Flexible Large-scale Agent Modeling Environment (FLAME) agents are based on mathematical notation of formal X-machines, to represent the agent architecture, their memory, messages, states and transition functions. FLAME uses message passing interface (MPI) to allow platform independence in implementation, by allowing the message to be packed into a certain binder, which can be sent across nodes easily and independently. The library uses distributed memory model Single Program Multiple Data (SPMD) paradigm to communicate messages efficiently. This chapter discusses agile software development which encourages principles for developing software, where requirements and solutions evolve through collaboration between clients and developers. Extensively being used in industrial software engineering practices, the approach has proven very successful by promoting collaboration, adaptive planning, early delivery and continuous improvement for the product being delivered. Software behavior has traditionally used finite state machines to model a system as inputs and outputs.