In digital ecosystems, where they are no central authorities or single points of failure or control, entities form dynamic relationships to facilitate transactions and knowledge sharing. These relationships are contextual, evolving and not subject to central moderation. The devolved structure of these emergent environments pose unique challenges for identity. In this paper, we build on previous work on identity in digital ecosystems by offering a closer examination of identity requirements and outlining a flexible and extensible identity model framework that uses OASIS SAML-like protocols and metadata to perform the equivalent of operations such as Single Sign-On (SSO). We also introduce an identity model software toolkit, IdentityFlow, that can be used to implement and execute identity protocols; and outline concrete use-cases for SSO protocol implementations.