NPAPI: differenze tra le versioni

Versione delle 17:11, 10 ago 2007

Versione delle 22:46, 10 ago 2007

Riga 46:

Microsoft sviluppò OLE2 ([[Object linking and embedding|Object Linking and Embedding]]) per rendere possibile la creazione di documenti composti in applicazioni quali Microsoft word. Per esempio, un documento scritto in un word processor potrebbe contenere un foglio di calcolo incorporato che potrebbe essere lanciato all'interno della finestra del word processor.

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OLE2 was based on [[Component Object Model|COM]] and defined interfaces for the various tasks that the container and the object needed to perform. An OLE2 control (sometimes known as an OCX) was a light OLE2 object that could be embedded into a container but did not save large amounts of data or require menus or toolbars to function.

OLE2 fu progettato sulla base di [[Component Object Model|COM]], e definiva delle interfacce per i diversi compiti che il contenitore e l'oggetto dovevano portare a termine. Un controllo OLE2 (noto anche come OCX) era un oggetto OLE2 leggero che poteva essere integrato in un contenitore ma che non salvava grandi quantità di dati, nè richiedeva menu o barre degli strumenti per funzionare.

A control was implemented as a DLL and loaded into the address space of the host container such as [[Visual Basic]]. Earlier versions of Visual Basic used a similar technology called [[Visual Basic Extension]]s but OCX controls were seen as superior. Each OCX implemented a well defined subset of the OLE2 interfaces that the container could use to manipulate the control, such as repositioning it, or to provide information about the container. The OCX also implemented an ''automation interface'' which allowed it to expose methods and properties that could be manipulated, and used mechanism in the other direction to fire events to the container.

Un controllo veniva implementato da una DLL, e caricato nello spazio degli indirizzi del contenitore ospite, come ad esempio [[Visual Basic]]. Le prime versioni di Visual Basic utilizzavano una tecnologia simile chiamata [[Visual Basic Extension]], ma i controlli OCX vennero considerati migliori. Ogni OCX implementava un sottoinsieme ben definito delle interfacce OLE2 che il contenitore poteva usare per manipolare il controllo, ad esempio per spostarlo, o per fornire informazioni sul contenitore. L'OCX implementava anche un ''meccanismo di automatione'' che permetteva la pubblicazioni di metodi e proprietà che potevano essere modificati, ed utilizzava un metodo complementare per restituire degli eventi al contenitore.

OLE2 was extremely complicated and support for COM in [[Microsoft Foundation Classes|MFC]] was poor. So Microsoft rationalised the specification to make it simpler, and rebranded the technology as [[ActiveX]]. Even after simplification controls were still required about 6 core interfaces that must be implemented. In response to this complexity, Microsoft produced wizards, ATL base classes, macros and C++ language extensions to make it simpler to write controls.

OLE2 era molto complicato, ed il suo supporto nelle [[Microsoft Foundation Classes|MFC]] era minimo, perciò Microsoft razionalizzò la specifica in modo da semplificarla, e ridenominò la tecnologia in [[ActiveX]]. Anche dopo la semplificazione i controlli richiedevano neccessariamente che all'incirca 6 interfacce fondamentali venissero implementate. Microsoft, per allievare questa complessità, produsse dei wizard, delle classi base ATL, delle macro e delle estensioni al linguaggio [[C++]] per semplificare la scrittura di controlli.

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Starting with Internet Explorer 3.0, support was added to host ActiveX controls within HTML content. If the browser encountered a page specifying an ActiveX control via an OBJECT tag (using non-W3C syntax), it would automatically download and install the control with little or no user intervention. This made the web experience "richer" but was perceived as divisive (since controls only ran on Windows) and a security risk due to the lack of user intervention. Microsoft have been forced to introduce security measures to address its shortcomings. For example:

* Control installation packages (Cabinet files and executables) must be digitally signed.

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[[Mozilla Firefox]] attempts to present a middle ground. If a plugin is missing, it will notify the user that the plugin is missing and initiate a secure connection to a plugin finder service hosted on mozilla.org. The user can permit Firefox to download and install the plugin. This model prevents content specifying where a plugin should be downloaded from – the plugin finder service does. This enables Firefox to present a fairly seamless installation mechanism but limit the service to trusted and compatible plugins from reliable sources. Of course this model implicitly trusts the plugin finder service to return "good" plugins, increasing the security required on the host site.

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== Popular plugins ==

== Plugin più utilizzati ==

* [[Adobe Acrobat]]

* [[Adobe Shockwave]]

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* [[Windows Media Player]]

== ReferencesFonti ==

<references/>

== ExternalCollegamenti linksesterni ==

* {{en}} [http://developer.mozilla.org/en/docs/Plugins PluginDocumentazione per lo sviluppo developmentdi documentationplugin] onsu Mozilla Developer Center

* {{en}} [http://www.mozilla.org/projects/plugins/ OlderHomepage pluginper developmentdella homepagedocumentazione più vecchia sullo sviluppo di plugin]

* {{en}} [http://www.mozilla.org/projects/plugins/npruntime.html WritingScrittura scriptingdi pluginsplugin withusando Mozilla]

* {{en}} [http://www.mozilla.org/projects/plugins/plugin-host-control.html AnUn controllo ActiveX controlche thatoffre hostssupporto pluginsper i plugin] – AComponente replacementsostituivo forper plugin.ocx, che thatè wasstato removedrimosso fromda Internet Explorer.

* {{en}} [http://news.com.com/IE+competitors+mull+ActiveX+alternative/2100-1032_3-5253504.html?tag=nl I rivali di IE competitorssostengono mullun'alternativa ad ActiveX alternative – CNET]

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[[Categoria:Web browser]]

[[Categoria:Mozilla]]