MuleSoft Error Handling using reusable Common Error handling

Introduction

Application logging and error handling are critical parts of log management and help a business run smoothly. If you don’t have any proper logging records, it is difficult to identify the events, making troubleshooting a long and time-consuming process.

Generally, developers use different logging practises to log the events, but in case of a mishap, it is a default to find the required data that is helpful for troubleshooting. This again requires a long process of additional coding or debugging to derive the relevant data.

To overcome the above scenarios, we have developed a framework for service utility service error handling. This essentially standardises the message logging and exception handling scenarios in any kind of MuleSoft API. The out-of-box utility service minimises developer efforts by 10-15%.

What is Utility Service?

Utility Service is a framework that logs messages with all the required information that would be helpful for troubleshooting. It has the capability to log the message in different formats.

Services offered by Utility Service

• It supports different log formats.
• Maintains one transaction across different layers (system, process, and experience). Using this, one can easily track the transaction from start to finish.
• No additional formatting or logging is required, and it is easily publishable to data aggregation platforms like Splunk, ELK, and others.
• It calculates the latency from start to end across layers, which is useful to monitor the performance of the application.
• Request level details can be tracked using RequestID and FunctionalID params. The RequestID will be unique for different layers.
• Additionally, it supports up to 10 context keys to log any other information.
• It will propagate the actual error details to the consumer, even in the case of an API-led approach.
• One can easily configure it to log the original and errored payloads.
• Logs the source and target names, which are helpful for the triage team.

Different formats are supported by Utility Service

• JSON
• XML
• CSV

Setting up the Utility Service

Using the Runnable Jar

1. Download the Utility Service Jar.

2. Include the Utility Service library in the Maven local repository using the below command.

mvn install:install-file -Dfile=\\co-utility-service-v1-1.0.0-mule-application.jar -DgroupId=com.co -DartifactId=co-utility-service-v1 -Dversion=1.0.0 -Dpackaging=jar -DgeneratePom=true

3. Add the below dependency to your mule project pom.xml

<dependency>
                   <groupId>com.co</groupId>
                   <artifactId>co-utility-service-v1</artifactId>
                   <version>1.0.0</version>
 </dependency>

4. Import “co-utility-service.xml” from the utility service into your project global elements and use the utility service for logging and error handling.

Code snippet

<import doc:name=“Import” doc:id=“6dfee7a7-d89a-499b-a4c6-4e24e28d1dd5” file=“co-utility-service.xml” />

Using Utility Service for Error Handling

The utility service is simply used by calling the flows defined using Flow Reference. From here, it automatically handles the errors and logs the transaction in the specified format.

Prerequisite properties to configure

Property	Usage	Supported values	Example
app.sysname	Application Name	Any	co-utility-service
app.version	Application Version	Any	V1
app.source	Source Name	Any	SFTP
app.target	Target Name	Any	Salesforce
app.log.originalPayload	Logs the original payload from the source if set to true	true/false   Default – false	true
app.log.erroredPayload	Logs the errored-out payload in case of error if set to true	true/false   Default – false	true
app.log.format	Logs the message in the specified format	json/xml/csv   Default – json	json

The Utility Service logs the below information

Log Fields	usage
serverName	Name of the server where application hosted
appName	Name of the Application
appVersion	Application Version
environment	Environment of the application
source	Source Name
target	Target Name
transactionId	Transaction Id
transactionState	Transaction state
requestId	Request Id
executionState	Execution State
serviceResource	End point called
serviceMethod	Method of the resource
payload	Payload
logTimeStamp	Current Time Stamp
logMessage	Logs the Message provided
functionalId	Any unique ID from the Request
contextKey1 .. contextKey10	Any additional details for logging
logLevel	Log Level
latency	Total time is taken for the process
errorAt	The component at which the error has occurred
errorCode	The Response Status code in error cases default is 500
errorType	Type of the error Ex: “Internal Server Error”
errorMessage	The appropriate error message

Global Error Handler

The globalErrorHandler flow logs the error details in the event of any errors. This flow works on “On Error Propagate” as well as “On Error Continue”. It logs the error messages in different formats like JSON, XML, and CSV.

Steps to configure

• Drag and drop ‘On Error Continue’ or ‘On Error Propagate’ based on the requirement.
• Drag and drop the flow reference inside the error handling.
• Select the globalErrorHandler as a flow name from the drop-down.
• Configure app.log.erroredPayload property to log the errored-out payload if required.
• Configure log format and other properties as per requirements.

The globalErrorHandler logs the root cause of the error.

Suppose the error occurs at the system layer; the same error will be propagated back to the process and application layers.

Snippet of globalErrorHandler

The globalErrorHandler set the actual error status code in the httpStatus variable. The same variable can be used in the HTTP response header to propagate the error status.

Sample error log

{
    "serverName": "LAPTOP-KALVA",
    "appName": "demo-sample-papi",
    "appVersion": "v1",
    "environment": "dev",
    "transactionId": "5da88430-08f8-11ed-bd7c-d20f0c30c779",
    "transactionState": "Transaction_Error",
    "requestId": "66870726-279b-45dc-8270-a48b165a2740",
    "executionState": "Error",
    "serviceResource": "/papi/orders",
    "serviceMethod": "GET",
    "payload": "{\n  \"orderId\": 987456321,\n  \"customerId\": \"12934\",\n  \"items\": [\n    \"ABB-123\",\n    \"ACC-452\"\n  ]\n}",
    "logTimeStamp": "2022-07-21T18:53:54+0530",
    "functionalId": 123,
    "contextKey1": "test",
    "logLevel": "Error",
    "latency": 1118,
    "errorAt": "demo-sample-sapi-flow/processors/4 @ demo-sample-sapi:demo-sample-sapi.xml:24 (Request)",
    "errorCode": 404,
    "errorType": "Not Found",
    "errorMessage": "No listener for endpoint: /test11111111"
}