "free" for your entire infrastructure by using public domain software then - and by all means, the option is there and yours for the taking - but, heed this warning: you will be setting yourself up for many headaches.

Maintenance & Support for OSS
Over the years, Linux has become quite stable. Its maintenance and support is practically a non-issue because so many people know about it. This situation is atypical of other Open Source software. Only when enough people know about it can enough people maintain it. Typically, high-level OSS applications aren't well known. Only segregated groups of people truly know them. Therefore, it isn't likely you'll find someone to depend on to fix it if it breaks.

Effective Tactics for Building Applications with OSS
Let's paint a picture. Think of each part of your infrastructure as a separate building block. The bigger the block, the less specialized it is and the more people are involved in its development. Take a look at Figure 1. The bottom block - the foundation - is the operating system. Everybody uses it. To some extent, as you build atop the foundation, the programs become more specialized. The next layer consists of blocks that are slightly smaller, which reflects less interest among developers. Each block represents various servers, such as applications servers or network servers. The top layer is made up of even smaller blocks. Each block represents an application and from a development perspective a specific niche.

The more knowledgeable people the lesser the risk.
The point is that the more people who know an OSS program, the lesser the risk you take using it. Most likely you have people on your own team who know it and can solve any problems you come across. But, as you build an infrastructure and the programs get more and more specialized and less and less people are interested in developing the application, the higher your risk in using Open Source. This is when it becomes wise to invest in support from a commercial company.

The broader the subject the greater number of knowledgeable people.
Another point is quality. When any subject is broad as with an operating system, there are a lot of developers who can work on it and maintain it. But when it becomes specified there are only two or three people who will work on it in their free time. Quality is hard to get. When it comes to Open Source, high quality can be had with programs in general use because there's a critical mass of people working on them. But high quality can't be achieved for the more specialized programs because public domain software doesn't draw enough people to work on it and improve it.

The more interest and hours invested the more refined the product.
The public domain has limited power. The power that exists is derived from the time invested by a group of people who work in the industry. Many people must be interested in a program for them to contribute their time. The key word here is "many." Enough hours must be accumulated to develop and refine a product.

How do you determine whether you should use OSS?
The answer might sound trite, but it comes now to weighing the power of the Open Source product. Do you have knowledgeable resources on your team to solve any problems that occur? Is the product popular enough to be high quality? This is where you draw the line. If your answers to the questions are "yes," go for Open Source. If the answers are "no," turn to commercial software.

OSS Applications at Work
Commercial software isn't going away. But that doesn't mean that Open Source has not had an impact on it. Sooner or later there's going to be a very good Open Source operating system for the desktop and devices because there are enough people interested in making that happen. That's something that's likely to bite into Microsoft - except its more specialized products. IBM, on the other hand, isn't as likely to be affected, since its focus is more on specialized products. That's why IBM supports and doesn't fight public domain software. What about the smaller ISVs? How does Open Source affect them? And what does all this have to do with you? Independent software vendors can actually benefit from OSS. Commercial developers can learn much from the experience of developers who work on Open Source. In fact, it's quite useful to take pieces of public domain software and use them as models. Doing so makes it relatively easy to build products for market and support them - specialized products that you need.

A couple of great examples are two different automated error prevention products. Jtest, which is a powerful static analysis and unit test tool for Java, uses an Eclipse-based GUI, Junit, as its testing framework, and some OSS metrics tools. Another example is SOAtest - a tool for testing Web Services on the client and server side. It uses the Apache Xerces XML parser and SOAP library, Xalan XSLT processor, GNU Regex Expression Library, and DNS Java tools. So all in all, it's safe to say that Open Source can create great opportunities for commercial vendors - especially the smaller independent companies.

Conclusion
The fact is that when Open Source software is well known and in knowledgeable hands, it can be a wise choice - especially for basic server operating systems, network support, and directory services. Leave the more specialized Open Source programs to commercial companies. They can refine the code and bring new in-demand products to market that are reliable and come with support. In short, be wise. Take time to investigate and figure out whether free is really free, or if an investment is the better option.