In my case, I'm doing a migration from Mule 3 to Mule 4.
I have some questions regarding the manual migration from Mule 3 to Mule 4.
How to use the expression component in Mule 4?
Are there any other ways to use session variables?
In Mule 3, I used an expression component to return Java code to my logic. I'd like to reuse that Java code in Mule 4.
The message enricher component is not supported in Mule 4.
Mule 4 does not support transformers such as DOM to XML, XML to String, and so on.
Please assist me.
Several of the questions asked are already explained in the Migration Guide.
How to use the expression component in Mule 4?
In Mule 4 the expression language is DataWeave 2. You should learn about DataWeave and read the migration guide from MEL to DataWeave.
Are there any other ways to use session variables?
No. This is mentioned in the migration guide Migrating Core Components: "Session variables have been removed. Users must explicitly pass headers across transport boundaries."
In Mule 3, I used an expression component to return Java code to my logic. I'd like to reuse that Java code in Mule 4.
You can call Java static methods directly from DataWeave. Also you can execute any Java method with the Java Module and store the output in a variable to be used in a DataWeave script.
Additionally you can create custom functions to add to DataWeave using the Mule SDK.
Note that in Mule 4 you should not use any Mule APIs in your Java code.
Generally speaking try to see if you can use pure DataWeave features before trying to call Java code.
The message enricher component is not supported in Mule 4.
There is no need for the enricher. Mule 4 can use target variables in any operation. This is mentioned in the migration guide.
Mule 4 does not support transformers such as DOM to XML, XML to String, and so on.
That's right. You should use DataWeave Transformations instead of transformers. Yet another topic mentioned in the migration guide.
Related
In mule application I am trying to parse RAML file. I knew that APIKit is doing same as it creates flows after parsing the RAML file. But still, what if I want to parse it in middle of the flow manually?
I have seen the raml parsers available but not finding the proper usage of those javascript libraries or java libraries on how to use them in mule application..
Yes you can parse your RAML in your java application using java class or groovy component implementing java.
There are java parser available like RamlModelBuilder which you can use to parse your application RAML like validation of your RAML file, getting APIs name, getting all resources name, method name, scopes, security schema and their names, query parameters, headers and many more...
Just check the example how it is used here. You can simply create a java class and get your RAML parsed
https://github.com/anirban37/Anirban-Custom-Oauth-Policy/blob/master/Anirban-RAML-Oauth-V3/OauthPolicies.xml#L594.
ramlModelResult = new RamlModelBuilder().buildApi(ac.getRaml())
will give you the current RAML file access of the application in the java class
Theres nothing in Mule to work with the RAML file at runtime.
But you can create any Java component that uses RAML Java libraries and invoke that from Mule in your flows.
The Mule4 SDK is one way of extending mule through Java.
For more information on Mule SDK can be found here https://mule4-docs.mulesoft.com/mule-sdk/v/1.1/
You can also invoke Java classes but they need to be decoupled from the Mule API and you need to extract any variables, properties or payload and explicitly pass the values to your class. For example passing a static String and a flow var as arguments to a Java constructor:
<java:new class="com.foo.AppleEater" constructor="MyClass(String, Apple)">
<java:args>#[{name: 'some string arg', apple: vars.apple}]</java:args>
</java:new>
In your class you could use the RAML Java libraries, and pass the file or path to RAML file to load from the classpath.
More on Java integration with Mule 4 here: https://docs.mulesoft.com/mule-runtime/4.1/intro-java-integration
Is it possible to use mule message properties (like payload and flowvars) in a Mule Management Console notification body or subject?
I think it's not possible.
You can only use the properties exposed by mule, as explained here:
http://www.mulesoft.org/documentation/display/current/Defining+SLAs+and+Alerts#DefiningSLAsandAlerts-PropertiesUsedinAlertExpressions
Maybe using a Management Script, but there is no much info about it (the links to the javadoc are broken)
http://www.mulesoft.org/documentation/display/current/Scripting+Examples#ScriptingExamples-AlertingExamples
Yes you can use it. Mule provide various properties common to all alerts from class com.mulesoft.console.alert.RaisedAlert that can be used in defining the certain values such as
Flow identifier
Flow name
You may refer to mule documentation for it
https://docs.mulesoft.com/mule-management-console/v/3.7/defining-slas-and-alerts#DefiningSLAsandAlerts-PropertiesUsedinAlertExpressions
I'm attempting to define a spring bean using as below:
<lang:groovy id="mmmm" name="GroovyRssGeneralTestServer" script-source="${app.home}/groovy/RssGeneralTestServerImpl.groovy">
<lang:property name="xmlFile" value="${app.home}/rss/GeneralTestServer.xml" />
</lang:groovy>
I've tried several different locations for the script-source, but have had no luck in getting mule to find the source for the groovy script.
Second, I'm curious whether I can even wire up a groovy component to use this bean even if I do get it configured correctly above?
Why are you trying Spring bean when there is a Groovy component in Mule that can execute external Groovy script ? Please refer :- http://www.mulesoft.org/documentation/display/current/Groovy+Component+Reference
and this :-
http://groovy.codehaus.org/Dynamic+language+beans+in+Spring
Hope this help
We purchased an Enterprise Mule license in May, and I have also bought and read your Mule in Action at Manning.com. I read Enterprise Integration Patterns, and I have used Mule doc extensively -- I cannot seem to find a comprehensive list of what endpoints produce what kind of data types, or what properties are available for that specific message at any one stage of a flow.
Example: I used a JDBC endpoint to read from a mySQL database and received back a list of maps. Yet i don't see a Mule object to process this list of maps, so i had to write a component in Java to process it and return the columns i wanted from the result set.
I stumbled in the dark thru this whole process, and I am not a rookie in Java EE; I have been using Java and WebSphere off and on for 10 years.
I had read the Mule and MVEL docs and all I see are the Mule object/context names, but no more about when and how they will be available or what data format they will return in.
Is there a comprehensive list of what endpoints (or any other Mule object(s)) produce what kind of data types and also what properties are available for that specific message at any one stage of a flow?
Unfortunately, the Mule reference guide still lacks a formal definition of the generated payload types and supported properties (inbound end endpoint). MuleSoft is aware of the lack and has started to document the latter, as you can see for the HTTP transport.
For now your best bet is to use visual breakpoints in Studio or <logger> elements to introspect the message characteristics.
I am new to Mule and hoping to avoid going in the completely wrong direction. I would like to create a component, which other devs can add to their Components lists in Mule Studio (to be dropped into their flows).
I see that I can create a Java class that implements callable, which can be added to a Flow by using a Java component and setting its "Class Name" to the one I created. Is there a good way that I can use this to package as a component that can be plugged in to Mule Studio? Or is Mule Devkit the best option for this?
Mule DevKit is the very best option for this. Other alternatives imply messing with Eclipse-related code. You don't want that, go DevKit: http://www.mulesoft.org/documentation/display/current/Mule+DevKit