How to prepare for MuleSoft Certified Developer Certification - Part IV

 Are you preparing for MuleSoft Certified Developer Certification and looking for some guidelines and material about how to prepare then you have reached the right place. During preparing for MuleSoft Certified Developer Certification, I captured notes. I thought let me share everyone so that it will be beneficial to whoever preparing for the certification. This is the fourth part of the notes. You can visit the previous part if you have not visited yet here - How to prepare for MuleSoft Certified Developer Certification - Part III. 

Item	Notes
Writing DataWeave transformations	1. DataWeave is used for                 XML, JSON, JAVA transformations                 Complex data structure transformations                 Define and use global and local variables and functions                 Coerce and format strings, numbers and dates                 Define and use custom data types                 Call Mule flows 2. Metadata is stored under src/main/resources folder in application-types.xml file 3. If we edit metadata in the input section of Transform Message component then sample file (json.json) is generated under sample_folder in src/test/resources 4. Types of DataWeave errors                 a. Scripting error                 b. Formatting error 5. Comments in DataWeave                 a. Single line -> //                 b. Multi-line -> /**    */ 6. To create a field as an attribute in XML use @(field). When we translate from XML to JSON use @ before consuming the attribute 7. map (object, index) -> { } functions                     $$ refers to an index                 $ refers to the value 8. If we would like index value to be appended to variable and map function DO NOT have definition of (object, index) then use $$ to append index e.g. 'flight$$' it will give results flight0, flight1 9. If we would like index value to be appended to variable and map function have a definition of (object, index) then use single $ with () e.g. 'flight$(index)' it will give results flight0, flight1 10. If we are transforming XML message to java and XML contains multiple child elements (e.g. returns) then {()} need to be removed to show all indexed java objects 11. 'do' clause requires body separator --- 12. 'format' schema property used to coerce                 a. when used for string, the format is associated with the output                 b. when used with a date, the format is associated with the input 13. To create custom datatype, use type header directive e.g. type abc = ''; --- payload   Another option is to use fully classified class name. 14. lookup function can be used to call the flow. lookup function cannot call subflow
Triggering flows	1. Connectors while working with the file is                 FILE, FTP, FTPS, SFTP                 Functionalities - file matching, locking the file, Overwriting, appending, generating new files 2. When the application deployed to ClouldHub, access is only to /tmp folder 3. Mule supports automatic and Manual watermarking                 For manual watermarking ObjectStore is used 4. Id column is used to make a sure the same record is not processed twice with concurrent processing 5. new poll can be executed before the watermark is updated if                 The poll interval is small                 The high volume of records to processed                 Processing of each record take longer time 6. JMS connector to publish and consume JMS messages                 Publish consume - Synchronous                 Publish - Asynchronous 7. The watermark column enable the On Table Row Operation to avoid duplicate processing of the records 8. File List the operation returns Array of Mule event objects
Processing records	1. For each scope is used to process records from the collection                 If an error occurs then for each scope processing stops and the event is returned to the error handler 2. batch scope is used to process records for the filter, aggregate 3. Phases of batch job                 Load and dispatch (implicit)                 Process (required) - Asynchronous                 On Complete (Optional) 4. Default configuration                 Blocks of 100                 Threads - 16 5. until a max number                 default 0 - stops process with first error                 -1 - batch continues without many errors                 +  - number of errors occurs these many numbers then process stops 6. Filters in batch step                 accept expression - the process records if evaluates true                 accept policy