ADF and HTTP compression

Question

Hello!
The customers compain that the their ADF application is not running as fast as their favorite sites (some of the customers have slow internet connection). We all know that the framework is rather heavy (the app is made with jdev 11.1.1.2.0), so is there any chance to speed it up with the http compression?
I need to figure out if ADF is compression-safe. If so, then how to enable the http for the application? Is there a specific weblogic filter, or I can use any such filter I found in the net?
Would I better use in-front Apache for this kind of job? Is there any documentation on how to set up the compression for the app, or maybe somebody has a positive experience that one can share?
Regards,
Eugene

Answer 1

Hi again,
I successfully patched the GZIPFilter to work with ADF Faces.
I found where and what the filter problem related to /faces/* URL is. It is related to the internal implementation of the Faces Servlet, which flushes the response's output stream before any real output has been written yet. In this way the response headers are flushed to the output stream before a header "Content-Encoding: gzip" has been added (which is done first time when some real output is written to the output stream). You can patch the GZIPFilter to support ADF Faces as follows:
1) Modify the method GZIPResponseWrapper.flushBuffer() as follows:
  public void flushBuffer() throws IOException {
    if (debug) p("flushBuffer");
    if (gstream == null) return;
    response.setHeader("Content-Encoding", "gzip"); // This line is added
    gstream.flush();
    super.flushBuffer();
  }2) Modify the method GzipServletOutputStream.init() as follows:
  private void init() throws IOException {
    if (os != null) return;
    response.setHeader("Content-Encoding", "gzip"); // This line is modified from addHeader() to setHeader()
  }3) Map the GZIPFilter to /faces/* URL-pattern in web.xml (not to the Faces Servlet, because there is some problem when the mapping is to the servlet instead of an URL-pattern);
4) Move the GZIPFilter before any other servlet filters in web.xml.
There is another one problem. There are some ADF Faces images accessed under the URL /faces/resources/images/*. If you map the servlet filter to the /faces/* URL-pattern (or to the Faces Servlet), then the filter will try to compress these images too. The problem is that the images are in "compressed" formats, so additional compression would be unnecessary overhead. The URL-pattern in filter mappings in web.xml does not allow specifying exclusions, so if you specify /faces/*, you will include these images too. To workaround this you can modify the method GZIPFilter.doFilter() to check the URI in order to avoid double-compressing the images:
  public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
    HttpServletResponse res = (HttpServletResponse)response;
    HttpServletRequest req  = (HttpServletRequest)request;
    if (req.getAttribute(WL_GZIP_FILTER) != null
        || req.getRequestURI().startsWith("/faces/resources/images", req.getContextPath().length()))) // This line is added
      chain.doFilter(request, response);
      return;
  }Dimitar