In previous tech tips, I’ve introduced the ThingWorx 9.0 active-active clustering feature and provided architectural details and configurations. If you haven’t already, I recommend you check them out to learn more about how active-active clustering enables higher availability for ThingWorx:
Today, I’ll provide more details around the load balancer in the active-active clustering architecture, some of its requirements, and a few configuration examples. Ready? Here we go! Here are the top four FAQs around the load balancer that will help you maximize your use of active-active clustering.
Load balancing is the process of distributing network traffic across multiple servers. An algorithm employed by the load balancer or a proxy, determines how the traffic is distrusted. Round robin, fastest response, and least established connections are some of the most common methods of load balancing and provide different benefits, but all fundamentally ensure no single server bears too much demand. By spreading the traffic, load balancing improves application responsiveness. It also increases availability of applications and websites for users. Modern applications cannot run without load balancers. In general load balancers can run as hardware appliances or as software-defined. Hardware appliances often run proprietary software optimized to run on custom processors. As traffic increases, the vendor simply adds more load balancing appliances to handle the volume. Software defined load balancers usually run on less-expensive, standard Intel x86 hardware. Installing the software in cloud environments like Azure VMs or AWS EC2 eliminates the need for a physical appliance.
Following the seven-layer Open System Interconnection (OSI) model, load balancing occurs between layers four to seven (L4-Transport, L5-Session, L6-Presentation and L7-Application), whereas network firewalls are at levels one to three (L1-Physical Wiring, L2-Data Link and L3-Network). Load balancers have a various capabilities, which include:
As is true of any load balancer, the load balancer required in the ThingWorx Foundation active-active clustering architecture is responsible for distributing incoming traffic across the nodes within the cluster.
In the Active-Active Clustering architecture for ThingWorx, the load balancer distributes the traffic using a round-robin method. Please note that there are a several algorithms that provide load balancing techniques and this article is a good read for further understanding of it. A round-robin method rotates servers by directing traffic to the first available server and then moves that server to the bottom of the queue.
In ThingWorx clustering setup, while both WebSocket and HTTP incoming traffic are handled in a round-robin manner, they are routed differently by the load balancer.
HTTP traffic is directly distributed amongst the ThingWorx Foundation Servers within the cluster. Sticky sessions are used for the HTTP sessions—sticky via cookie, so individual users are tied directly to a single server node and see all of their changes instantaneously.
WebSocket traffic is distributed across the and is balanced via source IP to ensure each request from a device goes through the same connection server. From the ThingWorx Connection Server, the device traffic is distributed amongst the underlying ThingWorx Foundation Servers, not requiring another load balancer between the ThingWorx Connection Servers and ThingWorx Foundation Servers.
Please note that the WebSocket traffic load does not necessarily get distributed evenly nor do the incoming requests due to stickiness. For example:
ThingWorx active-active clustering is pretty much load balancer agnostic, meaning if the load balancer of your choosing that you might be using in your IT center meets the requirements, it can be utilized within the active-active clustering architecture.
The load balancer is required to support the following features:
While you can use any load balancer that satisfies the above request and meets your IT standards, below are some of the third-party load balancers that provide the features that are required of the active-active clustering architecture:
Load balancers are another area where ThingWorx allows for flexibility and extensibility by enabling you to use the load balancer of your choosing that you’re most comfortable with or that best suits your needs (provided it meets the criteria above). You can also configure SSL or TLS for HAProxy when using ThingWorx HA clustering for end-to-end security. I hope this tech tip helped you develop a deeper understanding of how active-active clustering leverages load balancers to further increase your performance and thus availability and machine uptime, among many others.
If you’re not already on 9.0 and using active-active clustering, be sure to upgrade!