Foglight for Java EE Technologies 5.9.7.5 - Application Servers User Guide

Table 84. Properties single value or observation details
Data Displayed	Displays the name of the attribute, as well as its latest value, period values (if available), description, and source.
Where to go Next	Drill down on: Edit Configuration. Opens the Attribute - Topology Property Configuration dialog box, which allows you to edit the name, storage type, and metric derivations (if applicable).

Java Virtual Machine (JVM) dashboard

Purpose

Use the JVM dashboard to review the operating status of a selected JVM.

How to get here

On the JMX Explorer dashboard, click the JVM name. The JVM Summary view popup opens. Click the Heap Usage chart to open the JVM dashboard.

Description of the view

Table 85. JVM details

Data Displayed

•

System, Server, and JVM names and health icons

•

JVM Heap, GC, and Process Metrics charts

•

Properties, Spaces, Garbage Collectors, Threads, Deadlocked Threads, and Operating System tabs.

Where to go Next

Click any of the tabs to view details about the selected JVM metric.

Appendix: Regular Expressions

Regular expressions employ metacharacters. A metacharacter is a character with special meaning. It does not denote a normal letter, but instead affects the interpretation of other characters in a regular expression. Metacharacters only occur inside a regular expression; for example, an asterisk (*) in a data string is not a metacharacter. There are only a few metacharacters in the regular expression language, but their effect can be quite powerful.


	IMPORTANT: The regular expression implementation in Foglight for Java EE Technologies and Foglight for Microsoft .NET differs from that used in other Foglight components (such as Foglight for Infrastructure). For example, the {N,M} syntax is not supported, and Advanced Regular Expression features such as bounds are not included.

The following table lists the metacharacters in Foglight for JMX and Foglight for Microsoft .NET, and describes their function.

Table 86. Metacharacters and their function.

Metacharacter

Description and Example

asterisk (*)

alias: star

The metacharacter that matches zero or more repetitions of the literal character or sub-expression it follows.

For example: the regular expression ‘White *space’ matches ‘Whitespace’, or ‘White space’, or ‘White@@any number of space characters@@space’, but not ‘White *space’ (the string containing a literal asterisk).

NOTE: ‘nexus*’ does NOT match ‘nexus.bat’, or ‘nexusconfig’. Path name-style matching (file globbing) is not the same as regular expression syntax.

period (.)

alias: dot

The period is a metacharacter that matches any single character or sub-expression unless it is enclosed in a character class, in which case it is simply a period.

For example:

•

The regular expression ‘HTTP1[.]0’ matches HTTP1.0. Placing the period in a character class removes its metacharacter status.

•

The regular expression ‘HTTP1.0’ matches ‘HTTP1.0’ (the string containing the literal period), or ‘HTTP1A0’ or ‘HTTP110’, but not ‘HTTP1.x or ‘HTTP1..x’.

The combination ‘.*’ (dot-star) matches any string of characters. It is an idiom for ‘the rest of the characters’ in a string, but not including the end of line character.

For example: the regular expression ‘HTTP.*’ matches ‘HTTP1.0’, or
‘HTTP1://www.example.com/index.html’.

CAUTION: The regular expression ‘mayb.com.*’ matches ‘maybecompletely wrong!’. The dot in the regular expression matches any character, in this case an ‘e’.

NOTE: Because the dot is a metacharacter, use the character class [.] to match a literal dot in a string. It is more robust than attempting to protect the dot with a backslash (\.).

question mark (?)

The question mark metacharacter matches zero or one occurrence of the character or sub-expression it follows.

For example: the regular expression ‘i?www’ matches ‘www’ or ‘iwww’. The regular expression ‘(ab)?cd’ matches ‘abcd’ and ‘cd’.

plus (+)

The plus sign metacharacter matches one or more occurrences of the character or sub-expression it follows.

For example: the regular expression ‘i+www’ matches ‘iwww’ or ‘iiwww’, but not ‘www’.

square brackets ([])

A pair of bracket metacharacters enclose a character class. Any character in the class is a suitable character for the match.

For example: the regular expression ‘[bcp]at’ matches ‘bat’, ‘cat’, or ‘pat’, but not ‘mat’.

NOTE: The characters that are considered metacharacters are different inside character classes. The function of these characters is also different.

minus (-)
alias: dash

The minus sign is a metacharacter only if it occurs between two characters in a character class, in which case it represents a range of characters.

For example: the regular expression ‘[b-h]at’ matches ‘bat’, or ‘cat’, or ‘fat’, or ‘hat’, but not ‘mat’.

caret (^)

Unless it appears as the first entry in a bracketed character class, the caret metacharacter matches the special character that represent the start of a string. The combination ‘[^...]’ represents a negated character class. All characters except the ones listed are allowed in the match.

For example:

•

The regular expression ‘^abc’ matches ‘abcxyz’ but not ‘xyzabc’.

•

The regular expression ‘[^cpt]at’ matches ‘hat’, or ‘mat’, or any three-letter combination ending in ‘at’ that does not begin with the letters ‘c’, ‘p’, or ‘b’.

dollar sign ($)

Unless it appears as the first entry in a bracketed character class, the dollar metacharacter matches the special character that represents the end of a string.

NOTE: The dollar sign ($) is a shell metacharacter in Unix. If you are running Foglight for JMX on a Unix system and want to include the dollar sign as a metacharacter in a regular expression, surround the expression with single quotes.
For example:
sh nexusctl.sh start-recording -fir ‘\.[Gg][Ii][Ff]($|\?)/’

vertical bar (|)
aliases: or, bar

The vertical bar metacharacter matches either of the expressions it separates.

For example: the regular expression ‘foo|bar’ matches ‘foo’ or ‘bar’, but not ‘foobar’.

backslash (\) (reverse solidus)

This metacharacter enforces the literal interpretation of the character following it. It has no effect when placed before an ordinary character. When placed before a metacharacter, it cancels out the metacharacter status and reduces the character to its literal meaning.

For example: the regular expression ‘myhost\.com’ matches ‘myhost.com’, but not ‘myhostcom’.

parentheses (())

Parentheses are used for group, for example, to limit the scope of the ‘or’ operator.

For example: the regular expression ‘http://(my|our)host\.com’ matches ‘http://myhost.com’ or ‘http://ourhost.com’.


	CAUTION: Do not use parenthesized expressions followed by a plus sign (+) or an asterisk (*) in any of the configuration files for Foglight for Java EE Technologies and Foglight for Microsoft .NET.

How regular expressions are scanned

When ambiguities are possible, use these rules to decide how regular expressions do their matching.

The rules for applying regular expressions to target strings are as follows:

•

The first match is chosen

If a regular expression could possibly match two different parts of an input string then it will match the one that begins earliest. Example: if the regular expression is ‘a.*t’ and the target string is ‘cataract’, the match succeeds with everything after the ‘c’.

•

The left most choice in a parenthesized group wins

If a regular expression contains “|” operators, the left most matching sub-expression is chosen. Example: if the regular expression is ‘(cat|dog)’ and the target string is ‘cats and dogs’, the match succeeds with ‘cat’ after the first three letters have been scanned.

•

The longest match wins

In “*”, “+”, and “?” constructs, longer matches are chosen in preference to shorter ones. Example: if the regular expression is ‘^He’s ba*’ and the target string is ‘He’s baaaaack!’, the match succeeds with ‘He’s baaaaa’ after the full list of contiguous a’s have been scanned.

•

In sequences of expression components, the components are considered from left to right

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Foglight for Java EE Technologies 5.9.7.5 - Application Servers User Guide

MBean Property summary view

Java Virtual Machine (JVM) dashboard

Appendix: Regular Expressions

How regular expressions are scanned