Understand the Scheduler

The updated architecture of the Scheduler uses the Java Messaging Service (JMS) queue technology.

This architecture enables you to add multiple publishing servers to a cluster and then dedicate each server to a particular function: report generation, document generation, or specific delivery channels.

Architecture

The architecture of the Scheduler uses JMS queues and topics to provide a highly scalable, highly performing and robust report scheduling and delivery system.

The figure below displays the scheduler architecture.

The following list describes the tasks performed by the scheduler when a job is submitted:

  • Submit Job

    • Stores job information and triggers in Quartz tables

  • Job Processor

    • When quartz trigger is fired, puts job information in Scheduler job queue

  • Bursting Engine / Batch Job Process

    • Bursting Engine Listener

      • Takes the scheduled job information from the queue

      • Extracts data from data source

      • Splits data according to bursting split by definition

      • Stores data temporarily in temp folder

      • Puts report metadata into Report Queue

  • FO Report Processor

    • Listens to Report Q

    • Generates report based on metadata

    • Stores report in shared TEMP directory

    • Puts report delivery information in Delivery Queue

  • Delivery Processors

    • Listen to Delivery queue

    • Call delivery API to deliver to different channels

  • Publisher System Topic

    The Publisher System Topic publishes the runtime status and health of the scheduling engine. The topic publishes the status of all instances, the thread status of messages in the JMS queues, the status of all scheduler configurations such as database configuration, JNDI configuration of JMS queues and so on.

About Clustering

Clustering enables you to add server instances on demand to handle processing and delivery load.

The figure below illustrates clustering. Note that the report repository and the scheduler database are shared across the multiple instances; also, the JMS queues for scheduling and JMS topic for publishing diagnostic information are shared across the server by registering JMS queues and topics through JNDI services.

Each managed server instance points to the same report repository. In each managed server instance all the processes such as Job Processor, Report Processor, E-mail Processor, FTP Processor, Fax Processor, and Print Processor are configured. Therefore the moment a server instance pointing to the same repository is deployed, it is added to the cluster and all the processors in this instance are ready to run.

You can select the process to enable on any server instance, thereby using the resources optimally. Moreover, if there is a demand to process heavier jobs you can add more instances for report processing. Similarly, if e-mail delivery is the most preferred delivery channel, then more instances can be added to scale up e-mail delivery.

How Failover Works

The failover mechanism ensures that no report fails to deliver due to server unavailability.

Achieve this by balancing each process of the Scheduler using two or more nodes in a cluster thereby ensuring that a failure of any node must be backed up by the second node without any loss of data. For example, by enabling the Job Processor in two nodes, if one node fails, then the second node can process the pending jobs.

If a node goes down, the other nodes continue to service the queue. However, if a report job is in one of the following stages of processing: data retrieval, data formatting, or report delivery, the job is marked as failed, and must be manually resubmitted.

About Prioritizing Jobs

You can configure the processing order of jobs.

You can prioritize jobs and ensure that the high-priority report jobs run before the non-critical jobs when multiple jobs run simultaneously. In the General tab of the Report Properties page, you can set the job priority as Critical, Normal, or Low priority. When jobs are queued, the processing of a job depends on the priority specified for the job’s report. If you don’t prioritize jobs, the critical jobs, non-critical jobs, and on-demand queries can compete for resources and the critical jobs might get delayed. In the Report Job History page, you can identify the critical jobs and view the status of each job.