protected ServiceProvider() throws IOException {
// register service implementation object
Transaction txn = Transaction.open(Transaction.AWSAPI_DB);
txn.close();
serviceMap.put(AmazonS3SkeletonInterface.class, new S3SerializableServiceImplementation(engine));
serviceMap.put(AmazonEC2SkeletonInterface.class, new EC2SoapServiceImpl(EC2_engine));
}