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How to have an AWS Lambda/Rekognition Function return an array of object keys

This feels like a simple question and I feel like I am overthinking it. I am doing an AWS project that will compare face(s) on an image to a database (s3bucket) of other faces. So far, I have a lambda function for the comparefacerequest, a class library which invokes the function, and an UWP that inputs the image file and outputs a result. It has worked so far being based on boolean (true or false) functions, but now I want it to instead return what face(s) are recognized via an array. I struggling at implementing this.
Below is my lambda function. I have adjusted the task to be an Array instead of a bool and changed the return to be an array. At the bottom, I have created a global variable class with a testing array so I could attempt to reference the array elsewhere.
public class Function
{
//Function
public async Task<Array> FunctionHandler(string input, ILambdaContext context)
{
//number of matched faces
int matched = 0;
//Client setup
var rekognitionclient = new AmazonRekognitionClient();
var s3client = new AmazonS3Client();
//Create list of target images
ListObjectsRequest list = new ListObjectsRequest
{
BucketName = "bucket2"
};
ListObjectsResponse listre = await s3client.ListObjectsAsync(list);
//loop of list
foreach (Amazon.S3.Model.S3Object obj in listre.S3Objects)
{
//face request with input and obj.key images
var comparefacesrequest = new CompareFacesRequest
{
SourceImage = new Image
{
S3Object = new S3Objects
{
Bucket = "bucket1",
Name = input
}
},
TargetImage = new Image
{
S3Object = new S3Objects
{
Bucket = "bucket2",
Name = obj.Key
}
},
};
//compare with confidence of 95 (subject to change) to current target image
var detectresponse = await rekognitionclient.CompareFacesAsync(comparefacesrequest);
detectresponse.FaceMatches.ForEach(match =>
{
ComparedFace face = match.Face;
if (match.Similarity > 95)
{
//if face detected, raise matched
matched++;
for(int i = 0; i < Globaltest.testingarray.Length; i++)
{
if (Globaltest.testingarray[i] == "test")
{
Globaltest.testingarray[i] = obj.Key;
}
}
}
});
}
//Return true or false depending on if it is matched
if (matched > 0)
{
return Globaltest.testingarray;
}
return Globaltest.testingarray;
}
}
public static class Globaltest
{
public static string[] testingarray = { "test", "test", "test" };
}
Next, is my invoke request in my class library. It has so far been based on the lambda outputting a boolean result, but I thought, "hey, it is parsing the result, it should be fine, right"? I do convert the result to a string, as there is no GetArray, from what I know.
public async Task<bool> IsFace(string filePath, string fileName)
{
await UploadS3(filePath, fileName);
AmazonLambdaClient client = new AmazonLambdaClient(accessKey, secretKey, Amazon.RegionEndpoint.USWest2);
InvokeRequest ir = new InvokeRequest();
ir.InvocationType = InvocationType.RequestResponse;
ir.FunctionName = "ImageTesting";
ir.Payload = "\"" + fileName + "\"";
var result = await client.InvokeAsync(ir);
var strResponse = Encoding.ASCII.GetString(result.Payload.ToArray());
if (bool.TryParse(strResponse, out bool result2))
{
return result2;
}
return false;
}
Finally, here is the section of my UWP where I perform the function. I am referencing the lambda client via "using Lambdaclienttest" (name of lamda project, and this is its only instance I use the reference though). When I run my project, I do still get a face detected when it should, but the Globaltest.testingarray[0] is still equal to "test".
var Facedetector = new FaceDetector(Credentials.accesskey, Credentials.secretkey);
try
{
var result = await Facedetector.IsFace(filepath, filename);
if (result)
{
textBox1.Text = "There is a face detected";
textBox2.Text = Globaltest.testingarray[0];
}
else
{
textBox1.Text = "Try Again";
}
}
catch
{
textBox1.Text = "Please use a photo";
}
Does anyone have any suggestions?

Invalid cast from IDirect3DSurface to SoftwareBitmap

I try to implement processing frames from webcam to the WPF application using UWP API.
There is article how to work with MediaCapture & MediaFrameReader:
https://learn.microsoft.com/en-us/windows/uwp/audio-video-camera/process-media-frames-with-mediaframereader#handle-the-frame-arrived-event
If I set up MemoryPreference to cpu, SoftwareBitmaps are initialized to the null in the event. When I place Auto, I can see IDirect3DSurface objects are in the event, but in conversion to the SoftwareBitmap the exception "Specified cast is not valid." is raised.
How to convert IDirect3DSurface to SoftwareBitmap?
private async void MediaCaptureExample()
{
var frameSourceGroups = await MediaFrameSourceGroup.FindAllAsync();
MediaFrameSourceGroup selectedGroup = null;
MediaFrameSourceInfo colorSourceInfo = null;
foreach (var sourceGroup in frameSourceGroups)
{
foreach (var sourceInfo in sourceGroup.SourceInfos)
{
if (sourceInfo.MediaStreamType == MediaStreamType.VideoRecord && sourceInfo.SourceKind == MediaFrameSourceKind.Color)
{
colorSourceInfo = sourceInfo;
break;
}
}
if (colorSourceInfo != null)
{
selectedGroup = sourceGroup;
break;
}
}
capture = new MediaCapture();
var settings = new MediaCaptureInitializationSettings()
{
SourceGroup = selectedGroup,
SharingMode = MediaCaptureSharingMode.ExclusiveControl,
MemoryPreference = MediaCaptureMemoryPreference.Auto,
StreamingCaptureMode = StreamingCaptureMode.Video
};
await capture.InitializeAsync(settings);
var colorFrameSource = capture.FrameSources[colorSourceInfo.Id];
var preferredFormat = colorFrameSource.SupportedFormats.Where(format =>
{
return format.VideoFormat.Width >= 1080
&& String.Compare(format.Subtype, MediaEncodingSubtypes.Mjpg, true) == 0;
}).FirstOrDefault();
if (preferredFormat == null)
{
// Our desired format is not supported
return;
}
await colorFrameSource.SetFormatAsync(preferredFormat);
mediaFrameReader = await capture.CreateFrameReaderAsync(colorFrameSource);
mediaFrameReader.FrameArrived += MediaFrameReader_FrameArrived;
var result = await mediaFrameReader.StartAsync();
Console.WriteLine("Result = " + result.ToString());
}
private void MediaFrameReader_FrameArrived(MediaFrameReader sender, MediaFrameArrivedEventArgs args)
{
try
{
var mediaFrameReference = sender.TryAcquireLatestFrame();
var videoMediaFrame = mediaFrameReference?.VideoMediaFrame;
var softwareBitmap = videoMediaFrame?.SoftwareBitmap;
var direct3DSurface = videoMediaFrame?.Direct3DSurface;
if (direct3DSurface != null)
{
var softwareBitmapTask = SoftwareBitmap.CreateCopyFromSurfaceAsync(mediaFrameReference.VideoMediaFrame.Direct3DSurface).AsTask();
softwareBitmap = softwareBitmapTask.Result;
}
if (softwareBitmap != null)
{
using (var stream = new Windows.Storage.Streams.InMemoryRandomAccessStream())
{
var encoderTask = BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId, stream).AsTask();
encoderTask.Wait();
var encoder = encoderTask.Result;
encoder.SetSoftwareBitmap(softwareBitmap);
Task t = encoder.FlushAsync().AsTask();
t.Wait();
var image = new System.Windows.Media.Imaging.BitmapImage();
image.BeginInit();
image.StreamSource = stream.AsStream();
image.CacheOption = System.Windows.Media.Imaging.BitmapCacheOption.OnLoad;
image.EndInit();
imageElement.Source = image;
}
}
}
catch(Exception e)
{
Console.WriteLine(e.Message);
}
}

The issue was in format subtype. I changed format from Mjpg to Nv12, and everything start working properly (even for MediaCaptureMemoryPreference.Auto):
var preferredFormat = colorFrameSource.SupportedFormats.Where(format =>
{
return format.VideoFormat.Width >= 1080 && String.Compare(format.Subtype, MediaEncodingSubtypes.Nv12, true) == 0;
}).FirstOrDefault();

Update progress bar from Task.Run async

I have a method to generate software activation key from User Information:
private async void GenerateAsync()
{
await Task.Run(() =>
{
var secretstring = "CustomerName >> " + txtFullname.Text + " >> " + txtproducid.Text;
keymng = new KeyManager(secretstring);
var dateexp = numExpdate.Value;
if (dateexp == 0)
{
dateexp = 730000;
}
if (cbLicenseType.SelectedIndex == 0)
{
kvc = new KeyValueClass()
{
LicenseType = LicenseType.FULL,
Header = Convert.ToByte(9),
Footer = Convert.ToByte(6),
ProductCode = PRODUCTCODE,
Edition = (Edition)Enum.Parse(typeof(Edition), cbEdition.SelectedText),
Version = 1,
Expiration = DateTime.Now.AddDays(Convert.ToInt32(dateexp))
};
if (!keymng.GenerateKey(kvc, ref productkey))
{
//Handling Error
}
}
else
{
kvc = new KeyValueClass()
{
LicenseType = LicenseType.TRIAL,
Header = Convert.ToByte(9),
Footer = Convert.ToByte(6),
ProductCode = PRODUCTCODE,
Edition = (Edition)Enum.Parse(typeof(Edition), cbEdition.SelectedText),
Version = 1,
Expiration = DateTime.Now.AddDays(Convert.ToInt32(dateexp))
};
if (!keymng.GenerateKey(kvc, ref productkey))
{
//Handling Error
}
}
});
}
and I have progressbar. I want to run this method async and update progress to progressbar. How to update UI with async-await method. BackgroundWorker is alternative???

You should use the more modern IProgress<T>/Progress<T> types:
var progress = new Progress<int>(value => { progressBar.Value = value; });
await Task.Run(() => GenerateAsync(progress));
void GenerateAsync(IProgress<int> progress)
{
...
progress?.Report(13);
...
}
This is better than Invoke because it doesn't tie your business logic (GenerateAsync) to a particular UI, or to any UI at all.

I use this method in Winforms:
progressBar1.Invoke((Action)(() => progressBar1.Value=50))

SqlWorkflowInstanceStore WaitForEvents returns HasRunnableWorkflowEvent but LoadRunnableInstance fails

Dears
Please help me with restoring delayed (and persisted) workflows.
I'm trying to check on self-hosted workflow store is there any instance that was delayed and can be resumed. For testing purposes I've created dummy activity that is delayed and it persists on delay.
generally resume process looks like:
get WF definition
configure sql instance store
call WaitForEvents
is there event with HasRunnableWorkflowEvent.Value name and if it is
create WorkflowApplication object and execute LoadRunnableInstance method
it works fine if store is created|initialized, WaitForEvents is called, store is closed. In such case store reads all available workflows from persisted DB and throws timeout exception if there is no workflows available to resume.
The problem happens if store is created and loop is started only for WaitForEvents (the same thing happens with BeginWaitForEvents). In such case it reads all available workflows from DB (with proper IDs) but then instead of timeout exception it is going to read one more instance (I know exactly how many workflows is there ready to be resumed because using separate test database). But fails to read and throws InstanceNotReadyException. In catch I'm checking workflowApplication.Id, but it was not saved with my test before.
I've tried to run on new (empty) persistent database and result is the same :(
This code fails:
using (var storeWrapper = new StoreWrapper(wf, connStr))
for (int q = 0; q < 5; q++)
{
var id = Resume(storeWrapper); // InstanceNotReadyException here when all activities is resumed
But this one works as expected:
for (int q = 0; q < 5; q++)
using (var storeWrapper = new StoreWrapper(wf, connStr))
{
var id = Resume(storeWrapper); // timeout exception here or beginWaitForEvents continues to wait
What is a best solution in such case? Add empty catch for InstanceNotReadyException and ignore it?
Here are my tests
const int delayTime = 15;
string connStr = "Server=db;Database=AppFabricDb_Test;Integrated Security=True;";
[TestMethod]
public void PersistOneOnIdleAndResume()
{
var wf = GetDelayActivity();
using (var storeWrapper = new StoreWrapper(wf, connStr))
{
var id = CreateAndRun(storeWrapper);
Trace.WriteLine(string.Format("done {0}", id));
}
using (var storeWrapper = new StoreWrapper(wf, connStr))
for (int q = 0; q < 5; q++)
{
var id = Resume(storeWrapper);
Trace.WriteLine(string.Format("resumed {0}", id));
}
}
Activity GetDelayActivity(string addName = "")
{
var name = new Variable<string>(string.Format("incr{0}", addName));
Activity wf = new Sequence
{
DisplayName = "testDelayActivity",
Variables = { name, new Variable<string>("CustomDataContext") },
Activities =
{
new WriteLine
{
Text = string.Format("before delay {0}", delayTime)
},
new Delay
{
Duration = new InArgument<TimeSpan>(new TimeSpan(0, 0, delayTime))
},
new WriteLine
{
Text = "after delay"
}
}
};
return wf;
}
Guid CreateAndRun(StoreWrapper sw)
{
var idleEvent = new AutoResetEvent(false);
var wfApp = sw.GetApplication();
wfApp.Idle = e => idleEvent.Set();
wfApp.Aborted = e => idleEvent.Set();
wfApp.Completed = e => idleEvent.Set();
wfApp.Run();
idleEvent.WaitOne(40 * 1000);
var res = wfApp.Id;
wfApp.Unload();
return res;
}
Guid Resume(StoreWrapper sw)
{
var res = Guid.Empty;
var events = sw.GetStore().WaitForEvents(sw.Handle, new TimeSpan(0, 0, delayTime));
if (events.Any(e => e.Equals(HasRunnableWorkflowEvent.Value)))
{
var idleEvent = new AutoResetEvent(false);
var obj = sw.GetApplication();
try
{
obj.LoadRunnableInstance(); //instancenotready here if the same store has read all instances from DB and no delayed left
obj.Idle = e => idleEvent.Set();
obj.Completed = e => idleEvent.Set();
obj.Run();
idleEvent.WaitOne(40 * 1000);
res = obj.Id;
obj.Unload();
}
catch (InstanceNotReadyException)
{
Trace.TraceError("failed to resume {0} {1} {2}", obj.Id
, obj.DefinitionIdentity == null ? null : obj.DefinitionIdentity.Name
, obj.DefinitionIdentity == null ? null : obj.DefinitionIdentity.Version);
foreach (var e in events)
{
Trace.TraceWarning("event {0}", e.Name);
}
throw;
}
}
return res;
}
Here is store wrapper definition I'm using for test:
public class StoreWrapper : IDisposable
{
Activity WfDefinition { get; set; }
public static readonly XName WorkflowHostTypePropertyName = XNamespace.Get("urn:schemas-microsoft-com:System.Activities/4.0/properties").GetName("WorkflowHostType");
public StoreWrapper(Activity wfDefinition, string connectionStr)
{
_store = new SqlWorkflowInstanceStore(connectionStr);
HostTypeName = XName.Get(wfDefinition.DisplayName, "ttt.workflow");
WfDefinition = wfDefinition;
}
SqlWorkflowInstanceStore _store;
public SqlWorkflowInstanceStore GetStore()
{
if (Handle == null)
{
InitStore(_store, WfDefinition);
Handle = _store.CreateInstanceHandle();
var view = _store.Execute(Handle, new CreateWorkflowOwnerCommand
{
InstanceOwnerMetadata = { { WorkflowHostTypePropertyName, new InstanceValue(HostTypeName) } }
}, TimeSpan.FromSeconds(30));
_store.DefaultInstanceOwner = view.InstanceOwner;
//Trace.WriteLine(string.Format("{0} owns {1}", view.InstanceOwner.InstanceOwnerId, HostTypeName));
}
return _store;
}
protected virtual void InitStore(SqlWorkflowInstanceStore store, Activity wfDefinition)
{
}
public InstanceHandle Handle { get; protected set; }
XName HostTypeName { get; set; }
public void Dispose()
{
if (Handle != null)
{
var deleteOwner = new DeleteWorkflowOwnerCommand();
//Trace.WriteLine(string.Format("{0} frees {1}", Store.DefaultInstanceOwner.InstanceOwnerId, HostTypeName));
_store.Execute(Handle, deleteOwner, TimeSpan.FromSeconds(30));
Handle.Free();
Handle = null;
_store = null;
}
}
public WorkflowApplication GetApplication()
{
var wfApp = new WorkflowApplication(WfDefinition);
wfApp.InstanceStore = GetStore();
wfApp.PersistableIdle = e => PersistableIdleAction.Persist;
Dictionary<XName, object> wfScope = new Dictionary<XName, object> { { WorkflowHostTypePropertyName, HostTypeName } };
wfApp.AddInitialInstanceValues(wfScope);
return wfApp;
}
}

I'm not workflow foundation expert so my answer is based on the official examples from Microsoft. The first one is WF4 host resumes delayed workflow (CSWF4LongRunningHost) and the second is Microsoft.Samples.AbsoluteDelay. In both samples you will find a code similar to yours i.e.:
try
{
wfApp.LoadRunnableInstance();
...
}
catch (InstanceNotReadyException)
{
//Some logging
}
Taking this into account the answer is that you are right and the empty catch for InstanceNotReadyException is a good solution.

Operation is not valid due to the current state of the object

i am beginning in develop winphone and nokia imaging sdk. i have two function.
firstly, i call the function below to change image to gray color
private async void PickImageCallback(object sender, PhotoResult e)
{
if (e.TaskResult != TaskResult.OK || e.ChosenPhoto == null)
{
return;
}
using (var source = new StreamImageSource(e.ChosenPhoto))
{
using (var filters = new FilterEffect(source))
{
var sampleFilter = new GrayscaleFilter();
filters.Filters = new IFilter[] { sampleFilter };
var target = new WriteableBitmap((int)CartoonImage.ActualWidth, (int)CartoonImage.ActualHeight);
var renderer = new WriteableBitmapRenderer(filters, target);
{
await renderer.RenderAsync();
_thumbnailImageBitmap = target;
CartoonImage.Source = target;
}
}
}
SaveButton.IsEnabled = true;
}
then i call function to change image to binary color
private async void Binary(WriteableBitmap bm_image)
{
var target = new WriteableBitmap((int)CartoonImage.ActualWidth, (int)CartoonImage.ActualHeight);
MemoryStream stream= new MemoryStream();
bm_image.SaveJpeg(stream, bm_image.PixelWidth, bm_image.PixelHeight, 0, 100);
using (var source = new StreamImageSource(stream))
{
using (var filters = new FilterEffect(source))
{
var sampleFilter = new StampFilter(5, 0.7);
filters.Filters = new IFilter[] { sampleFilter };
var renderer1 =new WriteableBitmapRenderer(filters, target);
{
await renderer1.RenderAsync();
CartoonImage.Source = target;
}
}
}
}
but when it run to " await renderer1.RenderAsync();" in the second function, it doesn't work. How can i solve it. And you can explain for me about how "await" and "async" work ?
thank you very much!

I'm mostly guessing here since I do not know what error you get, but I'm pretty sure your problem lies in setting up the source. Have you made sure the memory stream position is set to the beginning (0) before creating an StreamImageSource?
Try adding:
stream.Position = 0;
before creating the StreamImageSource.
Instead of trying to create a memory stream from the writeable bitmap I suggest doing:
using Nokia.InteropServices.WindowsRuntime;
...
using (var source = new BitmapImageSource(bm_image.AsBitmap())
{
...
}