corda

问题 We have a use case which requires the following steps: (1) Initiator triggers the transaction flow through UI (2) The flow is initiated, signed by the initiator and sent to recipient for his verification and signatures (in Corda) (3) The initiator's flow should get suspended until the recipient validates the transaction by verifying the contract code and submits "verified" again through the UI (4) This should restart the initiator's flow and the remaining process should be followed as

问题 While running a corDapp(corDapp-example) for the first time using Kotlin-source, the IntelliJ throws this error - "error Class 'com.example.NodeDriverKt' not found in module 'cordapp-example". I looked for this class in my project structure and I can see a file named NodeDriver.kt which contains a function "main" but I could not see any class declaration. Any solution to remove this error would be much appreciated.IntelliJ 回答1: i had this same problem with the example cordapp. I was able to

问题 To get state I can use Vault, but what about transactions? How I can get them, for example, by txHash? Is it possible to do this by CordaRPCOps, there is internalVerifiedTransactionsSnapshot method, but it is deprecated now. 回答1: First, note that as of Corda 3, there are no stability guarantees regarding the behaviour of any method to retrieve a transaction or its dependencies. In particular, we cannot guarantee that the set of transactions retrieved will not change across Corda versions.

问题 Currently in v2, if a CorDapp references a module X, which has a transitive dependency to a module Y, such that Y is used by Corda, a potential version conflict can occur if the respective versions of Y for Corda and X differ. An example is the reuse of an existing internal library, containing business and serialisation logic, that depends on Jackson . In this case, the resulting CorDapp packaging and Corda runtime, seem to enforce the version of Y that is relevant for Corda. If the versions

问题 Background : We learned that corda is not tamper-proof but tamper-evident. So, if one of the node manipulated a state directly in the database, other nodes will be able to detect and flag it if that state was used in subsequent transactions. However, our test results were not as per our expectation. Corda did not flag the state that was tampered and in fact it recorded the new state with tampered data in all participant nodes. Prerequisites : Comment Out Contract Validations: We commented

问题 Background : We learned that corda is not tamper-proof but tamper-evident. So, if one of the node manipulated a state directly in the database, other nodes will be able to detect and flag it if that state was used in subsequent transactions. However, our test results were not as per our expectation. Corda did not flag the state that was tampered and in fact it recorded the new state with tampered data in all participant nodes. Prerequisites : Comment Out Contract Validations: We commented

问题 I need to communicate with external system inside Corda flow so there should be a way to deliver some configuration (e.g. username and password for external API). It may be .properties or .yaml file for example. Is there a best practice how to do that? Maybe even sample? 回答1: Corda 3 doesn't have built-in support for providing arbitrary configuration files to nodes. Support for this will be added in Corda 4 using CorDapp configuration files: https://docs.corda.net/head/cordapp-build-systems

问题 I have run Corda with PostgreSQL. How can Corda be extended to work with other databases? Is it enough to add the database driver as a Gradle dependency and try connecting to other databases? 回答1: Corda uses Hibernate 5.x with HikariCP JDBC connection pool. All queries are generated by Hibernate, expect one query from the finance module ( CashSelection uses a JDBC PreparedStatement with SQL constructs specific to each database vendor). Configuring the database At runtime, a node looks up the

问题 I am trying to write a FlowTest for a Flow with a LinearState. In the setup, I need to create a LinearState and then create a second version of that state (with the same unique identifier) by consuming the first in a second transaction. I followed the steps in the v2.0 tutorial on the corda docs. However, when I query for the states in the vault, I get two unconsumed states. I would have expected one of them to have been consumed (and thus have Vault.StateStatus.UNCONSUMED ). I have written a

问题 I've been trying to understand the concepts of Consensus and Notaries, there are some questions: do all nodes/participants require to do the verification consensus in order to assure the transaction inputs, outputs are valid? Does it somehow resemble verifying the Bitcoin input transactions? uniqueness consensus is a must when involving unique successor of a state (aka preventing double spending) and by using uniqueness consensus, notary service is involved? (this one confused me) in notary