The library i'm using is called Plugin.BLE. It doesn't have good documentation, and I'm just guessing.
First I scan for connected devices, then I connect to the bluetooth printer which is called "MTP-2" then I get it's service. From that service I get the characteristics, and I write data into it, but it doesn't actually do anything.
private async void Print(object sender, EventArgs e)
{
var adapter = CrossBluetoothLE.Current.Adapter;
var devices = adapter.GetSystemConnectedOrPairedDevices();
foreach (var device in devices)
{
var name = device.Name;
if (name == "MTP-2")
{
var cts = new CancellationToken();
var guid = device.Id;
await adapter.ConnectToDeviceAsync(device, new ConnectParameters(true, true), cts);
var services = await device.GetServicesAsync();
foreach (var _service in services)
{
var characteristics = await _service.GetCharacteristicsAsync();
foreach (var characteristic in characteristics)
{
var read = characteristic.CanRead;
var write = characteristic.CanWrite;
var update = characteristic.CanUpdate;
if (read && write && update)
{
await characteristic.StartUpdatesAsync();
var content = "Hi there.";
var data = System.Text.Encoding.ASCII.GetBytes(content);
await characteristic.WriteAsync(data);
await characteristic.StopUpdatesAsync();
return;
}
}
}
}
}
}
I think you have such options:
send a special character to initiate printing. I think the printer should have some documentation for this.
call a special method from the api.
Related
A bit of background, I am looking to replace existing code in a C# App from the existing Microsoft.Azure.Management.Fluent (now deprecated) to the newer Azure.ResourceManager components.
Existing code to copy a database:
public async Task<bool> CopyDb(string? server, string? fromName, string? toName)
{
_log.LogInformation("Connecting to Azure");
var azure = GetAzureObject();
var servers = await azure.SqlServers.ListAsync();
var fromServer = servers.FirstOrDefault(f => server != null && server.Contains(f.Name));
if (fromServer == null)
{
throw new InvalidOperationException("Unable to find original database server");
}
var toNameBackup = $"{toName}-Old";
var existingDbs = await fromServer.Databases.ListAsync();
var fromDB = existingDbs.FirstOrDefault(f => f.Name.Equals(fromName));
if (fromDB == null)
{
throw new InvalidOperationException("Unable to find original database");
}
if (existingDbs.Any(a => a.Name.Equals(toNameBackup, StringComparison.OrdinalIgnoreCase))
&& existingDbs.Any(a => a.Name.Equals(toName, StringComparison.OrdinalIgnoreCase)))
{
_log.LogInformation("Deleting any existing backup called {0}", toNameBackup);
await fromServer.Databases.DeleteAsync(toNameBackup);
}
if (existingDbs.Any(a => a.Name.Equals(toName, StringComparison.OrdinalIgnoreCase)))
{
_log.LogInformation("Renaming target database from {0} to {1} (if exists)", toName, toNameBackup);
await (await fromServer.Databases.GetAsync(toName)).RenameAsync(toNameBackup);
}
_log.LogInformation("Copying database from from {0} to {1}", fromName, toName);
var result = await fromServer.Databases.
Define(toName).
WithSourceDatabase(fromDB).
WithMode(Microsoft.Azure.Management.Sql.Fluent.Models.CreateMode.Copy).CreateAsync();
return result != null;
}
private Microsoft.Azure.Management.Fluent.IAzure GetAzureObject()
{
var clientId = _configuration["AzureClientId"];
var clientSecret = _configuration["AzureClientSecret"];
var tenantId = _configuration["AzureTenantId"];
var subscriptionId = _configuration["AzureSubscriptionId"];
var credentials = Microsoft.Azure.Management.ResourceManager.Fluent.SdkContext.AzureCredentialsFactory.FromServicePrincipal(
clientId: clientId,
clientSecret: clientSecret,
tenantId: tenantId,
environment: Microsoft.Azure.Management.ResourceManager.Fluent.AzureEnvironment.AzureGlobalCloud);
return Microsoft.Azure.Management.Fluent.Azure.Configure().Authenticate(credentials).WithSubscription(subscriptionId);
}
The newer components all work with resources and I've been struggling how to do a couple operations with the newer Azure.ArmClient. I've been able to query with it finding my SQL server and databases. I can even delete some DBs, but I'm unable to work out how to rename or copy databases like the above code. I know there are alternative ways to do this directly in SQL, but I'd prefer to see how to do it in code.
I have had a look around MS docs, I can only find information on the object definitions but no examples.
I have managed to get down to the point of renaming:-
var backupDb = fromServer.GetSqlDatabase(toName);
if (backupDb != null && backupDb.Value != null)
{
// What do I pass in to the definition?
var moveDefinition = new SqlResourceMoveDefinition()
{
// What to set here?
};
await (await backupDb.Value.GetAsync()).Value.RenameAsync(moveDefinition);
}
I'm not sure on how to define the SqlResourceMoveDefinition. I also can't work out at all how to perform the copy like in the older SDK.
Anyone have any guides on how to achieve these operations in C#?
Managed to work it out after eventually working from https://learn.microsoft.com/en-us/dotnet/azure/sdk/resource-management?tabs=PowerShell. There may be better ways to do this, and I'll edit the answer when I find them if others don't by then!
public async Task<bool> CopyDb(string? server, string? fromName, string? toName)
{
_log.LogInformation("Connecting to Azure");
var azure = GetAzureSubscription();
var servers = azure.GetSqlServers().ToList();
var fromServer = servers.SingleOrDefault(f => server != null && f.Data != null && server.Contains(f.Data.Name));
if (fromServer == null)
{
throw new InvalidOperationException("Unable to find original database server");
}
var oldName = $"{toName}-Old";
var databases = fromServer.GetSqlDatabases();
_log.LogInformation("Check for any existing backup called {0}", oldName);
if (await databases.ExistsAsync(oldName))
{
_log.LogInformation("Deleting for any existing backup called {0}", oldName);
var oldBackup = await databases.GetAsync(oldName);
await oldBackup.Value.DeleteAsync(WaitUntil.Completed);
}
_log.LogInformation("Check target database {0} exists", toName, oldName);
if (await databases.ExistsAsync(toName))
{
_log.LogInformation("Renaming target database from {0} to {1}", toName, oldName);
var toDbBackup = await databases.GetAsync(toName);
var resourceIdString = toDbBackup.Value.Data.Id.Parent?.ToString();
var newResourceId = new ResourceIdentifier($"{resourceIdString}/databases/{oldName}");
var moveDefinition = new SqlResourceMoveDefinition(newResourceId);
var toDb = await toDbBackup.Value.GetAsync();
await toDb.Value.RenameAsync(moveDefinition);
}
_log.LogInformation("Copying database from from {0} to {1}", fromName, toName);
var fromDb = await databases.GetAsync(fromName);
var result = await databases.CreateOrUpdateAsync(WaitUntil.Completed, toName, fromDb.Value.Data);
_log.LogInformation("Operation completed!");
return result.HasValue;
}
private SubscriptionResource GetAzureSubscription()
{
var configValue = _configuration["AzureSubscriptionId"];
var subscriptionId = new ResourceIdentifier($"/subscriptions/{configValue}");
return GetAzureArmClient().GetSubscriptionResource(subscriptionId);
}
private ArmClient GetAzureArmClient()
{
var clientId = _configuration["AzureClientId"];
var clientSecret = _configuration["AzureClientSecret"];
var tenantId = _configuration["AzureTenantId"];
var credentials = new ClientSecretCredential(
clientId: clientId,
clientSecret: clientSecret,
tenantId: tenantId);
return new ArmClient(credentials);
}
I have written an api to get all external storage drives connected to my computer. But i am not able to detect hard disk drives.
private async Task GetAllDrivesConnected()
{
await Task.Run(() =>
{
var drives = DriveInfo.GetDrives();
lock (this.myUsbDriveListLock)
{
foreach (var aDrive in drives .Where(theDrive => theDrive.DriveType == DriveType.Removable && theDrive.IsReady))
{
DriveLetter_Array.Add(aDrive.Name);
}
}
string LatestPath = DriveLetter_Array.LastOrDefault();
this.SetCurrentUsbPath(LatestPath);
var DeviceMessageEventArgs = new DeviceMessageEventArgs { Drive = LatestPath, UsbAdded = true };
FireEventAddPathRemovePath(DeviceMessageEventArgs);
});
}
I am making use of WML queries to listen to device inserted event:
private async Task DeviceNotification()
{
await Task.Run(() =>
{
var InsertQuery = new WqlEventQuery("SELECT * FROM Win32_VolumeChangeEvent WHERE EventType = 2");
myInsertionWatcher = new ManagementEventWatcher(InsertQuery);
myInsertionWatcher.EventArrived += this.DeviceInsertedEvent;
myInsertionWatcher.Start();
var RemoveQuery = new WqlEventQuery("SELECT * FROM Win32_VolumeChangeEvent WHERE EventType = 3");
myRemovalWatcher = new ManagementEventWatcher(RemoveQuery);
myRemovalWatcher.EventArrived += this.DeviceRemovedEvent;
myRemovalWatcher.Start();
});
}
Please try adding the wait for next event method after start
myInsertionWatcher.WaitForNextEvent();
It's not clear from your comment if you actually checked for other DriveTypes. If I run the following after having connected an external hard drive I get the output from the image:
DriveInfo.GetDrives().Where(d => d.IsReady)
As you can see it has DriveType Fixed, even if it's connected through a USB port.
You may want to change your foreach loop:
foreach (var aDrive in drives .Where(theDrive => theDrive.IsReady))
{
DriveLetter_Array.Add(aDrive.Name);
}
If you want to only see external hard drives, you may want to take a look at this answer
I get crashes when I work with my app with a slow internet when I keep pressing different buttons that gathers data via httprequests. how could i make a function so that if i do not recieve the data within for example 10 seconds, the attempt to gather the data from the httprequest should be cancelled.
This is my code:
static public async Task<JObject> getCategories ()
{
var httpClientRequest = new HttpClient ();
try {
var result = await httpClientRequest.GetAsync ("http://localhost");
var resultString = await result.Content.ReadAsStringAsync ();
var jsonResult = JObject.Parse (resultString);
System.Diagnostics.Debug.WriteLine (resultString);
return jsonResult;
}
catch {
return null;
}
}
async void createCategory (object sender, EventArgs args)
{
var getCategory = await parseAPI.getCategories ();
if (getCategory != null) {
foreach (var currentItem in getItems["results"]) {
id = currentItem ["ID"].ToString ();
objectid = currentItem ["objectid"].ToString ();
//connected
}
}
} else {
//no connection
}
}
You can use CancellationTokenSource which has a method provided in it which is CancelAfter():
var token = new CancellationTokenSource();
token.CancelAfter(10000); // after 10 secs
var result = await httpClientRequest.GetAsync ("http://localhost",token.Token);
var resultString = await result.Content.ReadAsStringAsync ();
Here is a article about using Cancellation with GetAsync which you may be interested to read.
You could also use the timeout on the httpclient.
var httpClientRequest = new HttpClient();
httpClientRequest.Timeout = TimeSpan.FromSeconds(10);
var result = await httpClientRequest.GetAsync("http://localhost");
I have a unique issue, I want to get the name of an application from it's AppID while I convert an XML file into objects. This is the code I'm using at present:
if (xdoc.Element("Application") != null)
{
var data = from query in xdoc.Descendants("AppID")
select new APP
{
AppID = query.Value,
AppName = GetName(query.Value).ToString(),
};
itemGridView.DataContext = data;
}
This is the code I'm using to convert the GUID into an app name using Microsoft's Store API. I can confirm that it does return the app name. I'm just unsure how I can get this to display.
private async Task<string> GetName(string guid)
{
try
{
string link = "https://services.apps.microsoft.com/browse/6.2.9200-1/615/en-NZ_en-NZ/c/NZ/cp/10005001/Apps/{0}";
string url = string.Format(link, guid);
var httpClient = new HttpClient();
var httpRequestMessage = new HttpRequestMessage(HttpMethod.Get, url);
var response = await httpClient.SendAsync(httpRequestMessage);
var xmlString = await response.Content.ReadAsStringAsync();
XmlDocument NameXML = new XmlDocument();
NameXML = await XmlDocument.LoadFromUriAsync(new Uri(url));
string sAppName = NameXML.GetElementsByTagName("T")[0].ChildNodes[0].NodeValue.ToString();
return sAppName;
}
catch(Exception)
{
return guid;
}
}
I think my problem is with the async / await tasks. I've just been exposed to it now... how would I load up the App Name alongside the AppID when I parse the xml file?
The output that's being displayed when I run the app is "System.Threading.Tasks.Task[System.String]" (The objects load and the links and everything works fine, its just that the above is displayed instead of the app name).
I've been debugging using breakpoints, it appears that the GetName method only seems to be triggered later on, I'm not sure however.
Try to change this line :
AppName = GetName(query.Value).ToString(),
To this :
AppName = await GetName(query.Value),
GetName will return Task<string> instead of string when not awaited. And the method where above code resides required to be async because of using await inside that method :
private async void SomeMethod()
{
....
if (xdoc.Element("Application") != null)
{
var data = from query in xdoc.Descendants("AppID")
select new APP
{
AppID = query.Value,
AppName = await GetName(query.Value),
};
itemGridView.DataContext = data;
}
....
}
UPDATE :
As you already noticed, LINQ has very limited support for async/await currently. So to workaround this limitation, we can use normal for loop to avoid calling async function inside LINQ :
private async void SomeMethod()
{
....
if (xdoc.Element("Application") != null)
{
var query = from query in xdoc.Descendants("AppID")
select query.Value;
var data = new List<App>();
foreach (var q in query)
{
data.Add(new App{ AppId = q, AppName = await GetName(q) });
}
itemGridView.DataContext = data;
}
....
}
I am trying to implement a basic SSDP (UDP) broadcast/listener for a Windows Store application using C#.
I have found that Windows.Networking.Sockets contains the DatagramSocket class which is what I need to use for UDP networking.
However, my current attempts seem to execute just fine but have no results via Wireshark and do not get a response back from the devices on the network.
Here is the code I am currently using (and running through the RT Simulator):
public async static Task<IEnumerable<HueBridge>> DiscoverAsync(TimeSpan timeout)
{
if (timeout <= TimeSpan.Zero)
throw new ArgumentException("Timeout value must be greater than zero.", "timeout");
var discoveredBridges = new List<HueBridge>();
using (var socket = new DatagramSocket())
{
while (true)
{
var bridgeWasFound = false;
socket.MessageReceived += (sender, e) =>
{
var bpx = true; // breakpoint here for success
};
var multicastIP = new HostName("239.255.255.250");
await socket.BindServiceNameAsync("1900");
socket.JoinMulticastGroup(multicastIP);
using (var writer = new DataWriter(socket.OutputStream))
{
var request = new StringBuilder();
request.AppendLine("M-SEARCH * HTTP/1.1");
request.AppendLine("HOST: 239.255.255.250:1900");
request.AppendLine("MAN: ssdp:discover");
request.AppendLine("MX: 5");
request.AppendLine("ST: ssdp:all");
writer.WriteString(request.ToString());
await writer.FlushAsync();
}
if (timeout > TimeSpan.Zero)
await Task.Delay(timeout);
if (!bridgeWasFound)
break; // breakpoint here for failure check
}
}
return discoveredBridges;
}
Any ideas on what I may be doing incorrectly? I don't get an exception and I have the proper Capabilities set in the manifest. My breakpoint at the break always gets hit and I am using a timeout of 10 seconds.
Seems I have found the problem(s).
First, I should use socket.BindEndpointAsync(null, string.Empty) instead of socket.BindServiceNameAsync("1900"), which will properly listen for broadcast packets.
Secondly, writer.FlushAsync() does not write to the socket; however, writer.StoreAsync() does.
Here is the final result, which does work (almost) perfectly:
public async static Task<IEnumerable<HueBridge>> DiscoverAsync(TimeSpan timeout)
{
if (timeout <= TimeSpan.Zero)
throw new ArgumentException("Timeout value must be greater than zero.", "timeout");
var discoveredBridges = new List<HueBridge>();
var multicastIP = new HostName("239.255.255.250");
var bridgeWasFound = false;
using (var socket = new DatagramSocket())
{
socket.MessageReceived += (sender, e) =>
{
var reader = e.GetDataReader();
var bytesRemaining = reader.UnconsumedBufferLength;
var receivedString = reader.ReadString(bytesRemaining);
// TODO: Check for existing bridges, only add new ones to prevent infinite loop.
// TODO: Create new bridge and add to the list.
bridgeWasFound = true;
};
await socket.BindEndpointAsync(null, string.Empty);
socket.JoinMulticastGroup(multicastIP);
while (true)
{
bridgeWasFound = false;
using (var stream = await socket.GetOutputStreamAsync(multicastIP, "1900"))
using (var writer = new DataWriter(stream))
{
var request = new StringBuilder();
request.AppendLine("M-SEARCH * HTTP/1.1");
request.AppendLine("HOST: 239.255.255.250:1900");
request.AppendLine("MAN: ssdp:discover");
request.AppendLine("MX: 3");
request.AppendLine("ST: ssdp:all");
writer.WriteString(request.ToString());
await writer.StoreAsync();
if (timeout > TimeSpan.Zero)
await Task.Delay(timeout);
if (!bridgeWasFound)
break;
}
}
}
return discoveredBridges;
}
According Specifications :
MAN REQUIRED by HTTP Extension Framework. Unlike the NTS and ST field
values, the field value of the MAN header field is enclosed in double
quotes; it defines the scope (namespace) of the extension. MUST be
"ssdp:discover".
then your code
request.AppendLine("MAN: ssdp:discover");
must be
request.AppendLine("MAN: \"ssdp:discover\"");
Hope this help.