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Cosmos React (early adopter)

Suggest edit Updated on February 2, 2022

Pega Platform version 8.6 introduces Cosmos React, a new run-time environment that supports the latest open-source technologies and frameworks to improve the user experience. This still-evolving architecture features a curated authoring experience that helps early adopters build an application in the low-code App Studio environment with less effort.

Feature set

Cosmos React uses the latest technology, but offers fewer functionalities compared to Theme Cosmos. Consequently, Cosmos React is best suited for early adopters who understand its narrower feature set and capabilities. As a best practice, use Theme Cosmos for complex applications and a mature, reliable architecture.

For more information on Pega Platform architectures, see Understanding UI Capabilities in Pega 8.6.

Constellation service

Cosmos React relies on the Constellation engine, which uses ReactJS libraries to create a new run-time architecture. From the system perspective, Constellation is a static content microservice that delivers React components, JavaScript code, and other static content to the browser. To obtain configuration, context, and data for Cosmos React applications, the Constellation client interacts with the server exclusively through DX APIs. By keeping the Constellation container separate from other services, you avoid dependencies, give developers tools to create new UI components without interfering with other work, and improve overall application performance.

When creating a new application, you can choose between a Constellation-based Cosmos React UI, a hybrid Theme Cosmos UI, or a traditional Theme UI-Kit application.

For more information on other UI architectures, see Theme Cosmos and Theme UI-Kit.


If you use Pega Cloud services or a client-managed cloud environment to host Pega Platform, the Constellation engine is already part of your development environment, and you only need to enable it for your applications.

If you run an on-premises system that you implemented through Helm for Kubernetes, a single multitenant Constellation instance is installed automatically for each Pega Infinity environment. If you need a different configuration, you can also opt in by manually deploying the framework through Docker or Helm for Kubernetes. For more information, see Setting up the Constellation service in Pega Platform.

Security for a multi-tenant regional service in Pega Cloud services

The Constellation Static Content Service (CSCS) for Pega Cloud services is a Regional multi-tenant service. A single deployment serves the static UI content to all customers. The single CSCS also hosts cached static images from all of customers' Cosmos React applications. Customer images are protected by the same JSON Web Token (JWT) technology that protects calls to the Infinity service. Consequently, one customer cannot pick up images from another customer. The end user can only access images for the Infinity environment and application that they have logged on to.

  • Designing with Cosmos React

    Cosmos React offers early adopters a new low-code paradigm for developing applications quickly by using out-of-the-box components and behaviors. This still-expanding framework creates products that require less maintenance and upgrade effort, but supports a narrower feature set and requires a slightly different approach to development when compared to Theme Cosmos.

  • Configuring portals

    Portals represent the main interface of your application, and provide users, such as case workers, managers, and customers, with the tools that they need to do their work. By configuring portals, you can set up an optimal environment for each of these user groups with minimal effort.

  • Configuring forms and views

    Forms and views enable your application to display and collect information, for example, to fulfill requests or process cases. By setting up intuitive forms and views, you help users process their work with less effort.

  • Branding your application

    Design systems help you introduce consistency to the applications that you build. By choosing to use a design system, you can scale your designs to maintain a unified presence across a number of platforms with less effort.

  • Configuring an accessible UI

    Reach the broadest audience for your application by building a user interface that addresses the needs of users with disabilities. Designing a UI for assistive technologies, such as screen readers, is important for compliance and provides essential access to users who have visual impairments.

  • Setting up the Constellation service in Pega Platform

    Prepare Pega Platform and your application for the new run-time framework that offers an updated set of UI capabilities. In the 8.6 release, you can build new applications with Cosmos React, or decide to use Theme Cosmos for a section-based architecture with updated landing pages and tables.

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