Azure Mobile Storage

Azure Storage in the Mobile World@glenntstephens

Welcome everyoneWhat will we cover?

In case we’ve not met...

I train developers To be Xamarin certified mobile

developers for Xamarin University

I develop appsABBA – Always Be Building

Apps

I play musicIn case you want to discuss

anything else. Politics, Comedy and Jackie Chan movies are good too

The need for Storage

Server Rule #1

From little things...

ASP.NET Server

File Storage

Databases

The two ways we’ll look atBlob Storage is what we’ll be looking for

1. Calling using WebApi2. Calling directly from a mobile app

Looking at the APIBlobContainer storage

Azure Storage API Housekeeping• Before we access it via the API:• Ensure the Azure Account is setup• Ensure we have a container setup

• Like many Azure services, the Portal has great documentation• Have a look at the services you can connect to

Common Scenarios• Here is our mobile app day-to-day:• Upload a file to the server• Download the file from the server (if authorisation is

required)• Get the public URL for a file (if its public)• Delete a file• List the files in the container

Encapsulate all the things• You will need to connect

in. • I find its easy to make a

façade to manage storage for Access• CloudHop

Common Scenario: Connecting• We need to connect to the container public class AzureStorageHelper { string settingName; string containerName; bool isPublic;

CloudBlobContainer container = null;

public AzureStorageHelper(string settingName, string containerName, bool isPublic = true) { this.settingName = settingName; this.containerName = containerName; this.isPublic = isPublic; }

Getting the Blob container (1/2)• Its access to the blob container that lets you perform

all the operations you need:

public CloudBlobContainer GetBlobContainer(){ if (container != null) return container;

var connStr = GetConnectionString(); var storageAccount = CloudStorageAccount.Parse(connStr); var blobClient = storageAccount.CreateCloudBlobClient(); var blobContainer = blobClient.GetContainerReference(this.containerName);

Getting the Blob container (2/2)• Its access to the blob container that lets you perform

all the operations you need: if (blobContainer.CreateIfNotExists()) { blobContainer.SetPermissions(new BlobContainerPermissions() { PublicAccess = isPublic ? BlobContainerPublicAccessType.Blob : BlobContainerPublicAccessType.Off }); }

container = blobContainer; return blobContainer;}

Common Scenario: Uploading• Uploading a single file to the container

public string UploadBlob(string filename, Stream stream){ if (stream.Length == 0) throw new ApplicationException("There was no content for the file");

var reference = GetBlobContainer() .GetBlockBlobReference(filename);

reference.UploadFromStream(stream);

return reference.Uri.AbsoluteUri;}

Note: The non-async mechanisms are used for this demo for simplicity. Use the async version for real power. Learn async if you haven’t used it before

Common Scenario: Downloading• Two options here• For public collections, provide the Url• For private collections use the API

Downloading to a stream• For when you want to manage the resources a little

more elegantlypublic void DownloadToStream(string name, Stream stream){ Uri ur = new Uri(name); string fname = Path.GetFileName(ur.LocalPath);

var foundFile = GetBlobContainer().GetBlockBlobReference(fname); foundFile.DownloadToStream(stream);}

Common Scenario: The public Url• Gather the Url from the source• Use HttpClient or other mechanisms to download the

resource

public string UriForFile(string filePath){ return container.ServiceClient.BaseUri.AbsoluteUri + containerName + "/"+ filePath;}

Common Scenario: Listing the files• Need to find what is there• I tend to use Guids as a way of keeping the files

uniquepublic List<string> ListAllBlobs(){ return GetBlobContainer() .ListBlobs() .Select(item => item.Uri.ToString()) .ToList();}

Common Scenario: Deleting a file• When you need to make sure the file is no longer there

public void DeleteBlob(string name){ Uri ur = new Uri(name); string fname = Path.GetFileName(ur.LocalPath);

var foundFile = GetBlobContainer().GetBlockBlobReference(fname);

if (foundFile != null) foundFile.Delete();}

Exposing it via Web Api[HttpPost][Route("api/ImageService/UploadNewImage")]public async Task<IHttpActionResult> DirectImageUpload(){if (!Request.Content.IsMimeMultipartContent()) throw new HttpResponseException(Request.CreateResponse(HttpStatusCode.NotAcceptable, "This request is not properly formatted"));

var provider = new MultipartMemoryStreamProvider(); await Request.Content.ReadAsMultipartAsync(provider);

var file = provider.Contents.First(); var filename = file.Headers.ContentDisposition.FileName.Trim('\"'); var stream = await file.ReadAsStreamAsync(); GetAzureStorageConnection().UploadBlob(filename, stream);

return Ok();}

Connecting from a mobile app• Easiest way is to use HttpClient to connect to the URL

to access the file contained in the Blob• If it is an image, you could use other mechanisms such

as Xamarin.Forms Image and ImageSource classes

DemonstrationLets run some code

Azure Mobile ServicesBlobContainer direct from the device

The Mobile App• Moments - Like a Snapchat application.• Credit goes to Pierce Boggan from the Xamarin team

for building the application.

What is Moments?• A snapchat clone built on

Xamarin.Forms• https://github.com/pierceboggan/Moments

• Connects to Azure for several services• Azure Mobile Services• Azure Storage

• Currently on the Android Play Store• Will be on the iOS Store at

some point Follow @pierceboggan on Twitter for updates on the app news

Moments DemoLets run it and see...

The Project Setup• Xamarin.Forms project• Services for the app indicate data access or implemented

capabilities such as Camera access• FriendService, AccountService for AMS Data Access• MobileServiceClientFactory for mobile access• MomentService for uploading an image and storing the moment on

the service• Custom renderers for iOS and Android for Camera Access• Shared Project setup

• Better approach for Azure and Xamarin.Forms• This configuration is not ideal for XAML though

A look at the code• Core Access:• Using Identity Service to identify users• Using AMS to store data

• Services:• Moment Service

• SendMoment• DestroyMoment• GetMoments

Code AnalysisLets see some code

Review• Most mobile apps need some level of server capability.• Especially connected apps

• Storage is an essential service that needs to be managed• Azure Storage gives you that capability to easily run it

regardless of the way you need to execute it• Using it in any configuration can be easily done using

Azure• Mobile Apps• WebApi or Web Apps

Resources• http://azure.microsoft.com/en-us/documentation/services/storage/• http://azure.microsoft.com/en-us/documentation/videos/azure-storage-5-minute-over

view/

• http://manage.windowsazure.com• http://developer.xamarin.com/guides/cross-platform/azure/• https://github.com/pierceboggan/Moments

ThanksKeep in touch via twitter @glenntstephens or email: glenn.stephens@Xamarin.com