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In this video, we are going to continue developing our product microservices as a lambda function and

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we will continue our development.

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If you open the visual code, we can come here and see that index JS is empty and before starting to

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developing our lambda function, we have to add a new model which is the dynamic DB client JavaScript

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module and it is good practice to create a separate Node.js module when connecting to dynamic DB object

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with using the SDK libraries in order to do that.

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In the last section, we use lots of time, which is the DB client JS file.

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I'm copy this file and come here and paste to my latest folder which is the product, product crud microservices

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and paste in here.

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Okay.

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Now I can close these files and focus on these DB client.

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JS so that means we create a new JavaScript file under our folder and this is the name DB client that

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means dynamic DB client object and develop this line of codes.

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So what is this line?

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Of course we basically use SDK and create any dynamic DB client object to interact with the dynamic

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DB API and specifying the region information.

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You can change region information as poor as per your cloud environment and we export the DB client

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to our application.

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You have already know and familiar with these codes and this is the best practice to create database

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connection before Lambda Handle method execution.

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By this way, it reduced the execution time and reduced the concurrency of lambda function and of course

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it reduce the costing pay as you go model because the execution time reduced dramatically if we have

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already database connection.

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So that's why it is best practice to exporting and creating separate node modules for the dynamic DB

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database connections.

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Okay.

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We can start our actual business code development into the index JS file edge.

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Note that index JS includes our lambda function handle method and we have verified that this handle

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method invoked by the API gateway.

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So if you remember to our architecture, we can check the Oracle architecture.

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We are going to implement synchronous serverless CRUD operations with using the API, Gateway, Lambda

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and Dynamo DB for product microservices.

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And this invocation will be the synchronous communication type.

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So that means our product lambda function will trigger from the API gateway and we have already exposed

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get post delete and put APIs for product root resource type into Amazon API Gateway.

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Now it is time to catch these events from our Lambda function and process them according to our current

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requirements.

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That means we should know that how a API gateway triggered our lambda function which requires JSON trigger

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to our lambda function.

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According to this JSON event object, we will catch the HTTP URL and method and develop our logic into

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product lambda function.

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Now we can start our actual code for product microservices.

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I will start writing the code.

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That means we will put the command about what we will do.

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Please open the index and now I'm going to develop our lambda function code or we can copy from the

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lambda function into the a cloud environment.

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But this is the same architecture you can see in here.

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Basically this is the minimum code for the lambda function which generates from the ADA itself and we

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have added the log operation at the beginning of the method and also I have added this to the statement

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which is accommodate the incoming event from the API gateway and perform CRUD operation and we will

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look at the event HTTP method.

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We can compare this method with the ADA environment, open the product function, come the code section

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and we you can copy and paste in here.

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But this is the exact same method body in our index file of the local folder structure.

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So that's why we will develop in here and upload after that.

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After finished our development, we will upload this method to the ADA Cloud environment.

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But before we proceed, I would like to perform some refactoring on this method.

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Since we have activated Script six and use Node.js 16 for our lambda function, we can refactor our

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lambda function implementation on indexes because in the package JSON file, we are using this type

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module statement.

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So that means we can use execute six standards into index.

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JS So with the ActionScript six standards, for example, we can refactor with these exports method.

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So basically my script has an export statement and we can define.

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These methods with this way it is exactly the same and working fine with the lambda function if we are

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using the Amos six.

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And using the Node.js 16 plus.

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So as you can see that we'd executed six and Node.js 16.

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We can use export const handler method and we use export statement instead of export 100 method.

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You can compare it with lambda function code on a machine console.

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This seems very minor change, but we will use Postscript six and that's why we start with the changing

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our method body definition.

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So we are going to develop our product lambda function with the latest Node.js runtime and the latest

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ActionScript six versions because Node.js and executed gives us very powerful benefits that we can use

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in the concurrency and avoiding code.

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Start issues on lambda function.

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So now before developing this function, the only thing we should check that the incoming event from

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the API gateway is remember that API gateway triggered product lambda function with the events.

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So let's collect these events and start development after that.