Packaging OFX Plug-ins

Where a host application chooses to search for OFX plug ins, what binary format they are in and any directory hierarchy is entirely up to it. However, it is strongly recommended that the following scheme be followed.

Binary Types

Plug-ins should be distributed in the following formats, depending on the host operating system….

  • Microsoft Windows, as “.dll” dynamically linked libraries,
  • Apple OSX, as Mach-O binary bundles,
  • IRIX and LINUX, as ELF dynamic shared objects.

Installation Directory Hierarchy

Each plug-in binary is distributed as a Mac OS X package style directory hierarchy. Note that there are two distinct meanings of ‘bundle’, one referring to a binary file format, the other to a directory hierarchy used to distribute software. We are distributing binaries in a bundle package, and in the case of OSX, the binary is a binary bundle. All the binaries must end with ".ofx", regardless of the host operating system.

The directory hierarchy is as follows…..

  • NAME.ofx.bundle
    • Contents
      • Info.plist
      • Resources
        • NAME.xml
        • PLUGIN_A.png
        • PLUGIN_A.svg
        • PLUGIN_B.png
        • PLUGIN_B.svg
      • ARCHITECTURE_A
        • NAME.ofx
      • ARCHITECTURE_B
        • NAME.ofx
      • ARCHITECTURE_N
        • NAME.ofx

Where…

  • Info.plist is relevant for OSX only and needs to be filled in appropriately,
  • NAME is the file name you want the installed plug-in to be identified by,
  • PLUGIN.png - is an optional portable graphics file image to use as an icon for the plug-in in the binary which has a matching pluginIdentifier field in the OfxPlugin struct,
  • PLUGIN.svg - is an optional scalable vector graphic file to use as an icon for the plug-in in the binary which has a matching pluginIdentifier field in the OfxPlugin struct,
  • ARCHITECTURE is the specific operating system architecture the plug-in was built for, these are currently…
    • MacOS - for Apple Macintosh OS X 32 bit and/or univeral binaries
    • MacOS-x86-64 - for Apple Macintosh OS X, specifically on intel x86 CPUs running AMD’s 64 bit extensions. 64 bit host applications should check this first, and if it doesn’t exist or is empty, fall back to “MacOS” looking for a universal binary.
    • Win32 - for Microsoft Windows (compiled 32 bit)
    • Win64 - for Microsoft Windows (compiled 64 bit)
    • IRIX - for SGI IRIX plug-ins (compiled 32 bit)
    • IRIX64 - for SGI IRIX plug-ins (compiled 64 bit)
    • Linux-x86 - for Linux on x86 CPUs (compiled 32 bit)
    • Linux-x86-64 - for Linux on x86 CPUs running AMD’s 64 bit extensions

Note that not all the above architectures need be supported, at least one.

This structure is necessary on OS X, but it also gives a nice skeleton to hang all other operating systems from in a single install, as well as a clean place to put resources.

The Info.plist is specific to Apple and you should consult the Apple developer’s website for more details. It should contain the following keys…

  • CFBundleExecutable - the name of the binary bundle in the MacOS directory
  • CFBundlePackageType - to be ‘BNDL’
  • CFBundleInfoDictionaryVersion
  • CFBundleVersion
  • CFBundleDevelopmentRegion

Installation Location

Plug ins are searched for in a variety of locations, both default and user specified. All such directories are examined for plug-in bundles and sub directories are also recursively examined.

A list of directories is supplied in the “OFX_PLUGIN_PATH” environment variable, these are examined, first to last, for plug ins, then the default location is examined.

On Microsoft Windows machines, the plug ins are searched for in,

  1. the ‘;’ separated directory list specified by the environment variable “OFX_PLUGIN_PATH”

  2. the directory returned by getStdOFXPluginPath in the following code snippet…

    #include "shlobj.h"
    #include "tchar.h"
    const TCHAR *getStdOFXPluginPath(void)
    {
      static TCHAR buffer[MAX_PATH];
      static int gotIt = 0;
      if(!gotIt) {
        gotIt = 1;
        SHGetFolderPath(NULL, CSIDL_PROGRAM_FILES_COMMON, NULL, SHGFP_TYPE_CURRENT, buffer);
        _tcscat(buffer, __T("\\OFX\\Plugins"));
      }
      return buffer;
    }
    
  3. the directory “C:Program FilesCommon FilesOFXPlugins”. This location is deprecated, and it is returned by the code snippet above on English language systems. However it should still be examined by hosts for backwards compatibility.

On Apple OSX machines, the plug ins are searched for in,

  1. the ‘;’ separated directory list specified by the environment variable “OFX_PLUGIN_PATH”
  2. the directory “/Library/OFX/Plugins”

On UNIX, Linux and other UNIX like operating systems,

  1. the ‘:’ separated directory specified by the environment variable “OFX_PLUGIN_PATH”
  2. the directory “/usr/OFX/Plugins”

Any bundle or sub-directory name starting with the character ‘@’ is to be ignored. Such directories or bundles must be skipped.

Plug-in Icons

Some hosts may wish to display an icon associated with a plug-in on their interfaces. Any such icon must be in the Portable Network Graphics format (see http://www.libpng.org/) and must contain 32 bits of colour, including an alpha channel. Ideally it should be at least 128x128 pixels.

Host applications should dynamically resize the icon to fit their preferred icon size. The icon should not have it’s aspect changed, rather the host should fill with some appropriate colour any blank areas due to aspect mis matches.

Ideally plug-in developers should not render the plug-in’s name into the icon, as this may be changed by the resource file, especially for internationalisation purposes. Hosts should thus present the plug-in’s name next to the icon in some way.

The icon file must be named as the corresponding pluginIdentifier field from the OfxPlugin, post pended with ‘.png’ and be placed in the resources sub-directory.

Externally Specified Resources

Some plug-ins may supply an externally specified resource file. Typically this is for tasks such as internationalising interfaces, tweaking user interfaces for specific hosts and so on. These are XML files and have DTD associated with the specific API, for example OFX Image Effect DTD is found in ofx.dtd.

The xml resource file is installed in the Resources sub directory of the bundle hierarchy. It’s name will be NAME.xml, where name is the base name of the bundle folder and the effect binaries.