Remote Data Source Executor

The remote data source executor executes the data source scripts that are stored on BandChain in order to retrieve data from the data providers. The executor itself is a Function-as-a-Service hosted on a cloud service provider, and is intended to separate data source script execution processes from those related to the validator node itself. From a validator's perspective, all they have to do to execute a data source is to send an executable file content in JSON format (the data source script), along with the relevant calldata, to an endpoint.

This separation of execution aims to prevent the validator nodes from being overloaded or from crashing in cases where the data sources are not working properly (e.g. infinite loop, bad code execution, etc.).

Resource

Endpoint	HTTP Request Method	Description
/execute	POST	execute data source script

Request

Headers

"content-type": “application/json”

JSON Body

Field	Type	Description
executable	string	Base64-encoded data source script that the executor will execute
calldata	string	Bash-encoded input parameters of data source script
timeout	number	Execution time limit (millisecond)

Example

{
"executable": "IyEvYmluL3NoXG5cbnN5bWJvbD0kMVxuXG4jIENyeXB0b2N1cnJlbmN5IHByaWNlIGVuZHBvaW50OiBodHRwczovL3d3dy5jb2luZ2Vja28uY29tL2FwaS9kb2N1bWVudGF0aW9ucy92M1xudXJsPVwiaHR0cHM6Ly9hcGkuY29pbmdlY2tvLmNvbS9hcGkvdjMvc2ltcGxlL3ByaWNlP2lkcz0kc3ltYm9sJnZzX2N1cnJlbmNpZXM9dXNkXCJcblxuIyBQZXJmb3JtcyBkYXRhIGZldGNoaW5nIGFuZCBwYXJzZXMgdGhlIHJlc3VsdFxuY3VybCAtcyAtWCBHRVQgJHVybCAtSCBcImFjY2VwdDogYXBwbGljYXRpb24vanNvblwiIHwganEgLWVyIFwiLltcXFwiJHN5bWJvbFxcXCJdLnVzZFwiXG4=",
"calldata": "bitcoin"
}

Response:

Headers

"content-type":  "application/json",
"access-control-allow-methods":  "OPTIONS, POST",

JSON Body

Field	Type	Description
returncode	number	exit code 0-255
stdout	string	data source script output
stderr	string	data source script error output
error	string	"" or error message from executor

400 Bad Request

Error	Error message
Missing executable value	executable field is missing from JSON request
Missing calldata value	calldata field is missing from JSON request
Missing timeout value	timeout field is missing from JSON request
Executable value exceed	executable value exceed max size
Calldata value exceed	calldata exceeded max size
Runtime value exceed	Runtime exceeded max size
Invalid timeout format	timeout type is invalid

200 OK

Exit code	Description	Error Message
0 - 255	Executable errors from data source script run successfully	N/A
111	Execution timeout	Execution time limit exceeded
112	Stdout exceed	Stdout exceeded max size
113	Stderr exceed	Stderr exceeded max sizeed
126	Execution fail	Data source script could not be invoked