Logging Aspect

Logging Aspect is an aspect and provides functionality of logging which includes free-form messages and tokens.

How logging aspect is different from logging?

Logging is part of the business component and you need to decide what needs to be logged at the design time. If any change is needed, then that business component has to go entire development life cycle .. design, development, built, test, deploy and the entire project may need to be restarted to pick up the changes.

Logging aspect is complementary to the logging. Logging aspect is external to components. The information thats being exchanged among components and the state of that message exchange can be logged. You can deploy this aspect any time you want and you can undeploy at your will without affecting your main project. And, its javafree thus no Java developer is needed.

How to create Logging Aspect

In Fuji Milestone 4 (M4), the aspects are taken a huge step forward to provide javafree aspects. Aspects user just need to specify a set of properties to enjoy the aspects.

In Fuji Milestone 7 (M7), aspects can be created at command line. The command for creation of aspect is "create-aspect key=value,key=value,*".

An example for creating an logging aspect.

-> fuji create-aspect name=Log-1 type=log status=Active log.content=Message

Alternatively, you can create aspects by the supported archetypes. Once after having Fuji, at least M4 version, here are the steps that are need to create Logging Aspects Project:

1. In Netbeans, create a maven based project from Logging Aspect Archetype.
2. For that project, edit log.properties under Other Sources/Aspects/Log.
3. Build, Deploy and start the project

Logging aspect is ready and you see the specified log content is available at the specified interception points.

How to create more logging aspects

You can create as many logging aspects as you want in either of the following ways:

1. Create multiple property files under Other Sources/Aspects/Log. Please ensure that "name" property is unique.
2. Create multiple logging aspect projects from the provided logging aspect archetype.

Properties of Logging Aspect

Interceptor related properties

You can specify any of the following interceptor related properties. You can refer How to write an Interceptor for the recent supported properties.

Property	For logging, intercept Message Exchange based on
name	Name of the Logging aspect. Must be unique in Fuji run time. By default, project name is chosen.
provider	service provider
consumer	service consumer
message	message type : ( "in", "out")
service	service name, can be the local name or the fully qualified service name
endpoint	endpoint name
status	message exchange status : {"DONE", "ERROR", "ACTIVE"}

Logging aspect related properties

And you can specify any of the following logging properties:

Property	Necessity	Description	Default Value
log.content	Needed	Free form messages, tokens, Header/Status/Message/Properties/All Ex: log.content=Status Ex: log.conent=Header,Properties Ex: log.content=First Name : {xpath://Employee/FName},Message,Status	Exchange:{exchangeid} Status:{status}
log.xpaths	Optional	Logs evaluated XPath expressions. Ex: /Employee/FName	None
log.token.<TokenName>	Optional	User defined token. Ex: log.token.country={xpath://Employee/Country} and this country token can be used log.content as log.conent={xpath://Employee/FName} lives in {country}.	None
log.console	Optional	True/False. Determines whether output is directed to console. Ex: log.console=true	If no other output option is chosen, its true.
log.config.dir	Optional	Directory name where the specified log.config.files resides.	<FujiDir>\trunk\packaging\release-packages\felix\target\classes\fuji
log.config.files	Optional	File names where logging is directed.	None
log.config.patterns	Optional	The pattern for naming the output file. Refer: http://java.sun.com/j2se/1.4.2/docs/api/java/util/logging/FileHandler.html	None
log.config.uris	Optional	URIs	None
log.config.file.limit	Optional	the maximum number of bytes to write to any one file	0
log.config.file.count	Optional	The number of files to use.	1
log.config.file.append	Optional	true/false. Specifies append mode	true
log.config.file.formatter	Optional	xml/simple	simple
log.header	Optional	Entire log.content can be given a heading of your choice. Ex: log.header=***This logging is for my MATH CALCULATIONS debugging*******	None
log.level	Optional	Logging level. This level need to be less restrictive than jdk logging level to log the log.content.	INFO

Tokens of logging aspect

A token is enclosed by curly brackets, {} and is evaluated for the value. A token can embed other tokens. The tokens are processed recursively until there are no valid tokens to evaluate.

Built-in tokens

The following are built-in tokens.

role
endpoint.name/endpointname
message.type/messagetype
exchange.id/exchangeid
endpoint
service
operataion
pattern
status
error
fault
interface.name/interfacename

in-place tokens

XPaths expressions and property expressions can be used as an in-place token, which will be evaluated while logging the content.

1. XPath expression in-place token example: {xpath://Employee/FName}
2. Property expression in-place token example: {property:groupid}

Example of Logging Aspect

If the properties are,

log.content = Attempt to invoke {operataion} on service {endpoint.name}., The message of {  xpath://Employee/FName} with {property:groupid} is being processed and his Address = {Emp.Address} . He is from {Country}.

log.token.Emp.Address={Emp.FullName} {Emp.Company}, {xpath://Employee/Street}, {xpath://Employee/City}, {xpath://Employee/State} - {xpath://Employee/ZIP}

log.token.Country = {xpath://Employee/Country}

and if the input is:

<Employee>
    <EmpId>123</EmpId>
    <FName>Ramesh</FName>
    <LName>Dara</LName>
    <Company>Sun Micro Systems</Company>
    <Street>800, Royal Oaks Dr</Street>
    <City>Monrovia</City>
    <ZIP>91016</ZIP>
    <State>CA</State>
    <Country>USA</Country>
</Employee>

The output would be:

Attempt to invoke {http://fuji.dev.java.net/application/myJRuby}requestReply on service transform_endpoint.
The message of Ramesh with 402af89d-cf28-4211-bb60-484b44fdb710 is being processed and his Address = Ramesh Dara, Sun Micro Systems, 800, Royal Oaks Dr, Monrovia, CA - 91016 . He is from USA.

This page (revision-8) was last changed on 02-Nov-09 12:59 PM, -0800 by RameshDara.
This page was created on 12-Feb-09 14:38 PM, -0800 by Nikita.

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