public static Execution onServer(RegionService regionService, String... groups) {
    return getInternalFunctionExecutionService().onServer(regionService, groups);
  }
Returns an {@link Execution} object that can be used to execute a data independent function on
a server that the given cache is connected to. If the optional groups parameter is provided,
the function is executed on one server of each group.
<p>
If the server goes down while dispatching or executing the function, an Exception will be
thrown.

@param regionService obtained from {@link ClientCacheFactory#create()} or
       {@link ClientCache#createAuthenticatedView(java.util.Properties)}.
@param groups optional list of GemFire configuration property "groups" (see
       <a href="../../distributed/DistributedSystem.html#groups"> <code>groups</code></a>) on
       which to execute the function. Function will be executed on one server of each group
@since GemFire 7.0
geode-core/src/main/java/org/apache/geode/internal/cache/execute/InternalFunctionService.java