code: public void registerCachedFile(String name, DistributedCacheEntry entry) throws IOException {
  		if (!this.cacheFile.containsKey(name)) {
  			this.cacheFile.put(name, entry);
  		} else {
  			throw new IOException("cache file " + name + "already exists!");
  		}
  	}
docs: register cache files in program level
  @param entry contains all relevant information
  @param name user defined name of that file
  @throws java.io.IOException