The dtSearch PDF Search Highlighter is a plug-in for Adobe Reader that makes it possible for search programs to highlight hits in retrieved documents inside Adobe Reader X. Earlier versions of Adobe Reader had this feature built in, so there was no need for a plug-in.
When a user clicks on a link to a PDF file on a web page, the browser loads Adobe Reader as a plug-in and uses it to display the page.
Adobe Reader versions prior to Adobe Reader X provided a way for search programs to send hit highlighting information so search hits could be highlighted in Adobe Reader, and users could click "Next Hit" and "Previous Hit" buttons in Adobe Reader to find hits quickly.
Adobe Reader no longer supports this URL syntax. dtSearch Corp. has created the plug-in to restore this very useful Adobe Reader feature. Subject to the included license agreement, a user can download the plug-in at no charge from the dtSearch web site and install the plug-in on any number of computers within the user's organization. The plug-in may be used with any compatible product or web site -- not just dtSearch products or web sites that use the dtSearch Engine.
To install the plug-in, download and run dtSearchPdfHighlighter.exe. dtSearchPdfHighlighter.exe is a self-extracting ZIP archive containing an MSI installation package, dtSearchPdfHighlighter.msi.
The installer adds the following to the user's system:
A folder in C:\Program Files named "dtSearch\dtSearch PDF Search Highlighter" with dtswebhits.api (the plug-in), dtspdfcfg.exe (a configuration program for the plug-in), and some HTML help files.
A Start Menu shortcut for the configuration program.
Copies of dtswebhits.api in the Adobe Reader and Adobe Acrobat plugins folders.
A registry entry that adds "dtsPdfWh" to the Internet Explorer User Agent string. (For the reason this is necessary, please see "Internet Explorer Compatibility.")
A Browser Helper Object for Internet Explorer that enables hit highlighting to work in Internet Explorer. (In a "Custom" installation, this can be disabled.)
A file named ProtectedModeWhitelistConfig.txt in the Adobe Reader program folder to allow dtswebhits.api to read highlighting data. (If this file already exists, the dtSearch-related entries will be added to it.)
A registry value bUseWhitelistConfigFile under HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Adobe\Acrobat Reader\<version>\FeatureLockDown set to 1 to enable use of the ProtectedModeWhitelistConfig.txt file.
Uninstalling the plug-in removes all of the above items from the user's system.
The plug-in uses settings stored under this registry key:
HKEY_CURRENT_USER\Software\dtSearch Corp.\dtSearch\PlugIns\dtswebhits.api
Each time a PDF file opens in Adobe Reader, the plug-in checks the URL used to open the file for hit highlighting data. If the URL includes a reference to highlighting data, the plug-in verifies that the reference to the highlighting data complies with the user's security settings, downloads the highlighting data, and uses it to add hit highlighting to the PDF file in Adobe Reader.
The format for the URLs that provide hit highlighting information is:
https://www.example.com/sample.pdf#xml=http//www.example.com/hits.xml
The #xml= portion of the link points to a URL that returns an XML stream describing the location of the hits in the PDF file. The format of the XML file is described Adobe Technical Note 5172 -- Highlight File Format (no public link available).
The #xml= portion of the URL can request the XML from a script or program, like this:
https://www.example.com/sample.pdf#xml=http//www.example.com/getPdfHits.asp?idoc=5
The dtSearch plug-in supports this URL syntax and also supports a variant, using ?xml= instead of #xml=. The variant is needed because the #xml= URLs are not visible to the plug-in when Adobe Reader is running inside a WebBrowser control.
