Not possible to stream attachments via WebServiceTemplate and WebServiceMessageSender

[koen-serneels]

Using ClientHttpRequestMessageSender and setting 'setBufferRequestBody' to false:
HttpWebServiceMessageSenderBuilder httpWebServiceMessageSenderBuilder = new HttpWebServiceMessageSenderBuilder();HttpWebServiceMessageSenderBuilder httpWebServiceMessageSenderBuilder = new HttpWebServiceMessageSenderBuilder(); httpWebServiceMessageSenderBuilder.requestFactory(() -> { HttpComponentsClientHttpRequestFactory httpComponentsClientHttpRequestFactory = new HttpComponentsClientHttpRequestFactory( configureHttpClient(HttpClients.custom(), endpointConfiguration, messageContextHolder)); httpComponentsClientHttpRequestFactory.setBufferRequestBody(false); return httpComponentsClientHttpRequestFactory; });

There is an exception thrown:  UnsupportedOperationException("getBody not supported");Which is caused by ClientHttpRequestConnection#getRequestOutputStream calling: AbstractClientHttpRequest#getBody -> HttpComponentsStreamingClientHttpRequest#getBodyInternal 

When using HttpComponentsMessageSender instead, it seems hardcoded to use an mem buffer for the actual attachment:
@Override protected void onSendAfterWrite(WebServiceMessage message) throws IOException { httpPost.setEntity(new ByteArrayEntity(requestBuffer.toByteArray()));