Although the product catalog does not provide any OOTB components to support configurable products, we will attempt to illustrate how the catalog can easily be extended to support such products. We will use the T-shirt example to illustrate our solution. Later, we will discuss design strategies for heavy product configurations and product bundles.

We identified several goals in the solution design. First, the solution had to provide an acceptable level of performance for the users wanting to purchase configurable items. Second, any new components should integrate not only with the catalog, but also with the order process, discount, and campaign components. Third, new functionality should not require changes to existing components, thereby minimizing future migration problems. Finally, administrators should be able to easily manage configurable items within the catalog hierarchy as a single item.

Item Configurators
In order to support light product configurations, we added a new component to the product catalog - item configurators. An item configurator represents a list of options that can be assigned to a product. In the T-shirts example, both color and size would be item configurators.

Figure 1 shows the component model representing the item configurators and the options associated with each configurator. Each component is represented in the database by a table of the same name. Instead of directly accessing the configurator components, we have created a Business Manager component called the ItemConfiguratorMgr. This component is responsible for providing configurator information to calling objects. The ItemConfiguratorMgr uses WebLogic Portal's Cache Framework to optimize access to the data. This framework also allows us to monitor the use of the product configurators.

We recommend that you name item configurators with reuse in mind. In the T-shirt example, if you don't expect the list of T-shirt colors to be reused for other items, you should name the color configurator explicitly for T-shirts. On the other hand, the list of T-shirt sizes will probably be identical to other types of shirts. Therefore, the size configurator should be given a more generic name in order to promote reuse.

Creating Configurable Items
Now that we have created our two item configurators - color and size - we need to tie them to our T-shirts. This is accomplished by first creating a generic T-shirt item using the standard catalog administration screens. Since this generic item will not be shown directly to the customer, you should make sure that the visible flag is not checked.

Next, we need to associate the configurators with the item. In addition to the standard Dublin Core attributes, WebLogic Portal facilitates the creation of custom item attributes, grouped into Catalog Structures. We have created a new Catalog Structure called ConfigurableItems, containing the following properties:

The GeneratorClass is the key to our solution. This class will generate new item SKUs based on the order of the listed configurators for a given item. The format of the generated SKUs will be the base item SKU plus a hyphen-separated list of the corresponding options in the order defined by the ConfigurableItems structure.

Going back to the T-shirt example, let's say we've created two configurators - T-Shirt Colors (ID=101) and Shirt Sizes (ID=102). We've also created a T-Shirt product item in the catalog with a SKU of 1001. Using our new ConfigurableItems Catalog Structure, we assign Configurator1 to 101 (colors) and Configurator2 to 102 (sizes). The class ConfigurableItemGenerator will create a new product for each combination of configurators. That is, if there are 8 colors and 4 sizes of T-shirts, the ConfigurableItemGenerator will create 32 new T-shirt items. The SKU associated with small, red T-shirts, for example, would be (1001-RD-S). Figure 2 shows an example configuration for our T-shirts.

Our ConfigurableItemGenerator can create distinct image names for each configured item. The "isVisual" attribute of the ItemConfigurators is used to determine which configurators will be used in generating image names. In our example, color is a visual configurator, but size is not. Therefore, only color will be used to generate the image name. If the base T-shirt product has an image URL of "images/tshirt.jpg", all red T-shirts will have "images/tshirt-RD.jpg" as their image URL. Likewise, if there are no visual configurators assigned to an item, all configured items will inherit the base item's image URL.

The ConfigurableItemGenerator also adds the keywords associated with each ItemConfigurator to the generated items. These keywords are added to the list of keywords associated with the base item.

Each generic item can have a custom GeneratorClass that defines the process of generating configurable items. By allowing you to assign a different GeneratorClass to each item, we have attempted to make the solution as flexible and pluggable as possible.

Managing Configurable Items
In order to effectively manage configurable items, we need to add two new options to the Catalog Management administration page (see Figure 3):

These items will have a look-and-feel that is very similar to the current category and item administration pages.

Clicking on the Item Configurators page link brings you to a list of current item configurators. Administrators will be able to edit the information associated with a particular configurator or delete it from the database. The Create Item Configurator button brings the administrator to a form where he or she can create new configurators.

Clicking on the Configurable Items page brings you to a list of management tasks for managing configurable items in batch. First, you can view the list of generic items that have an associated GeneratorClass for creating configurable items. For each item, the administrator will have the ability to generate configured items, delete generated items, etc.

Much of the administration of Configurable Items will be accomplished using the standard administration pages. For example, to create a generic item you can use the standard item create page to create the non-visible item. Then simply edit the ConfigurableItems properties associated with the product and add the desired GeneratorClass and one or more Configurators.

Similarly, configurable products can be assigned to a category using the "Modify Items Assigned to Category" page. Here we made a slight change to the category_add_ remove_items.jsp that checks added items to see if they have an associated GeneratorClass. If so, it also adds all generated items. Once all items have been assigned to the category, individual items can be unassigned using the same page.

User Navigation
Our solution does not require any changes to the user interface of the catalog. As you navigate through the hierarchy of categories and items, all the newly generated items will appear under their assigned categories. The search engine will also find any generated items that meet the search criteria.

However, in many cases it won't be desirable to show all combinations of configurable items as separate products. In these cases, we recommend that the configurable product be assigned to a dedicated category. Creating such a category will allow you to create and assign a custom layout that, instead of presenting a list of all generated items, presents the generic item information and the associated configurator options. Once the user selects the desired configurator options, the page automatically places the corresponding generated product in the user's shopping cart. Once you design a custom layout JSP, you can associate it with the dedicated category via the category attribute "Display JSP URL".

Creating a dedicated category offers an additional benefit, namely the ability to treat the configured products as a single entity when creating product discounts. Discounts can be offered on either individual products or products within a single category. Our dedicated category approach makes it easy to create a discount that requires the purchase of one or more products of any configuration from the category.

Benefits of this Approach
Our support for configurable products is based primarily on automating the process of generating new SKUs for each combination of configuration options available for a given product. We believe that this solution meets the objectives set out at the start of this article:

This example was built by extending the example wlcsDomain that comes with WebLogic Portal 7.0 sp2. It is published on http://dev2dev.bea.com as an unsupported example.