interfaces.go

/*
Copyright IBM Corp. 2016 All Rights Reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

		 http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package shim

import (
	"github.com/golang/protobuf/ptypes/timestamp"

	"github.com/hyperledger/fabric/protos/ledger/queryresult"
	pb "github.com/hyperledger/fabric/protos/peer"
)

// Chaincode interface must be implemented by all chaincodes. The fabric runs
// the transactions by calling these functions as specified.
type Chaincode interface {
	// Init is called during Instantiate transaction after the chaincode container
	// has been established for the first time, allowing the chaincode to
	// initialize its internal data
	Init(stub ChaincodeStubInterface) pb.Response

	// Invoke is called to update or query the ledger in a proposal transaction.
	// Updated state variables are not committed to the ledger until the
	// transaction is committed.
	Invoke(stub ChaincodeStubInterface) pb.Response
}

// ChaincodeStubInterface is used by deployable chaincode apps to access and
// modify their ledgers
type ChaincodeStubInterface interface {
	// GetArgs returns the arguments intended for the chaincode Init and Invoke
	// as an array of byte arrays.
	GetArgs() [][]byte

	// GetStringArgs returns the arguments intended for the chaincode Init and
	// Invoke as a string array. Only use GetStringArgs if the client passes
	// arguments intended to be used as strings.
	GetStringArgs() []string

	// GetFunctionAndParameters returns the first argument as the function
	// name and the rest of the arguments as parameters in a string array.
	// Only use GetFunctionAndParameters if the client passes arguments intended
	// to be used as strings.
	GetFunctionAndParameters() (string, []string)

	// GetArgsSlice returns the arguments intended for the chaincode Init and
	// Invoke as a byte array
	GetArgsSlice() ([]byte, error)

	// GetTxID returns the tx_id of the transaction proposal (see ChannelHeader
	// in protos/common/common.proto)
	GetTxID() string

	// InvokeChaincode locally calls the specified chaincode `Invoke` using the
	// same transaction context; that is, chaincode calling chaincode doesn't
	// create a new transaction message.
	// If the called chaincode is on the same channel, it simply adds the called
	// chaincode read set and write set to the calling transaction.
	// If the called chaincode is on a different channel,
	// only the Response is returned to the calling chaincode; any PutState calls
	// from the called chaincode will not have any effect on the ledger; that is,
	// the called chaincode on a different channel will not have its read set
	// and write set applied to the transaction. Only the calling chaincode's
	// read set and write set will be applied to the transaction. Effectively
	// the called chaincode on a different channel is a `Query`, which does not
	// participate in state validation checks in subsequent commit phase.
	// If `channel` is empty, the caller's channel is assumed.
	InvokeChaincode(chaincodeName string, args [][]byte, channel string) pb.Response

	// GetState returns the value of the specified `key` from the
	// ledger. Note that GetState doesn't read data from the writeset, which
	// has not been committed to the ledger. In other words, GetState doesn't
	// consider data modified by PutState that has not been committed.
	// If the key does not exist in the state database, (nil, nil) is returned.
	GetState(key string) ([]byte, error)

	// PutState puts the specified `key` and `value` into the transaction's
	// writeset as a data-write proposal. PutState doesn't effect the ledger
	// until the transaction is validated and successfully committed.
	// Simple keys must not be an empty string and must not start with null
	// character (0x00), in order to avoid range query collisions with
	// composite keys, which internally get prefixed with 0x00 as composite
	// key namespace.
	PutState(key string, value []byte) error

	// DelState records the specified `key` to be deleted in the writeset of
	// the transaction proposal. The `key` and its value will be deleted from
	// the ledger when the transaction is validated and successfully committed.
	DelState(key string) error

	// GetStateByRange returns a range iterator over a set of keys in the
	// ledger. The iterator can be used to iterate over all keys
	// between the startKey (inclusive) and endKey (exclusive).
	// The keys are returned by the iterator in lexical order. Note
	// that startKey and endKey can be empty string, which implies unbounded range
	// query on start or end.
	// Call Close() on the returned StateQueryIteratorInterface object when done.
	// The query is re-executed during validation phase to ensure result set
	// has not changed since transaction endorsement (phantom reads detected).
	GetStateByRange(startKey, endKey string) (StateQueryIteratorInterface, error)

	// GetStateByPartialCompositeKey queries the state in the ledger based on
	// a given partial composite key. This function returns an iterator
	// which can be used to iterate over all composite keys whose prefix matches
	// the given partial composite key. The `objectType` and attributes are
	// expected to have only valid utf8 strings and should not contain
	// U+0000 (nil byte) and U+10FFFF (biggest and unallocated code point).
	// See related functions SplitCompositeKey and CreateCompositeKey.
	// Call Close() on the returned StateQueryIteratorInterface object when done.
	// The query is re-executed during validation phase to ensure result set
	// has not changed since transaction endorsement (phantom reads detected).
	GetStateByPartialCompositeKey(objectType string, keys []string) (StateQueryIteratorInterface, error)

	// CreateCompositeKey combines the given `attributes` to form a composite
	// key. The objectType and attributes are expected to have only valid utf8
	// strings and should not contain U+0000 (nil byte) and U+10FFFF
	// (biggest and unallocated code point).
	// The resulting composite key can be used as the key in PutState().
	CreateCompositeKey(objectType string, attributes []string) (string, error)

	// SplitCompositeKey splits the specified key into attributes on which the
	// composite key was formed. Composite keys found during range queries
	// or partial composite key queries can therefore be split into their
	// composite parts.
	SplitCompositeKey(compositeKey string) (string, []string, error)

	// GetQueryResult performs a "rich" query against a state database. It is
	// only supported for state databases that support rich query,
	// e.g.CouchDB. The query string is in the native syntax
	// of the underlying state database. An iterator is returned
	// which can be used to iterate (next) over the query result set.
	// The query is NOT re-executed during validation phase, phantom reads are
	// not detected. That is, other committed transactions may have added,
	// updated, or removed keys that impact the result set, and this would not
	// be detected at validation/commit time.  Applications susceptible to this
	// should therefore not use GetQueryResult as part of transactions that update
	// ledger, and should limit use to read-only chaincode operations.
	GetQueryResult(query string) (StateQueryIteratorInterface, error)

	// GetHistoryForKey returns a history of key values across time.
	// For each historic key update, the historic value and associated
	// transaction id and timestamp are returned. The timestamp is the
	// timestamp provided by the client in the proposal header.
	// GetHistoryForKey requires peer configuration
	// core.ledger.history.enableHistoryDatabase to be true.
	// The query is NOT re-executed during validation phase, phantom reads are
	// not detected. That is, other committed transactions may have updated
	// the key concurrently, impacting the result set, and this would not be
	// detected at validation/commit time. Applications susceptible to this
	// should therefore not use GetHistoryForKey as part of transactions that
	// update ledger, and should limit use to read-only chaincode operations.
	GetHistoryForKey(key string) (HistoryQueryIteratorInterface, error)

	// GetCreator returns `SignatureHeader.Creator` (e.g. an identity)
	// of the `SignedProposal`. This is the identity of the agent (or user)
	// submitting the transaction.
	GetCreator() ([]byte, error)

	// GetTransient returns the `ChaincodeProposalPayload.Transient` field.
	// It is a map that contains data (e.g. cryptographic material)
	// that might be used to implement some form of application-level
	// confidentiality. The contents of this field, as prescribed by
	// `ChaincodeProposalPayload`, are supposed to always
	// be omitted from the transaction and excluded from the ledger.
	GetTransient() (map[string][]byte, error)

	// GetBinding returns the transaction binding
	GetBinding() ([]byte, error)

	// GetSignedProposal returns the SignedProposal object, which contains all
	// data elements part of a transaction proposal.
	GetSignedProposal() (*pb.SignedProposal, error)

	// GetTxTimestamp returns the timestamp when the transaction was created. This
	// is taken from the transaction ChannelHeader, therefore it will indicate the
	// client's timestamp, and will have the same value across all endorsers.
	GetTxTimestamp() (*timestamp.Timestamp, error)

	// SetEvent allows the chaincode to propose an event on the transaction
	// proposal. If the transaction is validated and successfully committed,
	// the event will be delivered to the current event listeners.
	SetEvent(name string, payload []byte) error
}

// CommonIteratorInterface allows a chaincode to check whether any more result
// to be fetched from an iterator and close it when done.
type CommonIteratorInterface interface {
	// HasNext returns true if the range query iterator contains additional keys
	// and values.
	HasNext() bool

	// Close closes the iterator. This should be called when done
	// reading from the iterator to free up resources.
	Close() error
}

// StateQueryIteratorInterface allows a chaincode to iterate over a set of
// key/value pairs returned by range and execute query.
type StateQueryIteratorInterface interface {
	// Inherit HasNext() and Close()
	CommonIteratorInterface

	// Next returns the next key and value in the range and execute query iterator.
	Next() (*queryresult.KV, error)
}

// HistoryQueryIteratorInterface allows a chaincode to iterate over a set of
// key/value pairs returned by a history query.
type HistoryQueryIteratorInterface interface {
	// Inherit HasNext() and Close()
	CommonIteratorInterface

	// Next returns the next key and value in the history query iterator.
	Next() (*queryresult.KeyModification, error)
}

// MockQueryIteratorInterface allows a chaincode to iterate over a set of
// key/value pairs returned by range query.
// TODO: Once the execute query and history query are implemented in MockStub,
// we need to update this interface
type MockQueryIteratorInterface interface {
	StateQueryIteratorInterface
}