OMA DM is developed by Open Mobile Alliance (OMA) primarily to standardize the device management functions, which is intended to support the typical uses, such as configuring devices, enabling and disabling features, updating software packages or fixing bugs, reporting error of the device, and so on (Steinke & Strohmenger, 2007; Lim et al., 2008; Ma et al., 2008). The DM working group of OMA is mainly responsible for the revision and publication of OMA DM specifications (Husain et al., 2008).
OMA DM Architecture and FUMO
A simple architecture of OMA DM for firmware update is shown in Figure 1. As shown in Figure 1, DM Server is the server-side implementation of the OMA DM protocol. Its task is to manage OMA DM compliant devices using different management operations, e.g., provisioning, configuration of device, updating software, and fault management (Shi et al., 2007). Content Server is in charge of providing and managing the software packages and multi-media contents for the software upgrades and bug fix of the mobile device.
The device to be managed is composed of hardware components, software modules for managing the hardware components, and device management agent that performs software updates/managements and firmware updates by connecting to the OMA DM server (State et al., 2004).
Each device that supports OMA DM contains a Management Tree. The Management Tree organizes all available management objects in the device in a hierarchical tree structure where all nodes can be uniquely addressed with a Uniform Resource Identifiers (URI) (OMA, 2008; IETF, 1998). DM Server realizes the management actions by manipulating the nodes in a device management tree.
DM Agent is a software component that resides in the mobile device. It is used to process the messages received from the DM Server, including parsing messages from DM Server, interpreting OMA DM commands, and executing relevant actions in the device. In addition, the DM agent can also generate relevant responses and send them back to the DM Server.
Firmware Update Management Object (FUMO) is an OMA specification for updating the firmware of mobile devices over-the-air, which allows mobile devices to be updated over-the-air using the industry-standard protocol OMA DM (2009). Additionally, FUMO also specifies a range of standard commands with relevant parameters and management objects that can be used for OTA firmware updates. Figure 2 shows a simple procedure of the firmware update.
Generally, FUMO Agent and other special purpose agents can coexist to provide additional functions on a managed device. FUMO Agent coexists with the DM Agent to provide firmware downloading and updating functions on the managed device.