Building a Rule-Based Script

Open DecisionScript to the default screen. In the Tree Window, highlight the Root node and type the following formula in the Definition Window:

Root:={
Welcome;
Best Plan;
if(askyesno)
  Order;
else
  Thank You;
}

Type the following text in the Form Window:

Jupiter Cellular's <%Best Plan%> is just right for you.

Would you like to sign up now?

Highlight the Welcome node in the Tree window and type Welcome:=say in the Definition Window. Then type the following text in the Form Window:

Welcome to Jupiter Cellular.

By answering the following questions, we can determine which of our
wireless service plans best meets your cellular phone needs.

Highlight the Best Plan node in the Tree Window and type the following formula in the Definition Window:

Best Plan:=firsttrue(
Security Plan,
Everyday Plan,
Deluxe Plan,
Office Mate Plan,
Office Deluxe Plan
)

In the Tree Window, each plan is displayed as a child of Best Plan.

To define each of the plans, select the corresponding node in the Tree Window and type the attributes, or rules, in the Definition Window. For the Security Plan, the rules can be defined as follows:

Security Plan:=!Business&&Minutes<30&&!Deluxe Features

Literally, this means that the Security Plan is for people who do not want to use the service for business (!Business), and plan to use their cellular phones for less than 30 minutes each month (Minutes<30), and do not need the deluxe features (!Deluxe Features).

The Not operator (!) is used to negate an expression, while the And operator (&&) is used to join rules. Other operators you can use include the Or operator (||) and comparison operators (<, <=, >, >=, !=).

Each rule that is used to define the Security Plan becomes a branch of the Security Plan node.

For the script to work, each rule must be defined to ask the Web site visitor a question or to combine other rules that ask questions. To ask yes or no questions, the function askyesno is used.

To define the Business node, highlight the node in the Tree Window and type the following formula in the Definition Window:

Business:=askyesno

Now, type the following text into the Form Window.

Do you plan to use your cellular phone for business calls?

To ask for a number, the function asknumber is used.

To define the Minutes node, highlight the node in the Tree Window and type the following formula in the Definition Window:

Minutes:=asknumber

Now, type the following text in the Form Window.

Approximately how many minutes of calls do you expect to make each month?

To define the last rule, highlight the Deluxe Features node in the Tree Window and type the following formula in the Definition Window:

Deluxe Features:=Call Forwarding||Call Waiting

Call Forwarding and Call Waiting now become branches of Deluxe Features that must be defined. To define them, highlight each node in the Tree Window, type the askyesno formula in the Definition Window, and ask if the service is needed by typing a question in the Form Window.

The complete script displayed in horizontal tree format looks like this:

As in the Decision Tree script, a customer who wants to sign-up for a service plan right away is directed to another page in your Web site via a redirect. Customers who do not want to sign-up are directed to the Thank You screen. The definition for Thank You is a little more complex than a regular say function because there is no need for a Next button on the last screen. Instead, you display Back and Done buttons.

To include the Back and Done buttons in your script, highlight the Thank You node and type the following in the Definition window:

Thank You:=say(
dialogtemplate,
null,
BTN_BACK+BTN_DONE
)

The codes BTN_BACK and BTN_DONE designate the Back and Done buttons, respectively. This definition will make more sense if you look at the online help listing for say and dialog.

As you can see, using rule-based scripts has a distinct advantage over decision trees in that they allow you to remove services as they become obsolete, or easily modify them as their features change. To make these changes, you don't need to consider exactly where in the sequence of existing questions you must insert new questions. In fact, you never explicitly define the order in which any questions are asked. DecisionScript does this for you. In addition, if you want to add a service that can be defined in terms of questions that are already defined in your script, adding the new service requires only one additional node definition.