Cross-platform support middleware: Difference between revisions

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{{short description|Software abstraction layer}}

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A '''Crosscross-Platformplatform Supportsupport Middlewaremiddleware''' (CPSM) is a software [[abstraction layer]] that guarantees the existence, and correct implementation, of a set of services on top a set of [[Platform_Platform (computing)|platforms]].<ref>{{cite web|first=Patricio|last=Zavolinsky|url=http://materias.fi.uba.ar/7500/zavolinsky-tesisdegradoingenieriainformatica.pdf|title=Abstracción en el desarrollo de software independiente de la plataforma: Análisis del proceso de desarrollo de Cross-Platform Support Middlewares (spanish)|accessdate=2008-09-25|publisher=Universidad de Buenos Aires, Argentina|archive-date=2009-04-11|archive-url=https://web.archive.org/web/20090411100126/http://materias.fi.uba.ar/7500/zavolinsky-tesisdegradoingenieriainformatica.pdf|url-status=dead}}</ref>

==Formal Model==

Formally, a CPSM can be represented by the following model:

* Let <math>S</math> be the set of provided services, and <math>s_m</math> the <math>M+1</math> elements of that set, with <math>m \in [0,M]</math>.

* Let <math>P</math> be the set of supported platforms, and <math>p^n</math> the <math>N</math> elements of that set, with <math>n \in [1,N]</math>.

* The special service <math>s_0</math> denotes the set of trivially cross-platform services provided (e.g. programming language, buffered I/O, etc).

* Thus, a CPSM can be defined as: <blockquote><math>A = CPSM(S, P)</math></blockquote> Where the strong condition for the existence of <math>A</math> is that every service in <math>S</math> is available in every platform in <math>P</math>.

The formal model may be extended to account for the abstract and concrete (native) interfaces of the services provided:

* Let <math>i_m^n</math> be the concrete (native) interface for service <math>s_m</math> in platform <math>p^n</math>.

* Let <math>I_d(S,P)</math> be the set concrete (native) interfaces (i.e. <math>i_m^n</math>).

* Let <math>i_m</math> be the abstract interface for service <math>s_m</math>, provided by the CPSM regardless of the underlying platform</math>.

* Let <math>I(S)</math> be the set abstract interfaces (i.e. <math>i_m</math>).

Formally, the strong condition for the existence of a CPSM can be expressed as:

<blockquote><math>

\forall s_m \in I(S), \forall p^n \in P \rightarrow \exists s_m^n.

</math></blockquote>

==Trivial CPSM==

There are two trivial cases of a CPSM: the single-platform CPSM and the inherently compatible CPSM.

A single-platform CPSM is compatible with one, and only one platform. Formally, <math>|P| = 1</math>, or, equivalently, <math> P = \{ p^1 \} </math>. In broad terms, an [[operating system]] might be considered a single-platform CPSM.

An inherently compatible CPSM is an abstraction layer that only provides services trivially compatible in every compatible platform. Formally, <math> |S| = 1 </math>, or, equivalently, <math> S = \{ s_0 \} </math>.

==Non-trivial CPSM==

A non-trivial CPSM must verify two conditions:

* The compatible platform set must contain at least two platforms.

* The provided services set must contain at least one non-trivial service.

Formally:

* <math>|P| > 1</math>

* <math>|S| > 1</math>

==Abstraction method==

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The second method takes advantage of the [[filesystem]] organization to divide the source code in different folders, one for each incompatible platform. Thus delegating the selection problem to the [[build system]].

Some distributions like [[MSYS]] and [[cygwinCygwin]] may help build the cross-platform code in a unix[[Unix-like]] environment even on Microsoft Windows. Both distributions provide a decent version of [[GNU Make]] that can direct the build process in a cross-platform fashion.

==See Alsoalso==

* [[Adaptive Communication Environment]]

* [[Boost C++ Librarieslibraries]]

* [[GTK+]]

* [[Netscape Portable Runtime]]

* [[Simple DirectMedia Layer]]

* [[wxWidgets]]

* [[Boost C++ Libraries]]

==References==

{{reflist}}

[[Category:Middleware]]