LMD LogTools tutorial

LogTools package

Introduction

Any programmer who is capable of writing complex applications is aware of the fact that some parts of code cannot be debugged with an interactive debugger (e.g. system service, threaded code, painting routines etc) or that situations exist, where an interactive debugger is unavailable. Common solution for for such cases is information logging. There many ways of logging - to files, to terminal, to system dialog boxes etc. To make life more simple we implemented a powerful logging system, that allows a developer to concentrate on main application logic instead of writing and debugging his own routines.

Class Structure

AnyLogger offer a flexible and extensible set of classes to log useful information. There are four main items: Message, Session, Transport and Manager. Message is container for information that should be logged. Session is class that wrap different information into Message and send it over Transport layer. Transport layer is responsible for physical delivery of Message. And at last but not least - the Manager allows user to create root (default) and user sessions, load/save user sessions and transport parameters. Secondary points are Router and Server (message Collector).
See also the following class diagram:

First Example

In this section we will write traditional in programmer's community example - 'Hello, World!' sample program. Firstly, we create new Delphi Console Application (File->New->Other...->Delphi Projects->Console Application). Then replace content of new project by below code:

<delphi> program HelloAnyLoggerWorld;

{$APPTYPE CONSOLE}

uses

 SysUtils,
 LMDLogMessage;

begin

 try
   LMDLog.SendString(‘First message’, ‘Hello, World!’); 
 except
   on E:Exception do
     LMDLog.SendException(E);
 end;

end. </delphi>

Second, we need to run AnyLogger console.After that compile and run HelloAnyLoggerWorld project. If everything is installed correctly you should see in AnyLogger console 'First message'='Hello, World!' line.

Now, let's take a closer look at what we did. First of all - we added LMDLogMessage unit in uses list. This unit contains declaration of all base needed types, classes and global variable LMDLog that contains object reference for root session (see. Sessions chapter). Secondly, we uses LMDLog global variable to call method of session - SendString which sends string using session transport (by default transport is WM_COPYDATA message which handled by AnyLogger console)

Basic Usage

Main purpose of this tool package is logging and monitoring actions of application. It should be used when you can't run regular debugger or when it useless - multi-thread application, system services, applications on client site etc.

To start use LogTools in your application you should add LMDLogMessage.pas unit to uses section of your unit, then you'll be able to use LMDLog instance of TLMDLogSession class.

<delphi> uses

 ..., LMDLogMessage, ...;

...

 LMDLog.SendString('Test', 'Hello, World!');

... </delphi>

TLMDLogSession class has methods to send some info into main log - TLMDLogSession.Send*, to watch data in Watch area - TLMDLogSession.Watch* (main different with Send* function that Watch* has just changed value of watched variables, but not add new record)

<delphi> uses

 ..., LMDLogMessage, ...;

...

 while i < 200 do
   LMDLog.WatchInteger('i', i);

... </delphi>

To logging flow of application, below methods available: TLMDLogSession.Enter*, TLMDLogSession.Leave*. Sample:

<delphi> uses

 ..., LMDLogMessage, ...;

... function TestFunction: HResult; begin

 LMDLog.EnterMethod('TestFunction');
 try
   ...
 finally
   LMDLog.SendHResult('Result', Result);
   LMDLog.LeaveMethod('TestFunction');
 end;

end; ... </delphi>

and methods that help to trace of application

<delphi> uses

 ..., LMDLogMessage, ...;

...

 for i := 0 to Count - 1 do
 begin
   LMDLog.SendInteger('Iteration', i);
   b := 20 + i;
   LMDLog.TouchCounter('Checkpoint');
   a := CalcA(b);
   LMDLog.TouchCounter('Checkpoint');
   c := a div 34;
   LMDLog.ReleaseCounter('Checkpoint');
 end;

... </delphi>

To control log storage TLMDLogSession has next methods - TLMDLogSession.ClearLog, TLMDLogSession.ClearWatch and TLMDLogSession.ClearCallStack

TLMDLogSession allow you to control level of you logging messages. It has two properties for it - TLMDLogSession.AllowLogLevel - set minimum log level for messages, TLMDLogSession.DefaultLogLevel - set default log level for messages where level is not set as parameter.

<delphi> uses

 ..., LMDLogMessage, ...;

...

 {$ifdef DEBUG}
 LMDLog.AllowLogLevel := LogAll;
 LMDLog.AllowLogLevel := LogAll;
 {$ELSE}
 LMDLog.AllowLogLevel := LogFatal; 
 LMDLog.DefaultLogLevel := LogOff;
 {$ENDIF}
 
 for i := 0 to 4 do
 begin
   try 
     LMDLog.SendInteger('i', i);
     a := 5 / i;
     LMDLog.SendReal('a', a);
   except
     on E: EDivideByZero do
       LMDLog.SendString(LogFatal, 'Error', 'Divide by zero');
   end;
 end;

... </delphi> Logging for 'a' and 'i' will be turned off when DEBUG undefined, but 'Error' will be sent to log in any case.

AnyLogger console application

This logging and monitoring console for LMD Log package. All data that you send from your application are collected and displayed here.

Creating Viewer plugin for AnyLogger console

NB. This API information can be changed before AnyLogger release

AnyLogger console can be extended  by pluggable modules (plugins). Plugins based on new package LMD Plugins. Currently you can create plugin to view custom data, that you sent to console, in more obvious form.

To create such plugin you will need LMD Plugins package and uCreatePlugin.pas unit.

<delphi> unit uCreatePlugin;

interface

uses

 SysUtils, Forms, LMDPluginManager, LMDPluginImpl;

type

 TLMDActionExecutor = class(TObject)
 public
   procedure GetCount(const AnAction: ILMDAction; var AResult: ILMDParameter); virtual; stdcall; abstract;
   procedure GetType(const AnAction: ILMDAction; var AResult: ILMDParameter); virtual; stdcall; abstract;
   procedure GetIcon(const AnAction: ILMDAction; var AResult: ILMDParameter); virtual; stdcall; abstract;
   procedure GetName(const AnAction: ILMDAction; var AResult: ILMDParameter); virtual; stdcall; abstract;
 end;

function CreatePlugin(AExecuter: TLMDActionExecutor; AFormClass: TFormClass): ILMDPlugin;

implementation

function CreatePlugin(AExecuter: TLMDActionExecutor; AFormClass: TFormClass): ILMDPlugin; var

 Plugin: TLMDPlugin;

begin

 try
   // Create the plugin
   Plugin := TLMDPlugin.Create('Author', 'AnyLogger plugin', 0, 1);

   // add GetSupportedSubTypesCount action
   Plugin.AddAction('GetSubTypesCount').OnPerformAction := AExecuter.GetCount;
   with Plugin.AddAction('GetSubTypeName') do
   begin
     with AddParameter('SubType') do
       ParameterType := ptGUID;
     OnPerformAction := AExecuter.GetName;
   end;

   with Plugin.AddAction('GetSubType') do
   begin
     with AddParameter('Index') do
       ParameterType := ptInteger;
     OnPerformAction := AExecuter.GetType;
   end;

   with Plugin.AddAction('GetSubTypeIconIndex') do
   begin
     with AddParameter('SubType') do
       ParameterType := ptGUID;
     OnPerformAction := AExecuter.GetIcon;
   end;

   // add form into plugin
   Plugin.AddForm(TLMDDelphiPluginForm.Create('Viewer', AFormClass));

   // return the plugin
   Result := Plugin;
 except
   Result := nil;
   exit;
 end;

end;

end. </delphi>

uCreatePlugin.pas create TLMDPlugin instance and init with three plugin method "GetSubTypesCount" - returns count of lmdlog message subtypes that will showed by this plugins. Next method is "GetSubTypeName" - returns name of subtype by it's index (0..GetSubTypesCount - 1). "GetSubType" method returns GUID that identificate subtype. And the last method is "GetSubTypeIconIndex" - it returns iconindex to show icon in AnyLogger console by subtype GUID.

So, uCreatePlugin.pas do above basic steps for you. Next, you need to create form with interface ILMDFormWithData, which described in LMDPluginManager unit from LMD Plugins package.

<delphi> { **************************** ILMDFormWithData **************************** }

 ILMDFormWithData = interface(IInterface)
   ['{8999ED41-2791-4471-BFEB-994923CE1CD4}']
   procedure SetFormData(AData: Pointer);
 end;

</delphi>
This interface is needed to fill form with you custom data. AnyLogger Console call SetFormData method with TLMDLogMessage instance as parameter. Here is example of such form:
<delphi> ... type

 TTextForm = class(TForm, ILMDFormWithData)
   edtText: TElMemo;
 private
   { Private declarations }
 public
   procedure SetFormData(AData: Pointer);
 end;

var

 TextForm: TTextForm;

implementation

{$R *.dfm}

{ TTextForm }

procedure TTextForm.SetFormData(AData: Pointer); begin

 edtText.Text := TLMDLogMessage(AData).MessageValue;

end; ... </delphi>

Next step is creating child class for TLMDActionExecutor from uCreatePlugin.pas and override handlers of plugin methods. Example:
<delphi> unit intfTextView;

interface

uses

 Classes, SysUtils, uCreatePlugin, LMDLogMessage, LMDPluginImpl, LMDPluginManager;

type

 TLMDTextActionExecutor = class(TLMDActionExecutor)
 public
   procedure GetCount(const AnAction: ILMDAction; var AResult: ILMDParameter); override; stdcall;
   procedure GetType(const AnAction: ILMDAction; var AResult: ILMDParameter); override; stdcall;
   procedure GetIcon(const AnAction: ILMDAction; var AResult: ILMDParameter); override; stdcall;
   procedure GetName(const AnAction: ILMDAction; var AResult: ILMDParameter); override; stdcall;
 end;

implementation

{ TLMDTextActionExecutor }

procedure TLMDTextActionExecutor.GetCount(const AnAction: ILMDAction; var AResult: ILMDParameter); begin

 AResult.AsInteger := 1;

end;

procedure TLMDTextActionExecutor.GetIcon(const AnAction: ILMDAction; var AResult: ILMDParameter); begin

 AResult.AsInteger := -1;
 if IsEqualGUID(AnAction[0].AsGUID, mstString) then
   AResult.AsInteger := 5;

end;

procedure TLMDTextActionExecutor.GetName(const AnAction: ILMDAction; var AResult: ILMDParameter); begin

 if IsEqualGUID(AnAction[0].AsGUID, mstString) then
   AResult.AsString := 'String';

end;

procedure TLMDTextActionExecutor.GetType(const AnAction: ILMDAction; var AResult: ILMDParameter); begin

 case AnAction[0].AsInteger of
 0: AResult.AsGUID := mstString;
 else
   AResult.AsGUID := mstNone;
 end;

end;

end. </delphi>

And final step is create Dll project with export function GetLMDPlugin (see LMD Plguins for details).
<delphi> library TextView;

uses

 SysUtils,
 Classes,
 Windows,
 Forms,
 uCreatePlugin,
 LMDLogMessage,
 LMDPluginImpl,
 LMDPluginManager,
 frmTextView in 'frmTextView.pas' {TableForm},
 intfTextView in 'intfTextView.pas';

{$R *.res}

var

 LOldApplication: TApplication;

function GetLMDPlugin(const AHostApplication: TApplication; var APlugin: ILMDPlugin): HRESULT; stdcall; begin

 try
   LOldApplication := Application;
   Application := AHostApplication;

   APlugin := CreatePlugin(TLMDTextActionExecutor.Create, TTextForm);
 except
   Result := E_UNEXPECTED;
   exit;
 end;
 Result := S_OK;

end;

procedure DllMain(AReason: integer) ; begin

 case AReason of
  DLL_PROCESS_DETACH:
    if Assigned(LOldApplication) then
      Application := LOldApplication;
 end;

end;

exports

 GetLMDPlugin name 'GetLMDPlugin';

begin

 LOldApplication := nil;
 DllProc := @DllMain;

end. </delphi>
Compile it and copy result dll file to Viewers folder in AnyLogger console installation path.