In Engine.handler, Cocoon tries to get an OutputStream to write the outBuf
data, but the dummy implementation provided by EngineWrapper returns null..!
Did that ever worked? =)

 Anyway, here's the patch:

Index: Cocoon.java
===================================================================
RCS file: /home/cvspublic/xml-cocoon/src/org/apache/cocoon/Cocoon.java,v
retrieving revision 1.21
diff -u -r1.21 Cocoon.java
--- Cocoon.java	2001/01/18 22:43:45	1.21
+++ Cocoon.java	2001/02/22 04:24:16
@@ -269,7 +269,7 @@
         String userAgent = null;
         String xml = null;
         String out = null;
-        PrintWriter writer = null;
+        OutputStream os = null;
         Configurations confs = null;
 
         if (argument.length == 0)
@@ -305,10 +305,10 @@
 
         EngineWrapper engine = new EngineWrapper(confs);
         if (out == null)
-          writer = new PrintWriter(System.out);
+          os = System.out;
         else
-          writer = new PrintWriter(new FileWriter(out), true);
-        engine.handle(writer, new File(xml));
+          os = new FileOutputStream(out);
+        engine.handle(os, new File(xml));
     }
 
     private static void usage() {
Index: EngineWrapper.java
===================================================================
RCS file: /home/cvspublic/xml-cocoon/src/org/apache/cocoon/EngineWrapper.java,v
retrieving revision 1.13
diff -u -r1.13 EngineWrapper.java
--- EngineWrapper.java	2001/01/11 13:52:19	1.13
+++ EngineWrapper.java	2001/02/22 04:24:17
@@ -83,11 +83,11 @@
         this.userAgent = (String)confs.get("user-agent");
     }
 
-    public void handle(PrintWriter out, File pathToDocument) throws Exception {
+    public void handle(OutputStream out, File pathToDocument) throws Exception {
         this.engine.handle(new HttpServletRequestImpl(pathToDocument), new HttpServletResponseImpl(out));
     }
 
-    public void handle(PrintWriter out, File documentPath, String document) throws Exception {
+    public void handle(OutputStream out, File documentPath, String document) throws Exception {
         this.engine.handle(new HttpServletRequestImpl(documentPath, document), new HttpServletResponseImpl(out));
     }
 
@@ -188,19 +188,33 @@
      */
     public class HttpServletResponseImpl implements HttpServletResponse {
         
-        private PrintWriter out;
+        private OutputStream out;
         
-        public HttpServletResponseImpl(PrintWriter out) {
+        public HttpServletResponseImpl(OutputStream out) {
             this.out = out;
         }
 
         public PrintWriter getWriter() throws IOException {
-            return this.out;
+            return new PrintWriter(new OutputStreamWriter(this.out));
         }
+
+        public ServletOutputStream getOutputStream() throws IOException {
+            return new ServletOutputStream()
+            {
+                public void write(int c) throws IOException
+                {
+                    out.write(c);
+                }
+                public void write(byte[] b, int off, int len)
+                    throws IOException
+                {
+                    out.write(b,off,len);
+                }
+            };
+        }
         
         public void setContentLength(int len) {}
         public void setContentType(String type) {}
-        public ServletOutputStream getOutputStream() throws IOException { return null; }
         public String getCharacterEncoding() { return null; }
         public void addCookie(Cookie cookie) {}
         public boolean containsHeader(String name) { return false; }