🚀 go-pugleaf

Joseph F. (Jeff) Hull (jhull@thor.NoSubdomain.NoDomain) wrote:
: 
..

: 
: |> The thing that makes an integrated circuit so reusable
: |> is that it is a member of a family of compatible integrated circuits.
: |> There are standard interfaces so that any of them can be mixed with
: |> any of the others.  Thus, we really need to be defining abstract interfaces
: |> as well as sets of objects that meet them.  
: 
: Absolutely!  Standard interfaces were the great enabler of hardware integration
: efforts and I believe they will perform the same role for software reuse.  The

We are getting a lot closer to having a complete set of standard
interfaces for system services, communications, security, etc.  Within
the next 3 years, the IEEE POSIX interface standards will grow from a
single standard (1003.1 kernel) to an entire bookshelf.  This will make
it more practical to build reusable components for domain-specific
services, since it will be possible to build one component that can be
ported to a variety of platforms, instead of one version for VMS, one
for System V, one for MVS, etc.  Object oriented language work has made
reusable components more feasible technically; open system standards
are helping to make them economically practical.  I wrote an article
for the Dec.  1991 IEEE Spectrum that touched on this briefly in a
survey of POSIX and related open system standards.  The combination of
object oriented languages and design methods, with open system
standards, may eventually make reusable components the rule rather than
the exception in software development.

: followup question is, "What characteristics of interfaces enable reuse?  (-or-
: How do we design interfaces to enable their implementing software to be easily
: reused?)"  Let's make this question a separate thread.
: 

These are major research questions, of course, but one problem with
such interfaces today is lack of rigorous definition of the services
provided.  Putting components together to get software that you can
rely on is a lot tougher if the interface descriptions have the
inherent ambiguities of natural language descriptions.  Both IEEE
standard interfaces, and the DoD reuse work that I've seen, use
English descriptions of what the software is supposed to be doing,
although they are at least more tightly defined than typical software
documentation.  Formal descriptions would be even better.

--

Rick Kuhn                                   Telephone: +1 301 975 3337       
Natl Institute of Standards & Technology    Fax:       +1 301 590 0932      
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