NDNph is my latest Named Data Networking (NDN) client library.
This article gives an overview of this library.
History and Motivation
In 2016, I started esp8266ndn.
It contains a copy of ndn-cpp-lite, UCLA REMAP's C++ library that does not use dynamic memory allocations.
I then added integrations with ESP8266's network stack and crypto functions, making esp8266ndn the first NDN library that works on the ESP8266 microcontroller.
Using this library, I built several projects, including a wearable jewelry and a call button.
University of Memphis also deployed several sensor nodes using esp8266ndn.
Over the years, esp8266ndn gained many new features, and widened platform support to include ESP32 and nRF52.
However, using ndn-cpp-lite as the core is becoming problematic:
- New protocol features show up slowly, because ndn-cpp-lite author would not add a feature until ndn-cxx has it, and design discussions for ndn-cxx sometimes take several years.
- There is no generic TLV encoder/decoder, making it difficult to support TLV structures in application layer.
- ndn-cpp-lite is bloated with obsolete features, due to their backwards compatibility guarantees.
Consequently, binary code size is unnecessarily large.
- Although I can add patches to ndn-cpp-lite during importing into esp8266ndn, it has been difficult to test these patches.
This isn't ndn-cpp-lite's fault, but is still an issue.
The title comes from a geocache named Thought Provoker #3.
Inside the container there is a thought provoking question:
If you could travel across the United States of America (and had no other obligations, financial or time constraints) what mode of transportation would you use and why?
Walk/run, ride a bike, ride a motorcycle, hitchhike, drive a car, drive a RV/motorhome, take trains, or something else?
Here are my answers.
First Choice: Geocaching Express 6000
The Geocaching Express 6000 GPS Receiver is a powerful GPS receiver, as shown in Geocaching International Film Festival (GIFF) 2019:
Geo-snatching is the act of finding loopholes instead of geocaches.
- armchair geocaching;
- hacking your smartphone's location so you can log Adventure Labs or solve Whereigo cartridges without visiting the location;
- logging an FTF on a friend's cache that you helped place;
- finding your own caches by adopting it to a sock puppet account (aka rule 52612);
- other general tomfoolery.
The term geo-snatching was invented by gsmX2 on this Facebook post.
This article explains what geo-snatching or geosnatching means in geocaching, and how a geo-snatcher or geosnatcher differs from an honest geocacher.
Content of this article does not necessarily reflect blog owner's views.
I'm creating a new Named Data Networking (NDN) client library, NDNts.
The initial NPM release,
v0.0.20191223-beta.1, was uploaded yesterday.
This article explains why I'm doing this, and why you should consider using my library.
I've been developing Named Data Networking (NDN) for several years.
Although my specialty is in the forwarding plane, I occasionally build NDN applications, such as a home surveillance camera.
A common ingredient of every NDN application is some sort of client libraries, which provides APIs that allow the application to encode/decode NDN packets and communicate over NDN networks in accordance with the NDN protocol.
One of these client libraries is the NDN Common Client Libraries (NDN-CCL), which provide a consistent API across several programming languages.
- Callbacks everywhere, leading to callback hell.
- The library inserts over 50 symbols to the browser's global scope, causing name conflicts.
- All features are bundled into a single file that weighs over 500KB.
- There's no unit testing for the most part, let alone continuous integration.
In 2015, I backed CHIP - The World's First Nine Dollar Computer on Kickstarter.
In 2018, Next Thing Co went out of business.
Disappearing along with them is the software updates.
Debian Buster was released in July 2019, but CHIPs are stuck with now two-generation old Debian Jessie, along with a 3-year-old Linux 4.4 kernel.
Without software updates, running C.H.I.P computers on the Internet is increasingly risky.
This week, I have decided to sell my collection of C.H.I.P single board computers.
They were sold for $77 (equals Kickstarter pricing) within two days of listing on eBay.
Sometime ago, I bought an Onion Omega2 Pro and flashed it with OpenWrt 18.06.
I plan to take my Omega on the road, so I installed a Li-Po battery on the device, so that it does not need to depend on USB power input.
One big question is: what's the remaining power level?
power-dock2 to View Battery Voltage
The standalone Power Dock has a set of battery indicator LEDs that visually tells how much juice is left.
However, the Omega2 Pro that I have does not have battery indicators.
Instead, I need to use
power-dock2 command to read battery level.
Let me try it:
-ash: power-dock2: not found
It does not work, because I flashed my Omega with OpenWrt 18.06, and
power-dock2 command is not included in the standard OpenWrt distribution.
The command comes from OnionIoT's OpenWrt feed (package source).
I must add the OpenWrt feed before I can install the
我在查询波特兰旅游信息时，找到了一个名叫“Shanghai Tunnels （上海隧道）”的旅游项目。
Geocaching.com's newest promotion, Mystery at the Museum, is online today.
To qualify for the first three souvenirs, you must find and log a number of geocaches, in a certain order.
Geocaching.com offers a filter function that shows which geocaches to find and log next.
However, it only allows me to select the clue tiers that I currently qualify for.
Since I haven't found any geocaches since the promotion started, I can only search for the Detective clue, but cannot search for any other clue types.
This is inconvenient for me, because I prefer to go geocaching offline.
I usually download a number of geocaches to my phone, go out to find them, and then log them at end of the day.
I want to be able to search for clue types beyond Detective, even if I don't currently qualify for them.
Then, I can go out, find enough geocaches to complete two or three souvenirs together, and then log them into the correct order.
I poked around the URI parameters in the address bar, and found two methods.
I thought I'd share them, in case anyone needs it.
My 7-day Oregon vacation is over.
It took even longer for me to blog about this experience:
- Planning and Departure explains why I chose Oregon, how I planned the trip, and a personal record I set on the departure day.
- GC12 and GC17 follows my adventure to Oregon's oldest geocache.
- Birthplace of Geocaching introduces a landmark that started one of my favorite sports.
- Hillsboro and Outlets tells how I met a Twitter friend in real life, how I contributed to American economy, and a painful DNF story.
- Eight Waterfalls, Two Beaches, and a Webcam takes me outdoors to the scenic Multnomah Falls recreation area.
- Portland calms me down in the peaceful Portland Japanese Garden, and gets me running around in Portland State University.
- Breakfast and Laundry Solutions discusses some logistic issues during my travels.
- GC16 in Molalla River makes me huff and puff in seek of a 19-year-old plastic jar.
- Oregon City lifts me up along the only vertical street in North America.
- Last Day brings me from the peak of Portland to the other side of the state line, and then back to the normal life.
My vacation did not have a planned day-to-day schedule, but adopted a semi-flexible strategy.
This differs from my previous vacations such as the Yuma Mega trip, where the planning covered exactly where to exit the highway and take a rest.
Being flexible allowed me to spontaneously decide where to go next, based on weather, mood, and other factors.
It enabled me to add destinations that I did not know before departure, such as Multnomah Falls and Oregon City, as well as fulfill friend's request of an IRL meet up.
This strategy did backfire once, when I went to a museum only to find it closed.
Eventually, my trip achieved an interleaved structure between rural and urban environments: