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In this video, we are going to continue the development of order, acknowledgment microservices and

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in the last video we have left the third and the first step.

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If you go to the our indexes, you can see that we are going to develop these two steps.

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And now I'm going to focus on the third step, which is the published message to topic on Amazon.

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Since using the SDK libraries.

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So before we start, it is good to check the documentation.

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If you open the source client documentation, this is the library for a SDK.

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You can see that we will use publish command and if you open the publish command, you can see all the.

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Basically it is send a message to Amazon sans topic and we will use these publish command in our example.

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If we send a message to Amazon says topic, Amazon says delivers the message to each end point that

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is subscribed to the topic.

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And the format of the message depends on the notification protocol for each subscribe.

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And in our case our subscriber systems are case.

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So we will use a SCS protocol for subscription to Amazon sans topic.

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Okay.

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If you come back to the documentation, you can see the publish command.

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If you scroll down here, you can see the example usage and you can check the input and outputs from

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the objects of the published command input.

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Here you can see that we will provide these information publishing an item into the sense topic and

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also you can see the publish command output.

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This will return us to message ID and sequence number.

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Okay, let's get started.

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The first thing we should create the client object.

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So when it comes to work, any sense?

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Object.

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Client object.

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First thing we should do is create separate client Node.js module in order to interact with sense client

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object.

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To do that, I'm going to open the command text and I have listed what we have done, what we are going

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to do.

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In this video, we basically examine the source client documentation and now I'm going to create a sense

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client JS file and implement this Node.js function.

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If you create a sense client JS and implement this code, this will be provided to interact with this

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client.

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We have done these methods before when we interacting the source SDK operations and after that now we

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can implement our actual logic.

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But before implementing the actual logic, it is best practice to use a lambda environment variables.

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So before start coding, it is good to create a source topic run as an environment variable for order

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acknowledge lambda function because we will use the aaron of the topic in the development of to publish

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message when we are providing the request parameters of the publish command.

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So for that purpose I'm going to open the or a console and first of all go to this topic and get the

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Aaron over to our order topic.

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If you come here, go to topics and open the order topic, you can copy this.

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Aaron And after that, go create, go to lambda of the management console and open the order acknowledgement

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lambda function and go to configuration.

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And if you go to environment variables, I'm going to create an environment variable at any one table

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which the value should be the or order topic.

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Aaron And the environment key will be topic.

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Aaron Please give and provide this environment variable copy from the order topic.

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Aaron And paste in the key of the topic.

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Aaron And click this button.

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So we will use this environment variable into our application.

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As you remember that this is the best practice.

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Get these names from the environment variables into lambda function.

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By this way, we don't change any Aaron if we are since provider is changed we only change the value

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in here.

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Don't change the lambda actual function code.

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If you open the our actual code now we can publish message to the sense in our lambda function code.

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So basically the idea is the same.

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We will prepare for the parameters.

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So I'm going to create a parameters.

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First, in the parameters, we are providing the message as a order request that we are prepared in

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the first two steps and after that we are pacing the topic.

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Aaron See that we are getting topic Aaron from process start and we the topic Aaron that we provide

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in the last couple of minutes.

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So after that we pass these parameters to the publish command.

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So in order to do that, I'm going to import record statement.

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So this is very important to add a required import statement, go on top of the page, and after that

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we will import the required package with importing publish command from the SNS client and also import

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source client.

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JS Separate module object to send required commands in our application.

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So after import these two statements, if you scroll down, you can see that our published command makes

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green and now we can send these publish command with using these parameters.

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And one of the.

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This comes from the lambda environment for us.

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Okay.

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That means we have successfully performed the third step, which is the published message to SNS and

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we are log the operation which is incoming from the published command data.

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Okay, very good.

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Now it is time to develop the fourth step in order to perform the fourth step, which is the save order

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item in dynamic DB.

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I have created on the command text file and several documentation.

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We will follow the same steps.

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First of all, we will check the documentation.

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We have already know that dynamo DB client documentation from a SDK, but this time we will use put

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item command.

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You can check the put item command.

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This will be basically insert an item on Dynamo TV and here you can see the input and output.

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When we are inserting any words from Dynamo DB, we will use also util dynamo DB library to make it

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simple.

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And these are the input parameters and these are the output parameters.

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OC After that, if you come back to our documentation, basically we will create the Dynamo DB Klein.

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JS This we will separate the Dynamo DB Client Node.js module.

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If you open the DB client JS, please create this file and implement this code.

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Have already know that this could provide to interact with Dynamo DB and if you come back the other

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items, the other item is set to environment variables.

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Again, I am going to open a maven console and go to configuration environment variables and I'm going

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to add new environment variable for the dynamo db table name is note that we will create an order table

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and I would like to get the table name from the environment.

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Variables of the order acknowledgements lambda function and click this Ableton.

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Okay, very good.

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We have now to my tables and now I'm ready to implement our Save Dynamo DB operation.

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If you come back to our index case and go to the save order item in Dynamo DB path and now we will follow

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the same steps.

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Basically this time we will use put item command and Marshall and Marshall operations from the util

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dynamo DB and I will use the Dynamo DB clients to do that.

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I would like to start with the adding to import segment because it is very important to adding record

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import statements.

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So please add the correct import statement as well as like me, you can see that we are adding to put

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item command in Dynamo DB client object and also we are using Marshall and Marshall from Util Library.

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And lastly, I have added to Dynamo DB client from our separate Node.js module to interact with Dynamo

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DB OC.

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After that, after importing these statements now we will develop our actual operation.

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So for that purpose I have prepared a dynamo DB parameters and after that paste these parameters into

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our client object.

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So you can see in this line of code we will provide this line of code in action for the for this action.

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Basically here you can find the dynamic DB parameters.

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Placing the table name and table name comes from the environment variables and placing the item.

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So if you check the item, this is the order request.

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So we will prepare the order request from the incoming event.

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But that's why we will validate and that's why we will set the ID as a UID because ID is the order partition

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key and we have to provide these ID information, otherwise it will get exception.

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So by this way, we can pass the whole order request as the item of the Dynamo DB table.

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Of course, using the Marshall Utility Library.

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Okay.

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After preparing the Dynamo DB parameters, the others are very similar.

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We are using the put item command to insert any item and sending with using the dynamic DB client object.

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And we got the create result and we are logging that successfully.

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Create an item on Dynamo DB OC.

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As you can see that we have successfully publish topic on Amazon SAS using a SDK libraries and after

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that we will save item on Dynamo DB order table.

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So we will finish the development of the order.

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Acknowledgements with interacting sense and Dynamo.

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DB Table.