Hello world project for Band Chain

Introduction

Contains all the Data Source and Oracle source code for my Band Chain blog post.

Prerequisites

Golang 1.17+
Python 3
Rust
Make
Requires the creation of a cloud function using the data-source-runtime.

Development

Update URLs and identifiers

Go to AeroDataBox and get yourself a free API key.
Add this key to the 2 Data Sources: ds.go and ds.py
Update call_executor.sh with your cloud function URL.
(After deploying the Data Sources) Update the Oracle script with the unique data source ids.

Build

make all

Test Go code logic

go test -v ./ds/...

E2E Data Source testing

Invoke call_executor.sh with no arguments for help.
Example invocation for flight data, using the Go binary
./call_executor.sh ds -t g -a "'EK29' '2022-06-08'"
Example invocation of 'Hello World', using Python
./call_executor.sh hello -t p -a "'Hello world'"

Deployment

Examples provided for a local chain deployment, using the default generated values from genesis.

Data Source

bandd tx oracle create-data-source \
    --name "AeroDataBox Data Source" \              # name of the created data source
    --fee 50000uband \                              # fee charged when using this data source
    --description "AeroDataBox using Python" \      # description of the data source
    --script ./python/ds.py \                       # path to the data source script
    --from requester \                              # sender account
    --owner band1p40yh3zkmhcv0ecqp3mcazy83sa57rgjp07dun \     # data source owner address (replace)
    --treasury band1p40yh3zkmhcv0ecqp3mcazy83sa57rgjp07dun \  # address to collect the fee (replace)
    --node http://localhost:26657 \                           # rpc node
    --chain-id bandchain \                                    # chain id (see genesis.json)
    --gas auto \                                              # transaction gas
    --keyring-backend test                                    # specify keyring (test,os,...)

Oracle

bandd tx oracle create-oracle-script \
    --schema "{flight:string,date:string}/{status:string,arrival_airport:string,scheduled_time_utc:string,actual_time_utc:string}" \  # schema of the input/output
    --name "Flight Arrival Status" \                      # name of the created oracle script
    --description "This Oracle queries multiple flight status data sources to give the status of a flight on a given date." \         # description of the oracle script
    --script "./oracle/target/wasm32-unknown-unknown/release/flight_arrivals.wasm" \                                                  # path to the oracle script script
    --from requester \                                    # sender account (replace)
    --owner band1p40yh3zkmhcv0ecqp3mcazy83sa57rgjp07dun \ # oracle script owner address (replace)
    --node http://localhost:26657 \                       # rpc node
    --chain-id bandchain \                                # chain id
    --gas auto \                                          # transaction gas
    --keyring-backend os                                  # specify keyring (test,os,...)

sgerogia/hello-bandchain