Extended Apis For Plug-Ins - Adobe ACROBAT 7.0.5 SDK Manual

Technologies Supported by the Acrobat SDK
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Plug-ins
Acrobat Support
The Acrobat Support (AS) layer provides platform-independent utility functions and allows
plug-ins to override the built-in file-handling mechanisms.
Cos Layer
The Cos Object System (Cos) layer provides access to the building blocks used to construct
documents. Cos methods allow plug-ins to manipulate low-level data such as dictionary
and string objects in a PDF file.
Whenever possible, you should use higher level APIs to access and manipulate PDF files.
Though you can use the Cos layer APIs to perform most types of access or manipulation of a
PDF file, it can be very difficult and requires in-depth knowledge of PDF file structure.
Platform-Specific Methods
In addition to the method groups represented in
platform-specific plug-in utilities to handle issues that are unique to Macintosh, Windows
and UNIX platforms. For more information, see the Acrobat SDK Plug-in Guide.

Extended APIs For Plug-ins

Plug-ins may expose their own functionality and make it available to other plug-ins, in the
same way that Acrobat functionality is available through the core API. For example, Acrobat
contains several plug-ins, such as Search and Digital Signatures, whose APIs are available to
plug-ins. In fact, the Acrobat architecture encourages the use of plug-ins to "expose" APIs
for use by other plug-ins. Acrobat uses many plug-ins to implement features; some of these
plug-ins expose their APIs.
API "exposure" is accomplished through a mechanism called the Host Function Table (HFT).
A plug-in can export an HFT for use by other plug-ins, and it can import the HFTs of other
plug-ins.
To learn how to import and export HFTs, see the Acrobat SDK Plug-in Guide and the Acrobat
and PDF LIbrary API Overview.
Plug-in APIs
The following are the plug-ins that export HFTs. For more information, see the Acrobat and
PDF Library Overview and the Acrobat and PDF Library Reference.
The Catalog Plug-in creates full-text indices, searchable with the Acrobat Search plug-in.
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The Digital Signature Plug-in handles the generic functions common to all digital
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signatures. You can write a plug-in that handles your specific kinds of signatures
(signing methods), such as public-private key (PPK), handwriting, retinal scans, or
fingerprints.
The Forms Plug-in helps make Acrobat a more powerful and comprehensive tool for
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creating and filling out electronic forms. With it, you can convert a PDF file into an
electronic form that looks just like the original paper form.
The PDF Consultant Plug-in allows you to inspect, analyze, and repair PDF documents.
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Figure 2.1, the core API includes
Acrobat SDK User's Guide