code: protected InputStream getInputStream(String pdbId) throws IOException{
  
  		if ( pdbId.length() != 4)
  			throw new IOException("The provided ID does not look like a PDB ID : " + pdbId);
  
  		// Check existing
  		File file = downloadStructure(pdbId);
  
  		if(!file.exists()) {
  			throw new IOException("Structure "+pdbId+" not found and unable to download.");
  		}
  
  		InputStreamProvider isp = new InputStreamProvider();
  
  		InputStream inputStream = isp.getInputStream(file);
  
  		return inputStream;
  	}
docs: Load or download the specified structure and return it as an InputStream
  for direct parsing.
  @param pdbId
  @return
  @throws IOException