~martijnbraam/bare-py

Python implementation of BARE messsages
2 days ago
3 days ago

#bare-py builds.sr.ht status

Python implementation of BARE. It should be a complete implementation. Unions might still cause weird behavior.

BARE is a binary encoding for datastructure that produces small messages, but is still 8-bit aligned. The usual workflow is writing a schema file and using the bare command to generate a python module representing your data structure.

#Example

The schema:

type PublicKey data<128>
type Time string # ISO 8601

enum Department {
	ACCOUNTING
	ADMINISTRATION
	CUSTOMER_SERVICE
	DEVELOPMENT

	# Reserved for the CEO
	JSMITH = 99
}

type Customer {
	name: string
	email: string
	address: Address
	orders: []{
		orderId: i64
		quantity: i32
	}
	metadata: map[string]data
}

type Employee {
	name: string
	email: string
	address: Address
	department: Department
	hireDate: Time
	publicKey: optional<PublicKey>
	metadata: map[string]data
}

type Person (Customer | Employee)

type Address {
	address: [4]string
	city: string
	state: string
	country: string
}

Generate schema.py with the bare command

$ bare schema.bare schema.py

#Packing data

from schema import Customer, Address, Person

address = Address()
address.address = ["Address line 1", "", "", ""]
address.city = "The big city"
address.state = "Drenthe"
address.country = "The Netherlands"

customer = Customer()
customer.name = "Martijn Braam"
customer.email = "spam@example.org"
customer.address = address
customer.orders = [
    {'orderId': 5, 'quantity': 1},
    {'orderId': 6, 'quantity': 2}
]
customer.metadata = {
    'ssh': b'jafsl8dfaf2',
    'gpg': b'jofa8f2jdlasfj8'
}

# Write a Customer as a BARE encoded file
with open('example.bin', 'wb') as handle:
    handle.write(customer.pack())

# Write it as a Person instead, only works with tagged unions
with open('person.bin', 'wb') as handle:
    handle.write(Person.pack(customer))
$ xxd example.bin
00000000: 0d4d 6172 7469 6a6e 2042 7261 616d 1073  .Martijn Braam.s
00000010: 7061 6d40 6578 616d 706c 652e 6f72 670e  pam@example.org.
00000020: 4164 6472 6573 7320 6c69 6e65 2031 0000  Address line 1..
00000030: 000c 5468 6520 6269 6720 6369 7479 0744  ..The big city.D
00000040: 7265 6e74 6865 0f54 6865 204e 6574 6865  renthe.The Nethe
00000050: 726c 616e 6473 0205 0000 0000 0000 0001  rlands..........
00000060: 0000 0006 0000 0000 0000 0002 0000 0002  ................
00000070: 0373 7368 0b6a 6166 736c 3864 6661 6632  .ssh.jafsl8dfaf2
00000080: 0367 7067 0f6a 6f66 6138 6632 6a64 6c61  .gpg.jofa8f2jdla
00000090: 7366 6a38                                sfj8

#Unpacking data

from schema import Address

with open('address.bin', 'rb') as handle:
    raw = handle.read()

address = Address.unpack(raw)
print(address.city)

#Debugging messages

The bare-dump command can be used to decode the binary messages with a supplied schema. It will output the bytes annotated with the information from the schema and the decoded data.

$ bare-dump cursor.bare Cursor --base64 MgGolKbTCwA=
struct Cursor
|count                    32                        INT = 25
|next                     01                        union, tag = 1 (INT)
||INT                     A8 94 A6 D3 0B            INT = 1563739412
|search                   00                        String =