Impedance mismatch
(New page: In electrical and electronic systems, an impedance mismatch infers an inefficient transfer of power. For time varying signals in an electrical or electronic system, an impedance mismatch c...) |
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| − | In electrical and electronic systems | + | In electrical and electronic systems impedance is a property that is used to work out the amount of resistance over varying frequencies that components like capacitors and inductors create. An impedance mismatch infers an inefficient transfer of power. For time varying signals in an electrical or electronic system, an impedance mismatch can result in [http://en.wikipedia.org/wiki/Standing_wave_ratio reflection of the signal] back to the source - a potentially catastrophic situation. Tis commonly happens where two different types of cable are joined together An impedance mismatch in software can have similar implications. |
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| + | "In fact impedance is very similar to refraction index, the difference being that they are practicaly relevant in completely different frequency domains. An example of mismatch is: you look thru a piece of glass (let's say you are admiring a new notebook in a store) and you see, vaguely, your face. This happens because air and glass have different refractive indexes so part of the light bounces back on the separation surface between air and glass. Exactly the same thing happens to signals when they cross from one type of cable (let's sey 50ohms) to another type of cable (let's say 75 ohms). | ||
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| + | Using "impedance mismatch" for the troubles you get when you try to fit a relational DB with an OO application is merely an analogy (while the two phenomenons presented above are actually the _same_ at a basic level). "{{Ref|1}} | ||
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| + | '''What it really means to us''' | ||
Where two or more software boundaries intersect, the interfaces exposed by these boundaries may not interact cohesively. | Where two or more software boundaries intersect, the interfaces exposed by these boundaries may not interact cohesively. | ||
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| + | In general this maxim refers to the problem that occurs when connecting a relational database with an object oriented program. As the properties objects in the context of OO design are quite different to the representation that in used in the database, the transfer of data from one side of the connection to another can be problematic. One example is, if the granularity of the objects is too big or too small then data transfer is not as easy or efficient as it could be. | ||
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| + | ==External links== | ||
| + | #{{Note|1}}http://haacked.com/archive/2004/06/15/impedance-mismatch.aspx | ||
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| + | http://en.wikipedia.org/wiki/Object-Relational_impedance_mismatch | ||
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| + | http://sbql.pl/Topics/ImpedanceMismatch.html | ||
Revision as of 03:26, 19 September 2008
In electrical and electronic systems impedance is a property that is used to work out the amount of resistance over varying frequencies that components like capacitors and inductors create. An impedance mismatch infers an inefficient transfer of power. For time varying signals in an electrical or electronic system, an impedance mismatch can result in reflection of the signal back to the source - a potentially catastrophic situation. Tis commonly happens where two different types of cable are joined together An impedance mismatch in software can have similar implications.
"In fact impedance is very similar to refraction index, the difference being that they are practicaly relevant in completely different frequency domains. An example of mismatch is: you look thru a piece of glass (let's say you are admiring a new notebook in a store) and you see, vaguely, your face. This happens because air and glass have different refractive indexes so part of the light bounces back on the separation surface between air and glass. Exactly the same thing happens to signals when they cross from one type of cable (let's sey 50ohms) to another type of cable (let's say 75 ohms).
Using "impedance mismatch" for the troubles you get when you try to fit a relational DB with an OO application is merely an analogy (while the two phenomenons presented above are actually the _same_ at a basic level). "[1]
What it really means to us
Where two or more software boundaries intersect, the interfaces exposed by these boundaries may not interact cohesively.
In general this maxim refers to the problem that occurs when connecting a relational database with an object oriented program. As the properties objects in the context of OO design are quite different to the representation that in used in the database, the transfer of data from one side of the connection to another can be problematic. One example is, if the granularity of the objects is too big or too small then data transfer is not as easy or efficient as it could be.
External links
- ^http://haacked.com/archive/2004/06/15/impedance-mismatch.aspx
http://en.wikipedia.org/wiki/Object-Relational_impedance_mismatch
