I would like to develop a simple ToDo app using Xamarin. It should allow the user to sign in with an account and access their notes on multiple platforms.

Microsoft offer a number of sample applications using different APIs (https://developer.xamarin.com/samples/android/Web%20Services), but to a beginner, it seems unclear what the advantages and disadvantages are of the different methods. I'd be grateful if you could outline these for me for the differing technologies (e.g. CosmosDB, REST, ASMX, DocumentDB, Azure Mobile App, and OAuth).

  • Take a look. If you still have any query feel free to share. Thanks and happy coding! – Md Farid Uddin Kiron Jun 7 at 10:15


Azure Cosmos DB is Microsoft's globally distributed, multi-model database service. With a click of a button, Cosmos DB enables you to elastically and independently scale throughput and storage across any number of Azure regions worldwide. For details You Could Check here


Representational State Transfer in short (REST), REST requires that a client make a request to the server in order to retrieve or modify data on the server. A request generally consists of:

  • an HTTP verb, which defines what kind of operation to perform
  • a header, which allows the client to pass along information about the request
  • a path to a resource
  • an optional message body containing data

There are many good article you could found online. you can check here


.asmx is Active server methods. Webservices have this extension in dotnet. ASMX provides the ability to build web services that send messages using the Simple Object Access Protocol (SOAP). SOAP is a platform-independent and language-independent protocol for building and accessing web services. You can find more details here


CosmosDb is the evolved version of documentDb. It is also important to point out that DocumentDB’s SQL dialect has always been just one of the many APIs that the underlying Cosmos DB was capable of supporting.

Azure Mobile App:

Azure App Service is a fully managed platform as a service (PaaS) offering for professional developers. The service brings a rich set of capabilities to web, mobile, and integration scenarios. You can start good tutorial here


OAuth is an open-standard authorization protocol or framework that describes how unrelated servers and services can safely allow authenticated access to their assets without actually sharing the initial, related, single logon credential. In authentication parlance, this is known as secure, third-party, user-agent, delegated authorization. You could check here

If you still have any query feel free to share. Thanks and happy coding!

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