Using Platform Events with Queueable Apex – User friendly Tech help

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Scenario:- How to call Queueable Apex inside platform events 

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Step1:- Have a button(can be vlocity action or vlocity Omniscript guided flow) on SFDC UI to call the “Apex Handler”

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Step2:- “Apex Handler” will call Platform Event

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         //calling PE with the required paramsn        Demo_Platform_Event__e peObj = new Demo_Platform_Event__e( EndPoint_Url__c = endPointUrl );n        Database.SaveResult sr = EventBus.publish(peObj);       n        if (sr.isSuccess()) {                        n            System.debug('Successfully published Demo_Platform_Event__e Event.');n        } else {n            for(Database.Error err : sr.getErrors()) {n                System.debug('Error returned on Publishing Demo_Platform_Event__e Event: ' +n                                err.getStatusCode() +n                                ' - ' +n                                err.getMessage());                     n            }n            n        }

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Step3:- “Platform Event” when called will launch the “Trigger”

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Setup > Platform Events > New Platform Events

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Add Trigger and Custom Fields as shown below:-

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Step4:- Inside “Trigger” call the Queueable Apex

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Here we can bulkification trigger to a batch size of 50, as supported by Queueable. 

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trigger demoTriggerHandler on Demo_Platform_Event__e(after insert) {n     List peListItems = new List(); n     Integer  counter = 0;n         for(Demo_Platform_Event_e__e peObj : peListItems) {n            counter++;n            System.debug('Counter = '+ counter);    n            if (counter >=  50) { //taking batch size of 50 Id's as supported by Queueable Apexn                break;n            }n             else{n                  peListItems.add(peObj);n            }n            //platform event busn            EventBus.TriggerContext.currentContext().setResumeCheckpoint(peObj.ReplayId);           n        }    n        // instantiate a new instance of the Queueable class and pass paramsn        calloutHelper objCallout = new calloutHelper(peList);n        ID jobID = System.enqueueJob(objCallout);n        System.debug('jobID = '+ jobID);n}

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Step5:- “Queueable Apex” will initiate “HTTP callout” to the external system.

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       //Sample HTTP callout n       Http http = new Http(); n       HttpRequest req = new HttpRequest(); n       req.setEndpoint(endPointUrl); n       req.setMethod('PUT'); n       req.setBody(inputData); nn       req.setHeader('content-type', 'application/json'); n       req.setHeader('Accept', 'application/json'); n       HTTPResponse res = http.send(req); n       outputMap.put(KEY_RESULTS, res.getBody()); n       Integer statusCode = res.getStatusCode(); n       System.debug('code ='+statusCode); n       if(statusCode == 200){ //do logic on the success } n       else{ //throw exception }

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