4.2 CLIENT DEVELOPMENT

4.2.1 Getting Started

In this document we will explain and describe the BGT client. The client is a simple command line application desgined for interacting with a DGT Node, You must have Python installed as well as the openssl library (used to geenrate private keys) or have a pair of public/private keys ready[^1].

The BGT transaction family is a demo transaction family and so some features of more fully realized transactions are lacking (for example: the wallets are named randomly instead of being dependant on public keys).

This guide assumes that you already have a functional Node running on a server, if not see the documentation. Addtionally, if you want more detail you can visit the sawtooth documentaion here.

Lastly, not that due to the use of the secp256k1 library, the client is not supported on Windows at this time. If you have a Windows machine, consider setting up a virtual machine ora WSL.

4.2.2 Installation

To install the client,you can run sudo pip install BGT-Client. If root is unavailable, you will have to add the local bins to the path. See how to do that here.

Manual Instaltion

Clone the DGT Matagami repo
Pip Install’requests’,‘ipaddress’,‘cbor’, ‘protobuf==3.20’,‘cryptography’,‘configparser’, and ‘secp256k1’
Run the bgtc.py file, or add it to the path.

4.2.3 Running the Application

Assuming you either installed with root or added the local bins to the path, the client canbe ran by typing $ bgtc [COMMAND] [OPTIONS]. There are a few special set-up commands that you must exectue before running any of the other ones.

Firstly, you must run $ bgtc connect [IP:PORT] to connect to a node. This command initilizes a config file which is then referenced throughout the application. The connect command opens a socket to the server, and if the connection doesn’t go through, it sends back the errno. Note that it doesn’t actually conenct to the node, as in the socket doesn’t stay open once the program is closed. The connection is essentially a test that ensures the other commands run smoothly. If the connection goes through, the IP:Port is written into the config file: where the other commands refernce it.

Then, you must also run $ bgtc key [PATH] with the path to your private key file. This is used for signing transactions.

Lastly, if you want the contents to be outputted, you must run $bgtc output [FILENAME] with the filename you want the output to be wrriten to.

The other commands are listed below.

version	Prints the current version of the BGT client
set WALLETNAME [TOKENS] [WAIT]	Creates a wallet with a specified number of tokens.
inc WALLETNAME [TOKENS] [WAIT]	Increases the wallet by the specified amount.
dec WALLETNAME [TOKENS] [WAIT]	Decreases the wallet by the specified amount
trans WAL1 WAL2 [TOKENS] [WAIT]	Transfers a given number of tokens from WAL1 to WAL2
show WALLET [WAIT]	Shows the number of tokens in the wallet.
list [Wait]	Returns a list of wallets and their coins in a plaintext format
exit	Exits the client.

If you want to run multiple commands, you must put $ bgtc execute [FILE] where FILE is a plaintext file with commands seperated by lines,each command must be of the same format as if youwere passing it into the command line directly.

4.2.4 Under the Hood

There are two parts to the bgtc program, the bgtc.py file and the cli.py file.

bgtc.py

The bgtc.py file is responsible for parsing user-provided information, verifing it, and sending to the cli.py file.

valIP, valPort, valFile, valOut, valWait, valToken and valArgs all work together to validate the information the user is supplying into the command line. Making sure the command and the paremeters arevalid.

initIP and updateIP handle the “node_ip” section of the config file. The former is run when the first time “connect” is ran, and the latter is run any time the user uses the “connect command after it’s been initially set up. Set output, similarly, adjusts the config file tto contain an”output” field. These config fields are used throughout the code.

The main method simply checks if the program is in “execute” mode. If it is, for each file in the execute file it runs the run() method, which does all the heavy lifting. If not, it passes the system arguments into the run() method.

The run method checks which command is requested and executes the apporpriate function. If the command requires the server it sends it over to the appropriate cli method.

cli.py

The send_request, _sha512, get_prefix(), and get_address method are helper methods which use various common libraries. The connect method simply opens a socket to the IP provided, and returns if it worked

The send method handles all “post” transactions, where we are submitting something to the server. First it creates the context and the private key, using those two to create a “signer” which is a utility object used to help with signing transcations. We then set the payload, that is the data the transaction is sending, including what type of transaction it is. After that, we create the transaction header, add the transaction the the batch and send it to the IP provided.

The show and list send a simple get resquest to the server to return their respective results.

[^1] To generate the private key you can use the following: openssl ecparam -name secp255k1 -genkey -noout -out private_key.txt