Methods and apparatus, including computer program products, implementing and using techniques for selectively accessing one or more web services from a client machine, the one or more web services and the client machine being accessible over a network. A request for information is received from a client machine with a conversion engine. The request is received over a synchronous interface. The request is processed in the conversion engine. The processed request is transmitted over an asynchronous interface from the conversion engine to at least one web service. Methods and apparatus, including computer program products, for converting a web service description language file for a synchronous web service into a web service description language file for an asynchronous client machine are also described.