Unit Testing The Azure Cosmos DB Change Feed In xUnit And C#

Introduction

Writing basic units for Azure Functions triggered by the Change Feed is straightforward with xUnit

While refactoring some of our microservices at work, I came across a service that didn’t have any unit tests for them! This service uses the Azure Cosmos DB Change Feed to listen to one of our write-optimized containers related to customers. If a new customer is created in that container, we then pick up that Customer document and insert it into a read-optimized container (acting as an aggregate store) which has a read friendly partition key value.

This read-optimized container is then utilized by other services within our pipeline when we need to query the aggregate for our Customer data.

Most of our services are triggered by message brokers (Event Hubs, Service Bus, etc.) so our process for unit testing these services is pretty standardized. But for whatever reason, this service didn’t have any unit tests, which is pretty bad in my opinion. So I’d thought I’d have a crack at it.

Turns out, it’s fairly straightforward.

So in this article, I’m going to show you how straightforward it is to write basic unit tests for an Azure Function that is triggered by the Azure Cosmos DB Change Feed using xUnit. This is the unit testing framework we use at work and I also use it in my side projects as well since it’s free, open-source, and super easy to get your head around.

Wait, What is the Change Feed again?

The Azure Cosmos DB Change Feed is a persistent record of changes that take place in a container in the order that they occur. It listens to any changes in a container and then outputs a sorted list of documents that were changed in the order in which they were modified.

#c# #xunit #azure

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Unit Testing The Azure Cosmos DB Change Feed In xUnit And C#
Eric  Bukenya

Eric Bukenya

1624713540

Learn NoSQL in Azure: Diving Deeper into Azure Cosmos DB

This article is a part of the series – Learn NoSQL in Azure where we explore Azure Cosmos DB as a part of the non-relational database system used widely for a variety of applications. Azure Cosmos DB is a part of Microsoft’s serverless databases on Azure which is highly scalable and distributed across all locations that run on Azure. It is offered as a platform as a service (PAAS) from Azure and you can develop databases that have a very high throughput and very low latency. Using Azure Cosmos DB, customers can replicate their data across multiple locations across the globe and also across multiple locations within the same region. This makes Cosmos DB a highly available database service with almost 99.999% availability for reads and writes for multi-region modes and almost 99.99% availability for single-region modes.

In this article, we will focus more on how Azure Cosmos DB works behind the scenes and how can you get started with it using the Azure Portal. We will also explore how Cosmos DB is priced and understand the pricing model in detail.

How Azure Cosmos DB works

As already mentioned, Azure Cosmos DB is a multi-modal NoSQL database service that is geographically distributed across multiple Azure locations. This helps customers to deploy the databases across multiple locations around the globe. This is beneficial as it helps to reduce the read latency when the users use the application.

As you can see in the figure above, Azure Cosmos DB is distributed across the globe. Let’s suppose you have a web application that is hosted in India. In that case, the NoSQL database in India will be considered as the master database for writes and all the other databases can be considered as a read replicas. Whenever new data is generated, it is written to the database in India first and then it is synchronized with the other databases.

Consistency Levels

While maintaining data over multiple regions, the most common challenge is the latency as when the data is made available to the other databases. For example, when data is written to the database in India, users from India will be able to see that data sooner than users from the US. This is due to the latency in synchronization between the two regions. In order to overcome this, there are a few modes that customers can choose from and define how often or how soon they want their data to be made available in the other regions. Azure Cosmos DB offers five levels of consistency which are as follows:

  • Strong
  • Bounded staleness
  • Session
  • Consistent prefix
  • Eventual

In most common NoSQL databases, there are only two levels – Strong and EventualStrong being the most consistent level while Eventual is the least. However, as we move from Strong to Eventual, consistency decreases but availability and throughput increase. This is a trade-off that customers need to decide based on the criticality of their applications. If you want to read in more detail about the consistency levels, the official guide from Microsoft is the easiest to understand. You can refer to it here.

Azure Cosmos DB Pricing Model

Now that we have some idea about working with the NoSQL database – Azure Cosmos DB on Azure, let us try to understand how the database is priced. In order to work with any cloud-based services, it is essential that you have a sound knowledge of how the services are charged, otherwise, you might end up paying something much higher than your expectations.

If you browse to the pricing page of Azure Cosmos DB, you can see that there are two modes in which the database services are billed.

  • Database Operations – Whenever you execute or run queries against your NoSQL database, there are some resources being used. Azure terms these usages in terms of Request Units or RU. The amount of RU consumed per second is aggregated and billed
  • Consumed Storage – As you start storing data in your database, it will take up some space in order to store that data. This storage is billed per the standard SSD-based storage across any Azure locations globally

Let’s learn about this in more detail.

#azure #azure cosmos db #nosql #azure #nosql in azure #azure cosmos db

Unit Testing The Azure Cosmos DB Change Feed In xUnit And C#

Introduction

Writing basic units for Azure Functions triggered by the Change Feed is straightforward with xUnit

While refactoring some of our microservices at work, I came across a service that didn’t have any unit tests for them! This service uses the Azure Cosmos DB Change Feed to listen to one of our write-optimized containers related to customers. If a new customer is created in that container, we then pick up that Customer document and insert it into a read-optimized container (acting as an aggregate store) which has a read friendly partition key value.

This read-optimized container is then utilized by other services within our pipeline when we need to query the aggregate for our Customer data.

Most of our services are triggered by message brokers (Event Hubs, Service Bus, etc.) so our process for unit testing these services is pretty standardized. But for whatever reason, this service didn’t have any unit tests, which is pretty bad in my opinion. So I’d thought I’d have a crack at it.

Turns out, it’s fairly straightforward.

So in this article, I’m going to show you how straightforward it is to write basic unit tests for an Azure Function that is triggered by the Azure Cosmos DB Change Feed using xUnit. This is the unit testing framework we use at work and I also use it in my side projects as well since it’s free, open-source, and super easy to get your head around.

Wait, What is the Change Feed again?

The Azure Cosmos DB Change Feed is a persistent record of changes that take place in a container in the order that they occur. It listens to any changes in a container and then outputs a sorted list of documents that were changed in the order in which they were modified.

#c# #xunit #azure

Software Testing 101: Regression Tests, Unit Tests, Integration Tests

Automation and segregation can help you build better software
If you write automated tests and deliver them to the customer, he can make sure the software is working properly. And, at the end of the day, he paid for it.

Ok. We can segregate or separate the tests according to some criteria. For example, “white box” tests are used to measure the internal quality of the software, in addition to the expected results. They are very useful to know the percentage of lines of code executed, the cyclomatic complexity and several other software metrics. Unit tests are white box tests.

#testing #software testing #regression tests #unit tests #integration tests

Ruthie  Bugala

Ruthie Bugala

1626494129

Using the new C# Azure.Data.Tables SDK with Azure Cosmos DB

Last month, the Azure SDK team released a new library for Azure Tables for .NET, Java, JS/TS and Python. This release brings the Table SDK in line with other Azure SDKs and they use the specific Azure Core packages for handling requests, errors and credentials.

Azure Cosmos DB provides a Table API offering that is essentially Azure Table Storage on steroids! If you need a globally distributed table storage service, Azure Cosmos DB should be your go to choice.

If you’re making a choice between Azure Cosmos DB Table API and regular Azure Table Storage, I’d recommend reading the following article.

In this article, I’ll show you how we can perform simple operations against a Azure Cosmos DB Table API account using the new Azure.Data.Table C## SDK. Specifically, we’ll go over:

  • Installing the SDK 💻
  • Connecting to our Table Client and Creating a table 🔨
  • Defining our entity 🧾
  • Adding an entity ➕
  • Performing Transactional Batch Operations 💰
  • Querying our Table ❓
  • Deleting an entity ❌

Let’s dive into it!

Installing the SDK 💻

Installing the SDK is pretty simple. We can do so by running the following dotnet command:

dotnet add package Azure.Data.Tables

If you prefer using a UI to install the NuGet packages, we can do so by right-clicking our C## Project in Visual Studio, click on Manage NuGet packages and search for the Azure.Data.Tables package:

Connecting to our Table Client and Creating a table 🔨

The SDK provides us with two clients to interact with the service. A TableServiceClient is used for interacting with our table at the account lelvel.

We do this for creating tables, setting access policies etc.

We can also use a TableClient. This is used for performing operations on our entities. We can also use the TableClient to create tables like so:

TableClient tableClient = new TableClient(config["StorageConnection"], "Customers");
            await tableClient.CreateIfNotExistsAsync();

To create our Table Client, I’m passing in my storage connection string from Azure and the name of the table I want to interact with. On the following line, we create the table if it doesn’t exist.

To get out Storage Connection string, we can do so from our Cosmos DB account under Connection String:

When we run this code for the first time, we can see that the table has been created in our Data Explorer:

Defining our entity 🧾

In Table Storage, we create entities in our table that require a Partition Key and a Row Key. The combination of these need to be unique within our table.

Entities have a set of properties and strongly-typed entities need to extend from the ITableEntity interface, which expose Partition Key, Row Key, ETag and Timestamp properties. ETag and Timestamp will be generated by Cosmos DB, so we don’t need to set these.

For this tutorial, I’m going to use the above mentioned properties along with two string properties (Email and PhoneNumber) to make up a CustomerEntity type.

#csharp #programming #azure #data #azure cosmos db #azure

Ikram Mihan

Ikram Mihan

1582683309

An Overview of Azure Cosmos DB

In this article, we will discuss Azure Cosmos DB. We will answer questions such as: What is a Cosmos DB? Why do we need to use the Cosmos DB? We will also learn how to create a new Azure Cosmos DB account using Azure subscriptions, how to create a new database and collection using Azure, and how to add data to the collection.

In this article, we will see the following,

  • What is Azure Cosmos DB?
  • Why do we need to use the Cosmos DB?
  • How to create a new Azure Cosmos DB account using Azure
  • How to create a new database and collection using Azure
  • How to add data to the collection using Data Explorer
  • How to use SQL Query to the collection using Data Explorer
  • How to get Cosmos DB connection string from Azure

Prerequisite

  • Azure Subscriptions

What is Azure Cosmos DB?

Azure Cosmos DB is a globally distributed database service. It supports multi-model approaches such as the document, Key/Value, wide columns and graph databases using APIs.

The list of APIs such as the following:

  • SQL API
  • MongoDB API
  • Graph API
  • Table API
  • Cassandra API

Why do we need to use the Cosmos DB?

Azure Cosmos DB is offering the following items:

  • Global distributions
  • Elastic scale out
  • Guaranteed low latency
  • Five consistency models
  • Comprehensive SLAs

How to create a new Azure Cosmos DB account using Azure

You can learn in this section, how to create a new Azure cosmos database account using the Azure portal with the following guidelines.

Go to open the new browser, you can copy and paste the following URL

https://portal.azure.com/

Then, sign in to the Azure portal using Microsoft Account credentials:

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After successfully logging into the Azure portal, you can see the dashboard looks like the following screenshot.

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You can go to create a resource-Databases - click the Azure Cosmos DB.

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The Azure Cosmos DB new account window will be opened and you can enter the following details, which are required. Then, click the Create button.

ID
API
Subscription Name
Resource Group Name
Location

The list of API options is available in the following screenshot:

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Now, you can see the notification window displaying the deployment in progress notification. Once it is completed you will get the deployment succeeded notification in the notification window. Then, click the go to resource button.

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After successfully creating the Azure Cosmos DB account, the Congratulations! Your Azure Cosmos DB account was created window will be opened, as in the following screenshot.

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How to create a new database and collection using Azure

You will learn in this section, how to create a new database and collection in Data Explorer using Azure portal.

You can go to Data Explorer - click the New Collections

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The Add Collection window will be opened and you can enter the following details, which are required. Then, click the OK button.

  • Database Id
  • Collection Id
  • Storage Capacity
  • Throughput

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You can see the new database and collection looks at the following screenshot.

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How to add data to the collection using Data Explorer

You can learn in this section, how to add sample data to the collection in Data Explorer using Azure portal at the following guidelines.

You can go to Data Explorer - Expand the Table collection in the Collection window, click the Documents - click the New Document.

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The new document window will be opened and add the data to the collection with the following format.

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{  
   “Id”: “1”,  
   “TableName”: “Table A”,  
   “Location”: “Front Row”,  
   “Status”: “Available”,  
   “Date”: “28-02-2018”  
}  

Once you have added json data to the document, click the Save button.

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After successfully added records to the collection it looks like the following screenshot:

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How to add SQL Query to the collection using Data Explorer

You can learn in this section, how to use SQL query to the collection in Data Explorer using Azure portal at the following guidelines.

You can go to Data Explorer - Expand the Table collection in the Collection window, click the New SQL Query

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The Query window will be opened as in the below screenshot

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Once you have executed query by clicking Execute Query button:

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You can use the Where condition and Order By for the select statement on SQL Query window in the Azure Cosmos DB as in the below screenshots:

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How to get Cosmos DB connection string from Azure

You will learn in this section, how to get the Cosmos DB connection string in Keys using the Azure portal.

You can go to Settings - click the Keys

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Now you can copy the URI and Primary Key into your web.config file in your project

Conclusion

I hope you understand now about Azure Cosmos DB, how to create a new Azure Cosmos DB account using Azure, how to create a new database and collection using Azure, how to add data to the collection using Data Explorer, how to use SQL Query to the collection using Data Explorer and how to get Cosmos DB connection string from Azure. I have covered all the required things. If you find anything missing, please let me know. Thank you!

#Azure #Azure Cosmos DB #Cosmos DB