[commits] [Wiki] changed: Doc/Dev/HordeLog

[Ralf Lang (B1 Systems GmbH)]

rlang  Sun, 21 Nov 2021 16:01:17 +0000

Modified page: https://wiki.horde.org/Doc/Dev/HordeLog
New Revision:  3
Change log:  Some details on logger

@@ -8,32 +8,48 @@

  The Horde Logging library was loosely based on the Zend 1 logging  
component back in H4. Recent upgrades implement PSR-3 logging and are  
informed by native PSR-3 implementations as well as Zend\Log's  
successor Laminas\Log

  Horde\Log internally delegates different aspects of log handling to  
formatters, filters and handlers, but exposes a unified Logger facade.
+
+Horde's Logger contains multiple building blocks:
+
+* The Logger is the facade implementing the PSR-3 LoggerInterface.  
This is the only surface consuming code needs to worry about
+* LogLevels have a criticality (integer) and a name (string).  
Multiple log levels of the same criticality might exist. The logger  
will only deal with messages for known log levels. You can either  
deliver custom log levels or fall back to a sane default.
+* The LoggerAware interface enables automatically configuring the  
logger into an application
+* Filters can control if a message is going to be processed. Filters  
can be applied globally or to individual handlers.
+* Handlers can deliver the message to filesystem or external  
resources like syslog, a logger software or similar. A Logger can have  
multiple handlers. Handler-level filters can deliver only certain  
messages to certain files or backends while others are delivered to  
some default facility.
+* Formatters can control how a message is supposed to look like.  
While you can stack multiple formatters, if might not make sense for  
all combinations. A formatter may combine message text with message  
context into an XML or JSON format or it may fill placeholders with  
data from context. It may also truncate messages, obfuscate passwords  
or add line breaks etc.
+* The LogMessage class is the common interchange format the Logger  
presents to Filters, Formatters and Handlers. It combines LogLevel,  
text and context.
+
+
+++ Usage

  ++ Bugs

  List any tickets on http://bugs.horde.org/ that cover this issue or  
are relevant to it.

  ++ People
-
+
  Ralf Lang for the H6 upgrade

  ++ Resources

  Include links to protocol descriptions, specifications, RFCs,  
external applications, presentations on http://horde.org/papers/ or  
elsewhere that are relevant, articles, API docs from  
http://dev.horde.org/ - anything that might be useful to someone  
working on this.
-
+
  ++ UPGRADING

  +++ 3.x (H6)
  ++++ Type hinting
  * Users should Type hint against either Horde\Log\LoggerInterface or  
Psr\Log\LoggerInterface
    * Use Psr if you only want to emit logs
    * Use Horde if you want to call into horde specific extensions
    While both technically work, more specific typing improves static  
analysis and IDE hints.
-
+
  ++++ Awareness
  * Use Psr/Log/LoggerAwareInterface for classes consuming loggers via  
setter injection
  * If you use setter injection and depend on horde-specific  
functionality, rather use the Horde\Log\LoggerAwareInterface. As both  
conflict and have different use cases, choose wisely.
+
+++++ Constraint Filter
+* The constraint filter is likely to go into a separate package soon.

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