Support for additional content types in SlingPostServlet

[Lars Trieloff]

Hi,

I am planning to add support for additional content types to the  
SlingPostServlet that would allow processing Web Forms 2.0, JSON  
(allowing an effective-round-tripping from Sling.js), XML (in JCR  
document notation), ATOM (in terms of the Atom publishing protocol).  
To do this I would like to propose a small API change: extracting a  
ResponseBuilder interface from our current HtmlResponse and renaming  
HtmlResponse subsequently to HtmlResponseBuilder. This would allow us  
to create a doPost method that would start like this (I think we  
should OSGi-ify this later to make content type handling pluggable)

protected void doPost(SlingHttpServletRequest request,
            SlingHttpServletResponse response) throws IOException {

        log.info("content-type: " + request.getContentType());
        String responseType;
    	//try to determine the request content type and set the response  
accordingly. Ordinary
    	//web forms (multipart/form-data or application/x-www-form- 
urlencoded) are getting HTML
        //response
    	if (request.getContentType().equals("application/x-www-form 
+xml")) {
                responseType = "application/x-www-form+xml";
                
                //TODO: handle Web Forms 2.0 POST
    	} else if (request.getContentType().equals("application/json")|| 
request.getContentType().equals("text/x-json")) {
                responseType = "application/json";
                
                //TODO: handle JSON POST
        } else if (request.getContentType().equals("text/xml")) {
                responseType = "text/xml";
                
                //TODO: handle XML POST
    	} else if (request.getContentType().equals("application/atom 
+xml")) {
                responseType = "application/atom+xml";
                
                //TODO: handle Atom POST
        } else {
                responseType = "text/html";
        }
        
        //check for user-specified override of response type
    	if (request.getHeader("Accept")! 
=null&&request.getHeader("Accept").length()!=0) {
                
                responseType = request.getHeader("Accept");
        }
        
        ResponseBuilder responseBuilder;
        if (responseType.equals("application/json")) {
                responseBuilder = new JsonResponseBuilder();
        } else if (responseType.equals("application/x-www-form+xml")) {
                responseBuilder = new WebForms20ResponseBuilder();
        } else if (responseType.equals("text/xml")) {
                responseBuilder = new XmlResponseBuilder();
        } else if (responseType.equals("application/atom+xml")) {
                responseBuilder = new AppResponseBuilder();
        } else {
                responseBuilder = new HtmlResponseBuilder();
        }

the general idea is not to break the current API, so that HtmlResponse  
stays the default, but that users sending a JSON request will get a  
JSON response, unless they explicitly request a different responseType  
using the Accept header.

If this sounds good to you, I would go on by writing the Web Forms 2.0  
part first and submitting a patch (on Youtube) including the proposed  
API changes.

regards,

Lars