How to send log events to client (delphi) example

Remoting SDK
1

Hi

I am trying to create a log visualizer in the client to see events of the server. I’m using Delphi and Remoting SDK.
What I am struggling now is in how to send real time data to client.

Is there any example of how to do it?
Does it slows down too much the server?

2

Hi,

you can examine these samples:

3

Hi
I verified the sample (HTTP Chat codefirst) and tried to implement a simple event/subscribe in our current infrastructure.
We already have codefirst Server/client implemented in production so we tried to implement just a simple method (tried to mimic sample’s login method).

We created an InMemorySessionManager and an EventRepository and hooked them up:

 FEventRepository.SessionManager := FSessionManager;
 FEventRepository.Message :=  FRoMessage; // server's FRoMessage

In our RoDataModule descendent, we coded RORemoteDataModuleCreate event to tell RO infra which session/event manager:

procedure TautenticacaoService.RORemoteDataModuleCreate(Sender: TObject);
begin
  EventRepository := getServer.EventRepository;
  SessionManager := getServer.SessionManager;
end;

When a client runs server’s code, it returns an “Abstract error” whenever we tried to get Session ou ClientID fields:

function TautenticacaoService.Login(
  const aUserID: Unicodestring): Unicodestring;
var
  ev: IRoEventWriter<IHTTPChatEvents>;
begin
  Session.Values['UserID'] := aUserID;
  result := GUIDToString(Session.SessionID); // ABSTRACT ERROR
  FCS.Enter;
  try
    RegisterEventClient(ClientID, 'HTTPChatEvents'); // ABSTRACT ERROR
    RegisterEventClient(ClientID, 'HTTPBroadCastEvents');
    ev := (EventRepository.GetWriter<IHTTPChatEvents>(Session.SessionID));
    ev.ExcludeSender := false; //para enviar para ele mesmo
    ev.Event.OnSendMessage(aUserID, 'teste', false );
  finally
    FCS.Leave;
  end;

end;

Should I have to set something else in order to make SessionManager work?

4

Hi,

Can you create a simple testcase that reproduces this issue, pls?
you can attach it hare or drop email to support@

5

I created and zipped it but I couldn’t attach it here (it shows an error). I will send it to support. Could you, please, verify if you have received?

6

The error in the sample is here:

function TchatService.Login( aUserId: string ) : string;
var
  ev: IRoEventWriter<IHTTPChatEvents>;
begin
  Session.Values['UserID'] := aUserID;
  result := GUIDToString(Session.SessionID);
  FCS.Enter;
  try
    RegisterEventClient(ClientID, EID_HTTPChatEvents);
    ev := (serverDataModule.EventRepository.GetWriter<IHTTPChatEvents>(Session.SessionID));

    ev.ExcludeSender := false; 
    ev.Event.OnSendMessage(aUserID, 'teste', false ); // ABSTRACT ERROR
  finally
    FCS.Leave;
  end;

end;
7

Hi,

as expected. TROEventRepository is base class that contains abstract methods that are implemented in descendants.

try to use TROInMemoryEventRepository instead:

 fEventRepository := TROInMemoryEventRepository.Create(self);
8

Hi
Now it runs flawlessly but I don’t receive any messages.
At client, the code is:

TClientForm = class(TForm, IHttpChatEvents)
    Message: TROBinMessage;
    Channel: TROWinInetHTTPChannel;
    RORemoteService: TRORemoteService;
    Button1: TButton;
    eventReceiver: TROEventReceiver;
    mmMessages: TMemo;
    procedure Button1Click(Sender: TObject);
  private
    procedure OnSendMessage(const aSenderUserID: Unicodestring; const aMessage: Unicodestring; const aIsPrivateMessage: Boolean);
    { Private declarations }
  public
    { Public declarations }
  end;

procedure TClientForm.Button1Click(Sender: TObject);
var
  userId: string;
begin
  EventReceiver.RegisterEventHandlers([EID_HTTPChatEvents], [Self]);
  { Starts polling }
  EventReceiver.Active := TRUE;
  userId := (RORemoteService as IchatService).Login('MARK');
  showMessage(userId);
end;

and

procedure TClientForm.OnSendMessage(const aSenderUserID,
  aMessage: Unicodestring; const aIsPrivateMessage: Boolean);
begin
  mmMessages.Lines.Add(aMessage); //DON'T ACCESS HERE
end;
9

Hi,

You haven’t assigned EventRepository for your service so events won’t be sent …

add

procedure TchatService.RORemoteDataModuleCreate(Sender: TObject);
begin
  Self.EventRepository := ServerDataModule.eventRepository;
end;

30942.zip (222.8 KB)

10

Hi
My mistake! But even adding that, I don’t receive any messages.
Does the zip attached is a working sample?

11

I tried to compile it but it complains that there is no uRONullable in chatLibrary_intf

image
image2836×1698 169 KB

12

Hi,

what version of Remoting SDK are you using?

try to regenerate files from .RemoteRODL

13

I am using version 10.0.0.1585
I couldn’t generate it because I cannot build server exe in order to update the interface.

14

why you can’t build server-side?

Code-First server-side doesn’t require _Intf for building.
you can replace constant EID* with it’s value like

  RegisterEventClient(ClientID, 'HTTPChatEvents');
15

In order to use constant EID*, I had to use _intf at server function. Replacing them with its values, it worked and sent messages flawlessly.
Thanks

16

Just a small question: RO generates this constant

const EID_HTTPLogEvents: string = 'HTTPLogEvents';

in the interface file from where?

I have this event sink:

[ROEventSink]
  IHTTPLogEvents = interface(IROEventSink)
  ['{75F9A466-518A-4B09-9DC4-9272B1EEFD95}']
    procedure OnSendLog(const aMessage: UnicodeString );
  end;

It generates ‘HTTPLogEvents’ constant from the name of the interface?

17

Hi,

You can specify event sink as

  [ROEventSink("myname")]
  IHTTPLogEvents = interface(IROEventSink)
  ['{75F9A466-518A-4B09-9DC4-9272B1EEFD95}']
    procedure OnSendLog(const aMessage: UnicodeString );
  end;

in this case, it will be generates as EID_myname = 'myname';

otherwise, I prefix will be removed and it will be generated as EID_HTTPLogEvents = 'HTTPLogEvents'.

18

Great

Last question, in order to stop listening to all interfaces, could I use:

UnregisterEventClient(ClientID);
19

Hi,

yes

RegisterEventClient and UnregisterEventClient methods work in pair

20

Hi

Another small question: When someone is connected to a server (TInMemorySessionManager) and server is shutdown (without client disconnecting), server was showing an exception when it was freeing TInMemorySessionManager.

After adding this line, the server does not complain:

FSessionManager.ClearSessions(false);

So, two questions:
Is it OK to do that? we’re hooking this line to destroy event in the form that has TRoHttpServer.

Is there a way to send a message to clients just before that in order to clean up things there?

We tried to hook an eventSink and send a message just before destroying the server but the message never gets there:

procedure TServerHttp.desconectAllSessions();
var
  ev: IRoEventWriter<IHTTPLogEvents>;
begin
  inherited;
  ev := (FEventRepository.GetWriter<IHTTPLogEvents>(EmptyGUID));
  ev.Event.OnMandatoryClose( 'Server is closing...');

  FSessionManager.ClearSessions(false);

end;