Do Azure Functions have a request pipeline of some kind? - azure

I would like to add some common authentication code to a collection of HttpTrigger Azure Functions (v3), which I'm using as an API. I know about the service-side auth associated with AuthorizationLevel.Function, but that won't work for me. The type of auth I need to do is relatively simple: just check a specific HTTP header for a specific value.
In ASP.NET, this kind of thing can be done in an HttpModule. Do Azure Functions have a similar request pipeline of some kind?
As far as I can tell from the documentation, it looks like new Function instances can call Startup.Configure() before calling the target method, if the project is appropriately configured. However, those calls are intended to support Dependency Injection, and don't have access to the HttpRequest object.
Obviously, I could just put an isAuthorized(request) call at the beginning of each API entry point, but that feels klunky, repetitive, and potentially error-prone. Is there a better way?

Related

Azure durable functions and synchronous read?

I'm trying to use Azure Durable Functions to implement a minimal server that accepts data via a POST and returns the same data via a GET - but I don't seem able to generate the GET response.
Is it simply not possible to return the response via a simple GET response? What I do NOT want to happen is:
GET issued
GET response returns with second URL
Client has to use second URL to get result.
I just want:
GET issues
GET response with requested data.
Possible?
I'm not really sure whether durable functions are meant to be used as a 'server'. Durable functions are part of 'serverless' and therefore I'm not sure whether it's possible (in a clean way).
To my knowledge durable functions are used to orchestrate long lasting processes. So for example handling the orchestration of a batch job. Using durable functions it's possible to create an 'Async HTTP API', to check upon the status of the processing a batch of items (durable function documentation). I've wrote a blogpost about durable functions, feel free to read it (https://www.luminis.eu/blog/azure-functions-for-your-long-lasting-logic/).
But as for your use case; I think you can create two separate Azure functions. One for posting your data, you can use an Azure Blob Storage output binding. Your second function can have a GET http trigger and depending on your data you can use an blob input binding. No need to use durable functions for it :)!
Not really a direct answer to your question, but hopefully a solution to your problem!

Pass parameters from C# function app to another Javascript function app in Azure

I need to set up an application in Azure and make communicate 2 functions (one written in C# and one written in JavaScript).
The C# fragment consists in analyzing a XML feed, get the data and save in objects then finally send them to the other JavaScript function by parameter.
I did read that we could establish communication between both functions using HTTP calls but is it possible to do it with parameters ?
If not, would have any suggestions in order to achieve something like this properly? I'm getting started with Azure and i don't have enough visibility to know what is recommened in such a situation
Thank you for your advices
Yes, this is absolutely possible. How you do this is up to you. If you look at the default HTTP trigger templates, you can see that they take parameters (for example, as query string parameters). You can find more examples in the HTTP and webhook recipes documentation.
You can use other trigger types for cross-function communication as well. Take a look at this documentation for related best practices: https://learn.microsoft.com/en-us/azure/azure-functions/functions-best-practices#cross-function-communication

Can Azure Functions be used with URI path IDs?

I am wondering if it is possible to configure an Azure Function App to accept a URI-path ID as is typically used in RESTful services, e.g. /api/foo/1, where the function is foo. I haven't been able to find documentation on this and the binding information that I have found suggests that this isn't possible (I don't see a way to map it). It doesn't "just work" with the typical HTTP trigger (which supports /api/foo?id=1). In that configuration one receives a 404 response, I'm guessing because it doesn't know to call the foo function with the ID suffix in the URI.
In case it matters, I'm using C# to write my function.
You are correct that URI parameters are not supported at this time. If you'd like, you can create a feature suggestion for this here in our repo. Thanks :)

Is there a way to link a specific method to a Route in ServiceStack?

The Problem
I'm aware of the basic way to create a route/endpoint in ServiceStack using methods with names like "Get", "Post", "Any", etc inside a service but in the particular case that I'm trying to work with I have an existing service (which I can make an IService via inheritance) that can not be retrofitted w/ServiceStack attributes and currently uses DTOs for the requests and responses.
This service contains many functions that I do not want to manually mask (as this is a pass-through layer) but otherwise already conform to ServiceStack's requirements. What I'm wondering is if there's a way to manually create these routes in a way that would work like I've mocked up here. My existing functions and DTOs already contain the information I would need to define the routes so if this approach is possible it would only require me to enumerate them at initialization time as opposed to generating the services layer manually.
I noticed there is an extension method on Routes.Add that takes an Expression of type Expression> but I was not able to get that working because I believe the underlying code makes assumptions about the type of Expression generated (LambdaExpression vs MemberExpression or something like that). I also may be barking up the wrong tree if that's not the intended purpose of that function but I can not find documentation anywhere on how that variant is supposed to work.
Why?
I'm not sure this is necessary but to shed some light on why I want to do this as opposed to retrofitting my existing layers: The current code is also used outside of a web service context and is consumed by other code internally. Retrofitting ServiceStack in to this layer would make every place that consumes it require ServiceStack's assemblies and be aware of the web service which is a concern I want separated from the lower code. We were previously using MVC/WCF to accomplish this goal but we want some of the features available from ServiceStack.
the current architecture looks like this:
data -> DAL -> discrete business logic -> composition -> web service
Hopefully that makes enough sense and I'm not being obtuse. If you would like any more details about what I want to do or why I'll try to update this post as soon as possible.
Thanks!
You might use the fallback route in order to provide your own routing mechanism.
Then you get the request.Path property and route using your own mapping of path:Function which can be stored in a simple dictionary.
Anyway, if you go this path I don't see much benefit in using servicestack. It seems you just need an http handler that routes requests to existing services.

ServiceStack.Examples\src\ServiceStack.Examples is not RESTful?

I'm struggling to see how this is RESTful. I'm referring to the downloaded GitHub ServiceStack.Examples\src\ServiceStack.Examples\ServiceStack.Examples.sln. I do not see anything restful about this, there is no RESTful routes here at all and the method names are all verbs but they're all like GEtThis, etc. I don't see any Http verb attributes, nothing here.
Can someone explain what this is here becuase I feel like it doesn't even belong in the ServiceStack examples...??
Nobody said that example was supposed to be RESTful.
ServiceStack is a general services framework that lets you implement SOAP, MQ or REST+Web/HTML services with the same service.
The example your looking at is one of the first examples ever created for ServiceStack which makes use the Old API. You can compare and contrast it with the New API here. Since the example implements IService<T> it's not a REST service, since every HTTP Verb will invoke the same implementation above. To provide different implementations for each verb with the Old API you would need to inherit RestServiceBase<T> instead, or preferably use the New API.
If you want to consume this service via SOAP or MQ hosts than you need to ensure its accessible via POST by either maintaining single operation per Request DTO like this or by using a method named either Post() or Any() in the New API.

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