Using variables to return information to your application

There are two ways you can return variable information to your application:

• Specify the METHOD=POST task option and use the variables to set the POST data (using the POSTDATA task option).

• Use the variables to set arguments for a URL query string

It is strongly recommended that you return variable information in POST data instead of query string arguments. This allows the UP.Link server to perform any necessary transcoding of data from the UP.Phone's character set to a character set understood by your application. For more information on character set and internationalization issues see Chapter 9.

The following section describe the two methods of returning information to your application.

---

Returning variable data as POST data

The following HDML allows the user to enter a stock symbol; it then generates a URL request with the stock symbol specified in an argument. This interface is shown in Figure 1-13.

<HDML VERSION=3.0>
    <ENTRY KEY=stock FORMAT=4A>
        <ACTION TYPE=ACCEPT TASK=GOSUB¹
            METHOD=POST POSTDATA="stk=$(stock)"
            DEST="http://foo.com/stock.cgi">
            Enter stock:
    </ENTRY>
</HDML>

FIGURE  1-13.     Setting POST data with variables

Suppose we want to allow the user to choose from a list of stocks instead of entering one. To do this, we could modify the previous example as follows:

<HDML VERSION=3.0>
    <CHOICE KEY=stock>
        <ACTION TYPE=ACCEPT TASK=GOSUB
            METHOD=POST POSTDATA="stk=$(stock)"
            DEST="http://foo.com/stock.cgi">
            Choose a stock:
        <CE VALUE=INTC>Intel
        <CE VALUE=ORCL>Oracle
        <CE VALUE=T>ATT
    </CHOICE>
</HDML>

FIGURE  1-14.     Setting POST data with variables

---

Returning data in query string arguments

Suppose you want to implement the interface shown in Figure 1-13 using query string arguments instead of POST data. The following HDML demonstrates how to do this.

<HDML VERSION=3.0>
    <ENTRY KEY=stock FORMAT=4A>
        <ACTION TYPE=ACCEPT TASK=GOSUB
            DEST="http://foo.com/stock.cgi?stk=$(stock)">
            Enter stock:
    </ENTRY>
</HDML>

FIGURE  1-15.     Setting query string arguments with variables