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86 lines
3.6 KiB
ReStructuredText
86 lines
3.6 KiB
ReStructuredText
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Corda Features to Versions
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==========================
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New versions of Corda introduce new features. These fall into one of three categories which have subtle but important implications for
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node owners, application developers and network operators.
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The first set are changes that have no impact on application developers or the Corda network protocol. An example would be support for
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a new HSM or database system, for example, and which are of interest only to a node's operator.
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The second set are new or changed APIs, which are of interest to CorDapp developers. When a release of Corda ships such features, the
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Platform Version of that node is incremented so that a CorDapp that relies on such a new or changed feature can detect this (eg to
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prevent it from running on a node without the feature or to trigger an alternative optimised codepath if the feature is present). The
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app developer should set the CorDapp's minimumPlatformVersion parameter to signal the minimum Platform Version against which the app
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can run or has been tested. If the application has also been tested against a greater platform version and can exploit it if present,
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the node can also set the targetPlatformVersion field.
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The third set of changes are those which could affect the operation of a Corda network. Examples would include a change to the
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serialisation format or flow/wire protocol, or introduction of a new transaction component. These are changes to the core data model and
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these features have the property that it is not safe for any node or application to take advantage of until all nodes on the network
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are capable of understanding them. Such features are thus only enabled in a node if the network to which it is connected has published
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a minimumPlatformVersion in its network parameters that is greater than or equal to the Corda Platform Version that introduced the
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feature. For example, Corda 4.0 nodes, which implement Corda Platform Version 4, can only take advantage of the Corda Reference States
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feature when connected to a network with mPV 4.
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Generally the rules work this way:
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- IF (CorDapp.mPV > node.PV) THEN
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prevent the CorDapp from running (this signals that it cannot run without the new feature).
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- IF (CorDapp.mPV <= node.PV AND CorDapp.targetPV < node.PV) THEN
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this means the node is ahead of the CorDapp so it might choose to trigger some code paths that emulate some old behaviour that the
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CorDapp expected on that version.
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- IF (CorDapp.mPV <= node.PV AND CorDapp.targetPV == node.PV) THEN
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just use the new mechanism because the CorDapp and the node are perfectly aligned.
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- IF (CorDapp.mPV <= node.PV AND CorDapp.targetPV > node.PV) THEN
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this means that the CorDapp is ahead of the running node, but it must have some alternative runtime code paths built in to be able
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to simulate the new behaviour using old apis.
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.. list-table:: Corda Features
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:header-rows: 1
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* - Feature
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- Corda Platform Version (PV)
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- Min Network Platform Version (network mPV)
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- Introduced in OS version
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- Introduced in Enterprise version
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* - Observer Nodes
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- 2
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- 2
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- 2.0
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- n/a
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* - Corda Serialization Framework
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- 3
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- 3
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- 3.0
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- 3.0
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* - Hash Constraints
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- 1
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- 1
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- 1.0
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- 1.0
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* - Whitelist Constraints
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- 3
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- 3
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- 3.0
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- 3.0
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* - Inline Finality Flow
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- 4
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- 3
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- 4.0
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- 4.0
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* - Reference States
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- 4
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- 4
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- 4.0
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- 4.0
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* - Signature Constraints
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- 4
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- 4
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- 4.0
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- 4.0
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* - Underlying Support for Accounts
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- 5
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- 4
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- 4.3
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- 4.3
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