Sophie: php-manual-en-4.3.0-2mdk noarch

php-manual-en-4.3.0-2mdk.noarch.rpm

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>Chapter 25. Extension Possibilities</A
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>External Modules</A
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>Built-in Modules</A
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>&#13;   As shown in <A
HREF="zend.overview.html#fig.internal-struct"
>Figure 24-1</A
> above, PHP can be extended primarily at
   three points: external modules, built-in modules, and the Zend
   engine. The following sections discuss these options.
  </P
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>External Modules</H1
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>&#13;    External modules can be loaded at script runtime using the
    function <A
HREF="function.dl.html"
><B
CLASS="function"
>dl()</B
></A
>. This function loads a shared
    object from disk and makes its functionality available to the
    script to which it's being bound. After the script is terminated,
    the external module is discarded from memory. This method has both
    advantages and disadvantages, as described in the following table:
    
    <DIV
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>Advantages</TD
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>Disadvantages</TD
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>&#13;         External modules don't require recompiling of PHP.
        </TD
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>&#13;         The shared objects need to be loaded every time a script is
         being executed (every hit), which is very slow.
        </TD
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>&#13;         The size of PHP remains small by "outsourcing" certain
         functionality.
        </TD
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>&#13;         External additional files clutter up the disk.
        </TD
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>&nbsp;</TD
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>&#13;         Every script that wants to use an external module's
         functionality has to specifically include a call to
         <A
HREF="function.dl.html"
><B
CLASS="function"
>dl()</B
></A
>, or the <TT
CLASS="literal"
>extension</TT
>
         tag in <TT
CLASS="filename"
>php.ini</TT
> needs to be modified
         (which is not always a suitable solution).
        </TD
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> To sum up, external modules are great for
    third-party products, small additions to PHP that are rarely used,
    or just for testing purposes. To develop additional functionality
    quickly, external modules provide the best results. For frequent
    usage, larger implementations, and complex code, the disadvantages
    outweigh the advantages.
   </P
><P
>&#13;    Third parties might consider using the
    <TT
CLASS="literal"
>extension</TT
> tag in <TT
CLASS="filename"
>php.ini</TT
>
    to create additional external modules to PHP. These external
    modules are completely detached from the main package, which is a
    very handy feature in commercial environments. Commercial
    distributors can simply ship disks or archives containing only
    their additional modules, without the need to create fixed and
    solid PHP binaries that don't allow other modules to be bound to
    them.
   </P
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