ch.epfl.dedis.byzcoin.contracts

Class DarcInstance

java.lang.Object

ch.epfl.dedis.byzcoin.contracts.DarcInstance

public class DarcInstance
extends Object

DarcInstance represents a contract of a darc in ByzCoin. It is self- sufficient, meaning it has a link to the byzcoin service it runs on. If you evolve the DarcInstance, it will update its internal darc.

Field Summary

Fields

Modifier and Type	Field and Description
static String	ContractId

Constructor Summary

Constructors

Constructor and Description
DarcInstance(ByzCoinRPC bc, DarcId spawnerDarcId, Signer spawnerSigner, Darc newDarc) Instantiates a new DarcInstance from an existing darc by sending a spawn instruction to ByzCoin and then creating the instance from the existing darcInstance.

Method Summary

Modifier and Type	Method and Description
void	evolveDarc(Darc newDarc, Signer owner) Takes a new darc, increases its version, creates an instruction and sends it to ByzCoin, without waiting an acknowledgement.
ClientTransactionId	evolveDarcAndWait(Darc newDarc, Signer owner, int wait) Asks byzcoin to evolve the darc and waits until the new darc has been stored in the global state.
Instruction	evolveDarcInstruction(Darc newDarc, Signer owner, int pos, int len) Creates an instruction to evolve the darc in byzcoin.
static DarcInstance	fromByzCoin(ByzCoinRPC bc, Darc d) Instantiates a new DarcInstance given a working ByzCoin service and an instanceId.
static DarcInstance	fromByzCoin(ByzCoinRPC bc, DarcId baseId) Instantiates a new DarcInstance given a working ByzCoin service and an instanceId.
static DarcInstance	fromByzCoin(ByzCoinRPC bc, InstanceId id) Instantiates a new DarcInstance given a working ByzCoin service and an instanceId.
Darc	getDarc()
DarcId	getId()
Instance	getInstance()
DarcInstance	spawnDarcAndWait(Darc d, Signer s, int wait) Spawns a new darc from the given darcInstance.
ClientTransactionId	spawnInstance(String contractID, Signer s, List<Argument> args) Like spawnInstanceInstruction, but creates a ClientTransaction with only this instruction and sends it to byzcoin.
Proof	spawnInstanceAndWait(String contractID, Signer s, List<Argument> args, int wait) Like spawnInstance but waits for the instance to be stored in byzcoin.
Instruction	spawnInstanceInstruction(String contractID, Signer s, List<Argument> args, int pos, int len) Creates an instruction for spawning an instance.
void	update() Update looks up the darc in ByzCoin and updates to the latest version, if available.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

ContractId

public static String ContractId

Constructor Detail

DarcInstance

public DarcInstance(ByzCoinRPC bc,
                    DarcId spawnerDarcId,
                    Signer spawnerSigner,
                    Darc newDarc)
             throws CothorityException

Instantiates a new DarcInstance from an existing darc by sending a spawn instruction to ByzCoin and then creating the instance from the existing darcInstance.

Parameters:

bc - a running ByzCoin service

spawnerDarcId - the darcId of a darc with the rights to spawn new darcs

spawnerSigner - the signer with the rights to spawn new darcs

newDarc - the new darc to spawn

Throws:

CothorityException - if something goes wrong

Method Detail

update

public void update()
            throws CothorityException

Update looks up the darc in ByzCoin and updates to the latest version, if available.

Throws:

CothorityException - if something goes wrong

evolveDarcInstruction

public Instruction evolveDarcInstruction(Darc newDarc,
                                         Signer owner,
                                         int pos,
                                         int len)
                                  throws CothorityCryptoException

Creates an instruction to evolve the darc in byzcoin. The signer must have its identity in the current darc as "Invoke_Evolve" rule.

TODO: allow for evolution if the expression has more than one identity.

Parameters:

newDarc - the darc to replace the old darc.

owner - must have its identity in the "Invoke_Evolve" rule

pos - position of the instruction in the ClientTransaction

len - total number of instructions in the ClientTransaction

Returns:

Instruction to be sent to byzcoin

Throws:

CothorityCryptoException - if there's a problem with the cryptography

evolveDarc

public void evolveDarc(Darc newDarc,
                       Signer owner)
                throws CothorityException

Takes a new darc, increases its version, creates an instruction and sends it to ByzCoin, without waiting an acknowledgement.

Parameters:

newDarc - the new darc, it should have the same version as the current darc

owner - a signer allowed to evolve the darc

Throws:

CothorityException - if something goes wrong

evolveDarcAndWait

public ClientTransactionId evolveDarcAndWait(Darc newDarc,
                                             Signer owner,
                                             int wait)
                                      throws CothorityException

Asks byzcoin to evolve the darc and waits until the new darc has been stored in the global state. TODO: check if there has been an error in the transaction!

Parameters:

newDarc - is the new darc to replace the old one

owner - is the owner that can sign to evolve the darc

wait - the maximum number of blocks to wait

Returns:

ClientTransactionId of the accepted transaction

Throws:

CothorityException - if something goes wrong

spawnInstanceInstruction

public Instruction spawnInstanceInstruction(String contractID,
                                            Signer s,
                                            List<Argument> args,
                                            int pos,
                                            int len)
                                     throws CothorityCryptoException

Creates an instruction for spawning an instance.

TODO: allow for multi-signatures

Parameters:

contractID - the id of the instance to create

s - the signer that is authorized to spawn this instance

args - arguments to give to the contract

pos - position in the ClientTransaction

len - total length of the ClientTransaction

Returns:

the instruction to be added to the ClientTransaction

Throws:

CothorityCryptoException - if there's a problem with the cryptography

spawnInstance

public ClientTransactionId spawnInstance(String contractID,
                                         Signer s,
                                         List<Argument> args)
                                  throws CothorityException

Like spawnInstanceInstruction, but creates a ClientTransaction with only this instruction and sends it to byzcoin.

Parameters:

contractID - the id of the instance to create

s - the signer that is authorized to spawn this contract-type

args - arguments to give to the contract

Returns:

the client transaction ID

Throws:

CothorityException - if something goes wrong

spawnInstanceAndWait

public Proof spawnInstanceAndWait(String contractID,
                                  Signer s,
                                  List<Argument> args,
                                  int wait)
                           throws CothorityException

Like spawnInstance but waits for the instance to be stored in byzcoin.

Parameters:

contractID - the id of the instance to create

s - the signer that is authorized to spawn this contract

args - arguments to give to the contract

wait - how many blocks to wait for the instance to be stored (0 = do not wait)

Returns:

the Proof of inclusion

Throws:

CothorityException - if something goes wrong

spawnDarcAndWait

public DarcInstance spawnDarcAndWait(Darc d,
                                     Signer s,
                                     int wait)
                              throws CothorityException

Spawns a new darc from the given darcInstance. The current darc needs to have the "spawn:darc" rule with an expression that can be evaluated to true by the signer s.

Parameters:

d - the new darc to store on ByzCoin

s - the signer allowed to spawn a new darc

wait - how many blocks to wait. If it is 0, the call returns directly

Returns:

a new DarcInstance, might be null if wait == 0

Throws:

CothorityException - if something goes wrong if something went wrong

getId

public DarcId getId()
             throws CothorityCryptoException

Returns:

the id of the darc being held

Throws:

CothorityCryptoException - if there's a problem with the cryptography

getDarc

public Darc getDarc()
             throws CothorityCryptoException

Returns:

a copy of the darc stored in this instance.

Throws:

CothorityCryptoException - if there's a problem with the cryptography

getInstance

public Instance getInstance()

Returns:

the instance of the contract.

fromByzCoin

public static DarcInstance fromByzCoin(ByzCoinRPC bc,
                                       InstanceId id)
                                throws CothorityException

Instantiates a new DarcInstance given a working ByzCoin service and an instanceId. This instantiator will contact byzcoin and try to get the current darcInstance. If the instance is not found, or is not of contractId "darc", an exception will be thrown.

Parameters:

bc - is a running ByzCoin ledger

id - of the darc-instance to connect to

Returns:

DarcInstance representing the latest version of the darc given in id

Throws:

CothorityException - if something goes wrong

fromByzCoin

public static DarcInstance fromByzCoin(ByzCoinRPC bc,
                                       DarcId baseId)
                                throws CothorityException

Instantiates a new DarcInstance given a working ByzCoin service and an instanceId. This instantiator will contact byzcoin and try to get the current darcInstance. If the instance is not found, or is not of contractId "darc", an exception will be thrown.

Parameters:

bc - is a running ByzCoin ledger that is running

baseId - of the darc-instance to connect to

Returns:

DarcInstance representing the latest version of the given baseId

Throws:

CothorityException - if something goes wrong

fromByzCoin

public static DarcInstance fromByzCoin(ByzCoinRPC bc,
                                       Darc d)
                                throws CothorityException

Instantiates a new DarcInstance given a working ByzCoin service and an instanceId. This instantiator will contact byzcoin and try to get the current darcInstance. If the instance is not found, or is not of contractId "darc", an exception will be thrown.

Parameters:

bc - is a running ByzCoin ledger

d - of which the base id will be taken to search in ByzCoin

Returns:

DarcInstance representing the latest version of the given baseId

Throws:

CothorityException - if somethings goes wrong