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Embedded Ethernet and Internet Complete
Axelson's writing style is a little difficult to describe. At times you feel you could be reading a "For Dummies" (TM, Patent Pending, Please Don't Sue Me) book since her writing style is so easy to digest, but simultaneously, she's covering quite a bit of depth and breadth which you expect from a more advanced volume. This seems paradoxical yet the point stands: you will retain what you read from Axelson.
ContentsThe networking basics sections describes the network protocol stack (Ethernet, TCP, UDP, and IP frames), collision mediation, and how to use a sniffer (Ethereal in her case). It's of moderate detail suitable for an introduction. Much more detail is provided in later sections. Axelson also uses this section to describe, in good detail, the Ethernet media access control scheme that arbitrates which device talks when and how to handle packet collisions.
These network hardware sections are an in-depth description of cabling (Cat-5, fiber, wireless, etc.) which includes bit rate, max lengths, encoding types, etc. She also includes a small section on building your own Cat-5 for you really cheap Joes. There is a cursory review of hubs, switches, and routers and the network architecture limitations imposed by each for each type of network cabling.
Axelson goes on to describe some common embedded systems including TINI (Java-based) and Rabbit (C-based), which are the two systems she uses and provides examples for. Thankfully, keeping with her Circuit Cellar hobbyist tradition, both of these systems are very affordable to the casual hobbyist. She also provides detailed descriptions of some common Ethernet chipsets down to the registers (at least for the ubiquitous NE2000 registers). Also included are schematics for typical interfaces to these chipsets for the reader who wishes to build his own Ethernet-aware embedded system.
The Internet basics sections describe the various connection solutions such as dial-up, DSL, and satellite and the benefits and limitations of each. Axelson provides a cursory discussion of firewalls, domain naming and DNS, URL dissection, DHCP, NAT, ARP, and ICMP. These sections, I believe, are suitably informational for the embedded system designer, but not exhaustive. She then launches into an in-depth discussion of IP addressing and the IPv4 header which, in my opinion, is required for anyone working at the packet level. Axelson uses some data from Ethereal to support her discussion of IPv4. She also reminds us that Ethernet communications need not use the full TCP or UDP stack but can, if desired, use only IP-wrapped packets or even just Ethernet frames to communicate.
We finally get to some real code in the TCP/UDP socket communication sections. Axelson begins with samples of UDP, then TCP, socket communications. She bounces back and forth between Rabbit C code and TINI Java code. Both sets of examples are properly threaded so as to be more than just academic-example hogwash. Then she delves into the details of UDP and TCP, beginning with descriptions of the frame headers, then concludes with handshaking/flow-control (SYN-ACK and so forth). She includes suggestions for other books that continue even deeper into socket communications which is very nice especially since they aren't gratuitous promotions from the same publisher. (They are, in fact, from two different publishers.) By the way, Lakeview Research is her own company, so Axelson self-publishes. Nice.
Fully half of the book is dedicated to describing the top layer of the protocol stack: applications. Specifically, HTTP client and server, receiving and sending email, and FTP client and server. The HTTP samples leverage the bundled TINI and Rabbit libraries to serve web pages. Axelson also includes examples of running a third-party servlet engine (Tynamo) on the TINI system. Similarly, the sections for sending and receiving email and the FTP client/server leverage the bundled libraries of Rabbit and TINI. I find this appropriate -- why write low-level socket code when there are available libraries that perform all the grunge work for you? If you do need to modify the support libraries, the Rabbit Dynamic C source code is available, but the TINI Java library source code is not.
The last few sections of the book discuss security. Axelson doesn't leave security as a footnote, as she does include sample code for basic authentication, but she also doesn't give security the depth she provided the other topics. Sure, security is a huge topic which would take numerous volumes to cover, but I thought this section could use a little more detail. I would like to have seen example code in the sections on encryption (both symmetric and asymmetric). I would like to have seen what is required to enable SSL in the web server examples. If these were not to be provided, I would have like to have her cite other books which would have completed her discussion as she did in the raw socket communications sections.
What Could Be ImprovedI don't really like the large font and spacing used in this book; I prefer a more condensed text which probably would have reduced the book size some 20% or so. But as I think about it, perhaps this is one characteristic that make Axelson's books so easy to read: there is little eye-strain.
In the hardware sections, I would like to have seen even a trivial example of an NE2000 device driver. It wouldn't even have to be an Ethernet-compliant driver, just something that demonstrates sending and receiving with flow and error control. This would be useful if you were building your own device which didn't include a protocol stack.
In the low-level socket communications sections, I would have preferred to see two things. First, I would have liked to see a test program that communicated between the C-based Rabbit and the Java-based TINI to demonstrate a heterogeneous distributed embedded system. Second, I would have like to seen an echo test program. When prototyping communications to any embedded system I always write an echo test program which begins by transmitting a small message with a numeric value, then listens for messages, increments their value, and sends them back out. Validation testing is performed during this process. This program is easy to write and a great diagnostic tool.
ConclusionSince this is my first book review I can't objectively give it an absolute rating like 4 stars or 8/10 since you have nothing to compare my judgment to. However, I can say that this book is well worth the money spent which, all too often, isn't the case anymore these days. I think Axelson has struck an ideal blend of detail where needed and summary when detail is not required. The book is organized well and should satisfy both the casual bathroom reader and the rigorous, horribly-cracked-binding, lab-bench-reference reader.
I like Axelson's writing style; it's an ideal blend of assume I'm an idiot-style when you need it and in-depth when you want to dig. Another great point: she doesn't stuff the appendices with data sheets, API documentation, or command syntax references. All those can be found on-line and have no place in a book, where they quickly become dated. If you absolutely must have a definite rating, then I'd give it an 8 or 9 out of 10. I would place books like Stevens' Unix Network Programming at a solid 10 and about 99% of the other books out there around a 5.
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And the usual code quality report courtesy PMD:
The Army reading list
fwiw, I've been using a Rabbit (RCM2200) for almost a year now on a personal project. It's connected to my house network, which is connected to the internet via the normal methods (Linksys hardware). The supplied libraries that come with the Rabbit are very capable as-is, but you can expand them if need be since you get the source (as the reviewer mentioned). I added code to be able to do authenticated smtp logins, for example. Getting code up and running to be able to do a telnet login to check on its status, and change settings was dead easy. It runs 24/7 and has been very reliable... the uptime hasn't exceeded a few months simply because I usually don't go that long without performing a code update of some kind, or otherwise powering down for a hardware reconfig, etc. Someday I may document the project and submit it to /. .... those who have seen it thus far think it's pretty kewl.
w
Not at all.
The fact that I'm as ugly as a smacked arse would put women off.
I was just pointing out that not all women are stupid.
You can answer this question in 5 seconds on Amazon or Google... Axelson wrote a book on USB development as well. Check it out here
/* Andrew */
As it happens, Jan Axelson has written this exact book, USB Complete. I am in the process of implementing a USB device and I give it a hearty recommend. The "standard" work is USB Design By Example by John Hyde; it's nice to have, but if you have to pick one, the Axelson is both more readable and more complete.
Most small PIC/AVR projects that I have seen use these: http://edtp.com The only problem is it's a SW solution so don't expect them to outlast even the saddest DoS attack :)
TCP/IP Lean by Jeremy Bentham, ISBN: 1-929629-11-7
Cirrus Logic CS8900a Ethernet module, it works in 8-bit mode
Buy a CS8900 module.
** Shameless plug **
Read my thesis about how to put it all together.
Digi has an embedded IP device called Connect ME.
You can get it with GNU tools which is nice if you are used to gcc and gdb.
There are a LOT of ways to do it these days. As with any CPU, you have to very carefully consider your volume expectations, r&d budget, and performance/feature requirements. The most MIPS for the dollar is probably the Ubicom ip2022 processor (120 or 160 MIPS for $10-$15 ea). This chip is used in the Squeezebox as well as some wireless access points and birdges. The ip2k is interesting because of its very fast interrupt latency which enables it do the ethernet MAC in software.
However there are other products such as the Rabbit platform which have royalty free software and cheaper development kits, so they're more suitable for small volume or lower speed applications such as control systems. It is a multi-chip design with external ethernet and memory though, so not cheap per-unit.
We routinely publish her work in Nuts & Volts (hobby electronics) as well as SERVO Magazine (personal robotics).
Dan Danknick
Technical Editor (of both)
Having spoken on the phone numerous times over the years, I can attest that Jan is, indeed a woman. However, since I never actually met her in person there is a fintite chance that this is some clever conspiracy.
RealTime Embedded Java www.systronix.com www.jstamp.com