IoT Protocol

IoT Protocol is a protocol over TCP based on HTTP and MQTT for lightweight data traffic.

Motivation:

HTTP 1.1 (http://) protocol is a request-response model is well-suited for web-based applications where clients need to request resources from servers and receive responses back. It is still more commonly used and more widely known among developers. But it uses too much data traffic for IoT context. Its minimum request size is 16 bytes (https://stackoverflow.com/a/25065027/1956719) and the HOST param is mandatory for all requests.
MQTT (mqtt://) is a publish-subscribe messaging protocol, use lightweight data traffic. Its minimum request size is 2 bytes. But it is not stateless and does not provide a request/response pattern, so it isn't restful. MQTT is designed to be a lightweight protocol that minimizes network overhead, which can make it more challenging to handle large or complex data payloads.

The IOT PROTOCOL (iot://) is based on HTTP and MQTT protocols over TCP/IP. Is a request-response model adapted for IoT context designed for low-bandwidth, low-power devices. Its minimum request size is 2 bytes without requiring the HOST param for all requests. Supports Full Duplex and can be used for real-time communication up to 255 bytes, middleweight request up to (2^16 -1) bytes (~65Kb) and streaming up to (2^32 -1) bytes (~4.29Gb). Can use TLS/SSL encryption to secure its communications.

IOT PROTOCOL uses middlewares and router's filtering features based on express nodejs module under its Application Layer. Yes, you can use .use(middleware), .use('/path/to/your/resource', router), response.send(data) methods to handle the requests.

Features

Lightweight protocol that minimizes network overhead
Minimum request size is 2 bytes
Request-response model like HTTP protocol
Adaptive requests methods for optimizing data length
Multipart (Send large data)
Streamming data

Comparison Summary HTTP vs MQTT vs IOT

	MQTT	HTTP 1.1	IOT
Full Name	MQTT (the OASIS standardization group decided it would not stand for anything)	Hyper Text Transfer Protocol	Internet Of Thing Protocol
Architecture	Publish subscribe (MQTT does have a request/reply mode as well)	Request response	Request response
Command targets	Topics	URIs	URIs
Underlying Protocol	TCP/IP	TCP/IP	TCP/IP
Secure connections	TLS + username/password (SASL support possible)	TLS + username/password (SASL support possible)	TLS + username/password (SASL support possible)
Client observability	Known connection status (will messages)	Unknown connection status	Known connection status (will messages)
Messaging Mode	Asynchronous, event-based	Synchronous	Asynchronous, event-based
Message queuing	The broker can queue messages for disconnected subscribers	Application needs to implement	Application needs to implement
Message overhead	2 bytes minimum. Header data can be binary	16 bytes minimum (header data is text - compression possible) + HOST	2 bytes minimum
Message Size	256MB maximum	No limit but 256MB is beyond normal use cases anyway	256 bytes / 65Kb / 4.29Gb maximum
Content type	Any (binary)	Text (Base64 encoding for binary)	Any (binary)
Message distribution	One to many	One to one	One to one (One to many not implemented yet)
Reliability	Three qualities of service: 0 - fire and forget, 1 - at least once, 2 - once and only once	Has to be implemented in the application	Has to be implemented in the application
Streaming	Application needs to implement	Application needs to implement	Yes

Overhead Performance in IoT

Overhead Performance in bytes for each operation

	MQTT (bytes)	HTTP 1.1 (bytes)	IOT (bytes)
Establish connection
Disconnect
For each message published
Sum for 1 message
Sum for 10 messages
Sum for 100 messages
Sum for 1000 messages

Time Performance in IoT

Time Performance in ms for response time per message

No. messages in a connection	MQTT avg. response time per message (ms) (QoS 1)	HTTP avg. response time per message (ms)
1	113	289
100	47	289
1000	43	289

Preamble Version 1

<MSCB>
<LSCB>
[ID]
[PATH]
[HEADER]
[BODY]

<...> REQUIRED

[...] OPTIONAL

Limitations

(PATH + HEADER) MUST NOT BE MORE THAN 1016 Bytes with IOT_PROTOCOL_DEFAULT_BUFFER_SIZE (1024 bytes)

  + 1024 Bytes : IOT_PROTOCOL_DEFAULT_BUFFER_SIZE
     - 1 Byte  : MSCB_SIZE 
     - 1 Byte  : LSCB_SIZE 
     - 2 Bytes : ID_SIZE 
     - 4 Bytes : BODY_LENGTH_MAXIMUM_SIZE (Streaming)
   ----------------
     + 1016 Bytes > [PATH]_SIZE + [HEADER]_SIZE

|---------------------------------------BUFFER_SIZE(1024)-----------------------------------|

|--MSCB(1)--|

            |--LSCB(1)--| 

                        |--ID_SIZE(2)--| 

                                       |--PATH--|

                                                |--HEADER--|

                                                           |--BODY_LENGTH_MAXIMUM_SIZE(4)--|

BUFFER_SIZE can be increase using Buffer Size Request/Response methods

Maximum of 255 headers per request

BUFFER_SIZE

BUFFER_SIZE is the maximum size of single transmission data (packet). If all data length > IOT_PROTOCOL_BUFFER_SIZE, the data is spplited in parts of IOT_PROTOCOL_BUFFER_SIZE length. Each part keeps the prefixed data (MSCB + LSCB + ID + PATH + HEADER + BODY_LENGTH) and attachs the remain body until its length is BUFFER_SIZE length or equals to body length.

Type: size_t | uint32_t
Size: 4 bytes
Default value: 1024
Can be changed using Buffer Size Request/Response methods

IOT_ETX

IOT_ETX byte serves to determine end of text

Type: char | byte | uint8_t
Size: 1 byte
Constant:
- char: ETX Unicode - End Of Text
- hex: 0x3
- decimal: 3
- binary: 0b11

IOT_RS

IOT_RS byte serves as record or key value pair separator

Type: char | byte | uint8_t
Size: 1 byte
Constant:
- char: RS Unicode - Information Separator Two - RecordSeparator RS
- hex: 0x1E
- decimal: 30
- binary: 0b011110

[0] MSCB

The Most Significant Control Byte.

Preamble: <MSCB> REQUIRED | SINGLE

Size: 1 byte
Default: 0b00000100 = 4 = 0x4

Name	Description	Bit 7	Bit 6	Bit 5	Bit 4	Bit 3	Bit 2	Bit 1	Bit 0	Default
VERSION	Version of iot protocol	X	X	X	X	X	X			0b000001
ID	Enable = 1 / Disable = 0 IDentification							X		0b0
PATH	Enable = 1 / Disable = 0 PATH								X	0b0

Version:

Range: from 1 up to 63. Zero is reserved.

[1] LSCB

The Least Significant Control Byte.

Preamble: <LSCB> REQUIRED | SINGLE

Size: 1 byte
Default: 0b00000100 = 4 = 0x4

Name	Description	Bit 7	Bit 6	Bit 5	Bit 4	Bit 3	Bit 2	Bit 1	Bit 0	Default
METHOD	Type of request	X	X	X	X	X	X			0b000001
HEADER	Enable = 1 / Disable = 0 HEADER							X		0b0
BODY	Enable = 1 / Disable = 0 BODY								x	0b0

METHODs:

Range: from 1 up to 63. Zero is reserved.

Methods Types

Name	Description	MSCB_ID	MSCB_PATH	LSCB_METHOD	LSCB_HEADER	LSCB_BODY	BODY_LENGTH	BODY_CONTENT	Minimum Total Length
Signal	Ligthweight signals like events	0	0/1	`0b000001`	0/1	0/1	`1 byte`	up to 255 bytes	2 bytes
Request	Request that needs response	1	0/1	`0b000010`	0/1	0/1	`2 bytes`	up to 65535 bytes	4 bytes
Response	Request's response	1	0	`0b000011`	0/1	0/1	`2 bytes`	up to 65535 bytes	4 bytes
Streaming	Streaming data	1	0/1	`0b000100`	0/1	0/1	`4 bytes`	up to (2^32 -1) bytes	6 bytes
Alive Request	Request Alive	0	0	`0b000101`	0	0	`0 byte`	`0 byte`	2 bytes
Alive Response	Respond the alive's request	0	0	`0b000110`	0	0	`0 byte`	`0 byte`	2 bytes
Buffer Size Request	Request to change buffer size	0	0	`0b000111`	0	1	`1 byte` fixed with value `= 4`	`4 bytes`	7 bytes
Buffer Size Response	Respond to change of buffer size	0	0	`0b001000`	0	1	`1 byte` fixed with value `= 4`	`4 bytes`	7 bytes

Alive Method

Heartbeat mechanism to determine if the connection is still alive or if it has been closed.

Both sides, client and server, keep sends alives requests. Who receives first, responds first and not emmit alives request.

Heartbeat interval defines the request period time in seconds. Client and server can have different heartbeat interval

Default heartbeat interval: 60 seconds

To disable heartbeat mechanism, set interval to 0 (zero) after start listen

Buffer Size

Buffer Size method allows to change the size of buffer for the next data transfers.

Default buffer size: 1024 bytes.

BODY_LENGTH: fixed with value = 4 (bytes).

BODY_CONTENT: uint32_t (4 bytes as Big Endian format) allows set the buffer size up to (2^32 -1) bytes.

To set to default value (1024) set body to 0 (zero).

[2] ID:

Unsigned random number with up to 2^16 that identifies the request.

Preamble: [<ID>] OPTIONAL | SINGLE

Type: uint16_t as Big Endian format
Size: 2 bytes
Example:
- decimal: 276
- uint_8[2]: [ 1 , 20 ]
- binary: 0b00000001 00010100

[3] PATH:

The path component contains data, usually organized in hierarchical form, that, serves to identify a resource URI > 3.3 Path.

Preamble: [<PATH> + <IOT_ETX>]. OPTIONAL | SINGLE

PATH

Type: string
Example: /foo/bar

[4] HEADER:

Header is a Key Value Pair that serves to set an attribute value for the request. Case sensitive. Maximum of 255 headers.

Preamble: [<HEADER_SIZE> + <HEADERs>]. OPTIONAL | SINGLE

HEADER_SIZE

The amount of headers from 1 until 255 headers. REQUIRED | SINGLE

Type: byte | uint8_t
Size: 1 byte

HEADERs

The key-value pair of one header.

Preamble: <KEY + IOT_RS + VALUE + IOT_ETX> REQUIRED | MULTIPLE (Minimum 1)

Type: uint8_t[]
KEY:
- Type: string
VALUE:
- Type: string
Example:
- Single header (HEADER_SIZE = 1): ["foo", IOT_RS, "bar", IOT_ETX]
- Multiple headers (HEADER_SIZE = 2): ["foo", IOT_RS, "bar", IOT_ETX, "lorem", IOT_RS, "ipsum", IOT_ETX]

[5] BODY

The final data to be sent for request receiver.

Preamble: [<BODY_LENGTH> + <BODY>]. OPTIONAL | SINGLE

BODY_LENGTH:

The body's length. REQUIRED

Type: uint8_t | uint16_t | uint32_t as Big Endian format
Size: 1 / 2 / 4 bytes. Depends on the used method
Example:
- uint8_t
  - decimal: 17
  - uint_8[1]: [ 17 ]
  - binary: 0b00010001
- uint16_t
  - decimal: 2321
  - uint_8[2]: [ 9 , 17 ]
  - binary: 0b00001001 00010001
- uint32_t
  - decimal: 67857
  - uint_8[4]: [ 0, 1, 9 , 17 ]
  - binary: 0b00000000 00000001 00001001 00010001

BODY_CONTENT:

The body contents of request. REQUIRED

Type: uint8_t[]
Example:
- String: the message
- Buffer: [ 116, 104, 101, 32, 109, 101, 115, 115, 97, 103, 101 ]

Middlewares

@TODO Explains what is a middleware and how its works

Listen

@TODO Explains what listener method does

Examples

@TODO List of examples on /examples

References

HTTP/1.1 Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke, Ed., "HTTP/1.1", STD 99, RFC 9112, DOI 10.17487/RFC9112, June 2022, https://www.rfc-editor.org/info/rfc9112.
URI Berners-Lee, T. Fielding, R. L. Masinter "Uniform Resource Identifier (URI): Generic Syntax" STD 66 RFC 3986 DOI 10.17487/RFC3986 https://www.rfc-editor.org/info/rfc3986.
UNICODE Compart. Unicode Character https://www.compart.com/en/unicode
MQTT MQTT. MQTT 5 Specification https://docs.oasis-open.org/mqtt/mqtt/v5.0/mqtt-v5.0.html

Name		Name	Last commit message	Last commit date
Latest commit History 36 Commits
.gitignore		.gitignore
LICENSE		LICENSE
README.md		README.md
iot_helpers.cpp		iot_helpers.cpp
iot_helpers.h		iot_helpers.h
iot_protocol.cpp		iot_protocol.cpp
iot_protocol.h		iot_protocol.h
library.properties		library.properties

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Repository files navigation

IoT Protocol

Features

Comparison Summary HTTP vs MQTT vs IOT

Overhead Performance in IoT

Time Performance in IoT

Preamble Version 1

Limitations

BUFFER_SIZE

IOT_ETX

IOT_RS

[0] MSCB

Version:

[1] LSCB

METHODs:

Alive Method

Buffer Size

[2] ID:

[3] PATH:

PATH

[4] HEADER:

HEADER_SIZE

HEADERs

[5] BODY

BODY_LENGTH:

BODY_CONTENT:

Middlewares

Listen

Examples

References

About

Releases

Packages

Languages

License

ItThinkIoT/iot-protocol-cpp

Folders and files

Latest commit

History

Repository files navigation

IoT Protocol

Features

Comparison Summary HTTP vs MQTT vs IOT

Overhead Performance in IoT

Time Performance in IoT

Preamble Version 1

Limitations

BUFFER_SIZE

IOT_ETX

IOT_RS

[0] MSCB

Version:

[1] LSCB

METHODs:

Alive Method

Buffer Size

[2] ID:

[3] PATH:

PATH

[4] HEADER:

HEADER_SIZE

HEADERs

[5] BODY

BODY_LENGTH:

BODY_CONTENT:

Middlewares

Listen

Examples

References

About

Resources

License

Stars

Watchers

Forks

Releases

Packages 0

Languages

Packages