Build a user interface

Now we know how our web service works we can think about integrating it into our site. There are a range of possibilities for even the simplest of web services.

It could be that our web service will be called using a fixed set of parameters and we simply display the latest result of calling the web service. For example, a website for a nature park may display the current weather for the location of the park integrated within the web site.

Another possibility is that some of the parameters may be fixed, but the user of your website may need to provide the remaining ones. For example, a foreign visitor to your site may enter their currency code on you web page and the page will determine the conversion rate from GB Pounds.

At the other extreme there is the totally generic user interface which allows the user to enter all the parameters so that the page can perform the function. For example, a language translation site may provide the user with a list of source languages and destination language and provide a space to type some text. The page will call the web service and return the translation.

It is up to you to determine how the interface is constructed. Bear in mind that the developer who writes the call to the web service will provide the link between your input elements and the result.

Example 1: Return the current temperature for a fixed location

This is the simplest of user interfaces. The web page developer provides an <asp:Label> element on the web page in the required location. The application developer will create code to call the web service and drop the result in the label.

Example 2: Return the latest conversion rate to an arbitrary currency

Here the web page design should allow for a drop down list for the user to select their currency. The local currency will always be GBP. An <asp:Label> or perhaps a read-only <asp:TextBox> will be placed on the page to receive the conversion rate. There may be a button to trigger the lookup or the page may automatically lookup when a currency is selected in the drop down list. The application developer writes the code to pass the value from the drop down list and GBP to the web service and place the result on the page.

Example 3: Generic page for translating text.

We can provide a drop down list for selecting one of the translation types. A multiple line text box is provided for the user to type text into (or paste). A button to action the translation is required and a multi-line label for receiving the result of the translation. All the parameters are available on the page for the developer to use when calling the web service. The result is dropped into the label.

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