/// <summary>
/// Sends a view model data to one or more clients.
/// </summary>
/// <param name="vmInfo">View model info.</param>
/// <param name="args">Arguments containing information on clients to send to.</param>
private void Send(VMInfo vmInfo, GroupSend args)
{
ResponseVMFilter.Invoke(vmInfo, args, filteredData =>
{
VMResponse(MULTICAST + nameof(GroupSend), vmInfo.Id, JsonSerializer.Serialize(args));
return(Task.CompletedTask);
});
}
/// <summary>
/// Push property changed updates on a view model back to the client.
/// </summary>
/// <param name="vmInfo">View model.</param>
/// <param name="vmData">Serialized data to be pushed. If null, it's coming from the view model.</param>
protected virtual void PushUpdates(VMInfo vmInfo, string vmData)
{
if (string.IsNullOrEmpty(vmData))
{
return;
}
ResponseVMFilter.Invoke(vmInfo, vmData, filteredData =>
{
var vmDataToSend = filteredData is GroupSend ? (filteredData as GroupSend).Data : (string)filteredData;
VMResponse(vmInfo.ConnectionId, vmInfo.Id, vmDataToSend);
return(Task.CompletedTask);
});
}
/// <summary>
/// Push property changed updates on all view models back to the client.
/// </summary>
protected virtual void PushUpdates()
{
foreach (var kvp in _activeVMs)
{
var vmInstance = kvp.Value.Instance;
lock (vmInstance)
{
var changedProperties = new Dictionary <string, object>(vmInstance.ChangedProperties);
if (changedProperties.Count > 0)
{
var vmData = Serialize(changedProperties);
ResponseVMFilter.Invoke(kvp.Key, vmInstance, vmData, filteredData =>
{
_vmResponse(kvp.Value.ConnectionId, kvp.Key, (string)filteredData);
// After the changes are forwarded, accept the changes so they won't be marked as changed anymore.
vmInstance.AcceptChangedProperties();
});
}
}
}
}
/// <summary>
/// Handles a request for a view model from a browser client.
/// </summary>
/// <param name="connectionId">Identifies the client connection.</param>
/// <param name="vmId">Identifies the view model.</param>
/// <param name="vmArg">Optional view model's initialization argument.</param>
/// <returns>Group name, if the request is for a multicast view model associated with one.</returns>
public async virtual Task <string> OnRequestVMAsync(string connectionId, string vmId, object vmArg = null)
{
BaseVM vmInstance = null;
if (_activeVMs.ContainsKey(vmId))
{
vmInstance = _activeVMs[vmId].Instance;
}
else
{
// Create a new view model instance whose class name is matching the given VMId.
vmInstance = CreateVM(vmId, vmArg);
// Let the instance complete its initialization. If multicast, make sure it's only called once.
if ((vmInstance as MulticastVM)?.RaiseCreatedEvent != false)
{
await vmInstance.OnCreatedAsync();
}
}
await RequestVMFilter.Invoke(vmId, vmInstance, vmArg, async data =>
{
string vmData = vmInstance.Serialize();
string groupName = vmInstance is MulticastVM ? (vmInstance as MulticastVM).GroupName : null;
// Send the view model data back to the browser client.
await ResponseVMFilter.Invoke(new VMInfo(vmId, vmInstance, connectionId, groupName), vmData, filteredData => VMResponse(connectionId, vmId, (string)filteredData));
// Reset the changed property states unless it's a multicast.
if (vmInstance is MulticastVM == false)
{
vmInstance.AcceptChangedProperties();
}
// Add the view model instance to the controller.
if (!_activeVMs.ContainsKey(vmId))
{
var vmInfo = new VMInfo(id: vmId, instance: vmInstance, connectionId: connectionId, groupName: groupName);
vmInstance.RequestPushUpdates += VmInstance_RequestPushUpdates;
if (vmInstance is MulticastVM)
{
var multicastVM = vmInstance as MulticastVM;
multicastVM.RequestMulticastPushUpdates += VMInstance_RequestMulticastPushUpdates;
multicastVM.RequestSend += VMInstance_RequestSend;
}
_activeVMs.TryAdd(vmId, vmInfo);
}
else
{
_activeVMs[vmId].ConnectionId = connectionId;
}
// If this request causes other view models to change, push those new values back to the client.
foreach (var vmInfo in _activeVMs.Values)
{
PushUpdates(vmInfo);
}
});
return(_activeVMs[vmId].GroupName);
}
