XML Logging

Primary purpose of the XML logging is to provide machine-readable description of automatically performed operations, such as when using scripting.

XML logging is useful e.g. to:

• Find a list of files that were actually uploaded/downloaded, when transferring whole directory or files matching a mask;
• Get directory listing;
• Record operations done during synchronization.

The XML logging is not intended for detection, if batch of operations (such as script file) succeeded or not1. See below.

XML logging is mostly useful with logging to file only. Overall format of the XML log file follows:

<?xml version="1.0" encoding="UTF-8"?>
<session xmlns="http://winscp.net/schema/session/1.0"
         name="martin@example.com" start="2009-03-02T19:34:57.734Z">
  <!-- operations -->  
</session>

The top level session tag represents one logical session, which may consist of several physical sessions, particularly when connection is lost. Attribute name refers to name of the logical session. Attribute start indicates time when the session was initiated2.

The session element includes child elements, where each element represents single log entry, i.e. single physical operation with remote file over the logical session.

Every entry in XML log represents single physical operation over the session. Typically this would be an operation with remote file.

Single logical operation (in scripting or GUI) may actually involve multiple physical operations, each represented with separate log element. For example upload of file (e.g. using put scripting command) may be represented by up to three elements, upload for actual upload, touch for preserving timestamp and chmod for preserving permissions.

Note that some logical operations does not have corresponding log element (e.g. creation of symbolic link). Such operations are omitted from the XML log.

First, note that the XML logging is not intended for detection, if batch of operations (such as script file) succeeded or not1.

XML log may not include some errors, even if they occur, for two reasons:

• The operation that failed does not have corresponding log element (see above).
• The error is not associated with particular physical operation. Simple example is authentication failure. More treacherous example is failure to list remote directory, to find list of files it contains, while uploading the directory. While this error occurs during upload operation, it is not associated with upload of any particular file. So it will be absent from the XML log.

With some protocols, each of the physical operations are performed individually. With some protocols, set of operations may be performed in atomic form. This may prevent mapping error to specific operation. In this case the error may be associated with more operations, resulting in its duplication in the XML log.

Result of an operation is represented by child result element of respective operation element. The result element has boolean success attribute.

<result success="true" />

If success is false, result element will typically include one or more message elements with error message(s). The error message is free text, that may be language-, protocol- or even server-specific.

The following example is from English version, connected with SFTP protocol to OpenSSH server:

<result success="false">
  <message>Cannot open remote file '/home/user/examplefile.txt'.</message>
  <message>No such file or directory.
Error code: 2
Error message from server: No such file
Request code: 3</message>
</result>