Volume 10

Chapter 64 364 - ToDo List 2016-05-27

The latest changes to the Spectrum Analyzer server seem to be working well so I now have to go back and clean up some of the mess I made along the way.

Make Special Test come up rather than <none> <NONE> on start up
Bin Shift does not seem to be working correctly
Add Try/Except/Finally to the Port select on the receiver and the antenna.

363 - Setup dbForge Studio to my liking 2016-05-26

I make heavy use of the dbForge Studio application from DevArt. Its great for editing and designing MySQL tables and for maintance of the database used at SETI Net.

I am fussy about the layout of the tool and can never remember how to set it up the way I like. This is the process:

Select 'Tools -> Options' from the main menu. The 'Options' window opens.
Navigate to the 'Environments -> Documents -> Object editors' branch.
Select the 'One main document view' radio-button.
Navigate to the 'Database Explorer -> General' branch.
Select the 'Retrieve data' radio-button.
Click 'OK'

362 - Fix Freeze on RO Objects 2016-05-25

After much screwing around I *finally* ask the good folks at RemObjects Software for help. I make heavy use of their technology for remote process control of the SETI Net Spectrum Analyzer over HTTP and it was throwing fits..

The problem was that the RO Server (SpecAna.exe) would freeze up when I touched it with the mouse while it was exchanging messages with the client (SETI.exe). They quickly pointed out that the messages launched from background threads need to make use of the main thread and therefor must be made 'Thread Safe'.

This is the working example of message exchange in the server that solves the problem:

procedure TSpecAna.setPaused(value: Boolean);
const
  WM_SETPAUSE_MESSAGE = WM_APP + 1;
var
	OnOff: String;
	p: pChar;
begin
	if value then 
        	OnOff := 'true'
	else
		OnOff := 'false';
GetMem(p, (Length(OnOff) + 1) * SizeOf(Char));
Move(OnOff[1], p^, (Length(OnOff) + 1) * SizeOf(Char));
PostMessage(Handle, WM_SETPAUSE_MESSAGE, 0, integer(p)); 
  end; 
procedure TSpecAna.WMsetPause(var MESSAGE: TMessage) { message WM_SETPAUSE_MESSAGE };
 var
	p: pChar;
begin
 try
	 p := pChar(Message.LParam);
		if p = 'true' then
		if p = 'true' then
	begin
		swPaused.State := tssOn;
		AudioIn.Paused := True
	end
else
	begin
		swPaused.State := tssOff;
		AudioIn.Paused := False;
	end;
	Freemem(p);
	except
	on E: Exception do
		Memo.Lines.Add(E.ClassName + ': ' + E.MESSAGE);
	end;
end;

Notice that this example does a clumsy job of sending a string in the message when it really should be a boolean. That is the next task.

The next day I asked the people on StackOverFlow how I could POST and recover boolean and integer. The answer came back.

This task is much simpler than string sending.

You don't need to allocate memory for these types, because message parameters are already Integer, and Boolean needs just simple casting.

PostMessage(Handle, WM_MY_MESSAGE, IntegerParam, Integer(BooleanParam));
  ....  
//in WM_MY_MESSAGE handler:

   IntVar := Message.WParam; 
    BooleanVar := Boolean(Message.WParam);

That solves the problem.

361 - Rebuilding File Manager XML bindings 2016-12-30

These are the steps necessary to modify the SML schema file and then rebuild the XML data bindings - Updated.

Please Note: These instructions have been moved to the Schema page and are maintained there from now on.

360 - ToDo list 2016-04-09

Always a good idea to keep a list - don't you think.

Sort out Status capture SpecAna causing server lockout. Might be as simple as increasing the timeout.
Add new SpecAna Server parameters to the SML and show in the Status update
Add new SpecAna Server parameters to the File Manager
Looks like chirp is not working correctly - not showing up on Control Panel
Add estimate to complet scan in minutes to the Status
Start additional search filter functions. High amplitude, Antenna move off axis, hit width in bins (over about 10 Hz skip)
Find better way to display SML in the JavaScript
Clean up HowStuffWorks directory
Set upper limit on frame buffer to 50,000 scans (about 3 GBytes).
Fix Status Station SETI Net SETI Net
Fix Status Recording On.
Add Revert to enterSetup at Scan End check box.

359 - RemoteObjects Building Code First Client/Servers 2016-03-21

This is a work flow I use for building a code first client/server and making changes along the way..

Do these steps:

Build new Client/Server - File|New|Other. Select VCL Standalone (Code First). OK. OK.
Build the server then launch the server directly (not from the UI). Set Windows Firewall to allow this new project access.
Set newProjectClient.exe as default project
Select Tools|Remoting SDK & Data Abstract|'Connect to Remoting SDK Server' menu item
Select 'Import a Service from the Web by its URL' the default is the servers URL. It should be http://localhost:8099/bin
Hit Import - This should create a file in the client group called 'NewLibrary.remoteRODL'

After these steps the following files will have been generated for the client:

NewLibrary.remoteRODL
NewLibrary_Intf.pas
NewLibrary_ServerAccess.pas

Verify that the client will now compile correctly

Now add some service to the Server:

Open the NewService_impl.pas file in the server
Add the Sum function

const
  __ServiceName = 'NewService';

type

  [ROService(__ServiceName)]
  TNewService = class(TRORemoteDataModule)
  private
  public
    [ROServiceMethod]
    function Sum(const A: integer; const B: integer): integer;
   end;

implementation

{ %CLASSGROUP 'System.Classes.TPersistent' }
{$R *.dfm}

function TNewService.Sum(const A: integer; const B: integer): integer;
begin
  result := A + B;
end;

Note the [ROServiceMethod]

Each function must have this above it.

Then add the call to the service in the client as in:

var
  ClientForm: TClientForm;

implementation

uses NewLibrary_Intf;

{$R *.dfm}

procedure TClientForm.Button1Click(Sender: TObject);
var
  service: INewService;
begin
  Screen.Cursor := crHourGlass;
  try
    service := CoNewService.Create(ROMessage, ROChannel);
    Edit1.Text := '';
    Edit1.Repaint();
    Edit1.Text := IntToStr(service.Sum(555, 111));
  finally
    service := nil;
    Screen.Cursor := crDefault;
  end; { try/finally }
end;
end.

Later when you want to regenerate the _Intf.pas for the client you:

Ensure the server is running
Right click on NewLibrary.remoteRODL file
Select: Update Interface file(s)

This will keep your autogenerated files up to date.

Tip: I open two instances of the RAD studio IDE and put client on the left and server on the right. That makes work flow much cleaner.

358 - Selecting Server Protocol and Message Type 2016-03-10

Channels

HTTP - More overhead, proxy friendly, savable to third party clients, allows Smart Services. Most common choice
Super HTTP - Same as HTTP plus keeps channel open, Callback events, Asynchronous capabilities, Allows Push
TCP - Raw TCP sockets, minimal overhead, not proxy-friendly, allows third party clients
Super TCP - Same as TCP plus keeps channel open, Callback events, Asynchronous capabilities, Allows Push
Local Channel - Como within same application
Named Pipes - Over LAN without TCP/IP
UDP - Lightweight packet-based. including the broadcast version
DLL Channel - Local App. talks to services in a DLL
Email - POP3/SMTP Como
WinMessage - Interprocess commo on same computer

Message Types

Bin - Proprietary. Supports Callback events
SOAP - Most complex and most flexible, XMLbased, high overhead.
XmlRpc - XML-based but simpler than SOAP
Post - Compatible with HTML forms
JSON - Capable of complex structures, supports Callback events

After working with RemoteObjects I have decided on the following layout:

Messaage type - JSON
No Compression
No envelopes
Channel protocol - HTTP
Indy
Keep-Alive
No gzip encoding

This combination seems to be the simplest and most reliable way to start.

357 - Reorganizing for 64 Bit (again) 2016-03-07

In chapter 63 item 356 I said that I ran into a problem with moving the database to 64 bit. After struggling with it for a very long time I found that I must be on the bleeding edge of this technology and might as well wait for the answer to come to me. Trouble is I still need to come up with a 64 bit solution to building very large arrays.

The current approach is to leave the entire application 32 bit and only move the Spectrum Analyzer to 64 bit. This will leave the DLL for antenna control at 32 bits, (which works fine and why screw with it) and the SQL database system at 32 bits which also works fine and therefore doesn't require cutting myself to pieces on that edge.

So the first step is to build a 32 bit SETI application that collects all the calls to the Spectrum Analyzer into one group of Getters and Setters so that they can be dealt with collectively and added to a 32 bit SETI Client and 64 bit SpecAna Server .

These are the functions that must be served.

Interface for the Spectrum Analyzer
Getters	Service Implementation
getSpecAnaBinShift	SetupStateUpdate
getSpecAnaRunning	OffStateUpdate SetupStateUpdate ScanStateUpdate HitStateUpdate
getSpecAnaHzPerBin	SetupStateUpdate
getSpecAnaInUse	SetupStateUpdate
getSpecAnaFFTSize	SetupStateUpdate
getSpecAnaCapture	SetupStateUpdate
getSpecAnaVisible	SetupStateUpdate
getSpecAnaWaterRunning	SetupStateUpdate
getSpecAnaWaterVisible	SetupStateUpdate
getSpecAnaDetecting	SetupStateUpdate
getSpecAnaETHit	HitStateUpdate
getSpecAnaETRFFreq	HitStateUpdate
getSpecAnaETAmplitude	HitStateUpdate
getSpecAnaETAmbiant	HitStateUpdate
getSpecAnaETBin	HitStateUpdate
getSpecAnaETJPGFile	HitStateUpdate
getSpecAnaETWAVFile	HitStateUpdate
getSpecAnaVerticalRangeCaption	SetupStateUpdate
getSpecAnaIntegeration	SetupStateUpdate
getSpecAnaThreshold	SetupStateUpdate
getSpecAnaSegmentSize	SetupStateUpdate

Setters (Client Side)	Service Implementation (Server Side)
SpecAnaHitReset	HitReset
setSpecAnaSML	setSML
setSpecAnaCapture	setCapture
setSpecAnaWavJpgLocation	setWavJpgLocation


setSpecAnaRunning	setRunning
CollectSpecAnaSnapshot	CollectSnapShot

Volume 10

Chapter 64

364 - ToDo List 2016-05-27