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SERIALISATION.md: Add note re CBOR.

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Peter Hinch 2024-02-22 12:26:48 +00:00
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SERIALISATION.md
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@ -61,6 +61,11 @@ The `protobuf` standard requires transmitter and receiver to share a schema
which defines the message structure. Message length may change at runtime, but which defines the message structure. Message length may change at runtime, but
structure may not. structure may not.
There has been some discussion of supporting [CBOR](https://cbor.io/). There is a
MicroPython library [here](https://github.com/onetonfoot/micropython-cbor). This
is a binary format with a focus on minimising message length. I have not yet had
time to study this.
## 1.1 Transmission over unreliable links ## 1.1 Transmission over unreliable links
Consider a system where a transmitter periodically sends messages to a receiver Consider a system where a transmitter periodically sends messages to a receiver
@ -77,7 +82,7 @@ signals the transmitter to request retransmission.
## 1.2 Concurrency ## 1.2 Concurrency
In `uasyncio` systems the transmitter presents no problem. A message is created In `asyncio` systems the transmitter presents no problem. A message is created
using synchronous code, then transmitted using asynchronous code typically with using synchronous code, then transmitted using asynchronous code typically with
a `StreamWriter`. In the case of ASCII protocols a delimiter - usually `b"\n"` a `StreamWriter`. In the case of ASCII protocols a delimiter - usually `b"\n"`
is appended. is appended.
@ -99,7 +104,7 @@ identical methods so this doc may be used for both.
The advantage of `ujson` is that JSON strings can be accepted by CPython and by The advantage of `ujson` is that JSON strings can be accepted by CPython and by
other languages. The drawback is that only a subset of Python object types can other languages. The drawback is that only a subset of Python object types can
be converted to legal JSON strings; this is a limitation of the be converted to legal JSON strings; this is a limitation of the
[JSON specification](http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-404.pdf). [JSON specification](http://www.ecma-international.org/publications/files/ECMA-ST/ECMA-404.pdf).
The advantage of `pickle` is that it will accept any Python object except for The advantage of `pickle` is that it will accept any Python object except for
@ -256,7 +261,7 @@ string can be done with:
```python ```python
import umsgpack import umsgpack
obj = [1.23, 2.56, 89000] obj = [1.23, 2.56, 89000]
msg = umsgpack.dumps(obj) # msg is a bytes object msg = umsgpack.dumps(obj) # msg is a bytes object
``` ```
Retrieval of the object is as follows: Retrieval of the object is as follows:
```python ```python
@ -458,7 +463,7 @@ emitting field headers as seen in regular repeated fields.
>>> packed=minipb.Wire('#z') >>> packed=minipb.Wire('#z')
>>> len(packed.encode(range(10000))) >>> len(packed.encode(range(10000)))
21748 21748
>>> >>>
``` ```
The author of `minipb` [does not recommend](https://github.com/dogtopus/minipb/issues/6) The author of `minipb` [does not recommend](https://github.com/dogtopus/minipb/issues/6)