(Updated) Categories of Mismatches between Producer and Consumer

["Roger L. Costello" <costello@mitre.org>]

Hi Folks,

Many thanks to those who contributed ideas to this category list.  I
have worked hard to incorporate everyone's ideas.  I welcome your
comments on this updated category list.  /Roger

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      Categories of Mismatches between Producer and Consumer
(Categories of those things/types that may affect interoperability)

Assumptions:
a. I assume that the producer and consumer are physically connected.  I
will not address physical connection mismatches.

b. I assume that the producer and consumer speak the same language, and
are using the same encoding schema when exchanging data.

c. I assume that the producer and consumer are using the same syntax,
e.g., XML.

Category 1: Interpretation Differences

- Structure mismatch: the producer creates data with a certain structure
and the consumer expects it in a different structure. 

   Example: The producer specifies a date as mm-dd-yy but 
   the consumer interprets it as dd-mm-yy

- Units mismatch: the producer and consumer use different units.

   Example1: the producer gives the data in inches but the 
   consumer interprets the data in centimeters.

   Example2: the producer gives the cost in USD but the 
   consumer interprets the cost in EUR.

- Meaning mismatch: the consumer interprets the data in a different way
than the producer intended.

   Example1: the consumer interprets an aircraft "departure 
   time" to mean the time the doors shut, while the producer 
   meant it as the  time the wheels touch off.

   Example2: the consumer interprets the total cost as the 
   cost listed, but the producer intended the total cost 
   as cost listed plus shipping & handling plus taxes.

- Reference system mismatch: the producer and consumer interprets the
data using different reference systems.

   Example1: the producer expresses time in Greenwich Mean 
   Time (GMT), the consumer interprets the time in Eastern 
   Standard Time (EST).

   Example2: the producer provides directions by giving 
   the distance to a town relative to the center of a 
   known town, while the consumer interprets the distance 
   relative to the outskirts of the known town.

Category 2: Terminology Differences

- Synonyms: the producer and consumer use different terms to mean the
same thing.

   Example1: the producer uses the term f-stop, while the 
   consumer knows it as aperture.

   Example2: the producer uses Roger_Costello as identification, 
   while the consumer knows him by the id MITRE.Emp.xxxx.

- Homonyms: the producer and consumer use the same term to mean
different things.

   Example: a "foot" to a medical system producer may mean 
   something very different to a physicist consumer.

Category 3: Knowledge of New Capabilities Differences

- New type-of: a producer may have information about a new class of
thing that the consumer has not been coded to understand.

   Example: a producer sends data about a new type of 
   Camera, the Xj3-SLR.  The consumer understands Cameras, 
   but not Xj3-SLR.

Category 4: Precision Required Differences

- Differing expectations of completeness: the producer and consumer may
have different ideas on what constitutes a complete set of data.

   Example1: the producer provides the address to the 
   Prudential Tower in Boston as  Prudential Tower, 
   Boston, MA 02215, while the consumer expects the 
   address to also include the street address.

   Example2: the producer provides directions by specifying 
   which roads to take, but the consumer additionally requires 
   an indication of the expected time required to traverse 
   each road.

- Accuracy required: the producer and consumer may have differing needs
for accuracy.

   Example1: the producer provides a GPS lat/lon reading with 
   4 digits precision, but the consumer needs it to 6 digits 
   precision.

   Example2: the producer provides an as-the-crow-flies length 
   measurement, but the consumer needs a more precise length 
   measurement.

   Example3: the producer provides the month and year, but 
   the consumer additionally needs the day.

- Granularity differences: the producer and consumer have differing
views on what constitutes a chunk of data.

   Example: the consumer wants info on military airports in a 
   region, but the producer only has the ability to provide 
   info on all airports (military and civilian) in the region.

- Quality Assurance: the producer and consumer may differ in their
confidence levels.

   Example1: The producer has a confidence level of 80% in 
   his data, but the consumer needs the data to have a 
   confidence level of 90%. 

   Example2: Computation inaccuracies: the producer may 
   have performed computations to arrive at his data.  
   The computations may have required rounding.  Such 
   rounding may impact the consumer.  Will the producer 
   inform the consumer of rounding decisions?

Category 5: Timeliness Differences

- Time-sensitive data: the producer and consumer have different needs on
the timeliness of data.

   Example1: The producer provides daily currency conversion 
   rates, but the consumer requires up-to-the-minute currency 
   conversion rates.

   Example2: The producer provides the previous day's 
   close-of-business stock prices, but the consumer requires
   up-to-the-minute stock price data.

Category 6: Access Differences

- The producer is able to deliver the data in one way, but the consumer
needs it delivered in a different way.

   Example: the producer only provides software on a CD 
   through the mail, but the consumer needs it instantly 
   via an FTP download.

Category 7: Source of Data Differences

- The consumer expects the data to come from one source (or set of
sources), but it receives data from another source (or set of sources).

   Example: The consumer expects data from one Federal agency 
   but instead receives data from another federal agency.

Category 8: Social Context Differences

- Social Context: the producer creates the data within a certain social
context that may not be shared by the consumer.

   Example1: A "flat" in the U.K. has a very different 
   meaning in the U.S.

   Example2: A doctor might interpret "foot" differently 
   than a physicist.