Node Dynamo DB App
This repository contains Demo Application for NodeJS which connects with DynamoDB.
As we know, Dynamo is fast, scalable, highly available AWS NoSQL Database Service. Although we have many other databases which are also fast, scalable and good enough, but for scaling/sharding the database, we must have good knowledge of that database, or we must have expert DBA for managing the our database.
That is not the case with DynamoDB. When we are working with DynamoDB, we don't have to care about the creating the replica, sharding the database or select the shard-key etc. All headache related to scalling/sharding purpose is already handled in AWS Dynamo Database Service. We have to just consume AWS Dynamo Database Service and concentrate on our project development, instead of spending lots of time on all this DBA related stuff.
You can checkout more about Dynamo DB form this link.
That's enough for theory part, now lets move to practical. Lets make a basic demo application with NodeJS, which will communicate with AWS DynamoDB Database Service.
For this demo application, we are connecting with local DynamoDB. To install DynamoDB locally follow this link.
Tip: First checkout full working source code from this link, and try to run. When you will run you will see output like this:
List Of Tables [ 'OrderLog' ]
Table OrderLog Dropped!
Table OrderLog Created!
Row {"Item":{"order_id":{"N":"1234"},"order_body":{"S":"{a:34, b:34}"}},"TableName":"OrderLog"} Inserted!
Result: { '0': undefined,
'1': [ undefined, undefined, undefined, undefined ] }Note: If your are facing error while running the DynamoDBTest.js file which looks like:
exception when clearing com.almworks.sqlite4java.SQLiteException: [8] DB[1] reset [attempt to write a readonly database]then DynamoDB is not having permission to write things to that particular directory/folder. So I will suggest run DynamoDB in home directory or run DynamoDB with sudo permission. And if you are running application second time then un-comment below code, so program can delete table first before creating again, otherwise it will throw an error for creating same table again.
tasks.push(function (callback) {
dynamoDB.deleteTable({TableName: tableName}, function (error) {
if (error) {
console.log("Error: ", error, error.stack);
callback(error);
} else {
console.log("Table ", tableName, " Dropped!");
callback(null);
}
});
});Lets understand what is happening into DynamoDBTest.js file? Open DynamoDBTest.js file into your favorite Editor, and you will find everything into comments which is require to enough to explain the code.
/**
* Created by Amit Thakkar on 17/9/14.
*/
(function () {
/*
* Define Configuration Here.
* To Connect with Local DynamoDB, We are providing dummy entries
* for required fields(accessKey, Secret and Region).
* To Connect with AWS DynamoDB Service place actual accessKey, Secret and Region.
* */
var dynamoDBConfiguration = {
"accessKeyId": "DummyKeyForLocalDynamoDB",
"secretAccessKey": "DummySecretAccessKeyForLocalDynamoDB",
"region": "eu-west-1"
};
// requiring aws-sdk, async
var AWS = require('aws-sdk');
var async = require('async');
// For Local DynamoDB define endpoint will be "http://localhost:8000"
var databaseConfig = {"endpoint": new AWS.Endpoint("http://localhost:8000")};
// provide your configurations
AWS.config.update(dynamoDBConfiguration);
// initialize DynamoDB Object.
var dynamoDB = new AWS.DynamoDB(databaseConfig);
var tasks = [];
var tableName = "OrderLog";
// Listing tables
tasks.push(function (callback) {
dynamoDB.listTables(function (error, data) {
if (error) {
console.log("Error: ", error, error.stack);
callback(error);
} else {
console.log("List Of Tables", data.TableNames);
callback(null);
}
});
});
/*
* Deleting Table
* When running first time remove this task as Table will not be present
* And it might be throwing an Error.
* */
/*tasks.push(function (callback) {
dynamoDB.deleteTable({TableName: tableName}, function (error) {
if (error) {
console.log("Error: ", error, error.stack);
callback(error);
} else {
console.log("Table ", tableName, " Dropped!");
callback(null);
}
});
});*/
// Creating Table
tasks.push(function (callback) {
// Describe table here.
var table = {
AttributeDefinitions: [ // Defining Primary Key
{
AttributeName: 'order_id',
AttributeType: 'N'
}
// Define Secondary key here.
],
KeySchema: [ // Defining Key Type Here.
{
AttributeName: 'order_id',
KeyType: 'HASH'
}
// Define Secondary Key Type Here.
],
// Define read per second and write per second here.
ProvisionedThroughput: {
ReadCapacityUnits: 1,
WriteCapacityUnits: 5
},
TableName: tableName // table Name
};
dynamoDB.createTable(table, function (error, data) {
if (error) {
console.log("Error: ", error, error.stack);
callback(error);
} else {
console.log("Table ", tableName, " Created!");
callback(null);
}
});
});
// Insert/Update a row
tasks.push(function (callback) {
var params = {
Item: {
order_id: {
N: '1234'
},
order_body: {
S: "{a:34, b:34}"
}
},
TableName: tableName
};
dynamoDB.putItem(params, function (error, data) {
if (error) {
console.log("Error: ", error, error.stack);
callback(error);
} else {
console.log("Row ", JSON.stringify(params), " Inserted!");
callback(null);
}
});
});
async.series(tasks, function (error, result) {
console.log("Result: ", arguments);
});
})();