Should You Use Revit Server or Collaboration For Revit (C4R)?

by Kuldeep Bwail Director, XS CAD Limited

Technological progress in the world of architecture and pre-construction design has led to significant achievements in software and collaboration; achievements that could only be dreamt of in the past. Projects today involve teams from around wide-ranging geographical areas - different towns, different states and different countries - simultaneously coordinating on the same project at the same time. These types of projects require a clear method of work-sharing that is efficient, transparent and extremely accurate. That’s where Revit Architecture used with Revit Server or Collaboration for Revit (C4R) for 3D BIM coordination plays an important role. Depending on the complexity and size of the project and the locations of the teams, either work-sharing method can be used.

With these two methods of Revit architectural services proving increasingly popular, we have examined both to see which is preferable. In essence, the two methods are:

1.    Server-based worksharing – Revit Server (RS)
2.    Cloud-based worksharing – Collaboration for Revit (C4R)

Revit Server (RS) is a server-based work-sharing method used over a wide area network (WAN). Central models are based in one or more Revit servers. These can be accessed using local Revit Server Accelerators, which offer better results during wide area communications.

Collaboration for Revit (C4R) is a cloud -based work-sharing method hosted in the cloud. BIM 360 Team (formally A360 Team) is a requirement for C4R. Team members can use a web browser to access BIM 360 Team if they are not using Revit. Then they will be able to preview models, upload and download other project documents, etc. With C4R, central models are stored in a file at a network location, with access for all team members.

Primarily, the workflows for both methods of Revit architectural services are almost the same, with the main difference being the different locations for storing the central model.

Features of Revit Servers

1.    Creating Local Files - The Revit open dialog is used to create a local file from a Central model on Revit Server.

2.    Work-sharing Monitor – An instant message application helps communicate with other team members.

3.    Revit Server Administrator for Folder Management - This administrator through the open dialog in Revit creates new folders, moves or copies, cuts or pastes projects for Revit Server.

4.    Overwriting Central Model - The central model must be saved with a new name, or it must be deleted or renamed.

5.    Recent Files List - The Recently Used Files list will only display local files. Central models do not appear.

6.    Restore Local Files – It is possible to roll back local files to a previously saved version, but this cannot be done with central models.

Revit Server runs on the concept of a central server hosting projects. The central model is split into folders and data streams with element permissions. The server communicates with local servers globally, which have the latest copies of project models. Local servers and the central server can be at the same location, and with network protocols, synchronising speed has been increased. So, those with access to a local server need not wait for data, even if they are outside the LAN, as updated versions are regularly streamed by the central server. Revit Server Administrator enables monitoring and review, allowing project and folder creations from a remote location.

A cloud-based application within Revit and on the web, Conceptual Energy Analysis (CEA), provides information about the sustainability of the project at early stages. After a design is created, a thermal analytical model is then devised. Materials, location shading, glazing and operating hours can be reviewed and the model is transferred to the cloud for calculations by Green Building Studio and the best possible environmental design is thus generated.

Revit Server Roles

Host: Revit Server is similar to a central server. The host would enable Revit Server instances geographically or organisationally to be central.
Accelerator: In this role, a Revit Server assimilates data from different sources. Members in the same local area network (LAN) as the Revit Server Accelerator enjoy better performance when connecting to central models.
Administrator: The Revit Server Administrator management tool is used to create, delete, rename and move folders and central models on Revit Server hosts and configures user or group level permissions.

To better understand how these roles function, let’s look at an example. If a company has its main office in London and others contributing to the project are in Bristol, Revit Server allows employees from both offices to work simultaneously on a Revit project file. This central file is saved in a local data server within its local area network (LAN). Individuals can access the central file on the data server. However, Revit automatically creates a copy of the central file on the individual client workstation, which is referred to as a local file, rather than open the central file. With subsequent changes, local files evolve differently from the central file. Hence, each local file is synchronised with the central file. This is better known as work-sharing.

In a LAN, load and sync speeds are fairly rapid, as the data is close to end users. When the same work-sharing occurs between two or more offices over the wide area network (WAN), the speeds of load and sync are slower. Revit Server lets two or more servers communicate across the WAN by caching (or replicating) the data on one server to the other. Thus, what is needed is to keep the data close to the end users. For this, each office must install a single instance of Revit Server on their data servers, creating a Revit Server Network.

The Revit Server in London could play host and administrator roles while the Revit Server in Bristol assumes the role of Accelerator. Thus, all central files would be in London and would be cached to Bristol. Using the Revit Server Administrator site via a web browser, the Revit Servers in the network can be administered.

What is C4R and what are the benefits?

When teams are working on a local area network (LAN), C4R, the cloud file-based work-sharing method, enables accurate performance. It does not need the installation of a Revit Server.

Similar to Revit Server, the C4R method uses cloud computing but this time also for storage and hosting of the model. Using BIM 360 Team, C4R provides access to, and collaboration on, central Revit models on the cloud to project teams across varied disciplines, locations and companies. This means that individuals or teams from any of the locations can add, delete or modify elements of the project at any time so that the alterations can be viewed by everyone else and be reviewed in a timely manner. In other words, C4R allows countrywide or international teams to work simultaneously across different time zones and collaborate in real-time.

Uses BIM 360 Team

C4R hosts a Revit model in a centralized location called the BIM 360 Team Hub. This location is a centralised storage place to share information. A BIM 360 Team Hub must be created before a model can be shared via C4R. Thus, the cloud can be used to share, store and communicate.

For Revit users, C4R is not separate software to install. It lives within Revit and provides new options in the ‘Collaborate‘tab. Revit users will however need to be associated with a BIM 360 Team project in order to use C4R features.

Easy Communication

C4R Communicator is a chat feature in Revit, with extras. Communicator connects users in the same model, in a different model but same project, or in a completely different C4R project. Chats are in real time and communication includes sending messages, files, screen shots from Revit from one user to another and even the chat log to share with others. Another feature, the Timeline, tracks comments, who is synchronising in real time, who completed, and when it was completed.

Publishing Revit Models to BIM 360 Team

Since only Revit users can see changes after every sync, for those using BIM 360 Team, a Revit user needs to publish the Revit model to the BIM 360 Team so that they can see all the views and sheets and all BIM metadata in the Revit model.

C4R Features

Integrated Project Delivery – C4R facilitates the sharing of server requirements and centralised systems by joint design ventures from separate locations. This accommodates the need for architects and engineers to communicate and share data seamlessly and practice qualified decision-making.

Cloud-based Technology – Since a majority of the tools in C4R are cloud-based, work methods and client support enjoy almost total flexibility, thus greatly reducing downtime and rework.

•    Management – Models and users can be managed with permissions and restrictions set up in a BIM 360 Team project in Revit.
•    BIM 360 Integration – Entire project teams, non-Revit users also, can view, comment, and mark up models through a web browser.
•    Communicator Tool – Team members can communicate with direct, real-time chat in C4R, within BIM project models.
•    Publishing Tool - Models in the cloud are published with the default 3D view and all 2D sheets, allowing communication between disciplines after updating changes.

Financially, the ROI from C4R projects saves an average of 30 minutes per individual team member every week. Over the course of an entire year, this could mean that C4R can virtually pay for itself.

Technical Issues and How Autodesk Supports C4R:

Bottlenecks in the code, capacity scaling under varying load, intermittent connectivity - Product teams across the cloud ensure that services have the right approaches and architecture to carry out their operations consistently and with high levels of reliability.

Degradations or outages - Services are designed so that dependencies are ‘soft’ and don't bring down core products.

Deviation of operational behaviour - Services are constantly logging operation results for ‘health checks’. Notifications of deviation of behaviour occur within minutes and can be rectified quickly. In addition, data trends are studied for usage patterns to improve capacity.

Overall, both Revit Server and C4R work-sharing methods have advantages and downsides, but depending on the organisation concerned and its specific needs, one may be more useful over the other. However, with the increased shift to subscription-based software licensing, C4R may be seen as the logical way forward for many firms that have not already invested in costly Revit server hardware and require easy to use and easy to operate cloud-based solutions for collaborating on their projects.