DMR Overview

As your enterprise grows, expands and becomes more global, your applications will also grow and evolve in complexity. Often those applications become distributed across multiple sites—which can include multiple public and private clouds as well as your legacy data centers—driving the need for an easy way to intelligently share information between multiple locations and interfaces. For example, your organization may have on-premises assets, such as IBM MQ, TIBCO, or Kafka that need to connect to new application frameworks such as Spring, or to new cloud services such as Google Bigtable, BigQuery, AWS EMR, or Kinesis. Or you may want to make your core data assets from databases on mainframes or on-premises distributed systems accessible to applications and services in the cloud.

DMR Enables the Event Mesh

Providing this sort of large-scale, uninterrupted operation can be accomplished using a Dynamic Message Routing (DMR) network, or event mesh, to automatically connect all those sites and exchange subscription information. An event mesh allows far-flung clients to be unconcerned that there could be multiple and disparate sites in the network. To the clients, the event mesh and its details are invisible: clients simply go about their business of exchanging messages without considering how to get those messages where they need to go.

Enterprise growth can also occur within the sites themselves. Individual event brokers have limits with respect to things like subscription counts, queue counts, message spool storage and so on. At some point even the largest, most generously provisioned event broker has its limits, but these can be overcome by networking several event brokers together with DMR and spreading the load among the participants. In this way, multiple event brokers can be connected together to service loads far in excess of that possible by a single one.

DMR Automatically Manages Routing and Subscriptions

Without DMR, you must know what publishers are producing the data you want, configure messaging connectivity to wherever that data is being published, and manually configure routing rules to move the data to where consuming applications want it. This works, but DMR makes it much simpler by automating all the labor by providing intelligent, self-learning routing capabilities.

DMR is based on established and robust Internet routing technology, and builds on the long-released Solace PubSub+ Multi-Node Routing (MNR) feature. However, where MNR only supported non-persistent messaging, DMR supports both non-persistent and persistent messaging. And DMR is easy to set up and get going as it can be configured using a Click-to-Connect wizard in Solace PubSub+ Broker Manager. However, if you prefer, you can also configure DMR using the Solace CLI.

What's Next?

Consider these:

Multi-Site Connectivity

Consider the fairly common situation where you have a number of on-premises applications all connected to a Solace PubSub+ backbone. In the above example, there are three such applications, red, blue and green, each within their own Message VPN. For reasons of cost, flexibility, security, robustness, or some other business driver, you may find that you need to migrate a number of clients of those applications to cloud providers. Solace PubSub+ software event brokers can also be deployed in those clouds to provide messaging services to both the migrated clients, and, through the use of DMR, to clients migrated to other clouds as well as those still residing on premises.

In the example, the red and green applications have had some of their clients moved to cloud providers, but some clients have been left on premises. The blue application has been completely migrated to the cloud. To get messages flowing among an application's clients as if they were all still residing on premises, simply ensure DMR is enabled on each Message VPN and configure a DMR control link between the neighboring event brokers. DMR automatically discovers the event brokers and advertises the subscriptions their clients need. Also, both direct and guaranteed messaging are supported so that the same messaging modes that were used on premises can still be used now that the applications are running across multiple sites.

Other sites can be added to your multi-site network as your enterprise continues to grow. For example, other public and private clouds can be added, and subscription distribution and data flow will continue to happen automatically.

What's Next?

You'll find instructions on how to set up and configure a Hybrid-Cloud / Multi-Site example over at Multi-Site Connectivity Configuration.

Horizontal Scaling

Consider a situation where you use a Solace PubSub+ software event broker as your MQTT server, with applications red, blue, and green, each within its own Message VPN.

Say, for example, you plan to increase your deployed client count from 100,000 to 400,000 MQTT clients, all of which need to intercommunicate with QoS 1 subscriptions. A single software event broker—the largest of which supports 200,000 queues—is not sufficient at this scale. While this might be possible with an appliance, you might not be interested in maintaining hardware, and instead opt for three 200,000 software event brokers configured in a DMR network, as shown in the following diagram.

Here the applications have been spread across all three software event brokers, which are interconnected with internal DMR links, with a combined capacity of 600,000 queues. This configuration can easily handle the needed number of clients, and scale even higher by adding additional software event brokers to the network over time. No manual subscription management is needed, because DMR dynamically discovers the subscriptions needed by each broker.

What's Next?

If you're ready to set up and configure a Horizontal Scaling example, you'll find instructions over at Horizontal Scaling Configuration.

DMR or a Message VPN Bridge?

DMR works for both persistent and non-persistent messages. Also, DMR eliminates the need to use topic namespaces to predefine what data needs to flow across which Message VPN bridge. With DMR, all of this becomes automatic, with the same persistent QoS you enjoyed.

In addition, the Solace PubSub+ Broker Manager includes a click-to-connect feature that can easily create a DMR mesh in a few mouse clicks.

Because of its support of persistent messages, automatic data connectivity management, and ease of configuration, DMR is the recommended choice.

Disaster Recovery (Replication) with DMR

You can take advantage of disaster recovery (using replication and Config-Sync) within your DMR network (or event mesh). Replication provides business continuity and allows mission‑critical applications to continue to function during a major service outage to a data center. For more information, see Replication Overview and Configuring Replication with a DMR Network.

Next Steps

  • DMR Technology gives you more background on the fundamental concepts of DMR technology.
  • Configuring DMR goes into the specifics of configuring and managing DMR links between neighboring nodes.
  • DMR Examples shows you how to get DMR up and running with some simple, easily configurable examples.