The xSDK4ECP project is working to enable the seamless combined use of diverse, independently developed software packages as needed by ECP applications.  We are extending draft xSDK package community policies and developing interoperability layers among numerical libraries in order to improve code quality, access, usability, interoperability, and sustainability. Focus areas of work are as follows:

• Coordinated use of on-node resources
• Integrated execution (control inversion and adaptive execution strategies)
• Coordinated and sustainable documentation, testing, packaging, and deployment.