title: In Tensorflow for serving a model, what does the serving input function supposed to do exactly
body: <p>So, I've been struggling to understand what the main task of a serving_input_fn() is when a trained model is exported in Tensorflow for serving purposes. There are some examples online that explain it but I'm having problems defining it for myself.</p>
  
  <p>The problem I'm trying to solve is a regression problem where I have 29 inputs and one output. Is there a template for creating a corresponding serving input function for that? What if I use a one-class classification problem? Would my serving input function need to change or can I use the same function?</p>
  
  <p>And finally, do I always need serving input functions or is it only when I use tf.estimator to export my model?</p>