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62 lines
2.3 KiB
Plaintext
62 lines
2.3 KiB
Plaintext
// Module included in the following assemblies
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//
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// * serverless/functions/serverless-developing-nodejs-functions.adoc
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:_content-type: REFERENCE
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[id="serverless-nodejs-functions-context-objects_{context}"]
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= Node.js context objects
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Functions are invoked by providing a `context` object as the first parameter. This object provides access to the incoming HTTP request information.
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.Example context object
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[source,javascript]
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----
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function handle(context, data)
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----
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This information includes the HTTP request method, any query strings or headers sent with the request, the HTTP version, and the request body. Incoming requests that contain a `CloudEvent` attach the incoming instance of the CloudEvent to the context object so that it can be accessed by using `context.cloudevent`.
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[id="serverless-nodejs-functions-context-objects-methods_{context}"]
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== Context object methods
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The `context` object has a single method, `cloudEventResponse()`, that accepts a data value and returns a CloudEvent.
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In a Knative system, if a function deployed as a service is invoked by an event broker sending a CloudEvent, the broker examines the response. If the response is a CloudEvent, this event is handled by the broker.
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.Example context object method
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[source,javascript]
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----
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// Expects to receive a CloudEvent with customer data
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function handle(context, customer) {
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// process the customer
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const processed = handle(customer);
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return context.cloudEventResponse(customer)
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.source('/handle')
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.type('fn.process.customer')
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.response();
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}
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----
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[id="serverless-nodejs-functions-context-objects-cloudevent-data_{context}"]
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== CloudEvent data
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If the incoming request is a CloudEvent, any data associated with the CloudEvent is extracted from the event and provided as a second parameter. For example, if a CloudEvent is received that contains a JSON string in its data property that is similar to the following:
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[source,json]
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----
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{
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"customerId": "0123456",
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"productId": "6543210"
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}
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----
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When invoked, the second parameter to the function, after the `context` object, will be a JavaScript object that has `customerId` and `productId` properties.
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.Example signature
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[source,javascript]
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----
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function handle(context, data)
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----
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The `data` parameter in this example is a JavaScript object that contains the `customerId` and `productId` properties.
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