indirection

Footnotes

1. Indirection refers to dispatch of communications via an intermediary. The intermediary is the cause of indirection, and is (strictly) an entity capable of examining a message and making a decision regarding it (e.g. on whether to forward it or answer it, or on where to forward it, etc.). There may be a chain of such intermediaries along a communications path, each constituting one level of indirection.
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2. For instance, to fix a slow storage system, one may reckon:
   • To add
     caching
     , an indirection of access. On each request, the cache manager decides whether to serve the request from the cache or to forward it to the storage system.
   • To
     parallelize
     and
     distribute
     access, an indirection over a
     load balancer
     . On each request, the load balancer decides which storage node to forward the request to.
   • To reduce iterated strength
     4
     — such as by refactoring logic out of loops or functions when computed effects can be shared across iterations or function calls (a sort of caching?).
   • At this scale of complexity, one perhaps needs yet another indirection in the form of a
     compiler
     (even
     real programmers
     need a compiler!).
   
   As the system complexity explodes, one reckons the collective ought to be refactored into smaller, "atomic" components, each abstracting away specific complexities and exposing a reasonable
   API
   for the next level of indirection to consume. But the complexity of each subsystem soon matches that of the original system. Voilà: the original pain is rediscovered, and recursion
   2
   beckons.
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   ↩²
3. The first two are
   premature optimization
   ,
   atrocious naming
   , and
   off-by-one errors
   .
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4. Made up our own terminology, have we?
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