In this section, we shall see the use of a URI variable, and URI variable expressions, as a subelement with the HTTP outbound gateway configuration.

If your URL contains URI variables, you can map them using the Uri-variable subelement. This subelement is available for the HTTP outbound gateway and the HTTP outbound channel adapter:

<int-http:outbound-gateway id="trafficGateway"
    url="http://local.yahooapis.com/trafficData?appid=YdnDemo&amp;zip={zipCode}"
    request-channel="trafficChannel"
    http-method="GET"
    expected-response-type="java.lang.String">
    <int-http:uri-variable name="zipCode" expression="payload.getZip()"/>
</int-http:outbound-gateway>

The Uri-variable subelement defines two attributes: name and expression. The name attribute identifies the name of the URI variable, while the expression attribute is used to set the actual value. Using the expression...