Managing contacts, events, and locations with KOffice's new RDF support

Hidden Meaning

By Ben Martin

The Resource Description Framework (RDF) [1] is a central feature in the spectrum of technologies at the heart of the quest for what is known as the semantic web. The goal of the semantic web is to add meaning to electronic information such as websites and office documents, so that a term referenced through the text is more than just text. For instance, the program would know that the string "Fred" is not just a permutation of four ASCII characters but refers to a specific person named Fred who has a specific address and phone number.

Of course, many office suites provide an interface with some kind of personal information management system; however, as you will learn in this article, RDF supports a deeper and more automatic level of integration that keeps the meta-information in easy reach and allows it to travel effortlessly with the text. Also, the universal nature of RDF means that other programs supporting RDF will know how to interpret this semantic information. The semantic knowledge becomes part of the document, and later programs can apply that information in ways that might not even be envisioned at the time the data is saved.

The Open Document Format (ODF) [2] provides a means for integrating RDF with office documents, and developers are slowly implementing RDF features with the major open source office suites. In early 2010, the KOffice suite picked up RDF support, letting you define contacts, events, and locations. This means KOffice can now know for certain that "Fred" means a particular contact, that an event starts in a specific time zone, and that a meeting will occur at an exact location.

Although many office programs can operate on individual information formats like iCalendar and vCard, each one of these formats has a specific way to encode information, and generally programs must be written to process these specific files. With RDF, an application like KOffice can load and save such information without needing to understand everything about it.

When you open that file in an RDF-aware office suite, you should be able to show the location on a map of your choice or send the contact and event information to other desktop applications or your mobile phone. Gone are the days of re-keyed information and sloppy cut-and-paste operations.

OpenOffice has also recently gained RDF support, and I am hoping to add support for RDF AbiWord this year. This gradual transition to RDF-enabled applications could eventually change the way users create and use office documents.

Getting into It ...

The easiest way to get RDF into your KOffice document is open a mail program like Evolution (Figure 1) and drag a contact or event into KOffice. Currently, you'll have to add the RDF side panel to KOffice and drop the contact or event onto it. In the future, you'll be able to drop contacts or events directly into the main document region. When you drop a contact into KOffice, you should then see something in the document text at the current cursor location. In Figure 2, I have dropped Frodo into the document, and the RDF side panel knows that "Frodo Baggins2" refers to a person. The side panel shows the RDF corresponding to the text under the cursor.

Figure 1: A contact for Frodo added to the Evolution application.

Figure 2: Dragging Frodo into the document shows his name, but as you can see in the RDF side panel, KOffice also knows this is a person.

If you right-click on Frodo in the side panel, you can import Frodo into your desktop address book, export him as a vCard, select the whole text that relates to him in the document (i.e., Frodo Baggins2) edit his details, and add other options.

When you edit the contact, you'll see something similar to Figure 3. This dialog will eventually expand to allow more in-depth editing of the contact information stored in RDF inside your documents. Once you have entered the contact information, you are using RDF. If you send the ODF file to another user, the user can import or export Frodo through vCard onto a mobile phone. A single file contains both a human-readable document and semantics that a computer can understand.

Figure 3: Editing the Frodo contact within KOffice.

In addition to dragging information into a document, you can insert a new contact (Figure 4), which brings up the same dialog used to edit a contact (Figure 3), allowing you to insert a fresh RDF contact directly from KOffice. As you can see in the menu, you can also insert a reference. This way, you can refer to Frodo 10 times throughout your document without having to duplicate the details. If you change Frodo's phone number through the RDF side panel, any place that refers to him will also know his new details.

Figure 4: Creating a new RDF object.

Stylesheets

The ability to refer to the same contact or event multiple times in the document is good, but you might also want someone who reads the document to see more than just Frodo's name in the text. For example, you might want to display his homepage or phone number, although you don't want to display it every time you refer to Frodo. Perhaps in the first reference, his phone number can appear, but in the letterhead you might also want to see his address. This is exactly what I created RDF stylesheets to do. When you right-click an object in the RDF side panel, you can apply either a system or user stylesheet to format how that object appears in the document text. In Figure 5, I have applied the name, phone system stylesheet so this reference to Frodo includes his phone number.

Figure 5: Applying a system stylesheet to determine how this reference to Frodo will be formatted in the document text.

Portability

If you select all or part of a contact, event, or location that has an RDF associated with it and copy the text, the RDF goes with it. In fact, if you copy an event or contact from one office document directly into another document, the semantics are copied over too. This portability is possible because the text that is copied between documents is a full ODF file. Note, though, that the file is not saved to disk, so using ODF instead of just copying plain text is not a huge overhead.

One great upside to this is that you should also be able to copy and paste RDF between KOffice, AbiWord, and OpenOffice documents through the regular copy-and-paste interface. Other toolkits that understand ODF can also get at the RDF inside the pasted text. For example, if you paste text from KOffice into KOrganizer, all the contacts from the RDF will automatically added to your address book.

Future Improvements

In the future, I hope to make the user interface expose the links between RDF entries. For example, you could right-click on Sam and see who he does gardening for. Then you would be able to navigate in the document to Frodo from a reference to Sam. Also, you should be able to link websites to events or jobs. This feature would let you know, for example, which five URLs are the most relevant to a particular invoice.

Wrap Up

Although the ODF specification provides strong support for RDF, RDF support in office suites has only just started hitting the free and open source desktop. KOffice and OpenOffice both have it now, and AbiWord should have it later this year.

Using desktop metaphors like drag and drop, you can easily add RDF objects to your documents and reference the same RDF objects multiple times, thus saving time and providing up-to-date information on contacts, events, and locations at a glance.

Figure 6: View system stylesheets and add user-defined stylesheets.