How to... occurrences?

[fsancho]

Hi again,

Now my problem is with occurrences...

As far as we understand from the documentation, what Wandora means for occurrences are something like "fields" where we can add information for the topics (we create an occurence type, for example "Date_birth", and associate it with the type topic "Person".. then we can add one date of birth for every instance in Person, right?).

Our problem is with other kind of occurrences: using them as general information resources that we want related with the topic...

Our solution has been to create a new Topic Type "Resources" and inside it (as subclasses) we created the several subtypes of resources we can use ("Web Pages", "Books", "Papers", "Others...", etc.). After that, an association type (Resource_assoc) from the class Resources to the different Topic Types will use these resources was created.
Every time we want to add a resource for an instance topic, we add a topic of type "Resources", with the SI as the URL we want to store, and we make an association Resource_assoc between the topic and the resource...

It works but... we would like to know if it is correct or there exists one more direct way to obtain the same result.

Thanks again, and congratulations for the tool...

[akivela]

Hello Fernando

I am happy you have found Wandora useful.

Occurrences are indeed text fragments you can attach to a topic. You may think occurrences as text fields, just as you noted. However, occurrences have some limitations in Wandora: Each topic may have only one occurrence of one type and one scope.

This limitation has consequences. If you think of one-to-many (or many-to-many) relations such as Person-Book, it is rather difficult to represent such relations if you are unable to attach person more than one Book-occurrence. Well, you could stack all different books into one occurrence of course but that is not very elegant.

If you want to attach Person various different resources, Person-Resource relation is one-to-many (or many-to-many) and I would suggest you to use associations. This means every person and resource is a topic. And then you could create a schema to ease person-resource association creation.

I have created two example Wandora projects that may help to see the difference between occurrences and associations. Projects are available at:

http://www.wandora.org/wandora/examplep ... xample.wpr

http://www.wandora.org/wandora/examplep ... xample.wpr

First project has a schema easing person-resource occurrence creation. You can add person three kind of resources: books, papers, and WWW pages. As stated earlier, Wandora allows only one book (paper and WWW page) occurrence per person. In this case this is a limitation indeed.

Second project has a schema easing person-resource association creation. You can associate person any number of book, paper, and WWW page resources. Both resources and persons are topics.

I don't know if I really answered your question about more direct way to obtain same result as you but please drop a clarifying question if I didn't get it right.

Kind Regards,
Aki Kivela
Wandora Team

[fsancho]

Hi Aki,

Thanks a lot for the fast and useful reply... it's exactly what I was looking for, and the two examples are very self-explanatory. In our case, we will use the solution by means of associations, because we need several resources for every topic in our map.

Your project is so interesting that we would like to help with something we can do...

In our group we are very interested in Topic Maps as a tool for storing and represent information, and we have chosen Wandora as main tool because of the big features it has. Now, we are starting to model our databases in TMs and we are very beginners in the area. In order to teach ourselves we are developing some documentation about TMs in general and how to use them with Wandora in particular.
I don't know if it could be of interest for you, but as soon as we have it we can give you. The first version is in spanish, because we are an almost hispanic group, but we plan to translate it to english as soon as it has almost finish.

Thanks again and see you soon

[akivela]

Hello Fernando

Sounds great! We welcome all help and documentation/documented user experiences are one of the top issues we are interested in. If your documentation is not top secret, please drop a line or two when first version is available. Not only English version, but also Spanish version might interest some Wandora users. Unfortunately I am able to comment only English version.

Also, if your application area is interested enough, I would like to encourage you to write a paper of your experiences/findings to TMRA (http://tmra.de/2008/index.html) or some other conference. If you are interested of such activity, of course.

Kind Reagrds,
Aki Kivela
Wandora Team