This study proposes mobile services with time constraints in ubiquitous computing environments based on on-demand mode. For real-time mobile service, the need of mobile service for a real-time database management model is strong and providing real-time response to mobile transaction has became basic strategies in mobile data management. However, the resource constraints of ubiquitous computing systems make it difficult to satisfy timing requirements of supported strategies. This study provides on-line scheduling strategies for mobile data with timing constraint on multichannel broadcasting environments based on on-demand mode. The goal of this study ensures the most requests meeting their deadlines, which differs from previously proposed scheduling algorithms that aim to minimize the mean access time. The study presents a study of the performance of traditional real-time strategies and demonstrates traditional real-time algorithms which do not always perform the best in a mobile environment. The experimental results show the proposed algorithm, called on-demand broadcast program with time constraint (BPTC), outperforms miss rate for data timely delivery to mobile clients.