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Commit 3bc6cee

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Merge pull request 41
2 parents 1647176 + bc1df9a commit 3bc6cee

37 files changed

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lines changed

‎code/lab-4/state-machine.asl.json

Lines changed: 75 additions & 21 deletions
Original file line numberDiff line numberDiff line change
@@ -36,29 +36,67 @@
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"Next": "ChargeFare"
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},
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"ChargeFare": {
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"Comment": "Add comment...",
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"Type": "Task",
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"Resource": "${PaymentChargeFunctionArn}",
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"Next": "CustomerAccountCredit",
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"Catch": [{
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"ErrorEquals": [
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"PaymentAuthException",
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"PaymentChargeException"
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],
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"Next": "SetFareStatusFailed",
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"ResultPath": "$.chargeError"
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}]
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"Resource": "arn:aws:states:::lambda:invoke",
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"OutputPath": "$.Payload",
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"Parameters": {
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"Payload.$": "$",
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"FunctionName": "${PaymentChargeFunctionArn}"
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},
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"Retry": [
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{
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"ErrorEquals": [
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"Lambda.ServiceException",
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"Lambda.AWSLambdaException",
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"Lambda.SdkClientException"
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],
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"IntervalSeconds": 2,
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"MaxAttempts": 6,
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"BackoffRate": 2
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}
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],
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"Next": "CreditCustomerAccount",
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"Catch": [
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{
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"ErrorEquals": [
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"PaymentAuthException",
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"PaymentChargeException"
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],
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"ResultPath": "$.chargeError",
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"Next": "SetFareStatusFailed"
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}
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]
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},
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"CustomerAccountCredit": {
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"Comment": "Add comment...",
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"CreditCustomerAccount": {
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"Type": "Task",
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"Resource": "${AccountCreditFunctionArn}",
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"Resource": "arn:aws:states:::lambda:invoke",
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"OutputPath": "$.Payload",
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"Parameters": {
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"Payload.$": "$",
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"FunctionName": "${AccountCreditFunctionArn}"
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},
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"Retry": [
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{
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"ErrorEquals": [
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"Lambda.ServiceException",
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"Lambda.AWSLambdaException",
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"Lambda.SdkClientException"
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],
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"IntervalSeconds": 2,
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"MaxAttempts": 6,
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"BackoffRate": 2
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}
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],
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"Next": "SetFareStatusCompleted",
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"Catch": [{
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"ErrorEquals": ["AccountCreditException"],
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"Next": "RefundFare",
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"ResultPath": "$.creditError"
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}]
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"Catch": [
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{
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"ErrorEquals": [
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"AccountCreditException"
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],
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"Next": "RefundFare",
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"ResultPath": "$.creditError"
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}
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]
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},
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"SetFareStatusCompleted": {
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"Type": "Task",
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"Type": "Succeed"
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},
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"RefundFare": {
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"Comment": "Add comment...",
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"Type": "Task",
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"Resource": "${PaymentRefundFunctionArn}",
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"Resource": "arn:aws:states:::lambda:invoke",
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"OutputPath": "$.Payload",
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"Parameters": {
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"Payload.$": "$",
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"FunctionName": "${PaymentRefundFunctionArn}"
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},
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"Retry": [
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{
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"ErrorEquals": [
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"Lambda.ServiceException",
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"Lambda.AWSLambdaException",
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"Lambda.SdkClientException"
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],
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"IntervalSeconds": 2,
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"MaxAttempts": 6,
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"BackoffRate": 2
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}
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],
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"Next": "SetFareStatusFailed"
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},
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"NotifyFailure": {

‎code/lab-4/template.drawio

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<mxfile host="" modified="2020年05月24日T15:21:41.060Z" agent="5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Code/1.45.0 Chrome/78.0.3904.130 Electron/7.2.4 Safari/537.36" version="13.1.3" etag="lrwgP8mNOWNbAz78NI_h" pages="2">
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<diagram id="diagramid" name="Diagram">
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<mxGraphModel><root><mxCell id="0"/><mxCell id="1" parent="0"/><mxCell id="8" value="WildRydesFareProcessingTopic" style="outlineConnect=0;fontColor=#B3B3B3;gradientColor=#F34482;gradientDirection=north;fillColor=#BC1356;strokeColor=#ffffff;dashed=0;verticalLabelPosition=bottom;verticalAlign=top;align=center;html=1;fontSize=12;fontStyle=0;aspect=fixed;shape=mxgraph.aws4.resourceIcon;resIcon=mxgraph.aws4.sns;" vertex="1" parent="1"><mxGeometry x="250" y="100" width="50" height="50" as="geometry"/></mxCell><mxCell id="9" value="WildRydesFailedTransactionsQueue" style="outlineConnect=0;fontColor=#B3B3B3;gradientColor=#F34482;gradientDirection=north;fillColor=#BC1356;strokeColor=#ffffff;dashed=0;verticalLabelPosition=bottom;verticalAlign=top;align=center;html=1;fontSize=12;fontStyle=0;aspect=fixed;shape=mxgraph.aws4.resourceIcon;resIcon=mxgraph.aws4.sqs;" vertex="1" parent="1"><mxGeometry x="250" width="50" height="50" as="geometry"/></mxCell><mxCell id="10" value="WildRydesSuccessfulTransactionsQueue" style="outlineConnect=0;fontColor=#B3B3B3;gradientColor=#F34482;gradientDirection=north;fillColor=#BC1356;strokeColor=#ffffff;dashed=0;verticalLabelPosition=bottom;verticalAlign=top;align=center;html=1;fontSize=12;fontStyle=0;aspect=fixed;shape=mxgraph.aws4.resourceIcon;resIcon=mxgraph.aws4.sqs;" vertex="1" parent="1"><mxGeometry x="250" y="200" width="50" height="50" as="geometry"/></mxCell><mxCell id="12" value="WildRydesFaresFailedSubscription" style="outlineConnect=0;fontColor=#B3B3B3;gradientColor=#F34482;gradientDirection=north;fillColor=#BC1356;strokeColor=#ffffff;dashed=0;verticalLabelPosition=bottom;verticalAlign=top;align=center;html=1;fontSize=12;fontStyle=0;aspect=fixed;shape=mxgraph.aws4.resourceIcon;resIcon=mxgraph.aws4.sns;" vertex="1" parent="1"><mxGeometry y="50" width="50" height="50" as="geometry"/></mxCell><mxCell id="13" value="WildRydesFaresSuccessfulSubscription" style="outlineConnect=0;fontColor=#B3B3B3;gradientColor=#F34482;gradientDirection=north;fillColor=#BC1356;strokeColor=#ffffff;dashed=0;verticalLabelPosition=bottom;verticalAlign=top;align=center;html=1;fontSize=12;fontStyle=0;aspect=fixed;shape=mxgraph.aws4.resourceIcon;resIcon=mxgraph.aws4.sns;" vertex="1" parent="1"><mxGeometry y="150" width="50" height="50" as="geometry"/></mxCell><mxCell id="WildRydesFareProcessingTopic|WildRydesFaresFailedSubscription" value="TopicArn" style="edgeStyle=orthogonalEdgeStyle;rounded=1;orthogonalLoop=1;jettySize=auto;html=1;labelBackgroundColor=none;fontColor=#EA6B66;noEdgeStyle=1;orthogonal=1;" edge="1" parent="1" source="12" target="8"><mxGeometry relative="1" as="geometry"><Array as="points"><mxPoint x="62" y="85"/><mxPoint x="238" y="115"/></Array></mxGeometry></mxCell><mxCell id="WildRydesFailedTransactionsQueue|WildRydesFaresFailedSubscription" value="Endpoint" style="edgeStyle=orthogonalEdgeStyle;rounded=1;orthogonalLoop=1;jettySize=auto;html=1;labelBackgroundColor=none;fontColor=#EA6B66;noEdgeStyle=1;orthogonal=1;" edge="1" parent="1" source="12" target="9"><mxGeometry relative="1" as="geometry"><Array as="points"><mxPoint x="62" y="65"/><mxPoint x="238" y="25"/></Array></mxGeometry></mxCell><mxCell id="WildRydesFareProcessingTopic|WildRydesFaresSuccessfulSubscription" value="TopicArn" style="edgeStyle=orthogonalEdgeStyle;rounded=1;orthogonalLoop=1;jettySize=auto;html=1;labelBackgroundColor=none;fontColor=#EA6B66;noEdgeStyle=1;orthogonal=1;" edge="1" parent="1" source="13" target="8"><mxGeometry relative="1" as="geometry"><Array as="points"><mxPoint x="62" y="165"/><mxPoint x="238" y="135"/></Array></mxGeometry></mxCell><mxCell id="WildRydesSuccessfulTransactionsQueue|WildRydesFaresSuccessfulSubscription" value="Endpoint" style="edgeStyle=orthogonalEdgeStyle;rounded=1;orthogonalLoop=1;jettySize=auto;html=1;labelBackgroundColor=none;fontColor=#EA6B66;noEdgeStyle=1;orthogonal=1;" edge="1" parent="1" source="13" target="10"><mxGeometry relative="1" as="geometry"><Array as="points"><mxPoint x="62" y="185"/><mxPoint x="238" y="225"/></Array></mxGeometry></mxCell></root></mxGraphModel>
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</diagram>
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</mxfile>

‎code/lab-4/template.yaml

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Globals:
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Function:
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Timeout: 3
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Runtime: python3.7
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Runtime: python3.9
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MemorySize: 512
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Tags:
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project: wild-rydes
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End: true
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Policies:
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- CloudWatchPutMetricPolicy: {}
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- LambdaInvokePolicy:
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FunctionName: !Ref PaymentChargeFunction
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- LambdaInvokePolicy:
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FunctionName: !Ref PaymentRefundFunction
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- LambdaInvokePolicy:
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FunctionName: !Ref AccountCreditFunction
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- DynamoDBWritePolicy:
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TableName: !Ref FaresTable
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- DynamoDBReadPolicy:
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TableName: !Ref FaresTable
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- SNSPublishMessagePolicy:
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TopicName: !GetAtt WildRydesFareProcessingTopic.TopicName
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Tags:
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project: wild-rydes
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workshop: asynchronous-messaging-workshop
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FareProcessingTable: !Ref FaresTable
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FareProcessingTopicArn: !Ref WildRydesFareProcessingTopic
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Policies:
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- CloudWatchPutMetricPolicy: {}
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- LambdaInvokePolicy:
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FunctionName: !Ref PaymentChargeFunction
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- LambdaInvokePolicy:

‎workshop/content/orchestration-and-coordination/_index.md

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Make sure you executed the **[Workshop Prerequisites](/prerequisites.html)** first, before you start with this lab!
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{{% /notice %}}
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AWS Step Functions is a fully managed Serverless workflow management service for managing long running processes and coordinating the components of distributed applications and microservices using visual workflows. But did you know it can also help you deal with the complexities of dealing with a long lived transaction across distributed components in your microservices architecture? In this Builder session, you will learn how AWS Step Function can help us implement the Saga design pattern.
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AWS Step Functions is a fully managed Serverless workflow management service for managing long running processes and coordinating the components of distributed applications and microservices using visual workflows. But did you know it can also help you deal with the complexities of dealing with a long lived transaction across distributed components in your microservices architecture?
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In this Builder session, you will learn how AWS Step Functions can help us to implement the Saga design pattern.
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## What problems are we trying to solve
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When building cloud-based distributed architectures, one of the questions we need to ask ourselves is how do we maintain data consistency across microservices that have their own database / persistence mechanism? We do not have support for Distributed Transaction Coordinators (DTC) or two-phase commit protocols responsible for coordinating transactions across multiple cloud resources. We need a mechanism coordinate multiple local transactions.
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## What is the Saga Pattern
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## The Saga Pattern
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A Saga is a design pattern for dealing with "long-lived transactions" (LLT), published by Garcia-Molina and Salem in 1987. Their original paper can be found here [https://www.cs.cornell.edu/andru/cs711/2002fa/reading/sagas.pdf](https://www.cs.cornell.edu/andru/cs711/2002fa/reading/sagas.pdf).
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> "LLT is a saga if it can be written as a sequence of transactions that can be interleaved with other transactions." (Garcia-Molina, Salem 1987)
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Fundamentally it is a failure management pattern, that provides us the means to establish semantic consistency in our distributed applications by providing compensating transactions for every transaction where you have more than one collaborating services or functions.
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Fundamentally the Saga Pattern is a failure management pattern that provides a mechansim for providing semantic consistency in our distributed applications by providing compensating transactions for every transaction where you have more than one collaborating services or functions. This compensating transactions ensures the system remains in a consistent state by rolling back or compensating for partially completed transactions.
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## Why AWS Step Functions
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* allowing us to build our state machines using visual workflows
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* provides us with a way to manage state and deal with failure
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## Lab Objective
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## Lab Objectives
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The core objective for this lab is to **build a state machine** that implements a Saga for the Wild Rydes Fare Collection process.
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1. **Payment Service**: calls a payment gateway for credit card pre-authorisation, and using the pre-authorisation code, completes the payment transaction
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1. **Customer Accounting Service**: once the payment has been processed, update the Wild Rydes Customer accounting system with the transaction details.
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In this lab, you will acquire the following skills:
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+ **How to create a Step Functions State Machine**
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+ **How to use the Step Functions Workflow Studio**
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+ **How to catch exceptions and manage retries in a Step Functions State Machine**
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+ **How to manage successful and non-successful execution flows in a Step Functions State machine**
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Let's get started!

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