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Docs: more work on the upgrade/release notes:
* Address Shams' review comments * Add some more discussion of app splitting, note the finance jar changes.
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@ -43,10 +43,14 @@ You should also ensure you're using Gradle 4.10 (but not 5). If you use the Grad
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Otherwise just upgrade your installed copy in the usual manner for your operating system.
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Step 2. Add a "cordapp" section to your Gradle build file
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---------------------------------------------------------
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Step 2. Update your Gradle build file
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-------------------------------------
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This is used by the Corda Gradle build plugin to populate your app JAR with useful information. It should look like this::
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There are several adjustments that are beneficial to make to your Gradle build file, beyond simply incrementing the versions
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as described in step 1.
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**Provide app metadata.** This is used by the Corda Gradle build plugin to populate your app JAR with useful information.
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It should look like this::
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cordapp {
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targetPlatformVersion 4
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@ -75,29 +79,39 @@ API semantics changes or disabling workarounds for bugs that may be in your apps
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are promising that you have thoroughly tested your app on the new version. Using a high target version is
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a good idea because some features and improvements are only available to apps that opt in.
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The minimum platform version is just the (major) version number of the node that you require, so if you
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The minimum platform version is the platform version of the node that you require, so if you
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start using new APIs and features in Corda 4, you should set this to 4. Unfortunately Corda 3 and below
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do not know about this metadata and don't check it, so your app will still be loaded in such nodes and
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may exhibit undefined behaviour at runtime. However it's good to get in the habit of setting this
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properly for future releases.
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.. note:: Whilst it's currently a convention that Corda releases have the platform version number as their
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major version i.e. Corda 3.3 implements platform version 3, this is not actually required and may in
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future not hold true. You should know the platform version of the node releases you wan to target.
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The new ``versionId`` number is a version code for **your** app, and is unrelated to Corda's own versions.
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It is used to block state downgrades: when a state constraint can be satisfied
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by multiple attachments, the version is tracked in the ledger and cannot decrement. This ensures security
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fixes in CorDapps stick and can't be reversed by downgrading states to an earlier version. See
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":ref:`contract_non-downgrade_rule_ref`" for more information. In future, the version attached to the
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workflow JAR will also be used to help implement smoother upgrade and migration features. You may directly
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reference the gradle version number of your app when setting the cordapp specific versionId identifiers
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if this follows the convention of always being a whole number starting from 1, you can just refer to that
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variable directly to set the version id.
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":ref:`contract_non-downgrade_rule_ref`" for more information.
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The duplication between ``contract`` and ``workflow`` blocks exists because you should split your app into
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**Split your app into contract and workflow JARs.** The duplication between ``contract`` and ``workflow`` blocks exists because you should split your app into
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two separate JARs/modules, one that contains on-ledger validation code like states and contracts, and one
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for the rest (called by convention the "workflows" module although it can contain a lot more than just flows:
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services would also go here, for instance). For simplicity, here we use one JAR for both, but this is in
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general an anti-pattern and can result in your flow logic code being sent over the network to arbitrary
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third party peers, even though they don't need it.
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In future, the version ID attached to the workflow JAR will also be used to help implement smoother upgrade
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and migration features. You may directly reference the gradle version number of your app when setting the
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cordapp specific versionId identifiers if this follows the convention of always being a whole number
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starting from 1.
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If you use the finance demo app, you should adjust your dependencies so you depend on the finance-contracts
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and finance-workflows artifacts from your own contract and workflow JAR respectively. Although a single
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finance jar still exists in Corda 4 for backwards compatibility, it should not be installed or used for
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updated apps. This way, only the code that needs to be on the ledger actually will be.
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Step 3. Security: Upgrade your use of FinalityFlow
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--------------------------------------------------
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@ -269,7 +283,7 @@ automatically use them if your application JAR is signed. **We recommend all JAR
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with developer certificates is deployed to a production node, the node will refuse to start. Therefore to deploy apps built for COrda 4
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to production you will need to generate signing keys and integrate them with the build process.
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Step 8. Security: package namespace handling
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Step 8. Security: Package namespace handling
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--------------------------------------------
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Almost no apps will be affected by these changes, but they're important to know about.
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@ -279,8 +293,8 @@ There are two improvements to how Java package protection is handled in Corda 4:
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1. Package sealing
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2. Package namespace ownership
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**Sealing.** App isolation has been improved. Version 4 of the finance CorDapp (*corda-finance.jar*) is now built as a sealed and signed JAR file.
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This means classes in your own CorDapps cannot be placed under the following package namespace: ``net.corda.finance``
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**Sealing.** App isolation has been improved. Version 4 of the finance CorDapp (*corda-finance.jar*) is now built as a set of sealed and
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signed JAR files. This means classes in your own CorDapps cannot be placed under the following package namespace: ``net.corda.finance``
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In the unlikely event that you were injecting code into ``net.corda.finance.*`` package namespaces from your own apps, you will need to move them
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into a new package, e.g. ``net/corda/finance/flows/MyClass.java`` can be moved to ``com/company/corda/finance/flows/MyClass.java``.
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@ -37,7 +37,7 @@ A reference input state is a ``ContractState`` which can be referred to in a tra
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of input and output states but, significantly, whose contract is not executed as part of the transaction
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verification process and is not consumed when the transaction is committed to the ledger. Rather, it is checked
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for "current-ness". In other words, the contract logic isn't run for the referencing transaction only.
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Since they're normal states, if they occur in the input or output positions, they can evolve on the ledger,
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Since they're normal states, if they do occur in the input or output positions, they can evolve on the ledger,
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modeling reference data in the real world.
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Signature constraints
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