Remote Data Source Executor

The remote data source executor executes the data sources 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.

The goal of this design is to separate data source execution processes from processes related to the validator node itself. This separation of execution will be beneficial in cases where the data sources are not working correctly ( infinite loop, bad code execution, for example). In those cases, such separation can prevent validator nodes from overloading or crashing due to the error. Also, 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, thus minimizing the work they have to do themselves.

Resource

Endpoint	HTTP Request Method	Description
/execute	POST	Executes the data source

Request

Headers

"content-type": “application/json”

JSON Body

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

Example

{
"executable": "IyEvYmluL3NoXG5cbnN5bWJvbD0kMVxuXG4jIENyeXB0b2N1cnJlbmN5IHByaWNlIGVuZHBvaW50OiBodHRwczovL3d3dy5jb2luZ2Vja28uY29tL2FwaS9kb2N1bWVudGF0aW9ucy92M1xudXJsPVwiaHR0cHM6Ly9hcGkuY29pbmdlY2tvLmNvbS9hcGkvdjMvc2ltcGxlL3ByaWNlP2lkcz0kc3ltYm9sJnZzX2N1cnJlbmNpZXM9dXNkXCJcblxuIyBQZXJmb3JtcyBkYXRhIGZldGNoaW5nIGFuZCBwYXJzZXMgdGhlIHJlc3VsdFxuY3VybCAtcyAtWCBHRVQgJHVybCAtSCBcImFjY2VwdDogYXBwbGljYXRpb24vanNvblwiIHwganEgLWVyIFwiLltcXFwiJHN5bWJvbFxcXCJdLnVzZFwiXG4=",
"calldata": "bitcoin",
"timeout": 1000
}

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 output
stderr	string	Data source error output
error	string	"" or error message from executor

Response Codes

200 OK

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

400 Bad Request

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