In order to plan for and accomplish a complex set of interdependent activities, it is useful to have a specification of the goals and the activities that need to be accomplished to satisfy those goals. Motivated by the world of military planning, we use the term Mission Modeling to refer to the activity of capturing and representing all of the goals, preferences, and constraints, along with the detailed execution plan that satisfies each of them. DOLL's specification-based mission modeling approach supports the top-down generation of detailed interdependent activity plans, an execution mechanism that ensures that all activities are performed in the correct order, and provides continuous assessment of the status of all subparts of the plan along with the aggregate status of the overall mission. Using this assessment mechanism during plan execution, the contributing impact of the successful and unsuccessful mission activities can be determined, allowing the overall mission success to be maximized. Since assessment is performed continuously, mission resiliency is achieved. For a resource-constrained problem, these assessments allow the user and/or the system to drop those activities from the plan that have the least negative impact on the overall mission success. DOLL has initially applied this approach to planning problems in the military cybersecurity domain. It is also applicable to any problem that can be decomposed into a collection of subtasks. For example, it can be applied to commercial domains such as manufacturing, and diagnosis and repair.