Client/Server--Bolstering Throughput

Prinergy can scale its client/server architecture to increase system throughput in small-to-large commercial printing operations. The objective: Add software and hardware components until the workflow is keeping up with the pace of CTP.

BY MARIE RANOIA ALONSO

Client/server technology has been implemented in many industries. Whether booking reservations for air travel or making a last-minute stop at an ATM, both are direct links to some form of client/server architecture designed to improve speed and performance.

Now, prepress is following suit.

Yes, client/server architecture—a term just vague enough to encompass a variety of digital workflow solutions that link users at their desktops to the servers processing their files—is targeting prepress.

Why? The benefits of client/server architecture in prepress include: wider access to information on the server; improved visibility in a digital workflow; improved communication across shifts, departments and locations; and improved system reliability—one client workstation can crash without affecting other users.

The newest such solution to hit the block is Prinergy, a page-based workflow solution launched at Seybold San Francisco last month by Creo and Heidelberg Prepress.

Prinergy is the first workflow management system, to date, that utilizes not only Adobe PDF, but also Adobe Extreme, a prepress architecture based on Adobe PostScript 3 that uses Adobe PDF and the Adobe Portable Job Ticket Format (PJTF) to automate prepress processes. Prinergy's goal is to provide a distributed digital workflow. As a client/server architecture, Prinergy sports a universal interface, allowing for cross-platform publishing.

"When we were defining the requirements of our new workflow system, a multi-client/multi-server model was at the very top of the list. Bottlenecks change quickly in prepress, and a printer needs a flexible system that can adapt software and hardware resources to keep pace with the platesetter and the presses," reports Creo's Shannon MacLeod, product manager for Prinergy. "Because Prinergy was designed with distribution in mind, we made specific choices about which software protocols and standards to use."

Working with Heidelberg Prepress, Creo chose CORBA (a TCP-IP Internet protocol) for the link between the client software and server software. This enables remote access and WAN environments, with multiple clients at servers at different locations. Creo also chose JAVA for the client (user interface application) software, which can run on either a Mac or Windows workstation.

"We chose Adobe's Extreme as the communications and processing hub," MacLeod adds. "Extreme is client/server capable, with multiple software engines running on multiple servers."

Prinergy is unique because software and hardware can be added independently to add resources exactly where needed. This also makes adding throughput more affordable because it can be done in small chunks. Every Prinergy system has a Primary Server. This is where an Oracle database resides.

Serving the Client
To better understand how Prinergy operates as a client/server architecture, it's important to understand the nature of the client/server itself Generally, there are three levels of any client/server implementation: single client/single server; multi-client/single server; and multi-client/multi-server.

Single Client/Single Server: The server does the primary workload of processing the files; the client serves as the user interface. As a read-only queue manager or an accessible application used to control the software at this level, the client and the server are somewhat tied together. If a second server is added, a second client is added. Each client can only see its original server.

Multi-Client/Single Server: With multiple clients, a number of operators can access the one server—the software may or may not be groupware, depending if the software has a custom user interface.

Multi-Client/Multi-Server: In this environment, the server can distribute or farm out processing tasks to additional computers in order to prevent a bottleneck with its own limited CPU resources. Multiple clients can access the software running on all servers.

At this level of a client/server implementation, resourcing (managing CPU and network bandwidth) and licensing (enforcing software licensing) come into play. This model of client/server also has huge potential for remote production. The client can be at any publisher, design firm, commercial printing site or prepress house and the servers can be at the same or other locations.

This is the model that reflects the activities of Prinergy. A multi-client/multi-server approach to prepress is a plus because it can, if correctly implemented, offer a solution to the following production failures—all near and dear to the heart of any paranoid prepress director.

For example, what about fail-over and system backup? When one server goes down, can the remaining server continue? Or what about the need for a reliable, central repository? A database is better than a folder of text files. Prinergy has on-line and off-line system backup to copy the contents of the database for disaster recovery.

"When the primary server is running at full capacity, a secondary server can be added to further increase system throughput," advises MacLeod. "Any software engine can be installed on a secondary server."

As an example, MacLeod explains that normalizing and proofing software is usually duplicated on both the primary and secondary servers. Individual software engines can be added incrementally to either a primary or secondary server for a completely customized workflow.

There is no inherent limit to the number of secondary servers or software engines a Prinergy system can have and, thus far, Creo has specified five different configurations.

"The configurations are measured in system throughput (pages and plates per eight-hour shift) and range from 40 plates per shift to 300 plates per shift. Eventually, the throughput can only be increased by adding more CTP devices," MacLeod says.

When additional software engines or servers are added, Prinergy automatically tracks the new components in the database and automatically load-shares jobs between system resources for maximum throughput. As a result, it is very easy to scale a Prinergy system to address specific bottlenecks, without retraining operators or manually managing multiple print queues.

"System reliability and support are also benefits of a client/server in prepress," MacLeod advises.

The bigger picture? Client/server architectures represent the logical end to the days when three prepress operators were forced to crowd around a computer in order to work on their jobs. Now, operators can edit traps, make imposed proofs, output plates and archive files from the comfort of their desks—Prinergy does the rest.