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Customize the Processing of the Jobs

Without customization, the jobs are processed (converted) using defaults which already fit in most cases. For the configuration of the processing, so-called flows are used which are read and executed by the seal-convert-dispatcher service.

Basically, a flow is an asynchronous Javascript function, defined by the special def keyword. A flow gets the current job metadata as parameter and may call other flows or converters or manipulate the job metadata. Additionally, it can directly access additional functions and objects provided as program context.

The flows are kept in the MongoDB and can be administrated via PLOSSYS CLI.

The first flow to be executed for every job is the main flow. More standard flows (see below) are provided and you may also implement your own customer-specific flows which then overwrite the standard flows with the same name.

Standard Flows for Conversion

The following standard flows are called by the main flow for the conversion in the specified order:

  1. preconvert

    The preconvert flow converts non-PDF formats into PDF for further processing. For each known non-PDF format, a conversion service is called for the conversion into PDF.

  2. format

    The format flow prepares the document created by the preconvert flow for the printers media, for example, by scaling or rotating.

  3. render

    The render flow changes the document content created by the format flow, for example, by adding stamps or watermarks.

  4. postconvert

    The postconvert flow converts the document created by the render flow into PostScript for the output to the printer.

Customer-specific User Exits

Each standard flow for the conversion can be extended by calling customer-specific user exits:

  • before_<flow_name> is called before the <flow_name> flow.

  • after_<flow_name> is called after the <flow_name> flow has been finished.

Use a Customer-Specific Flow

For customizing the processing of a job, you can implement a new flow and import this to the configuration by using PLOSSYS CLI.

  1. Implement a new flow and save it to a file.

    For implementation details, refer to the Implementation Details.

  2. Import the new flow by using PLOSSYS CLI:

    plossys flow import <file_with_new_flow> --flowname <flow_name>

  3. Restart the following service:

    • seal-convert-dispatcher

Implementation Details

Supported Functions and Objects

The following functions and objects are supported when implementing a flow:

Name Type Description
def(flowName, func) function Defines a new flow with name flowName and async flow function func
uuidv4() function Returns a new unique UUID v4 identifier
log object Logging; contains methods debug, info, warn and error for the different log levels
Error object Standard Javascript error object for throwing conversion or custom errors
convert(job, serviceParams) function Calls a service for converting a job

convert(job, serviceParams)

convert is a function for calling a service to convert the job. The serviceParams object contains the string property service and the optional object property convertParams containing key-value pairs with converter-specific configuration.

  • job Job to be converted

  • serviceParams Object containing the service name and converter-specific options

convert is a function for calling a service to convert the job. The serviceParams object contains the string property service and the optional object property convertParams containing key-value pairs with converter-specific parameters, which in case of converting with an executable are given to this executable (e.g. sapgofu2pdf.exe).

await convert(job, { service: 'convert-dummy', convertParams: { '-convert-it': 'this way' } });

Job Objects

In addition to the metadata, the job object provides functions for calling another flow and for testing if a flow exists.

Name Description
exist(flowName) Synchronous function returning true if a flow with the name flowName exists; otherwise, false
call(flowName, args) Asynchronous function calling the flow called flowName and optional args parameters

Example - syntax

def('main', async function (job) {
  log.info('main dummy flow', {
    uuid: job._id,
    jobId: job.refId
  });
  if (job.current.printerName === 'pcl_1') {
    if (job.exist('move2printer') {
      await job.call('move2printer', { printer: 'printer2' });
    } else {
      throw new Error('Flow move2printer is missing.');
    }
  }
  return job;
});

def('move2printer', async function (job, args) {
  log.info('move2printer flow', {
    uuid: job._id,
    jobId: job.refId,
    args
  });
  job.current.printerName = args.printer;
  return job;
});

Environment Variables

The following environment variables are evaluated by the seal-convert-dispatcher service:

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