Simple Log is a cross-platform logging framework for Delphi, that aims to be as simple as possible to use.
Simple Log provides a simple interface for logging messages, via the Log interface. Each method sends a log message with a specific log level, and a message.
Log.d // Debug level
Log.e // Error level
Log.f // Fatal level
Log.i // Info level
Log.m // Method level
Log.w // Warning levelEach method takes a format string and an array of parameters, similar to the Format method in Delphi.
The m method is a special case, and is useful for tracing method calls. Use m at the beginning of a method, and it logs a message that the method has started. When the method exits, it will automatically log a message that the method has ended, e.g:
procedure TMyClass.MyMethod;
begin
// Call m at the beginning of the method to log a message that the method has started
Log.m('MyMethod');
// Do something in this method, here
// When the method exists, a message will be logged that the method has ended
end;The Tag property of the Log interface can be used to set a tag for log messages that are sent to the system log. This is used only on Android, and is ignored on other platforms.
Classes that implement ILogProvider can be added to the Log interface using the AddProvider method, and messages will be sent to all providers. Simple Log includes built-in providers - see the Getting Started section for more information.
Similar to DW.OSLog from Kastri (in the Core folder), Simple Log provides logging of messages to the system log, via a built-in provider.
Simply add SimpleLog.Log to the uses clause of the unit(s) where you need logging, and add calls to the logging methods (described above). NOTE: Since the FMX.Types unit also has a reference called Log,if you are using that unit you will need to ensure that SimpleLog.Log is added to the uses clause AFTER FMX.Types.
See the Viewing operating system logs section for more information on how to view the logs on your platform.
Add a file log provider by calling Log.AddLogProvider with an instance of TFileLogProvider, e.g.:
Log.AddLogProvider(TFileLogProvider.Create(LFileName));Where LFileName is a string containing the path to the file where the log will be written. Calling any of the logging methods will be output via the file log provider.
TFileLogProvider also has a constructor that allows log files to be created depending on what is specified in the TFileLogSettings parameter, which is declared as:
TFileLogCreationOption = (UseSame, NewAtStart, NewOnDayChange);
TFileLogSettings = record
public
class function Defaults: TFileLogSettings; static;
public
CreationOption: TFileLogCreationOption;
FileNameExt: string;
FileNameDateTimeFormat: string; // e.g. 'yyyy-mm-dd'
Path: string;
end;The CreationOption property of the TFileLogSettings record can be set to one of the following values:
UseSame- use the same file for all log messagesNewAtStart- create a new file at the start of the applicationNewOnDayChange- create a new file when the day changes
FileNameExt is a string that is appended to the file name, e.g. '.log'
FileNameDateTimeFormat is a string that is used to format the date and time in the file name, e.g. 'yyyy-mm-dd'
Path is a string that is used to specify the path to the file where the log will be written.
Calling the constuctor that takes APath and ASettings parameters will populate the Path member of the settings with the APath parameter. This allows a TFileLogProvider to be created with a path and the default settings, like this:
Log.AddLogProvider(TFileLogProvider.Create(LPath, TFileLogSettings.Defaults));Where LPath is a string containing the path to the directory where the log files will be written.
The Defaults method of TFileLogSettings sets these values:
CreationOptiontoNewOnDayChangeFileNameExtto'.log'FileNameDateTimeFormatto'yyyy-mm-dd'
Simple Log was created mostly to provide sending of SysLog messages, so support for this is included.
The most basic form is to create a provider similar to how one is created for file logging. In the case of the included TSysLogProvider, for example:
Log.AddLogProvider(TSysLogProvider.Create(LAddress));Where LAddress is a string containing the address of a SysLog server. The constructor also accepts a port number, which defaults to 514 (the default for SysLog).
TSysLogProvider also includes support for encrypting the messages being sent, however this of course means that the server side will need to handle decryption, which is included in SysLogServer, in the SimpleLog.Server.SysLog unit.
Encryption/Decryption is achieved by implementing the ICipher interface. The following implementations are included in Simple Log:
TSimpleCipher (in SimpleLog.Cipher.Simple) - ridiculously basic "encryption". Please just use this for testing purposes
TOpenSSLCipher (in SimpleLog.Cipher.OpenSSL) - much stronger encryption, that is dependent on OpenSSL 3.x
Alternatively you can implement your own encryption using your preferred encryption library.
Encryption/Decryption is enabled by calling the SetCipher method on the ISysLogProvider reference on the client side, and also on SysLogServer if this is chosen for the server side.
See also the SysLogViewer demo.
A very basic demo application called SimpleLogDemo is included in the Demos folder, that demonstrates the use of Simple Log. It demonstrates basic logging, as well as how to create and add a TSysLogProvider and set the cipher for encryption.
An application called SysLogViewer is included, that demonstrates the use of Simple Log to receive and display SysLog messages, including setting a cipher for decryption of messages received from clients that send encrypted messages.
The demo makes use of the SysLogServer reference in the SimpleLog.Server.SysLog unit, to act as the server. When the unit is used, the SysLogServer reference is created at startup. Listener classes that implement ISysLogListener can be added by using the AddListener method. The main form in the demo implements ISysLogListener, and displays the received messages in a grid.
An application called SysLogRelay is included, that demonstrates the use of Simple Log to receive and forward SysLog messages to another SysLog server.
If your client application is sending log messages across the internet, you may wish to use encryption to secure the messages in transit. SysLogRelay could be used to receive those messages, decrypt them, and forward them on a local network to the preferred SysLog server that does not support encryption, e.g. the popular Visual SysLog Server.
The Console application (in the /Applications/Utilities folder) can be used to view logs from iOS and macOS devices. There is some more detail available about using Console here.
The recommended way to view system logs on Windows is to use DebugView, which can be downloaded from Sysinternals.
Use your favorite logcat viewer. I highly recommend using Device Lens (disclaimer: I am the author)