Web Services have become a popular way to expose application functionality and enable better interoperability between the resources of various enterprises. They broaden the capabilities of mobile applications and simplify the development process.

Implementing web services in a mobile environment can be challenging because connectivity may not be available (or may be interrupted) and because of other limitations of wireless environments and devices. For example, a user working with a mobile application may want to make a request to a web service while offline and obtain the response when they go online, or an IT administrator may want to specify rules that restrict the size of web service responses based on the type of network connectivity the mobile application is using (such as GPRS, 802.11, or cradled).

QAnywhere addresses these challenges with mobile-optimized asynchronous web services that leverage the QAnywhere store-and-forward messaging architecture. By using QAnywhere mobile web services, your mobile applications can make web service requests, even when they are offline, and have those requests queued up for transmission later. The requests are delivered as QAnywhere messages and then a web services connector on the server side makes the request, gets the response from the web service, and returns the response to the client as a message. QAnywhere transmission rules can control which requests and responses are transmitted based on a wide variety of parameters (network being used, size of request/response, location, time of day, and so on). The result is a sophisticated and flexible architecture that allows mobile applications to tap into the vast functionality of web services using proven technology and a simple programming model.

From a development point of view, you can work with web service proxy classes much as you would in a connected environment and QAnywhere handles the transmission, authentication, serialization, and so on. A WSDL compiler is provided to take a WSDL document and generate special proxy classes (either .NET or Java) that a mobile application can use to invoke a web service. These classes use the underlying QAnywhere infrastructure to send requests and receive responses. When an object method call is made, a SOAP request is built automatically and delivered as a message to the server where a connector makes the web service request and returns the result as a message.

 See also