Getting a SAS URL by just creating a locator - how?

Question

I have code from a very helpful blogger that shows how to use JavaScript to upload to Azure. This means that he has created a webpage that will let any user who accesses it upload a file to a blog on his Azure storage. However, I want the user to upload
a video file to my "Azure media services" and not just to a regular "blob".  I'm actually not sure this is necessary, because I think videos can be viewed when just uploaded to standard blobs without even using media services. 
But I asked him how he would do it, and he said:
1. create an asset in media service
2. For that asset, create a locator with write permission
3. Use that locator to give you a SAS URL.
His JavaScript webpage asks the user to enter a SAS URL, but if I can use Visual Basic code in the code-behind page to generate a SAS URL, I don't have to ask the user to know it.  Also, it lets me use media services.
So I looked at the sample code that Microsoft provides for uploading to media services, and I have a few questions.  So here is a fragment of code and then the questions:
Public Function CreateAssetToGetSASurl(assetCreationOptions As AssetCreationOptions, singleFilePath As String) As IAsset
Dim theDate As DateTime
theDate = Now
Dim strDate As String
strDate = Replace(CType(theDate.ToOADate, Double).ToString, ".", "_")
Dim assetName = "UploadSingleFile_" & strDate & "_" & keepalphanum(Session("username"))
Dim asset = CreateEmptyAsset(assetName, assetCreationOptions)
Dim fileName = Path.GetFileName(singleFilePath)
Dim assetFile = asset.AssetFiles.Create(fileName)
Dim Duration As TimeSpan = lifetime
Dim accessPolicy = _context.AccessPolicies.Create(assetName, Duration, AccessPermissions.Write Or AccessPermissions.List)
Dim locator = _context.Locators.CreateLocator(LocatorType.Sas, asset, accessPolicy)
' locator.Delete()
' accessPolicy.Delete()
Return asset
End Function
I believe the locator created above is correct, but I think I should get rid of the lines that do this:
 Dim fileName = Path.GetFileName(singleFilePath)
        Dim assetFile = asset.AssetFiles.Create(fileName)
After all, I'm not uploading a file from my server, instead I'm relying on javascript code to upload a file.  So I would think I could get rid of these 2 lines, but I'm not sure my locator then points to anything. 
I also don't know how to get the SAS at this point.
Finally, there are two lines at the end of the function that delete the locator and the access policy, but I assume that if I do that, my SAS URL is no longer valid.  So my question is, when would I delete the locator -- after I was sure the file was
uploaded?  After it was encoded?
Thanks in advance,
Gideon

Answer 1

Hi,
I would suggest you have a look at this code sample. From the description we can see the introduction.
Details:
Introduction
The c# code in this project uses Windows Azure Storage SDK, Windows Azure Media Services Client SDK, and Media Services REST APIs to demonstrates the following:
•how to upload a stream to the storage blob associated with the Windows Azure Media Services account
•how to associate the file in the blob with the asset using the Media Services REST APIs.
•how to get a SAS URL pointing to the uploaded file. 
From my experience, this sample may give you some help.
#Sample Code:
http://code.msdn.microsoft.com/windowsazure/How-to-Upload-a-Stream-to-40ab9cc3
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