In this work we propose GXLA, a language for the specification of Service Level Agreements (SLA). GXLA represents the implementation of the Generalized Service Level Agreement (GSLA) information model we proposed in a previous work. It supports multi-party service relationships through a role-based mechanism. It is intended to catch up the complex nature of service interactivity in the broader range of SLA modeling of all sorts of IT business relationships. GXLA is defined as an XML schema which provides a common ground between the entities in order to automate the configuration. GXLA can be used by service providers, service customers, and third parties in order to configure their respective IT systems. Each party can use its own independent SLA interpretation and deployment technique to enforce the role it has to play in the contract. An illustrative VoIP service negotiation shows how GXLA is used for automating the process of SLA negotiation and deployment.