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As one can see from the above, there are a number of algorithms that taken together implement DFDL's unparsingthe Daffodil unparser runtime. Note that the above are all about the runtime mechanism. This doesn't really discuss the schema compilation algorithms needed to support these runtime behaviors.

Furthermore, all of the above mechanisms can be composed recursively - that is, an element whose length is needed for an OVC, that element may be of complex type, and within that complex type may be other OVC elements, referring to yet later elements. All these must compose properly so that a DFDL format that contains an OVC can be combined together into a larger format without constraint on how that larger format works.

Each of the above topics is deserving of a design note of its own. While DFDL parsing is also complex, the above ought to convince you that DFDL unparsing is very much more complex due to the interaction of streaming behavior with OVC calculations.

However, the subject of this page is the I/O (output really) layer's buffering system.

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