This paper reports on the results of the research regarding the Triple-Agile concept that has been introduced for supporting agile SMEs with cloud services agilely. The Triple-Agile concept implies three aspects of agility: agility of SME’s processes agility of transition to cloud services, and agility of cloud service provision. The paper proposes to use viable system model, in general, and viable service bus design principles, in particular, to reflect services in small and medium sized enterprise ecosystem where both service providers and service consumers are small and medium enterprises. The use of viable system model gives an opportunity to better understand relationships between services and thus may help to improve agility of service provision. The viable system model is applied in triple-agile ecosystem from two viewpoints: the viewpoint of service and business relationship maturity and the viewpoint of service functions.