Add guide for multi-app-solution

content/app/guides/multi-app-solution/_index.en.md

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+---
+title: General approach for making a multi-app solution in Altinn
+linktitle: Multi-app solution
+description: Considerations and explanations of how to go about when creating a multi-app solution
+weight: 250
+aliases:
+
+- /app/multi-app-solution/
+
+---
+
+Before continue reading these guidelines, please consider if
+a multi-app solution is what you need to fulfill the purpose
+of your form(s).
+
+## What is a multi-app solution?
+
+A multi-app solution is a solution consisting of two or more
+cooperating apps, where typically (as per now) the "
+original" application(s) will trigger a creation of a new
+instance of the receiving application. As a part of the
+instantiation of the receiving application it is possible
+prefill the instance with specific data from the running
+instance of the original application.
+
+## Do I need a multi-app solution?
+
+A multi-app solution is in most cases not a necessary
+architectural choice for an Altinn form.
+
+### Use cases where you can consider utilize a multi-app solution:
+
+Criteria that should be met if you could consider creating a
+multi-app solution:
+
+- My forms will be answered by users that does not have
+  Altinn
+- It is okay that my receiving forms must be deleted in
+  order to end the lifecycle of the form.
+- The receiving form will act as temporary dashboard in
+  order to view and/or process the incoming forms, since you
+  dont have any receiving platform that are processing the
+  forms.
+
+### Alternative solution using eFormidling
+
+It might be that the solution you are looking for is a form,
+or multiple forms, that is set up to interact with _
+eFormidling_, which is another service offered by
+Digitaliseringsdiriktoratet. Read more about
+eFormidling [here](../../development/configuration/eformidling/_index.en.md)
+. A solution that is integrated with eFormidling can
+implement custom code on process-changes by using the
+predefined methods i app-backend. Read more about
+that [here](../../development/configuration/process/_index.en.md)
+. This custom code can build up a
+message, with some form-specific content, that can be sent
+to some public institution, instead of using
+instantiating a second application being the receiving form.
+Be aware that Altinn and eFormidling integration has some
+limitations in terms of supported message types, which as
+per now is limited to DPO and DPF.
+Which means that you will not need to follow this guide.
+
+{{<children description="true" />}}

content/app/guides/multi-app-solution/_index.nb.md

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+---
+title: Generell fremgangsmåte for å utvikle en multi-app løsning i Altinn
+linktitle: Multi-app løsning
+description: Vurderinger som burde gjøres og forklaringer på hvordan å gå frem når man utvikler en multi-app løsning
+weight: 250
+aliases:
+
+- /app/multi-app-solution/
+---
+
+Før du leser videre i denne guiden, vær så snill å gjør en vurdering om en multi-app løsning er det du trenger for å realisere skjemaet ditt.
+
+## Trenger jeg en multi-app løsning?
+...
+
+{{<children description="true" />}}

content/app/guides/multi-app-solution/considerations/_index.en.md

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+---
+title: Considerations you should do before developing a multi-app solution
+linktitle: Considerations involving multi-app solution
+description: Considerations that should have been made when creating a multi-app solution
+weight: 30
+aliases:
+
+- /app/multi-app-solution/considerations/
+
+---
+

content/app/guides/multi-app-solution/considerations/_index.nb.md

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+---
+title: Considerations you should do before developing a multi-app solution
+linktitle: Considerations involving multi-app solution
+description: Considerations that should have been made when creating a multi-app solution
+weight: 30
+aliases:
+- /app/multi-app-solution/considerations/
+---

content/app/guides/multi-app-solution/instructions/_index.en.md

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+---
+title: Instructions for making a multi-app solution in Altinn
+linktitle: Multi-app solution instructions
+description: Explanations of how to go about when creating a general multi-app solution
+weight: 20
+aliases:
+
+- /app/multi-app-solution/instructions/
+
+---
+
+{{<children description="true" />}}
+
+## General Modifications
+
+In general, there are a few things that one must remember to
+do in the process of developing these applications.
+
+1. Remember adding custom services to
+   the `RegisterCustomAppServices` method in `program.cs`
+2. If adding any values as prefill for the new instance of
+   the receiving application, remember to add them to the
+   data model of the receiving application

content/app/guides/multi-app-solution/instructions/_index.nb.md

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+---
+title: Instructions for making a multi-app solution in Altinn
+linktitle: Multi-app solution instructions
+description: Explanations of how to go about when creating a general multi-app solution
+weight: 20
+aliases:
+
+- /app/multi-app-solution/instructions/
+
+---
+
+{{<children description="true" />}}

content/app/guides/multi-app-solution/instructions/receiver-app/_index.en.md

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+---
+title: Receiver Application
+linktitle: Multi-app solution instructions
+description: Instructions for setting up the receiver application
+weight: 20
+aliases:
+
+- /app/multi-app-solution/instructions/receiver-app
+
+---
+
+## Getting Data From the Trigger Application
+
+The receiving application needs much less configuration as a
+bare minimum receiver application, at least. The main task
+for the receiver application is to fetch the data received
+from the trigger application(s) and represent them in a way.
+This is done by utilising the `ProcessDataRead` method in
+the `DataProcessor` service along with the `UpdateData`
+method on the `dataClient`. See example code below:
+
+```csharp
+public async Task<bool> ProcessDataRead(Instance instance, Guid? dataId, object data)
+{
+   bool edited = false;
+
+   if (data.GetType() == typeof(DataModel))
+   {
+       DataModel model = (DataModel)data;
+
+       DataElement attachments = instance.Data.FirstOrDefault(de => de.DataType == "vedlegg");
+
+       if (attachments != null)
+       {
+           _logger.LogInformation("// App 2 // Received data");
+
+           var instanceGuid = Guid.Parse(instance.Id.Split("/")[1]);
+
+           await _dataClient.UpdateData(model, instanceGuid, typeof(DataModel), instance.Org, instance.AppId, int.Parse(instance.InstanceOwner.PartyId), Guid.Parse(instance.Data.Where(de => de.DataType == "datamodel").First().Id));
+           edited = true;
+       }
+   }
+   return await Task.FromResult(edited);
+}
+```
+
+## Stopping a Running Instance
+
+Since this receiving application, in most cases, will act as
+an on-demand dashboard for collecting data from trigger
+apps, the application has no natural way of ending its
+process, since it is not sent in as any other normal form.
+To bypass this obstacle, the incoming forms should either;
+
+1. be manually deleted after being read, or
+2. they must be implemented with a demand of some sort of
+   user interaction
+   that will trigger the process to end. 

content/app/guides/multi-app-solution/instructions/receiver-app/_index.nb.md

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+---
+title: Mottaksapp
+linktitle: Multi-app solution instructions
+description: Instruksjoner for mottaksappen
+weight: 20
+aliases:
+
+- /app/multi-app-solution/instructions/receiver-app
+
+---