code: private boolean isSipServletArchive(File file) {
  		if (file.getName().toLowerCase().endsWith(SAR_EXTENSION)) {
  			return true;
  		} else if (file.getName().toLowerCase().endsWith(WAR_EXTENSION)) {
  			try{
                  JarFile jar = new JarFile(file);                                  
                  JarEntry entry = jar.getJarEntry(SipContext.APPLICATION_SIP_XML);
                  if(entry != null) {
                          return true;
                  }                
  	        } catch (IOException e) {
  	        	if(logger.isInfoEnabled()) {
  	        		logger.info("couldn't find WEB-INF/sip.xml in " + file + " checking for package-info.class");
  	        	}
  	        }
  			return SipApplicationAnnotationUtils.findPackageInfoInArchive(file);
  		} 		
  		return false;
  	}
docs: Check if the file given in parameter match a sip servlet application, i.e.
  if it contains a sip.xml in its WEB-INF directory
  @param file the file to check (war or sar)
  @return true if the file is a sip servlet application, false otherwise