📃WitnetRequestFactory

Bound to the WitnetOracle contract, this artifact enables smart contracts and offchain worfklows to programmatically build both WitnetRequest and WitnetRequestTemplate instances, based on a provided list of data sources, attestation filters and computational Radon scripts that transform and aggregate the data as extracted from those sources.

The address of this appliance can be obtained by calling to the factory() method on the public domain Wit/Oracle artifact, as deployed by the Witnet Foundation on each supported chain.

Interfaces

^ Pure methods that neither write nor read from storage.

= View methods that read from immutable code storage.

:: View methods that read from storage.

+ Methods that may potentially alter storage.

$ Payable methods that may potentially alter storage.

[]! Methods that may revert under certain conditions.

IWitnetOracleAppliance

Methods	Description
= class(): string	Returns the name of the contract that's actually implementing the ABI's specs() logic.
= specs(): bytes4	Returns the immutable ERC-165 id of the expected functionality as for the WitnetRequestFactory ABI.
= witnet(): WitnetOracle	Address of the WitnetOracle contract that produced WitnetRequest and WitnetRequestTemplate instances will be compliant with.

IWitnetRequestFactory

Methods	Description
+! buildWitnetRequest( bytes32[] retrieveHashes, Witnet.RadonReducer aggregate, Witnet.RadonReducer tally ): address	Builds a WitnetRequest instance that will provide the bytecode and RAD hash of some Witnet-compliant Radon Request, provably made out of some previously verified data sources (i.e. Radon Retrievals), aggregate and tally Radon Reducers. Produced addresses are counter-factual to the given values. Reverts if: - unverified retrievals are passed; - any of the given retrievals is parameterized; - retrievals return different data types; - unsupported reducers are passed.
+! buildWitnetRequestTemplate( bytes32[] retrieveHashes, Witnet.RadonReducer aggregate, Witnet.RadonReducer tally ): address	Builds a WitnetRequestTemplate instance made out of one or more parameterized data sources (i.e. Radon Retrievals), aggregate and tally Radon Reducers. Produced addresses are counter-factual to the given values. Reverts if: - unverified retrievals are passed; - none of given retrievals is parameterized; - retrievals return different data types; - unsupported reducers are passed.
+! verifyRadonRetrieval( Witnet.RadonRetrievalMethods, string requestURL, string requestBody, string[2][] requestHeaders, bytes requestRadonScript ): bytes32	Verifies and registers the specified Radon Retrieval (i.e. public data source) into the WitnetRadonRegistry of the WitnetOracle attached to this factory. Returns a unique hash that identifies the verified Radon Retrieval. All parameters but the retrieval method are parameterizable (i.e. by using embedded wildcard \x\ substrings, with x = 0..9). Reverts if: - unsupported retrieval method is given; - no url is provided on Http/* requests; - non-empty strings given on Rng requests.

Events

IWitnetRadonRegistryEvents

Events	Arguments	Description
NewRadonReducer	bytes16 hash	Emitted every time a new Witnet.RadonReducer gets successfully verified and stored into the WitnetRadonRegistry.
NewRadonRetrieval	bytes32 hash	Emitted every time a new Witnet.RadonRetrieval gets successfully verified and stored in the WitnetRadonRegistry.
NewRadonRequest	bytes32 radHash	Emitted every time a new Witnet.RadonRequest gets successfully verified and stored in the WitnetRadonRegistry.

IWitnetRequestFactoryEvents

Events	Arguments	Description
WitnetRequestBuilt	address request	Emitted every time a new counter-factual WitnetRequest gets verified and built.
WitnetRequestTemplateBuilt	address template	Emitted every time a new counter-factual WitnetRequestTemplate gets verified and built.

Structs

Witnet.RadonFilter

Struct defining the data filtering to be applied at either the Aggregate or Tally stages within the resolution of a data request within the Witnet blockchain.

Field	Type	Description
opcode	Witnet.RadonFilterOpcodes	Filtering function.
cborArgs	bytes	CBOR-encoded array of filter parameters. Empty if no parameters are to be specified.

Witnet.RadonReducer

Struct defining the array of filters, if any, and reduce function to be applied at either the Aggregate or Tally stages within the resolution of a data request within the Witnet blockchain.

Field	Type	Description
opcode	Witnet.RadonReducerOpcodes	Reducing function.
filters	Witnet.RadonFilter[]	Zero, one or more filters to be orderly applied to input dataset before actually executing the reduce function.

Witnet.RadonRequest

Struct containing the Retrieve-Attestation-Delivery parts of a Witnet-compliant Data Request Object.

Field	Type	Description
retrieve	Witnet.RadonRetrieval[]	One or more public data sources (i.e. Radon Retrievals) out from where data will be retrieved by all witnessing nodes in the Witnet-blockchain attending the resolution of this data request.
aggregate	Witnet.RadonReducer	Filtering and reduce operations that will executed by every single witnessing node as to aggregate the data extracted from the request's data sources.
tally	Witnet.RadonReducer	Filtering and reduce operations that will be applied to the aggregated data revealed by each witnessing node. Witnessing nodes revealing data that gets ultimately filtered out, will get slashed.

Witnet.RadonRetrieval

Struct containing all parameters that fully describe the Radon Retrievals that can form part of Witnet-compliant Data Request Objects.

Field	Type	Description
argsCount	uint8	Number of indexed parameters to be provided whenever this Radon Retrieval is to be included into a Radon Request.
method	Witnet.RadonRetrievalMethods	Immutable method to be used for retrieving data.
dataType	Witnet.RadonDataTypes	Deterministic data type that successful executions will return.
url	string	Request URL. Mandatory on HttpGet, HttpPost and HttpHead retrieving methods.
body	string	Request body. Optional on HttpGet and HttpPost retrieving methods.
headers	string[2][]	Request key/value headers. Optional on HttpGet and HttpPost retrieving methods.
radonScript	bytes	Optional CBOR-encoded Radon Script that will transform whatever value is returned from the source. Not supported on RNG retrievals.

Enums

Witnet.RadonDataTypes

Primitive data types that can be contained in successful results to Witnet data requests.

Hex	Caption	Description
0x00	Any	CBOR-encoded value of undetermined type.
0x01	Array	An array of CBOR values.
0x02	Bool	A CBOR-encoded boolean value.
0x03	Bytes	A CBOR-encoded bytes buffer.
0x04	Integer	A CBOR-encoded integer value.
0x05	Float	A CBOR-encoded float value.
0x06	Map	A key/value map of CBOR values.
0x07	String	A CBOR-encoded string value.

Witnet.RadonFilterOpcodes

Dataset filtering methods currently supported on the Witnet blockchain.

Hex	Caption	Description
0x05	StandardDeviation	Filters out all input items that deviates from the average more than a threshold. Requires a CBOR-encoded float as single but mandatory filter parameter. Works only with arrays of numbers (integers or floats) as input datasets.
0x08	Mode	Filters out all input items that diverge from the mode.

Witnet.RadonReducerOpcodes

Reducing functions currently supported on the Witnet blockchain.

Hex	Caption	Description
0x02	Mode	Returns the mode value from the input dataset.
0x03	AverageMean	Returns the average mean from the input dataset. Works only with arrays of numbers as input datasets.
0x05	AverageMedian	Returns the median from the input dataset. Works only with arrays of numbers as input datasets.
0x07	StandardDeviation	Returns the standard deviation calculated out from the input dataset. Works only with arrays of numbers as input datasets.
0x0B	ConcatenateAndHash	Returns the SHA-256 hash of the concatenation of the input buffers. Works only with arrays of buffers as input datasets. Used mainly on RNG requests for mixing randomness produced by independent and randomly selected witnessing nodes.

Witnet.RadonRetrievalMethods

Possible data request methods that can be specified on a Radon Retrieval.

Hex	Caption	Description
0x01	HttpGet	Data shall be retrieved from HTTP-GET requests.
0x02	RNG	Random seeds shall be independently produced by the witnessing nodes themselves.
0x03	HttpPost	Data shall be retrieved from HTTP-POST requests.
0x04	HttpHead	Data shall be retrieved from HTTP-HEAD requests.