Web Services Essentials

Arrays

Example 6-6, shown later in this section, is a sample WSDL file that illustrates the use of arrays. This is the Price List Service we created in Chapter 5. The service has one public method, called getPriceList, which expects an array of string SKU values and returns an array of double price values.

The WSDL file now includes a types element. Inside this element, we have defined two new complex types. Very broadly, the XML Schema defines simple types and complex types. Simple types cannot have element children or attributes, whereas complex types can have element children and attributes. We have declared complex types in our WSDL file, because an array may have multiple elements, one for each value in the array.

The XML Schema requires that any new type you create be based on some existing data type. This existing base type is specified via the base attribute. You can then choose to modify this base type using one of two main methods: extension or restriction. Extension simply means that your new data type will have all the properties of the base type plus some extra functionality. Restriction means that your new data type will have all the properties of the base data type, but may have additional restrictions placed on the data.

In Example 6-6, we’ll create two new complex types via restriction. For example:

<complexType name="ArrayOfString"> <complexContent> <restriction base="soapenc:Array"> <attribute ref="soapenc:arrayType" wsdl:arrayType="string[]"/> </restriction> ...