Short answer: you can use both get_operation_by_name()and parameters get_tensor_by_name(). Long answer:
tf.Operation
When you call
op = graph.get_operation_by_name('logits')
... it returns an instance of a type tf.Operation, which is a node in a computational graph that executes some op on its inputs and produces one or more outputs. In this case, it is a plusop.
You can always evaluate op in a session, and if this operator needs some placehoder values to be submitted, the engine will force you to provide them. Some operating systems, for example. reading a variable has no dependencies and can be performed without placeholders.
( ) logits x, logits x.
tf.Tensor
,
tensor = graph.get_tensor_by_name('logits:0')
... tensor, tf.Tensor:
Operation.
A tensor Operation. , TensorFlow tf.Session.
, , , , , .
tensor ? A tensor Operation, . , .