8.8

pens inadvertently (we hope, anyways), the pens would be signing the "wrong" documents all
day and, when docked, would update the wrong documents in the database.
In all of these cases, the errors often do not appear when the wrong document is updated - it
actually occurs when the "right" data is processed. This happens precisely because the Pen
and Production have no idea that the wrong data is received and will generally close the
document after that "wrong" data has been processed - this often works with no error. However,
when the "right" data is processed, then it tries to update a document that has already been
closed by the "wrong" data, and thus fails.
Safeguards
There are certain safeguards against contamination:
l PlanetPress Capture checks for pattern size and placement. If the data contains ink for a
specific pattern but the ink location does not correspond to the Capture Fields of the
document it's updating, it will fail.
l Errors can be set to stop and revert the whole current batch. If a single error occurs during
the pen data processing, it is possible for this processing to be stopped and all changes
the Capture Database reverted. In implementations where the pen signs high number of
documents, this can especially be an easy way to do this, as chances are the data will not
match in at least one case.
Conclusion
l PlanetPress Workflow can only generate 20,000 unique patterns
l One pattern is used (locked) for each page containing a pattern.
l Processing the ink data from a pen and closing the document releases the pattern
l Most implementations will not need more than 20,000 patterns
l When necessary, patterns can be extended using multiple servers or Pattern Sequences
(as long as these are used in separate physical locations).
l It is extremely critical that contamination be avoided at all costs.
l Whenever possible, always avoid using pattern sequences unless it is absolutely
necessary to do so.
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