Object Exchange (OBEX)

OBEX is a transfer protocol that defines data objects and a communication protocol two devices can use to exchange those objects. OBEX is designed to enable devices supporting infrared communication to exchange a wide variety of data and commands in a resource-sensitive standardized fashion.

Usage Scenario

The typical example could be an object push of business cards to someone else. A more complex example is synchronizing calendarson multiple devices using OBEX.

Example Products

Here are a few examples of the types of devices that you might find using the OBEX:

• PC
• Notebook
• PDA
• Mobile Phone

Getting Technical

Overview

OBEX uses a client-server model and is independent of the transport mechanism and transport API. A Bluetooth enabled device wanting to set up an OBEX communication session with another device is considered to be the client device. The OBEX protocol also defines a folder-listing object, which is used to browse the contents of folders on remote device. RFCOMM is used as the main transport layer for OBEX.

OBEX enables applications to work over the Bluetooth technology protocol stack as well as the IrDA stack. For Bluetooth enabled devices, only connection-oriented OBEX is supported. Three application profiles have been developed using OBEX which include SYNC, FTP and OPP.

Bluetooth Application Profiles Using OBEX

Synchronization

• Basically, the synchronization means comparing two object stores, determining their inequalities, and then unifying these two object stores.

• At the minimum, the File Transfer profile is intended for sending and retrieving generic files to and from the Bluetooth device.

• The Object Push profile is the special case of the File Transfer Profile forbeaming objects and optionally pulling the default objects.

File Transfer applications canbe implemented using OBEX. For the Object Push and Synchronization applications,content formats can be the vCard, vCalendar, vMessage,and vNotes formats. The vCard, vCalendar, vMessage, and vNotesdescribe the formats for the electronic business card, the electronic calendaring and scheduling, the electronic message and mails, and the electronic notes, respectively.

Bluetooth Protocol Hierarchy

The figure below depicts part of the hierarchy of the Bluetooth architecture and showsthe placement of the OBEX protocol and the application profiles using it (Seethe full spec for more details). The protocol can also communicate with the service discovery DB even though the figure does not show it.

Need more? View the Object Exchange (OBEX).