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| Note | ||
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If using Maven as the build tool, such gateway apps can be easily created using the sender gateway maven archetype. |
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| title | Sample |
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Sample
See the nvx-sample-db-integration-sender-gateway
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sample in
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the X Platform Samples Repository
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Integrating App to External Source
Data is copied/moved from X app state to an external data source using either a Gateway App or CDC.
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| Note | ||
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If using Maven as the build tool, such gateway apps can be easily created using the receiver gateway maven archetype. |
Sample
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| title | Sample |
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See
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the nvx-sample-db-integration-receiver-gateway
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sample in
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the X Platform Samples Repository
Use CDC
The use of a gateway app to integrate your apps' state with an external source works well in situations where the gateway app can tap into the application's message stream to detect changes in state. In situations where an app's message stream does not clearly reflect the changes being made to the app's state, additional messages reflecting the changes to the application state would need to be published for the gateway app integration method to work. This can become cumbersome rather quickly and potentially pollute the architecture at play by leaking an application's private state to the outside world. In such situations, integrating the app's state with the external data source via CDC would be the preferred mechanism,
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The CDC runner automatically conflates data in the transaction log. The runner dispatches both the conflated objects and the individual changes to objects to the CDC processor. For example, if the app makes 10 updates to a Customer object in memory, the CDC runner will dispatch all 10 changes as well as the final (conflated) state of the object to the CDC processor. Therefore, the CDC runner's change feed can be used as both an audit trail of changes to the app state objects as well as a conflated stream of coarse grained changes to the app state objects. Since most external data sources, such as RDBMSs, analytical cubes and centralized storage engines have a performance capability that is generally much less than what a X application can process, the ability to only push the conflated changes to objects to the external data source while the app processes all fine grained changes allows for the integration of the app's state and the external source possible and stable. Without this capability, the external source would result in pushing back on the app resulting in queueing of data somewhere in the system effectively causing either a resource exhaustion or a slow down of the app.
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Sample
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| title | Sample |
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See
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the nvx-sample-db-integration-cdc
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sample in the X Platform Samples Repository