what is tlv (tag-length-value)?

Question

What is TLV?

To put hooks (functions) in the code instead of if/else?

If I have one piece of code running on different platforms, at different places in code, I can put TLV function hooks to identify what platform I am on and do accordingly? Or something like that?

Benefits can be cleaner code? Easy to maintain? When a new platform is added, only TLV code needs to change and not the source code?

I may be completely wrong here.

Answer 1

TLV is Tag-length-value encoding. Often it is better referred to by it's original name, type-length-value.

The first field is the "type" of data being processed, the second field specifies the "length" of the value, the third field contains a "length" amount of data representing the value for the "type".

Multiple pieces of data can be transmitted in the same message by appending more triplets to a previously existing message.

There's a page on wikipedia covering it in just a little more detail. Don't get confused though, each triplet is a "top level" description, there is typically no nesting of items in TLV (although you could come up with a way to do so by encoding TLV triplets in the V of another tag).

Answer 2

TLV is a way of storing data to facilitate quick parsing of that data.

Typically, you read the type(tag), length and value and then send those datum to a processor function. This processor functions only function will be to process type X. Then, you read the next type, it's length and value and send it to the appropriate processor.

It's typically used as an easy way to process data without a lot of extra overhead.