How Documentum Print Control Services Works

December 15, 2011 at 1:18 pm | Posted in Architecture | 1 Comment
Tags: , ,

This is the second part of a mini series of articles on Documentum Print Control Services (PCS) and how to use it effectively. The first part provided an introduction and overview of PCS. In this article I will take a much more in-depth technical look at the product.

PCS consists of a number of components:

  • A DFS-based web service that is deployed on a JBoss application server
  • A set of DARS that contain services that can be used by user-facing applications
  • Optional WDK components for Webtop and Taskspace (as mentioned in the first article this PCS support is built into Documentum Compliance Manager)

As we will see later PCS also relies on PDF and Postscript rendition generation so DTS or ADTS is required.

So what happens when a controlled print request is issued from an application? The printing user-interface will usually collect some information from the user relating to the object to be printed. This will include the name of the printer and a reason for the print. Once the request is received by the application server control will be passed to the PCS ControlPrintService.requestPrint() function.

The requestPrint function does 3 things. First PDF Stamping Services (PSS) is used to create a watermarked copy of the main PDF rendition. I may cover PSS in more depth in another article, however the key point here is PSS takes an existing PDF rendition and generates a watermarked PDF that can include metadata overlaid in headers, footers or other areas of the document. PCS and PSS have tight integration where PSS exposes a Controlled Print-specific configuration and PCS can pass in Controlled Print attributes such as copy number, recipient and printing reason to be watermarked on the document.

Click to view in a new window

Next a dmc_pss_print_copy object is created in the repository. The watermarked PDF is the primary rendition for this object and the object is linked to the /Temp/PCSCopies folder. At this point the object’s print_status attribute is set to ‘Created’.


Click to view in a new window

Finally, a request for a Postscript rendition for the dmc_pss_print_copy object is made. The rendition will have a page_modifier of ‘PS4Print’. The server will wait for up to 2 minutes for the rendition to be generated and then return to the caller. Either way the print_status field is set to ‘PsRequested’. Up to now all the processing is synchronous, but now control is returned to the user of application.


Click to view in a new window

At this point the user is probably expecting the printer to output the printed document, however no print request has yet been sent to a printer, there is simply a dmc_pcs_print_copy object created possibly waiting for Postscript rendition to be created. There are 2 asynchronous task still required to be completed. First the Postscript rendition needs to be created:

Click to view in a new window

Of course it may have been created during the earlier synchronous processing but there is no guarantee. Continuous uninterrupted operation of controlled printing requires that your DTS or ADTS infrastructure is resilient, scalable and sized for all the rendition requests generated in a production environment. If your users have requested prints that don’t seem to be appearing your first port of call for troubleshooting is to confirm that DTS/ADTS is working and that Postscript renditions are being created for your dmc_pss_print_copy objects.

The Print Control Services server is ultimately responsible for sending your document to the required printer. Calling the Print Control Services server is the responsibility of the PcsAsyncPrintJob. For controlled print (and recall) requests to be completed in a reasonable amount of time this job needs to be set to run every couple of minutes and needs to be monitored for regular execution and successful job completion.

When PcsAsyncPrintJob runs it queries for all dmc_pss_print_copy objects that have print_status = ‘PsRequested’.

Click to view in a new window

For each dmc_pss_print_copy object the PCSAsyncPrintJob does the following:

  1. Ensures that a Postscript rendition has been created. If not no further processing is done on this execution of the job.
  2. Then calls the remote ControlPrintService DFS endpoint on the PCS server, calling the ‘print’ method.

Once the print request is received by ControlPrintService component the following happens:

  • The audittrail is checked to ensure that the same document has not been printed with the requested copy number. If for some reason there is already an audittrail entry for this copy number an error is raised.
  • The postscript file is sent to the printer using the Java Printing Service API.
  • The service monitors the print job until completion (or failure) and then returns a response to the PcsAsyncPrintJob job.
  • Creates an audittrail entry to record the controlled print


Click to view in a new window

The actual “printing” part of PCS is carried out using the Java Printing Services (JPS) API. If you are going to be making use of PCS in your organisation it may be worth your while getting to know the JPS a little better. I’ll discuss JPS in more depth in a later article. Once PCS has sent the document for printing it sets the print_status attribute to ‘PrintRequested’ – this is the last status update for the document. Note you only know that PCS has requested a print from the printer – there is no way for PCS to ‘know’ whether that print was successful and so it can not update the object further.

The key points to take away from this article are as follows:

  1. First, when the WDK application server returns control back to the user after a print request has been made there is no guarantee that the document has been sent to the printer. There are 2 layers of asynchronous processing required to print a document; depending on the speed, capacity and availability of the relevant servers it may take some time for the print to appear.
  2. Second the print may even not appear at all if there is a problem with one of the asynchronous components. This fact may not be obvious to the end user who may just assume that printing is “slow”.
Advertisements

An Introduction to Documentum Print Control Services

December 5, 2011 at 1:31 pm | Posted in Architecture | 3 Comments
Tags: , ,

This is the first part of a mini series of articles on Documentum Print Control Services (PCS) and how to use it effectively.

Documentum PCS originated in the compliance products however from the 6.6 release it is a standalone product. If you haven’t worked in regulated environments before you may be a little unclear as to what its purpose is. PCS “controls” the printing of certain important documents, ensuring that a number of things happen when a “Controlled Print” takes place.

I’ll discuss the what first and then explain the why. First whenever a controlled print of a document is made that fact is recorded in the audit trail. A copy number is associated with the document and recorded in the audit trail entry; if you print another copy of the document then the copy number is incremented. In effect every print of a document is uniquely identified by object id and copy number. In fact PCS works in close tandem with Documentum PDF Stamping Services (PSS) to allow a watermark including the copy number to be overlayed on the printed document.

Additionally every printer in the organisation has to be added to the PCS configuration so controlled prints can only be made to well-known printers. Again the printer to which the print is sent is recorded in the audit trail.

Finally, subsequent to executing the controlled print, it may be necessary to record a ‘Recall’ of the print. A ‘Recall’ is recorded in the audit trail against a unique document print (the object id and copy number). The reasons for needing a recall maybe part of the operational lifecycle – one or more documents may have been superseded by an updated version and so all prints of the old version must be physically removed and that removal needs to be recorded. Alternatively it may simply be that a print was stuck in a printer or damaged or lost. It’s worth bearing in mind that when ‘Recalling’ a document with Documentum PCS the only thing that happens is that the recall is recorded in the audit trail as evidence and for reporting. PCS won’t, for example, halt print requests already sent to the printer.

A recall results in a notification sent to the inbox of interested parties. The recipient has to confirm acknowledgement of the notification, at which point a further audit trail entry is created. Thus there are 3 types of audit entry that can be created:

  1. On print
  2. On recall
  3. Recall confirmed

As pointed out in the comments both print and recall actions require the user to authenticate themselves before they are able to proceed.

So now we know what PCS does but it may not be clear why an organisation would need this functionality. As I alluded to earlier printing control is often used in regulated environments. Typical examples would be pharmaceutical or medical manufacturing, or aircraft production. These activities often take place in a factory or lab and need to follow defined and documented processes. Often this process documentation is physically printed, as online reference to the documentation is inconvenient or difficult.

In these types of scenario it is clearly essential that correct and up-to-date documentation is used by production staff (how happy would you be if certain components on the plane you are flying on were manufactured using out-of-date processes?). Not only does it make sense for management in these organisations to know there is a process to record what documentation is in use and when it is updated but in many cases regulatory authorities will required evidence that such systems are in place and demonstrated to work.

Given the above it is unsurprising that this functionality originated in the Documentum Compliance Manager (DCM) product. In earlier versions of DCM watermarking and print control were achieved using integrations with Liquent’s PDF Aqua products. However PCS was introduced as part of DCM 6.5 sp1 and became a separate product in 6.6. Controlled Print and Recall functions are provided as part of the DCM user interface but the latest release of PCS product comes with components that can be installed in the Webtop and Taskspace interfaces. This is part of EMCs policy of moving compliance functionality into the core stack and making it available to all clients rather than retaining a dependency on specialised interfaces. No doubt these features will be available in the C6 products at a later date.

The next installment will dig into the guts of the PCS architecture to see how it works.

Update (14 Dec 2012): I wonder where the new Life Sciences products announced with D7 will fit in with PCS? Will they use PCS and PSS or is there some other technology to do this?

 

Create a free website or blog at WordPress.com.
Entries and comments feeds.