[Technology Report]
My Embedded System Is On The Internet–What About Yours?
In the fight for seamless communications, embedded and information systems are joining forces and drawing upon the Net.
Joining IT And Embedded Worlds The only certainty is that embedded communications devices won't continue to remain separate from the enterprise computing infrastructure. Corporate databases, Internet service providers, and embedded systems are all converging into the same application spaces.
For embedded developers, this translates into more dependence on traditional information technology than at any time in recent history. For engineers who have successfully resisted following advances in PC and server technology, this means a crash course in server application programming interfaces, object-oriented technologies like CORBA and COM, and relational databases.
The digital cell phone, for one, will become an extension of the enterprise information server, creating and uploading database queries and downloading regular production statistics. The device itself will be a special-purpose extension of the network, gaining many features from the network rather than itself. Look at the way QNX provides the ability to manage its systems through a Windows interface (Fig. 2).
This doesn't necessarily mean that the cell phone will run Windows or Unix and become a client as is understood today in client/server technology on the desktop. But it will force every device designer and embedded software developer to incorporate features with an enterprise or ISP server in mind.
It's already started. Relational databases, once the exclusive preserve of corporate information systems, are starting to make significant inroads into embedded-systems development. Sybase's SQLAnywhere and Centura Software's SQLBase are both targeting data storage and organization tasks for embedded systems. With its VxDCOM, Wind River Systems scales down Microsoft's DCOM technology so that it will suit embedded systems and then embeds it onto its Tornado II integrated development environment (Fig. 3). VxDCOM enables programmers to create fast and compact embedded applications that interact with PCs using Microsoft's distributed technologies.
Standards help a great deal in this regard, enabling design diversity without necessarily hindering interoperability. Take the family of protocols under the TCP/IP umbrella. It represents an almost universal standard for packet-switched communications.
From an applications standpoint, some ad-hoc standards also exist. An e-mail client can have any look, feel, and features that make sense for the device, as long as it uses either the POP or IMAP protocols for communicating with the server. But choosing what standards to support can influence the overall design. POP represents a client-centric orientation, while IMAP is typically implemented through a server-based infrastructure.
Custom Processors Can Use Standards Standards may be built into custom-processor versions, ease the design process, and speed time-to-market. NETsilicon's NET+ARM is an integrated package that incorporates standard hardware and system software solutions. It's built around the ARM7 processor. NET+ARM includes a 10/100 Ethernet MAC-level interface, integrated cache, memory controllers, bus controller, timer and clock generator, and I/O.
Problems do exist with the existing infrastructure that may affect the future viability of some standards, however. There clearly aren't enough IP addresses for each device to have its own. Only about four billion IP addresses reside in the traditional naming scheme, and some are reserved for specific uses. Typically, on traditional computer networks, addresses are dynamically allocated as they are required. But many embedded devices will require addresses at all times. IPng (also known as IPv6), which adds another triplet to the existing scheme, is being reviewed by standards committees. Unfortunately, possible embedded devices could overwhelm even this enhancement.
Here's where the minimal client approach might have an advantage. A proprietary interface between a set of clients and a gateway means that only the gateway needs an Internet addressing scheme, but each full TCP/IP client must have an address.
Solutions also exist that work to resolve issues with the full RTOS, including using a gateway that spoofs the network into thinking that a network segment is actually a single machine with one IP address. This product decision is largely based on the surrounding network architecture and various services available for individual devices.
For possibly the first generation ever of embedded devices, C and assembly language aren't automatically the best alternatives for application development. In the past, both languages offered the high efficiency and small executable footprint needed to wring the most out of an embedded systems' limited computing resources.
Today, Java's potential for cross-platform applications is making that language a mainstream alternative on embedded systems. Java is really the only choice for applications intended to be stored on a server and downloaded to an unknown client. Plus, the language and environment include network components that must be developed separately for other languages.
Some enterprising vendors have already found ways to use Java in cases where soft or possibly even hard real-time responses are required. NewMonics has its own real-time Java Virtual Machine (JVM). To enable that hard, real-time response, it's made a few extensions of the language to its clean-room implementation. Others have worked out ways to avoid invoking garbage collection, or have even enabled a just-in-time (JIT) native compilation on the device for faster execution.
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