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Union is a development platform for creating connected applications. Use Union to build:

  • Social interaction: chat, meeting applications, multiuser whiteboards, collaborative editing tools, and shared interfaces
  • Realtime Multiplayer Games: online action games, head-to-head racing, social worlds, online chess, massively multiplayer trivia, turn-based card and word games
  • Realtime Datafeeds: live scores, realtime inventory availability, live surveys, realtime charts, graphs, and analytics dashboards
  • Publish/subscribe Channels: topic-based news feeds, project notifications, celebrity chat, sports spectation, live real-estate listings, product sales updates, remote system administration, realtime monitoring

Union applications run in desktop and mobile web browsers (JavaScript/HTML5), Adobe® Flash®, Java, C#, and your favorite language.

Union is free for up to 1000 simultaneous connections. To get started building your own Union applications, follow the Union Quick Start guide.

Union News

Union 2.1.1 Released

Union 2.1.1 is now available for download. This release introduces banning by IP range, activity-based client timeout, a room-message event for room modules, random-delay client reconnection, delayed "first attempt" client reconnection, and bug fixes.

For more information on the 2.1.1 release, see the Union 2.1.1 Release Notes.

Union 2.1.0 Released

Union 2.1.0 is now available for download. This release adds official support for encrypted TLS/SSL communications over WSS (WebSocket Secure) and HTTPS.

For information on using TLS/SSL in a Union application, see:

For more information on the 2.1.0 release, see the Union 2.1.0 Release Notes.

Union Platform Adds TLS/SSL Support

Announcing Union 2.1.0 Beta 1, Union Platform's first release with official support for encrypted TLS/SSL communications over WSS (WebSocket Secure) and HTTPS. Starting with this release, Union applications can securely transmit sensitive data such as banking information and personal records in realtime. TLS/SSL support opens Union developers to a wide variety of new enterprise-grade applications in industries such as ecommerce, finance, and medicine. By communicating over TLS/SSL, Union applications can also prevent man-in-the-middle attempts to cheat in online games.

For information on using TLS/SSL in a Union application, see:

Union 2.1.0 Beta 1 is available for download here:

Union 2.0.1 Now Shipping

Union 2.0.1 is now available for download. This release includes client and server bug fixes, and improvements to Union Admin. Union Admin now includes bandwidth statistics, and monitoring of both raw-connections and client-connections per second. Administrator clients can now also connect to Union Server's administration port over WebSocket and HTTP (previously connections to Union Server's administration port were limited to XMLSocket-format TCP connections).

For complete details, please see the Union 2.0.1 Release Notes.

Union 2.0.0 Now Shipping

The official Union 2.0.0 final release is now available for download. This update fixes a small set of issues discovered during the Union 2.0.0 beta period.

For complete details, please see the Union 2.0.0 Release Notes.

Union 2.0.0 Beta 3 Now Available

Union 2.0.0 Beta 3 is now available for download. This release adds a new Cluster tab to Union Admin and fixes a variety of issues discovered during the Union 2.0.0 beta period.

For complete details, please see the Union 2.0.0 Beta 3 Release Notes.

Orbiter 2.0.0 Beta 2 Now Available

Orbiter 2.0.0 Beta 2 is now available via Union CDN and download. Orbiter 2.0.0 Beta 2 fixes a compatibility issue with Internet Explorer 8, and various other minor issues. This is a bug-fix-only Orbiter release that does not require any updates to Union Server, Reactor, OrbiterMicro, or other client code. This update is highly recommended for all users of the previous version, Orbiter 2.0.0 Beta 1.

Union 2.0 Adds Massive Scale, Profound JavaScript Support to Realtime Platform

USER1 Subsystems today announced Union 2.0, a major upgrade to the popular realtime platform. Union 2.0 revolutionizes connected-application development with two key new features: Union Server clustering and Orbiter.

Union Server clustering is an API for building truly colossal social experiences. Orbiter is a JavaScript framework for creating realtime web content and connected applications.

Millions of Simultaneous Users

Whether you’re building a nation-wide interactive television show, a cloud-based collaboration service, or one of the world’s largest online chess communities, your application has to scale. With Union 2.0, it will. Union 2.0’s new clustering API connects multiple Union Server instances together, expanding Union Platform’s concurrent-connection capacity to colossal proportions. Applications that were previously limited to tens-of-thousands of simultaneous users can now be scaled to hundreds-of-thousands or millions.

With Union 2.0’s clustering API, it’s now almost trivial to spread client communications and application logic across multiple servers. Just make a list of servers, send a remote event, respond to that event, and your application is clustered. To expand your application’s capacity, add any number of machines to the cluster. Then bring on the masses.

And where better to find those masses than on the web.

Realtime JavaScript on the Open Web

JavaScript has evolved, and so has Union Platform. WebSocket gave the web fast, persistent socket communications. HTML5 gave the web a sophisticated GUI framework. Union 2.0 brings the two together, giving the web connected applications. With Union 2.0, developers can now use Orbiter to build collaborative, realtime features into traditional web content. Orbiter provides a simple, productive set of JavaScript building blocks for connected-application development, including connection reliability, user groups, data sharing, user-awareness, spectation, user accounts, synchronized user lists, group-and-private messaging, filtering, saving data to a data source, handling server-push data feeds, and security-role management. In short, everything you need to confidently build reliable connected applications. And developers who prefer to code in JavaScript even on the server can also use Union Platform’s server-side JavaScript modules for a complete end-to-end JavaScript solution.

Examples like Google Docs prove that collaboration and instant updates are indispensible to the user experience. But realtime-connected applications are still rare on the web. Why? Because they’re simply hard to build. Orbiter changes that. Using Orbiter, developers with standard web-development skills can create collaborative content cost-effectively and quickly. Coupled with Union Cloud, a fully managed deployment solution, Orbiter simplifies the process so dramatically that JavaScript programmers can literally create connected applications directly in a web browser.

Click the "+" button to edit this Union Chat live on JSFiddle:

Colin Moock, Union Platform co-founder, said “This latest release makes adding realtime connectivity so easy that it seems almost absurd to make an application without it. It’s like releasing a console game without a multiplayer mode, or at least live highscores. From a business perspective, and for the quality of the user experience, it just doesn’t make sense—not when the tools now exist to add collaboration so effortlessly.”

Moock noted that effect of the new release has been deeply felt, even on the Union Platform team: “It’s hard for us to believe, but after 12 years of developing collaborative applications, Union 2.0 has actually paradigm-shifted everything we do. We recently made a remote load-tester for an interactive television deployment. With no appreciable extra effort, we included a shared user interface: if you start a test on one computer, the realtime results are instantly shared with all other viewers. Later in the project, we built a broadcast scheduler to trigger trivia games on television. Again we thought, why not connect all these schedulers to Union Server so we can monitor their health? A day later we had a remote administration interface showing the realtime status of every scheduler in the broadcast network. We’re finally seeing realtime connectivity play a fundamental role in everything we build, right down to the testing and administration tools.”

Derek Clayton, creator of Union Server and Union Platform co-founder, added “Union 2.0’s ease-of-use and massive scale redefine what you can even dream about. You can now build connected applications without worrying whether they’ll break as user demand grows. The leap from small-scale success to extreme popularity is a fragile time in an application’s growth. If a technology doesn’t scale, developers are forced to rebuild from scratch, and that can kill a project. Union 2.0’s new scalability effectively removes that growth risk. It lets you actually start building tomorrow’s vision today. We’ve run installations with over 200,000 connected clients, and we’re just getting started. That’s World of Warcraft territory already, easily enough to handle the world’s biggest concurrent-user experiences. It’s incredibly exciting to bring that kind of industrial-strength reliability to the web industry.”

Clayton was especially happy with the team’s decision to implement Union Server clustering as a core feature.

“Union 2.0’s scale isn’t an add-on. It’s not a plugin, a third-party library, or an afterthought,” said Clayton. “It doesn’t require specialized knowledge; there’s no whitepaper to read. It’s just in there, and it just works. If you’re running Union Server, you’ve already got a single-instance cluster. Building scale into Union Server’s core at the deepest level let us retain the bulletproof reliability we’re known for without overcomplicating the API or the development process. It also ensures that every size of deployment will continue to benefit from the platform’s advancements, from huge commercial installations to tiny 10-user art pieces or academic research projects.”

So that’s Union 2.0. Massive scale. Indestructible dependability in the distributed environment. Profound JavaScript support. All with an astonishingly intuitive developer API.

It’s the industry’s most accessible platform for building truly colossal social experiences,
and the richest JavaScript framework for creating realtime web content and connected applications.

Union 2.0 is now available.

Announcing Union CDN

Union CDN, Union Platform's official JavaScript CDN, is now live. Union CDN gives developers instant, globally distributed access to Orbiter and OrbiterMicro, Union's JavaScript frameworks for creating connected content and realtime applications.

Union's CDN file locations are posted on the official Union CDN file list. All files are freely available for public use in both development and production deployments.

Union Platform's tutorials and samples now use the CDN links, allowing developers to instantly run all JavaScript examples by simple copy-and-paste, with no downloads and no installation. Union CDN helps expose Union's JavaScript source code to the developer community, aiding in the learning and discovery of connected-application development practices.

Union CDN also benefits production deployments in the form of reduced bandwidth costs. And end-users of Union CDN-based applications will experience faster content start times due to the global availability and local caching of Union CDN files.

Union Platform's CDN hosting is graciously provided by Influxis.

Together with Influxis, we're proud to bring you these important improvements as part of our deep commitment to JavaScript, HTML, and the open web.

Union 1.1.0 Released

Union 1.1.0 is now available for download. Key new features include:

  • Official support for WebSocket in all browsers that support it, including Chrome 10+, Safari 5+, Firefox 6+, and iOS 4.2+. In JavaScript/HTML5 applications built with OrbiterMicro, WebSocket speeds up network communications and reduces bandwidth consumption. For complete details, read Introduction to WebSocket.
  • A new module-annotation system to ease Java module development
  • Overhauled UPC-message processing that improves server performance and stability
  • A "UPC Messages" screen in Union Admin for debugging and tuning heavily loaded servers
  • OrbiterMicro now provides optional HTTP connection failover and alternate backup server/port failover

For more information about this release, please see the Union 1.1.0 Release Notes.