1. Built-in Auto scale support – App service can be configured to scale up/down or scale in/out automatically based on your usage. Scale up/down increase the cores and RAM where as in/out increases or decreases the number of instances that are running your app.
2. High Availability – Deploy your apps anywhere in Microsoft global data centers and with the right plan App service provides high availability for your application.
3. IDE Integration – you can create, deploy and debug your azure app service application using visual studio, visual studio code, Java IDEs’ like Maven, Eclipse, IntelliJ. 
4. Continuous Integration and Deployment support – In the Azure portal, App service provides continuous integration and deployment with sources like Azure DevOps, GitHub, Bitbucket, FTP or local Git Repo from your local machine. Connect your application with the sources and App service will automatically synchronize your changes in the future. 
5. Deployment Slots – when you deploy your web app you can use separate deployment slot(staging) instead of production slot to test your changes with standard tier and above. Deployment slots have its own separate host names and you can swap content and configurations between deployment slots including the production slot. The swap operation warms up necessary worker processes to match your production scale with no downtime. 
6. Authentication – App service provides built-in authentication and authorization capability so your users can login to the App and access data based on the permissions with minimal changes to your code. You can use third party identity providers Microsoft, Facebook, Google, Twitter and GitHub.
7. Multi language and Framework support – you can develop your application or APIs with .NET, PHP, Node.js, Python or Java of your choice even you can write power shell script to run back ground jobs. Easily manage your apps in App service by writing Power shell or Azure CLI scripts. 
8. Integrate with other services and SaaS Platforms – Easily integrate with other Azure service like API management, Azure SQL, Logic apps (SaaS connectors) and many more. You can access your on-premises data using Hybrid connection or Azure virtual network configuration with app service. 
9. API and Mobile scenarios - App service provided CORS support for Rest API’s and supports mobile apps scenarios like authentication, push notifications and offline data synchronization. 
10. Serverless Functions – you can use Azure App Service to run Azure functions with out managing underlying infrastructure. You will pay only for the compute time when your code is executed. 

1. First one is consumption tier which is built per number of API executions and it is easier to start with even if your application is just picking the API traffic because Microsoft offers one million API executions for free every month. It does not incur any fixed costs. 
2. The other set of tires are the so-called dedicated tiers( called Developer, Basic, Standard, and Premium) where you are billed on an hourly basis, a fixed price and the offer more features than consumption tiers.

• https://www.youtube.com/watch?v=NGG38bewVNg 
• https://learn.microsoft.com/en-us/azure/api-management/plan-manage-costs 

1. To send emails or notifications
2. Processing the file data - When the blob is added or updated you can run Azure functions
3. Integration with the different systems
4. Run batch processes on schedule time - Using Timer Trigger you can schedule jobs
5. Database backups and cleanups - To administer your DB activities
6. IoT data processing - using Azure Event Hub biding you can collect data from IOT devices
7. Build APIs and microservices - Using the HTTP trigger endpoint you can build APIs

• Azure functions provide ready-to-code environments and easy-to-code programming models as a Serverless solution.
• It helps developers to focus on coding and delivering key value to your organization without the need to set up servers and maintain infrastructure by themselves. 
• If you are a .NET developer, you want to get started on .NET programming while taking advantage of cloud-based highly scalable, on-demand resources needed to run your applications, Azure functions are a way to go. 
• Azure functions focus on event-driven scenarios, and it simplified the integration with many Azure services like Event Grid, and cosmos DB and with a broader range of events and bindings which allows one to connect other azure services with ease declaration. 
• Supports the latest version of. NET. Always azure functions team works with the latest .NET features from the preview mode. 

1. Server-less -  Focus more on building your apps faster to add business value without managing infrastructure. 
2. Language of your choice - You can develop your function code using C#, Java, JavaScript, Powershell and Python languages of your choice.
3. Custom development  - you can bring your own dependencies using  Nuget and NPM to extend your application logic.
4. Continuous Integration and Deployment - you can set up your function code with continuous integration and deployment using GitHub, Azure DevOps, bitbucket and other CI/CD processes.
5. Built-in Security - Protect your functions with SSL Bindings, VNet integration and OAuth providers. Authenticate users with the OAuth standard from providers such as Active Directory, Facebook, Twitter, Google, and Microsoft Account.
6. Scale on demand - Automatically scale out whenever there is a need  by adding compute power and scale in when the code is stopped running.
7. Optimized Pricing - Pay only when your app runs.
8. Performance and Monitoring - Easily configure Azure App Insight to your App for monitoring and analyzing the app performance.
9. Connect to Other Services - Use triggers and bindings that enable your server-less applications to respond to events and connect to other services seamlessly.
10. Choice of hosting plan - Based on your need, you can opt for Consumption, Premium or App Service Plan.

1. Consumption Plan - is billed based on per-second resource consumption and executions.
2. Dedicate(App Service) Plan - Runs like your web apps. If the app service plan is shared between your applications and functions there is no additional cost for functions run.
3. Premium Plan - It contains Pre-warmed instances that are always readily available to respond immediately. Also, it contains VNET connectivity for security. In this plan,  you pay for Pre-warmed instances and any additional instance which you use to scale your app in and out.

1. Serverless -  Focus more on building your apps faster to add business value without managing infrastructure.
2. Language of your choice - Develop your function code using C#, Java, JavaScript, Powershell and Python languages of your choice
3. Custom development  - Bring your own dependencies using  Nuget and NPM to extend your application logic.
4. Continuous Integration and Deployment - Set up your function code with continuous integration and deployment using GitHub, Azure DevOps, bitbucket and other CI/CD processes.
5. Built-in Security - Protect your functions with SSL Bindings, VNet integration and OAuth providers. You can authenticate users with the OAuth standard from providers such as Active Directory, Facebook, Twitter, Google, and Microsoft Account
6. Scale on demand - Automatically scale out whenever there is a need  by adding compute power and scale in when the code is stopped running
7. Optimized Pricing - Pay only when your app runs.
8. Performance and Monitoring - Easily configure Azure App Insight to your App for monitoring and analyzing the app performance
9. Connect to Other Services - Use triggers and bindings that enable your serverless applications to respond to events and connect to other services seamlessly
10. Choice of hosting plan - Based on your need, you can opt for Consumption, Premium or App Service Plan

1. Tool based deployments - deployments are managed locally. Useful when you are doing local development and requires multiple ad-hoc deployments manually.
• Visual Studio Code publish
• Visual Studio publish
• Core tools deployments (using Zip deploy or docker container)
2. App Service Deployment - deployments are managed from the Azure App Service under Deployment section. Useful when you want to deploy as part of source control commits or from a container registry.
• Deployment center - Continuous deployment using Azure Repos, GitHub, Bitbucket and Local Git or Manual deployment using One drive, Dropbox, External Git and FTP.
• Container deployments
3. External Pipelines - deployment are managed by pipelines. Useful for Production scenarios where you want to do some additional validations as part CI/CD.

• DevOps pipelines
• GitHub actions

1. Dedicated app service plan
2. Consumption plan
3. Premium plan (called as elastic premium plan)

• VNET Integration- To add more security to your app, you can configure a VNET and add your function app. With this, your function app is secured with service endpoints. VNET integration is not available in other plans.
• Pre-warmed instances to avoid cold start - In consumption plan, if there are no execution/calls to your function app it scales in to Zero instances. Once it goes to zero instances, if we make any function call, it takes some time(called as cold start time) to respond to the first call (from zero to one). This latency can be avoided in Premium plan with pre-warmed instances.
• Unlimited execution duration - Consumption plan has a 10 minutes limit whereas Premium plan defaults to 30 minutes but you can modify it to unlimited(60 minutes guaranteed). Use functiontTimeout property in host.json file to change the configuration.
• Premium hardware - Provides best cores(1, 2 and 4), memory and storage.
• Multiple function apps can be deployed to the same plan and all function apps in premium plan shares pre-warmed active instances.
• Automatic Scaling - Like consumption plan, your app will scale in or scale out based on the need.

• 1.x - Supports .NET Framework
• 2.x - Supports .NET Core2.1
• 3.x - supports .NET Core3.1

1. Azure Functions V3(.NET Core) 
2. Azure Functions V2(.NET Core) 
3. Azure Functions V1(.NET Framework)

<TargetFramework>net461</TargetFramework>
<AzureFunctionsVersion>v1</AzureFunctionsVersion>

2.x version setting in .csproj file

<TargetFramework>netcoreapp2.1</TargetFramework>
<AzureFunctionsVersion>v2</AzureFunctionsVersion>

<TargetFramework>netcoreapp2.1</TargetFramework>
<AzureFunctionsVersion>v2</AzureFunctionsVersion>

1. Blob Trigger - Creates a function trigger when a blob is added to a container
2. Cosmos DB  Trigger - Creates a function trigger when a document change in document collection
3. Event Grid Trigger - Creates a function trigger when an event grid receives a new event
4. Event Hub Trigger -  Creates a function trigger when an event hub receive a new event
5. HTTP Trigger -  Creates function triggered by HTTP Request
6. IoT Hub Trigger -  Creates a function trigger when an IoT hub receives a new event on the event hub endpoint
7. Queue Trigger - Creates a function trigger when a message is added to specified azure storage
8. Service Bus Queue Trigger - Creates a function trigger when a message is added to specified service bus queue
9. Service Bus Topic Trigger - Creates a function trigger  when a message is added to specified service bus topic
10. Timer Trigger - Creates a function trigger on a specified schedule

1. Creates a new instance of the SPWeb object, and we are responsible to dispose after using it.
2. OpenWeb() with out sending parameters opens root web of current site collection. If OpenWeb() with parameters opens specific web site.
3. Expensive call - It cost more resources than reusing an existing one.

1. Gives you access to the current instance of SPWeb, and you must not dispose it
2. Gives current Subsite if you are at web other than root web.