What the EMS API Really Does

Abstractly speaking - The good thing about API's is that there are so many to choose from. Generally speaking an API for a particular application opens it up so that other programs can be plugged in and extend the original application. Each API supports some specific set of extensions. Creating a plug-in for most API's requires programming in C or some other language. The EMS API is designed to support transformations, translations or conversions on messages. Eudora (windows only) also supports MAPI, another API that allows other kinds of extensions to Eudora. Eudora also supports a number of other facilities for extensions, such as resource plug-ins, scripting and command line options.

Text transformations - The most simple transformations a plug-in can perform are on text. This can include lots of things:

• upper to lower case conversion
• human language translation
• digital signature for the message text
• sorting
• format conversion

The EMS API can make the text of a message available to such a translator as the message is received or sent. The translations can also be performed on the message as it is viewed or when it is being composed.

Processing attachments and MIME structure - The EMS API also allows processing on attachments and the full MIME structure of the message. On receipt of a message, a plug-in has access to any part of the message. Eudora does all the difficult MIME parsing and makes attachments available to the plug-in one at a time. The plug-in indicates which ones it wants to work based on the MIME type. The MIME processing a plug-in may do on a recieved message is extremely flexible and open ended. It basically can take any MIME structure and turn it into any other MIME structure.

Speaking practically, it can do some of the following:

• Compress/decompress selected attachments
• Convert documents, images and attachments from one format to another

Encapsulating & unencapsulating the message - Because the EMS API supports very general processing on the MIME structure it can be usedto encapsulate the whole MIME message. Some examples of this are:

• Compressing the whole message including all attachments, images, sounds etc.
• Digitally signing the whole message.

How it looks in the Eudora user interface

Plug-ins show up in the user interface in a couple of ways.

What plug-ins are loaded

Screenshot -- List of Currently Loaded Plug-Ins (4K)

To find out which plug-ins are loaded in Eudora on the Macintosh, select the About Message Plug-ins menu item under the Apple menu for the Classic version of Eudora, and under the Eudora menu for OSX. For Windows select the Message Plug-ins Settings item under the Specialmenu. Both will display a list of the currently loaded plug-ins.

On request text processing plug-ins

Screenshot -- On-Request Plug-Ins (13K)

These plug-ins show up under the Edit menu. When they are selected they perform a transformation on the current message or the current selection. Some plug-ins will present a dialogue box if they need to interact with the user. Many will just perform the translation.

Translation on outgoing message

Screenshot -- Outgoing Message Plug-Ins (7K)

These show up as icons in the message composition bar. On the Macintosh each translator shows up. On Windows there is a pull down. When checked the translation is selected and will be performed when the message is sent or queued. Some plug-ins of this nature will present a dialogue box when selected.

Translations on received messages

Plug-ins that work on received messages are of two kinds. Some will just automatically process the message as it is down-loaded from the server and never interact with the user. Others work when you select the translator's icon from within the message text itself.

Plug-ins setting

Each plug-in may have its own setting panel, though many don't. The Macintosh settings are accessed from the Plug-in Settings command in the Special menu. The Windows settings are accessed from the window mentioned above that displays the loaded plug-ins. Click on the plug-in icon or the setting button for the plug-in's settings.