## 1 Introduction  
The Space-Air-Ground Integrated Network (SAGIN) enables ubiquitous and seamless connectivity through the introduction of network devices such as Low Earth Orbit (LEO) satellites and High-Altitude Platforms (HAPs). SAGIN expands the coverage area of the existing network and is, therefore, capable of handling tasks that cannot be performed using terrestrial networks alone, and it has become an important direction in the development of the Internet in the future [1, 2]. SAGIN, through the interaction of heterogeneous devices, can provide new solutions for processes in industry/agriculture that are not suitable for direct manual operation. For example, satellites can be used in the interaction of heterogeneous equipment in SAGIN to remotely send machine operation instructions which can realize the remote monitoring and operation of pesticide spraying, mechanical operation, terminal cargo transportation, etc. This can not only save much of the labor cost, but also promote the intelligentization of production. However, SAGIN still faces two significant challenges. The first is the management of heterogeneous network resources. SAGIN includes satellite networks, aircraft networks, and ground networks, and these heterogeneous devices can cause complex end-to-end resource allocation due to differences in the configurations, standards, and performance. The second is the problem of regional network resource constraints. Although many studies have considered the application of Mobile Edge Computing (MEC) on satellitesand HAPs to reduce the computational pressure on terrestrial networks [3], the problem of the unbalanced allocation of regional computing resources still needs to be solved. For example, more service base stations are often deployed in economically developed regions, which tend to possess excess resources. In contrast, remote regions usually face the problem of resource shortages and need help even to achieve the expected delivery of user services. Therefore, a reasonable resource management and scheduling structure is needed to access heterogeneous devices in SAGIN, which ensures accurate and fast access to resource information, different Qualities of Service (QoSs), and the efficient deployment of tasks. In addition, proper resource scheduling algorithms are needed to allocate different resources for various services, reducing the amount of computing nodes that are turned on and the deployment cost while scheduling inactive resources in other nearby areas on time to satisfy the network demand and ensure that the latency is within a tolerable range. Network Function Virtualization (NFV) and Software-Defined Networking (SDN) provide the technical basis for managing SAGIN heterogeneous device resources. The introduction of the SDN and NFV releases SAGIN from the constraints of proprietary hardware, enabling efficient access to different devices and dynamic sharing of network infrastructure and resources between heterogeneous networks. The SDN separates the control and data planes, enabling the ability to defining and controlling the network in a software-programmable structure [4]. The SDN has been proposed to enable flexible resource management and resource allocation in Earth observation missions [5]. NFV enables the data plane virtualization and hardware implementation of communication devices in software [6; 7; 8]. In the SDN/NFV structure, a Service Function Chain (SFC) composed of multiple Virtual Network Functions (VNFs) can guide user traffic according to precise policies and efficiently utilize limited computing, storage, bandwidth, and other network resources. In SAGIN, the VNFs must be matched with heterogeneous resources, and the deployment strategies are further designed and optimized by resource scheduling algorithms to reduce the operator costs while ensuring tolerable communication latency. Researchers have performed much work on these two issues and have produced many excellent results.