Developing Apama Applications > Developing Apama Applications in Event Modeler > Using Standard Blocks > The Utility blocks > History Logger v2.0
History Logger v2.0
The History Logger block maintains an ordered and (optionally) time-stamped history of text messages. This is normally used in conjunction with multi-line entries in dashboards, such as history lists, where a fixed size list is used to contain a rolling window of constantly changing information.
Parameters
Parameter
Description
entry
An entry to be added to the history.
timestamps
Index for an add, clear or retrieve operation.
most recent first
Set to true to order the history so that the most recent element is first, false for least recent first.
max size
Maximum number of entries to retain - set to 0 to retain all entries.
delimiter
String to separate history entries when output by the block. If not specified, the default is "\n" (linefeed).
time format
String format to display time-stamps, if required. A default format is used if this is not set.
Operations
Operation
Description
add
Adds the content of entry to the history - an output update will automatically be produced.
clear
Clears the history.
retrieve
Causes the latest history to be output from the block as a single, delimiter-separated string.
Input feeds
This block has no input feeds.
Output feeds
Feed
Field
Description
history
size
Number of entries in the history.
text
Text representation of the history, where each entry is optionally time-stamped and separated by the delimiter string.
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