Data Format Description Language (DFDL) v1.0 Specification
OGF Proposed Recommendation GFD-P-R.174, January 31, 2011
DFDL is needed in an era where there are so many standard data formats available, because there are a number of social phenomena in the way software is developed that have lead to the situation today where DFDL is needed to standardize descriptions of diverse data formats.
First, programs are very often written speculatively, that is, without any advance understanding of how important they will become. Given this situation, little effort is expended on data formats since it remains easier to program the I/O in the most straightforward way possible with the programming tools in use. Even something as simple as using an XML-based data format is harder than just using the native I/O libraries of a programming language.
In time, however, it is realized that a software program is important because either many people are using it, or it has become important for business or organizational needs to start using it in larger scale deployments. At that point it is often too late to go back and change the data formats. For example, there may be real or perceived business costs to delaying the deployment of a program for a rewrite just to change the data formats, particularly if such rewriting will reduce the performance of the program and increase the costs of deployment. (It takes longer to program, but at least it's slower when you are done ☺)
Additionally, the need for data format standardization for interchange with other software may not be clear at the point where a program first becomes 'important'. Eventually, however, the need for data interchange with the program becomes apparent.
The above phenomena are not something that is going away any time soon. There are, of course, efforts to smoothly integrate standardized data format handling into programming languages. Nevertheless, we see a critical role for DFDL since it allows after-the-fact description of a data format.
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