Preactor on Google+ Preactor on Twitter Preactor on Facebook Preactor on LinkedIn
Collaborative Scheduling
We understand the nature of modern business means operations are often split over several sites.

Whether it is the complexity of the work which means it is too much for one person to manage, or the specific knowledge of processes or customers held by individuals, or even basic organisational or geographic issues, the responsibility for making scheduling decisions is often divided.

That’s why Preactor is equally at home scheduling with multiple planners as it is with a single user.

We also know that, how you have decided to split your planning decisions between employees has likely already been tailored to suit your business.

That’s why Preactor has been designed to fit smoothly into your existing set-up, rather than forcing you to change to accommodate Preactor.

The software is so flexible it can be configured to work in an almost infinite number of planning situations.

However, many will follow one of five basic scenarios each with its own advantages and disadvantages, which are described below.

Whatever the scenario that fits your requirements, Preactor can help you.


In a parallel scenario, each system has sole control of its capacity and workload.

All routings are contained within each system, and although orders may be passed between them, this must be done through external communications.

Preactor was used in a parallel system at a British multinational tobacco company.

Marcus Block, Preactor’s Consulting Services Manager, describes the system, “At this company the resources and workload were divided, so different planners had separate areas of responsibility, such as domestic or export products.”

“In some cases, the resources were not interchangeable at all although the machines were roughly the same for each planner.  Here it made sense to separate the operations because of the type and source of demand. It was easier for one planner to deal with the domestic supply chain, and another to deal with exports.”

Here the simplicity of the set-up suited the company’s requirements. It allowed each planner to be responsible for an end-to-end supply chain, and enjoy frequent contact with the customers of a limited range of products.

On the downside, a parallel set-up can cause problems if departments are not completely separate.

Over time, resources may need to be informally shared or transferred if the balance of work changes between departments.



In a sequential scenario each system is scheduled consecutively to take account of changes in the preceding system.

The results could be directed upstream (for example, from a department tasked with packing a product to a department tasked with making that product), thus allowing downstream systems to set accurate due dates for upstream systems.

Alternatively, the scheduling could be directed downstream (in the same example, from the ‘making’ department to the ‘packing’ department), thus creating accurate availability dates for downstream systems.

There are advantages and disadvantages in both methods, and you are likely to have already come to a decision about which scenario best suits your business.

Preactor can fit snugly into either scenario to enhance your scheduling process.

Marcus Block again.  “A sequential scenario is primarily used in two-stage or more production processes, such as food processing or even printing. One planner is responsible for an upstream process, such as the batch production of bulk material, and another for the downstream end, such as packaging.  The processes are separated because they are planned in very different ways, traditionally requiring planners with different experiences.”

A sequential system with Preactor offers you a simple solution to your scheduling problems, and allows you to exploit the expertise you already possess in each area of your business.

However, because it is usually necessary to plan each area consecutively, it can cause time lags and the requirement for back-and-forth communications.

It can also encounter problems if some routings are moved from upstream to downstream and then back to upstream, as the upstream planner will not know how much time to allow between processes until the downstream schedule has been finalised.



In a hierarchical scenario the master system has a complete view over its subsidiary planner systems, although not necessarily with the same level of detail.

In most cases, that means the master setting a time window for the subsidiary systems by dictating earliest start and latest finish times to the planners.

If the planner cannot schedule within that time window, the master will either investigate why or pass the workload to another planner.

This system helps to solve the problems with routings that are inherent in the sequential scenario (hyperlink).  Because end-to-end routing is planned by the master, clear production windows are given to each planner for detailed scheduling.  This scenario worked particularly well at a British firm which manufactures premium seats for the airline industry.

The business, which is split across two main sites, introduced a master system with five planner systems in 2007.  The master system generated a top-level schedule from their ERP system, which was then passed down to separate departments to be fine-turned and translated to the factory floor.  All relevant information was then fed back into the ERP system in time for the next master schedule.

The system resulted in immediate benefits, including an £8,000-a-week saving in one department.

Marcus Block commented on this type of scenario, “A hierarchical set-up is particularly suitable for businesses with complex assembly processes. At this company, where departments were very different in terms of their sequencing priorities or process constraints, it was an ideal way of giving each department the flexibility it needed.  A hierarchical system with Preactor gives you a total picture of your production chain at the master level, and often suits businesses which already subscribe to the notion of a master planner. However, that picture does have to be simplified, and the set-up can result in time lags in the planning cycle.”



In a modular scenario a master system is responsible for managing data, arbitrating across schedules and providing communication and visibility.

However, it does not have the same authority as it would in a hierarchical scenario, and it is up to each individual business to decide whether the master or the planners are responsible for defining capacity.  The system, which is essentially an enhancement of the parallel scenario, was inspired by the installation of Preactor at a British drinks manufacturer which operates several distinct packaging lines.

Marcus Block again, “This structure means several planners can work separately on different resources, but there is also an amalgamated schedule. This allows the workload to be spread, but also some common constraints to be assessed or applied via the master system. Like the parallel scenario, it works best in fast-moving consumer goods, consumer packaged goods or other production line industries. A Preactor modular system allows you to split your workload over several sites efficiently, while still maintaining a complete view of what is happening on the factory floor. It could be used as a stepping stone to move from a multi-planner environment to a single configuration. However, it does present complexity issues and cannot easily be applied in situations where routings pass through areas scheduled by different planners.”



A scenario in which resources and workloads are not separated (the common theme of the other distributed scheduling models explained in this section) might be termed a truly multi-access system.

Each user is able to access the same schedule, with some elements locked down or subject to conflict resolution measures to prevent problems.

At one of the world’s leading suppliers to the pharmaceutical, healthcare and life science industries, Preactor installed an asynchronous multi-access set-up in which each user could time-share the same configuration.

Marcus Block describes this system, “Each planner was generally responsible for different workloads and resources, but had some need to borrow or share resources. This system allowed them to do that.  Alternatively, Preactor can also be used in a synchronous system, in which small units such as orders or operations can be immediately locked.  This might work in a bookings or appointments system, in which each order is scheduled and then effectively locked. Access to resources is on a first come, first served basis, so any work which is unscheduled releases the resource and allows someone else to take it.”

Such a multi-access set-up has the advantage of being truly multi-user – often the goal of many businesses when they set out to find a planning and scheduling solution.

However, it does not come without drawbacks. Such a system rarely allows a holistic scheduling approach which can balance competing priorities.  If it did, it could only be done by a background process which would potentially override user requests.

There are also time-sharing restrictions, which limit when each planner can access the schedule, and it raises questions over who holds overall responsibility.


Although no multi-user planning scenario can solve the needs of every company, with Preactor’s flexibility, there is a scenario that will match each and every need.

View a Distributed Scheduling Presentation (pdf)