ExecutorAgent¶
Class Name | ExecutorAgent |
---|---|
Extends | Executor |
Source | executor-agent.ts |
Examples | executor-agent.spec.ts |
The ExecutorAgent
module is designed to cover basically the same tasks as the Executor module. While the last one performs the transactions directly with an account, that is given as inputOptions, the ExecutorAgent
module wraps those transactions by submitting them to a smart agent.
The smart agent receives those transactions and performs them with its own account, if a valid tokens has been passed to it alongside the transaction data. Tokens for transactions can be issued at the smart agent as well (a password is required for this).
Using the ExecutorAgent
allows to delegate transactions to users that do not have their own blockchain accounts. Delegating those transactions requires that smart agent user to be invited into the contract instead of the users, that will interact with the contract.
Users without accounts are then interacting with the front-end the same way as regular users, but do not submit their transactions themselves, they make a REST request against a smart agent server. To prevent spamming and scamming, the users use tokens for their transactions. Tokens are basically like prepaid telephone card and allows to perform a limited set of functions for a limited amount of times. Tokens can only be created with a valid password.
Let’s say, we have created a DataContract, that contains three questions, that should be answered by someone without an own blockchain account (think of a customer survey or something similar).
To allow that, first invite the corresponding smart agent account into the contract. Smart agent accounts for this should be known to the party, that wants to delegate transactions and their funds are maintained by this party, we’ll use an example address for this here.
For abbreviation we assume, we have the following values:
let dataContractInstance; // our data contract with the survey questions
let contractOwner; // 'we' - the contract creator and owner
let businessCenterDomain = 'testbc.evan'; // contracts business center
let smartAgentId; // account id of our smart agent
let password; // password, for token generation
So let’s invite the smart agent to our contract:
await dataContract.inviteToContract(
businessCenterDomain,
dataContractInstance.options.address,
contractOwner,
smartAgentId,
);
Now with the smart agent being able to perform transactions, create a token for transaction delegation. We want the user to be able to:
- accept the invitation
- write three answers
- mark their state as “done”
const txToken = await executor.generateToken(
password, [
{ contract: dataContractInstance, functionName: 'changeConsumerState', count: 2, },
{ contract: dataContractInstance, functionName: 'addListEntry', count: 3, },
]);
Allowing addListEntry
three time is to allow them to write three answers. One of the changeConsumerState
times is for accepting the contract, which is done by setting the own state to Active
. The other one is for marking editing as done (setting the own state to Terminated
).
The resulting token txToken
is a string, that can be handed over to our users without an account. This is usually done by sending them an email with a link, that contains the token and skips the login step for them and routes them directly to the contract, they should respond to.
Let’s switch sides. The next steps are performed in the front-end by a user without a blockchain account, that has received the token.
To make transaction via a smart agent, create an instance of the ExecutorWallet
and assign the token from before as token
.
const executor = new ExecutorAgent({
agentUrl
config,
eventHub,
signer,
web3
});
executor.token = txToken;
To use the ExecutorWallet
instance created this way in your other modules, hand it over to their contstructor like instead of a normal Executor
instance. Then use your modules, that have the ExeutorWallet
instance like you would use them for making transactions with your own account.
const surveyAnswer = {
foo: 'sample',
bar: 123,
};
await dataContract.addListEntries(dataContractInstance, ['surveyAnswers'], [sampleValue], smartAgentId);
Note, that the last sample uses the smartAgentId as the performing account. Because transactions are estimated before being executed and in some cases the underlying modules require an “active” account, that is used as the users identity, this has to match the smart agents account id. The smart agent account id is passed alongside the token via the link in the email for users wihtout blockchain accounts. References, that would point to a users account have to be replaced with this smart agent account id.
constructor¶
new ExecutorAgent(options);
Creates a new ExecutorAgent instance.
The ExecutorAgent allows to pass the defaultOptions
property to its constructor. This property contains options for transactions and calls, that will be used if no other properties are provided in calls/transactions. Explicitly passed options always overwrite default options.
Parameters¶
options
-ExecutorAgentOptions
: options for ServiceContract constructor.config
-any
: configuration object for the executor instancedefaultOptions
-any
(optional): default options for web3 transactions/callseventHub
-EventHub
:EventHub
instancesigner
-SignerInterface
:SignerInterface
instanceweb3
-Web3
:Web3
instanceagentUrl
-string
(optional): agent url, including protocol, host and port, defaults to'http://localhost:8080'
log
-Function
(optional): function to use for logging:(message, level) => {...}
logLevel
-LogLevel
(optional): messages with this level will be logged withlog
logLog
-LogLogInterface
(optional): container for collecting log messageslogLogLevel
-LogLevel
(optional): messages with this level will be pushed tologLog
Returns¶
ExecutorAgent
instance
init¶
executor.init(name);
initialize executor
Parameters¶
options
-any
: object with the property “eventHub” (of the type EventHub)eventHub
-EventHub
: The initialized EventHub Module.
Returns¶
void
.
executeContractCall¶
executor.executeContractCall(contract, functionName, ...args);
run the given call from contract
this is done as a rest call against the smart agent
a token is not required for performing calls
Parameters¶
contract
-any
: the target contractfunctionName
-string
: name of the contract function to call...args
-any[]
: optional array of arguments for contract call. if last arguments is {Object}, it is used as the options parameter
Returns¶
Promise
resolves to any
: contract calls result.
Example¶
const greetingMessage = await runtime.executor.executeContractCall(
contract, // web3.js contract instance
'greet' // function name
);
executeContractTransaction¶
executor.executeContractTransaction(contract, functionName, inputOptions, ...functionArguments);
execute a transaction against the blockchain, handle gas exceeded and return values from contract function
this is done as a rest call against the smart agent
transactions, that transfer EVEs to a target account, will be rejected
this requires a valid token issued with generateToken
beforehand, tokens can be set at the executor with:
executor.token = someToken;
Parameters¶
contract
-any
: contract instancefunctionName
-string
: name of the contract function to callinputOptions
-any
: options objectfrom
-string
(optional): The address the call “transaction” should be made from.gas
-number
(optional): The amount of gas provided with the transaction.event
-string
(optional): The event to wait for a result of the transaction,getEventResult
-function
(optional): callback function which will be called when the event is triggered.eventTimeout
-number
(optional): timeout (in ms) to wait for a event result before the transaction is marked as errorestimate
-boolean
(optional): Should the amount of gas be estimated for the transaction (overwritesgas
parameter)force
-string
(optional): Forces the transaction to be executed. Ignores estimation errorsautoGas
-number
(optional): enables autoGas 1.1 ==> adds 10% to estimated gas costs. value capped to current block.
...functionArguments
-any[]
: optional arguments to pass to contract transaction
Returns¶
Promise
resolves to: no result
(if no event to watch was given), the event
(if event but no getEventResult was given), the
value returned by getEventResult(eventObject).
Because an estimation is performed, even if a fixed gas cost has been set, failing transactions are rejected before being executed. This protects users from executing transactions, that consume all provided gas and fail, which is usually not intended, especially if a large amount of gas has been provided. To prevent this behavior for any reason, add a force: true
to the options, though it is not advised to do so.
To allow to retrieve the result of a transaction, events can be used to receive values from a transaction. If an event is provided, the transaction will only be fulfilled, if the event is triggered. To use this option, the executor needs to have the eventHub
property has to be set. Transactions, that contain event related options and are passed to an executor without an eventHub
will be rejected immediately.
Example¶
const accountId = '0x...';
const greetingMessage = await runtime.executor.executeContractTransaction(
contract, // web3.js contract instance
'setData', // function name
{ from: accountId, }, // perform transaction with this account
123, // arguments after the options are passed to the contract
);
Provided gas is estimated automatically with a fault tolerance of 10% and then used as gas limit in the transaction. For a different behavior, set autoGas in the transaction options:
const greetingMessage = await runtime.executor.executeContractTransaction(
contract, // web3.js contract instance
'setData', // function name
{ from: accountId, autoGas: 1.05, }, // 5% fault tolerance
123, // arguments after the options are passed to the contract
);
or set a fixed gas limit:
const greetingMessage = await runtime.executor.executeContractTransaction(
contract, // web3.js contract instance
'setData', // function name
{ from: accountId, gas: 100000, }, // fixed gas limit
123, // arguments after the options are passed to the contract
);
Using events for getting return values:
const contractId = await runtime.executor.executeContractTransaction(
factory,
'createContract', {
from: accountId,
autoGas: 1.1,
event: { target: 'FactoryInterface', eventName: 'ContractCreated', },
getEventResult: (event, args) => args.newAddress,
},
);
executeSend¶
executor.executeSend(options);
creating contracts directly is not supported by the walled based executor, use a regular Executor for such tasks
createContract¶
executor.createContract(contractName, functionArguments, options);
creates a contract by contstructing creation transaction and signing it with private key of options.from
this is done as a rest call against the smart agent
transactions, that transfer EVEs to a target account, will be rejected
this requires a valid token issued with generateToken
beforehand, tokens can be set at the executor with:
executor.token = someToken;
Parameters¶
contractName
-string
: contract name (must be available withing contract loader module)functionArguments
-any[]
: arguments for contract creation, pass empty Array if no argumentsoptions
-any
: options objectfrom
-string
: The address the call “transaction” should be made from.gas
-number
: Provided gas amout for contract creation.
Returns¶
Promise
resolves to any
: new contract.
Example¶
const newContractAddress = await runtime.executor.createContract(
'Greeter', // contract name
['I am a demo greeter! :3'], // constructor arguments
{ from: '0x...', gas: 100000, }, // gas has to be provided with a fixed value
);
generateToken¶
executor.generateToken(password, functions);
generate a new token for transactions (or contract creations)
this generates a new token for the given functions, this token can be used for each requested function (either only once or multiple times, if a count > 1 has been requested)
Parameters¶
password
-string
: password for token creationfunctions
-any[]
: array of function signatures as abi objects
Returns¶
Promise
returns string
: token for given transactions
Example¶
Tokens can be created for transactions by passing the contract and the function name to it:
const txToken = await executor.generateToken(
password, [{ contract: contract, functionName: 'addListEntry', }]);
When the token should be able to perform those transactions multiple times, pass a count alongside:
const txToken = await executor.generateToken(
password, [{ contract: contract, functionName: 'addListEntry', count: 3, }]);
When wanting to perform a contract creation without a factory contract, this contract has to be known to the smart agent. Then the contract name can be passed as ‘signature’:
cosnt ccToken = await executor.generateToken(
password, [{ signature: 'Owned', }]);