The Yahoo! Mail Web Service has a call batching mechanism. Use the BatchExecute method to execute up to five methods in a single call. Batch calls can be chained, so that each call is dependent on the previous call’s successful execution. In addition, with the parameter field, each call can reference data specified by the source and destination paths.
Each batch call can have a dependency on the successful execution of other batch calls. To do this, add an id attribute to each batch call that must execute before any following calls. To subsequent batch calls, add a dependency tag that specifies the id of any calls that must successfully execute before this one. Calls with one or more dependencies will not execute unless all call(s) listed in its dependency tag have executed.
You can associate data with a batch call using the parameter tag which can contain a "source" and a "destination" path. The source path specifies the location, starting with a call ID, of a piece of data. The destination path specifies the location, starting with the call ID of the current call, of a placeholder. Yahoo! Mail will look up the source path and place that piece of data into the current call request at the location given by the destination path.
The following example calls BatchExecute to create and rename a folder in one call.