Logging

OpenTwin provides a Logger Service that can receive log messages from multiple services. The Logger Service stores the received log messages and forwards them to any registered Log Receiver.

Use Logging in a Service

To use the logging functionallity use the openTwin/ServiceLogger header file which is part of the OpenTwinCommunication library. This header file contains the LogMessage and ServiceLogger classes.

Setup Logger

When a service is started the logger should be setup by providing at least the current services information.

#include "OTCore/Logger.h"

char * init(const char * _serviceURL, const char * _localDirectoryServiceURL, const char * _unused1, const char * _unused2) {
#ifdef _DEBUG
    ot::LogDispatcher::initialize("MyServiceName", true);
#else
    ot::LogDispatcher::initialize("MyServiceName", false);
#endif
    ...
}

If you want to use the central logging system you need to initialize the ServiceLogNotifier. This notifier will register itself at the LogDispatcher aswell as call the initialize for the LogDispatcher upon initialization.

#include "OTCommunication/ServiceLogNotifier.h"

char * init(const char * _serviceURL, const char * _localDirectoryServiceURL, const char * _unused1, const char * _unused2) {
// Note that the _DEBUG must be defined in your projects debug configuration
#ifdef _DEBUG
    ot::ServiceLogNotifier::initialize("MyServiceName", "LoggingServiceURL", true);
#else
    ot::ServiceLogNotifier::initialize("MyServiceName", "LoggingServiceURL", false);
#endif
    ...
}

Note

If the service was created by using the ServiceTemplate the logger setup is performed automatically.

When creating the Service Logger instance, it sets the logging options from the following environment variables.

Name	Description
OPEN_TWIN_LOGGING_URL	The URL where the Logger Service is running at. If the URL is either empty, or starts with // then the log messages won’t be send to the Logger Service
OPEN_TWIN_LOGGING_MODE	Sets the active log flags that determine which log messages will be generated. A union of multiple flags can be created by splitting them with a ‘|’ character (without any blank space) INFORMATION_LOG: General information log DETAILED_LOG: Detailed information log WARNING_LOG: Warning log ERROR_LOG: Error log INBOUND_MESSAGE_LOG Execute enpoint message received log QUEUED_INBOUND_MESSAGE_LOG Queue endpoint message received log ONEWAY_TLS_INBOUND_MESSAGE_LOG One way tls endpoint message received log OUTGOING_MESSAGE_LOG Outgoing message log TEST_LOG Test (e.g. Runtime Test) message log ALL_GENERAL_LOG_FLAGS All general log flags will be set (Default, Detailed, Warning, Error) ALL_INCOMING_MESSAGE_LOG_FLAGS All flags for incoming messages will be set ALL_OUTGOING_MESSAGE_LOG_FLAGS All flags for outgoing message will be set ALL_MESSAGE_LOG_FLAGS All flags for incoming and outgoing messages will be set ALL_LOG_FLAGS All log flags will be set

Note

The environment variables are optional. Also the variables will be set when running OpenTwin by using the batch files provided with OpenTwin.

Generate Log Messages

To generate log messages at any point in your code use the macros defined in the OTCore/Logger.h header file. Log messages will be send to the Logger Service if the provided log flags are allowed. When the service is running in Debug Mode, the Log Messages will also be written to std::cout.

#include "OTCore/Logger.h"

namespace test {
    void foo(void) {
        OT_LOG_I("Hello World!");
    }
}

The example above will generate a log message with:

• Service name: The service that was set in the initialize function

• Function name: test::foo

• Type: Information

• Text: “Hello World!”

• LocalSystemTime: The time where the Log message object was generated (UTC)

• GlobalSystemTime: The time when the Log message was received by the LoggerService (UTC)

Log Macros

• OT_LOG_I Information log: General information.

• OT_LOG_D Detailed log: Detailed information.

• OT_LOG_W Warning log.

• OT_LOG_E Error log.

• OT_LOG_T Test log.

If any other log type(s) should be set for the log message, use the OT_LOG macro.

The Information, Detailed, Warning and Error logs have the following special types:

• A Assert before log. The log message will be displayed in the assert messsage. Message must be a C-String (const char*) (e.g. LOG_EA(“Test”) -> Log Error & Assert).

• AS Assert simple before log. The Assert will have no message set. Especially useful when wanting to assert but to log a std::string at the same time (e.g. LOG_EAS(“Test: “ + myString) -> Log Error & Assert simple).

View the Log

There are two approaches to view the log messages.

The first one is to register a receiver at the logger service, this receiver will get all the currently buffered log messages when registrating at the Logger Service. Afther the registration the receiver will receive a copy of every new log message.

The second approach is to request the currently buffered log messages.