What is difference between Azure Durable Function & Logic App 21st July 2021


We have already discussed quite a bit about Azure Durable Functions. I did write up on a bit of history and why we need Azure Durable functions. You can read that article here..link below Why do we need Azure Durable Functions and its history
I also wrote about what are Azure durable functions
And then if you are keen to know about various application patterns available ,that can benefit from Azure Durable function then read my article Patterns and Best Practises:Azure Durable Functions
And then if you want to get hands on and get some dev experience , here is a good point of start Simple Azure Durable function implementation

Microsoft's Azure has two great tools for creating a workflow. One is Azure Logic Apps and the other is Azure Functions. Until recently, one could argue that Azure Functions were code triggered by events while Logic Apps were event-triggered workflows. However, after the release of Azure Durable Functions, things changed. Azure Durable Functions, a cloud implementation of the durable task framework, offers you a way to define a workflow using code, and therefore I guess developers love it more since it offers more control to developers. Durable Functions is an extension of Azure Functions that allow you to add statefulness to otherwise stateless serverless applications. On the other hand, with Azure Logic Apps you can create stateful and serverless workflows through a visual designer and there is no need to write any code. If you are architecting a solution and you have to choose one of these two options, you might be wondering how to choose between Azure Durable Functions and Logic Apps. This blog of mine tries to solve exactly that by comparing both platforms and therefore shedding some light that may help you better choose a platform that fits your needs

Solution Azure Durable Functions Logic Apps
Summary Azure Functions is a serverless compute service that lets you run event-triggered code without having to explicitly provision or manage infrastructure. You can build Azure Functions in various languages like C#, F#, Node.js & Typescript, Python, Java and Powershell. Azure Logic Apps is a cloud service that helps you schedule, automate, and orchestrate tasks, business processes, and workflows when you need to integrate apps, data, systems, and services across enterprises or organizations.
Development Code First (imperative)
Since it is code first developers love it more
“Designer-First” (declarative) experience
Connectivity & Actions About a dozen built-in binding types(mainly for other Azure services).
You can write custom code to create bindings as per your need (If there isn’t an existing binding available already).
There is lightweight but limited configuration available within the Azure Portal. Unlike Logic Apps there is no visual workflow designer available.
Azure Functions do not have connectors. It relies on triggers and input and output bindings – like Event Hubs, Service Bus, Cosmos DB and Storage.
Bindings in Azure Functions provide a way to connect to data with code declaratively. List of bindings are very much limited when you compare with Logic Apps
    Logic Apps have plenty of connectors to:
  • Azure Services,
  • SaaS applications (Microsoft and others),
  • FTP and
  • Enterprise Integration Pack for B2B scenarios
Furthermore, it has the ability to build custom connectors if one isn’t available.Each pre-existing connector has a collection of ready-made actions. You integrate custom logic through custom connectors.Has a visual workflow designer available via the Azure Portal.
Execution Context Can run locally, on any self managed server, in containers or in Azure (serverless). Runs only in Azure
Development Experience Code being triggered by an event
Can be developed and debugged on local workstation, which is a big plus to increase developer productivity
Worfklow triggered by an event
Cannot debug ,test or run run Logic Apps locally, as it runs only in cloud and has a depdency on Microsoft-managed connectors(mixed)
Monitoring Done through Azure Application Insights . Its little tough to manage/monitor for non-technical users Azure portal, Azure Monitor logs. Much easier for non-technical users to manage as .Each run can be monitored within the Azure portal (mixed)
Deployment Like mentioned above, Azure functions are code first.
    Options for deployment are through:
  • Visual Studio,
  • Azure DevOps,
  • FTP
Logic apps can be created & updated directly in the azure portal. What it also means is that it will create a JSON template. This JSON template can also be deployed via Az DevOps and Visual Studio (Mixed)
Exception Handling Since it is code-driven, you need to build your own exceptional handling. For eg, say you want to handle a a scenario where your application falls over when trying to connect to a third-party system, then you should create the logic yourself. There is no retry, resume or resubmit capabilities, unless of course your develop them yourself using standard try-catch .With Azure Functions you do not have the out-of-the-box retry capability like Logic Apps except for Azure Queue and Blob Storage Provide out-of-the-box functionality with retries, scopes, and run after configuration. In case you still have issues, you can solve the problem by reviewing it in the Azure portal, looking for a workflow that gets a failed status and then you can easily resubmit it.
Details Azure Documentation link for Azure functions on pricing Azure Documentation link for Logic Apps on pricing

To conclude,I hope you would have got a better understanding on which platform to select when given a choice to architect your application. The platform better suited really depends on the functional and non-functional requirements and also on your preferences.The choice between the two is on how much control you need and how complex is your target solution.As a wrap up,we could say that

Use Logic apps when:

For fast and codeless services integrations. Use it for high-load and performance sensitive tasks.Since there are extensive list of connectors,time-to-market may be shortened
If it's ok to just run on Azure
Less coding is preferred.It has a visual designer
Visual tools to manage and troubleshoot workflows are required

Use Azure Durable functions when:
Provides an excellent out-of-the-box solution for various scenarios that cannot be held by Azure FaaS service alone.
The list of available bindings is sufficient to meet the requirements,
You prefer to have all the power and flexibility of a robust programming language.

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