A composite application is a quick, simple, "no code" SharePoint application intended to provide a solution to a particular business problem. It is constructed by a SharePoint Power User possessing an intimate knowledge of the problem to be solved. A composite application draws upon any or all of the SharePoint features explored in this book, melding them together until a satisfactory solution is produced. There is no right or wrong way to do this. Composite applications are normally developed through "trial and error"—prototyping and evaluating the application until something useful is produced.
The best types of composite applications to create on SharePoint are those which require collaboration, the sharing of documents, tasks, electronic forms, and simple workflows. SharePoint provides extensive out of the box tools and functionality to do this.
Powerful as composite applications are, it is also important to appreciate what they are not and to know where to draw the line between an informal Power User development and a formal software engineering project, with all the project management, governance, rigorous process, costs, and resource, which that entails.
Please don't read this chapter thinking that you can construct a new banking system, sophisticated payroll, or accounting solution as a composite application. You can't. You may be able to build solutions to those problems on SharePoint, but you will need a formal project, team-based development, designs, test plans, and lots of resources to be successful. You will definitely need to write code and will more than likely need to involve a whole range of other technologies as well. SharePoint may well make building those applications easier too, but that is not what this book is about.