Title: Connecting External Engines through OMEI: Open Mathematical Engine Interface Authors: Weidong LIAO, Dongdai LIN, Paul S. Wang Affiliation: Institute of Computational Mathematics, Dept. of Computer Science, Kent State University Abstract: Open Mathematical Engine Interface (OMEI) is an application programming interface specification for providing computational services through external engine for compute servers. The background and use scenarios of OMEI, the OMEI specification and its implementation in Java environment are discussed. The Internet has been a platform for a variety of services for more than one decade, but the deployment of mathematical services over the Internet has relatively lagged behind. Cooperating with other institutions worldwide, the Institute of Computational Mathematical at Kent State University initiated an IAMC project to provide an infrastructure and framework for bringing mathematical computational and educational services over the Internet. The IAMC infrastructure includes a layered protocol model for connecting IAMC client and server effectively and efficiently over the Internet environment, an external engine interface (EEI) for binding external compute engines to the IAMC server to provide real computational services, and a software framework for facilitating the development of IAMC systems. The OMEI is an example of EEI; it is a programming interface that intends to standardize the access pattern to external compute engines. In this paper we concentrate on OMEI. First we introduce the background and motivation behind OMEI. Then several use scenarios of OMEI specification will be described; we can see that OMEI cannot only be used with compute servers, but also the regular front-ends. The OMEI specification and OMEI implementation in Java environment will be also discussed. Finally we provide some conclusions and our plans about OMEI.