You’re probably familiar with this UI in Visual Studio. It hasn’t changed much since it was first created:

A list of properties, data type, scope and a default value. Admittedly, it makes things simple. However, with my WPF .NET application that I created a few years ago (SnugUp), I’ve always been troubled by the magic of the settings. It was too easy to get in a situation where a user would loose their settings doing uninstalls, reinstalls, upgrades.

While I’m sure it’s possible to make the built in settings classes to work, it wasn’t worth the effort for me to understand them and learn what the nuances of where they’re placed, how to do a decent upgrade, how not to loose them, etc.

In the SnugUp WPF UI, the code uses a two-way bindings to directly edit the settings of the application (like: "{Binding AppSettings.DebugMode}"). It was simple, and all I needed. It’s handy that ApplicationSettingsBase implements the INotifyPropertyChanged interface which WPF needs for simple two-way data bindings.

My solution, which I admit is heavier than the original as it requires a large additional assembly is to use JSON.NET as the serializer/deserializer for a new settings class I created.

So, the basic pattern:

   1: public class ApplicationSettings : INotifyPropertyChanged

   2: {

   3:     public event PropertyChangedEventHandler PropertyChanged;

   4:  

   5:     private bool _debugMode;

   6:     private string _albumNameFormat;

   7:     private string _extraFileExtensions;

   8:     private bool _automaticRun;

   9:     private string _galleryCreationSubCategory;

  10:     private bool _filenameOnlyCheck;

Properties created the standard way for INotifyPropertyChaged:

   1: private DateTime _nextUpdateCheck;

   2: public DateTime NextUpdateCheck

   3: {

   4:     get { return _nextUpdateCheck; }

   5:     set

   6:     {

   7:         if (_nextUpdateCheck != value)

   8:         {

   9:             _nextUpdateCheck = value;

  10:             RaisePropertyChanged("NextUpdateCheck");

  11:         }

  12:     }

  13: }

I wanted a predictable path for storing settings (so it would be easy to document and backup for users). I used the AssemblyCompany attribute and the AssemblyProduct attribute as the folder names:

   1: internal static string GetSettingsDirectory()

   2: {

   3:     string path = Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData);

   4:     var attrs = Assembly.GetEntryAssembly().GetCustomAttributes(typeof(AssemblyCompanyAttribute), false);

   5:     if (attrs.Length == 1)

   6:     {

   7:         path = Path.Combine(path, ((AssemblyCompanyAttribute)attrs[0]).Company);

   8:  

   9:     }

  10:     attrs = Assembly.GetEntryAssembly().GetCustomAttributes(typeof(AssemblyProductAttribute), false);

  11:     if (attrs.Length == 1)

  12:     {

  13:         path = Path.Combine(path, ((AssemblyProductAttribute)attrs[0]).Product);

  14:     }

  15:     return path;              

  16: }

In this WPF application, in the AssemblyInfo.cs file, the attributes are set as follows:

   1: [assembly: AssemblyCompany("WiredPrairie.us")]

   2: [assembly: AssemblyProduct("SnugUp")]

On my machine, that maps to this path:

d:\Users\Aaron\AppData\Roaming\WiredPrairie.us\SnugUp\

Loading settings then is straightforward using JSON.NET:

   1: public static ApplicationSettings Load(string filename)

   2: {

   3:     ApplicationSettings settings = null;

   4:     var directory = GetSettingsDirectory();

   5:     var path = Path.Combine(directory, filename);

   6:  

   7:     if (File.Exists(path))

   8:     {

   9:         string fileData = File.ReadAllText(path);

  10:         try

  11:         {

  12:             settings = JsonConvert.DeserializeObject<ApplicationSettings>(fileData, new JsonSerializerSettings { });

  13:         }

  14:         catch { }

  15:     }

  16:     if (settings == null)

  17:     {

  18:         settings = new ApplicationSettings();

  19:         SetDefaults(settings);

  20:         // initialize settings once

  21:         Save(settings, filename);

  22:     }

  23:     return settings;

  24: }

In my code, if the settings file didn’t exist or fails to serialize into something meaningful, a new settings file is created with a few defaults. (I haven’t decided what to do when there’s an exception when reading the file, hence the empty catch).

Saving the settings is just as easy:

   1: public static void Save(ApplicationSettings settings, string filename)

   2: {

   3:     Debug.Assert(settings != null);

   4:     var directory = GetSettingsDirectory();

   5:     var path = Path.Combine(directory, filename);

   6:  

   7:     JsonConvert.SerializeObject(settings);

   8:  

   9:     if (!Directory.Exists(directory))

  10:     {

  11:         Directory.CreateDirectory(directory);

  12:     }

  13:  

  14:     var fileData = JsonConvert.SerializeObject(settings, Formatting.Indented, new JsonSerializerSettings { NullValueHandling = NullValueHandling.Ignore, DefaultValueHandling = DefaultValueHandling.IgnoreAndPopulate });

  15:     try

  16:     {

  17:         using (StreamWriter writer = File.CreateText(path))

  18:         {

  19:             writer.Write(fileData);

  20:             writer.Close();

  21:         }

  22:     }

  23:     catch { }

  24: }

The SerializeObject method returns a string which is then written to a file using a StreamWriter.

I added a Save method to the instance of the ApplicationSettings:

   1: public void Save()

   2: {

   3:     ApplicationSettings.Save(this);

   4: }

This preserved the functionality that exists in the built in Settings support in .NET (which was being used in my application).

By keeping all of the property names the same and making a few tweaks to the types of some fields in my application, I had swapped out the entire “settings” infrastructure in about 45 minutes.

I’m planning some other JSON activities within my application, so the overhead of using JSON.NET is acceptable.

The best part of this alternative is that there isn’t any magic. It’s all easy to manage. Further, I can easily modify my installer to properly handle/update, etc., the settings file with just a few clicks.

I’m not going back to the built-in .NET settings support again. I’ve learned my lesson. 

What have you done for “user” settings?

New features:

• (Changed to version 2)
• Completely revamped look and feel (which did remove a few ‘flashy’ features)
• Uses Click once for application updating (which should make it easier to push updates and bug fixes out to users)
• Added settings for automatic upload (when application starts)
• Added setting for Subcategory selection (only selection, no creation of subcategories through SnugUp)
• Added setting for custom gallery naming
• Completely changed settings user interface to more logically group and explain settings
• Fixed a number of bugs (that shouldn’t have appeared to user anyway!)
• Added support for new file extensions (to upload videos in particular)

It does require .NET 4.0 Framework Client profile (which likely you’ve already got on your machine, but if you don’t the installer SHOULD make it easy to download).

Go here (http://www.wiredprairie.us/SnugUp) for more information and to download. I’d recommend uninstalling the old version first.

When I woke up this morning, I decided that I’d use the remote features of my Nest Thermostat to increase the temperature of the first floor as the normal schedule hadn’t started yet.

Here’s what I saw on my iPad:

Basement: ?

First Floor: ?

When I tapped the Basement image, this alert was displayed:

“Thermostat Disconnected: The thermostat Basement last connected to nest.com more than 7 hours ago.”

What?

I next checked the First Floor. Thankfully, it said that it had only been 17 minutes since it last connected. I’ve seen that issue before and it usually resolves. But, I’ve never seen one go more than about 50 53 minutes without reporting in.

The fact that I was using the iPad and the Nest application meant that WiFi Internet was available in our house.

I went to the Basement thermostat and noticed this glaring issue after clicking through to settings:

What?  Seriously?

As I wasn’t sure what the best option was at 6:45AM for support, I decided to re-add the thermostat to our account. The thermostat had no trouble accessing the Nest cloud and obtaining one of the one time connection keys. (So, I maintain, it’s not general Internet connectivity issues).

After deleting and adding it back, the web site still reported it as MIA. So, I tried a reset:

After resetting, and waiting several minutes after it had completely restarted, it appeared again on the Nest web site.

However, 3 hours later:

It’s again, gone missing.

So, I called support this fine Sunday morning and talked to one of the same support engineers I’ve spoken with in the past (“DK”). I explained the general problem (and emphasized that my biggest concern was that it had lost my account information), my “solution”, and said that it was again not reporting in. In a typical (somewhat ironic) support fashion, as I was explaining the issue and walking to the basement, the thermostat reported in successfully to the Nest cloud.

He had me drop the account, add it to my account, and restart it again. He said that resolves the problem in about 70% of the cases. In the other 30%, he mentioned that they often manually update the firmware and that will help. [ugh]

I’m going to keep an eye on it and will add more details as needed/available.

If you want to talk and discuss more about digital thermostats with others, I’d suggest here: digtstat.com (it’s a web site I created to help provide a better place to have discussions about the Nest thermostat).

When I went to use it this morning, I plugged it in, and then turned it on. After a few minutes of use, the battery status still showed as “not charging.”

The light on the mag-safe connection was green, as if the battery was completely charged.

When I depressed the battery indicator button on the side of the MacBook Pro, the response was 5 quick green flashes on the first LED. According to Apple support, that indicates the battery hasn’t been charged to what’s required for a single indicator light yet. However, while my MacBook Pro had discharged like this before, it would normally start charging right away.

So, apparently, before taking it in for a repair (which is what a lot of people in forums were recommending), you might try resetting the System Management Controller. One of the issues that a reset could fix is that the battery does not appear to be charging properly.

To reset the controller, perform these steps (as documented on the Apple Support web site):

1. Shut down your laptop completely.
2. Plug in the MagSafe power adapter to a power source, connecting it to the MacBook if its not already connected.
3. On the built-in keyboard, press the (left side) Shift-Control-Option keys and the power button at the same time.  [Wow, it’s awkward to do that! I pressed the S-C-O keys first and then the power button and it worked]
4. Release all the keys and the power button at the same time.
5. Press the power button to turn on the computer. 
   Note: The LED on the MagSafe power adapter may change states or temporarily turn off when you reset the SMC.

A few moments after I performed the steps above, the mag safe LED light switched to an orange color (charging) and the battery indicator no longer blinked 5 times quickly.

Problem resolved, and much simpler than taking it to a local Apple “Genius” bar.

As this wasn’t an obvious fix, I’ve decided to put this on my blog in the hope that someone else might find it useful, and so when I have this happen again, I don’t need to go hunting for the solution!

I have done just that this afternoon.

It’s brand new, and hasn’t had the tires kicked much yet (just the absolute basics), but I thought I’d put something out there as the comments and discussion have outgrown my installation of WordPress (and it’s ability to nicely manage a discussion effectively about multiple topics). I really enjoy the conversation and thought it might be best provided in a different forum (pun intended).

It’s here: digtstat.com. (It’s short for Digital Thermostat)

If there’s enough traffic to warrant it, I’ll definitely promote some others as moderators, as it will be kept a civil location for discussions about digital thermostats.

Enjoy.

A few new things have occurred since I last posted.

January 11, 2012: Nest Labs updated the firmware of the thermostat to version 1.0.6. There isn’t any publically available information about what was updated however other than “bug fixes.” Thanks to GregN for pointing it out. Here’s a link to their current software releases and updates for anyone interested:

http://support.nest.com/customer/portal/articles/246009-nest-learning-thermostat-nest-mobile-software-updates

This week, one of my thermostats in “learning” mode wiped out some of the set points I had specifically added for the weekend (this has happened before). I have no rational explanation for why it would do this as our weekend schedule on the floor where it happened is routine enough that it shouldn’t have made that choice. Nest Labs support suggests turning off “learning” mode when this has occurred to see if it’s related to learning mode. They apparently don’t have a way to track the causes or triggers unfortunately (a debug log would come in very handy now). I turned it off for the time being and have added the deleted set points to see if the problem occurs again.

UPDATE: 1/25/2012:  One of our thermostats that still has “learning” turned off decided that our morning set points for our first floor weren’t important and deleted them. Apparently, we didn’t want the house to start warming before we got out of bed.

I found an interesting issue with the Away Temperature settings that you’ll want to watch out for until they fix it (as it could affect triggers for “auto away”).

Essentially, there are values that when you put them into the away temperature field, they won’t “stick.” You won’t necessarily notice this right away unless you click around:

In the video (GIF) above, you’ll see how the “58” won’t stay 58F. It switches to 57 (it happens with 60F as well). I’ve sent a support request to Nest about the issue (they responded the following day and said they’d look into it). Since their web API deals with Celsius, I speculate it could be a rounding issue in their JavaScript code.

Update: 1/24/2012 The bug appears appears to have been corrected in the few places I happened to check earlier today (as I’m not their QA team, I didn’t check around much ).

Randal pointed out that there was someone who’d done some analysis of the temperature readings of a working Nest thermostat (compared to another thermostat). I’d concur that the readings do seem to be far more consistently accurate on the Nest thermostat on average and that our house is more comfortable. However, I’m certainly aware that this comfort will come at a cost. The house is more consistently warmer (now in the heating season). So, depending on your old thermostats and how you handled the temperature in the house, you may find your heating costs rise a bit. Simple way to compensate: you may be able to turn down the thermostat a few degrees! The temperature may read lower, but the actual temperature may be closer to what you had grown accustomed to. We may do that.

I’m still trying to understand why “Auto Away” is sometimes triggered when I wouldn’t expect it. I believe that once it was because the “away” temperatures were one degree LESS than the typical set point. So, the house would not “see us” around, and compared the day time (at work for example) set point (60F) to the “away” temperature (59F) and activate the “away” mode. I found the issue with the away temperature above when I was trying to make everything match one evening this week.  The problem with Auto-away activating is that your scheduled set points won’t be used until it is overridden via the remote interface or locally.

Update: 1/25/2012: Apparently, auto-away unfortunately can trigger even when the temperature settings match exactly. (Even when there’s nothing to do). I don’t understand what it’s “auto-awaying” from.

Here’s a few relevant tweets from @Nest:

Although I admit to not understanding the topmost tweet. My tweet had been:

I honestly didn’t feel like trying to clarify again in 140 characters.

The project is hosted on GitHub. It uses JSON.NET for parsing the return values from the Nest servers.

There are three projects, with the lib containing the assembly that is used by the two test applications. One is a console app and the other a simple WPF application:

(My thermostats are named Zero, One, and Two).

If there’s interest, I plan on adding some methods to the library which allow modification of data (such as the current temperature), and ideally, support for live updates from the devices if I can make sense of the data that is returned.

A few things are going on, the majority as you’d probably expect.

The web interface is using a long polling technique apparently to watch for updates to the schedule, temperature, etc.

I haven’t determined what the frequency is though, or the wait time. It’s very inconsistent, even when I wouldn’t expect much new “live” data to be available on the network, it frequently updates and polls again.

There are a few constants set in the HOME page script:

C.ABSENT_USER_THRESHOLD     = +('300') || 0;  // seconds
C.DEAD_DEVICE_THRESHOLD     = +('300') || 0;  // seconds
C.pollingInterval           = +('2500') || 0;       // ms
C.WEATHER_POLLING_INTERVAL  = +('120000') || 0; // ms

If the C.pollingInterval value were for the subscribe endpoint mentioned above, I’d see a LOT more calls than I do – so I’m still not clear how the polling interval is decided.

The API calls, for the most part are using JSONP syntax over an HTTPS connection.

The most frequent request is to “subscribe.” It sends as part of the GET request a large block of encoded JSON (using encodeURIComponent and then JSON.stringify).

I’m not familiar with the key/value system that they’re using (it may just be something they’ve constructed in-house – although given the number of open source JavaScript libraries they’re using, I thought someone might recognize it):

“key”, “{actualkey}.{value}”

I don’t understand why they’ve redundantly specified “key” in a list of keys when it’s evident that the actual key is contained within the value as a delimited string. It’s more data to send and more data to parse this way. So, again, maybe it’s based on some DB or model system I’m not familiar with. (Anyone recognize it?)

I’ve substituted the actual values (as they are serial numbers of my devices) with text representations of what the value represented below:

{"keys":
    [{"key":"user.#USERID#",
        "version":209478897,"timestamp":1324159145000},
    {"key":"user_alert_dialog.#USERID#",
        "version":-1320296685,"timestamp":1325967612000},
    {"key":"structure.#STRUCTURE-GUID#",
        "version":656192675,"timestamp":1325967612000},
    {"key":"device.#DEVICE 1 SERIAL NUMBER#",
        "version":1485027516,"timestamp":1326034984000},
    {"key":"shared.#DEVICE 1 SERIAL NUMBER#",
        "version":588844038,"timestamp":1326034818000},
    {"key":"schedule.#DEVICE 1 SERIAL NUMBER#",
        "version":1187107985,"timestamp":1326005677000},
    {"key":"track.#DEVICE 1 SERIAL NUMBER#",
        "timestamp":1326035650601,"version":1041047847},
    {"key":"device.#DEVICE 2 SERIAL NUMBER#",
        "version":149169270,"timestamp":1326034820000},
    {"key":"shared.#DEVICE 2 SERIAL NUMBER#",
        "version":659841570,"timestamp":1326034820000},
    {"key":"schedule.#DEVICE 2 SERIAL NUMBER#",
        "version":-2016290692,"timestamp":1326005625000},
    {"key":"track.#DEVICE 2 SERIAL NUMBER#",
        "timestamp":1326035650862,"version":528978433},
    {"key":"device.#DEVICE 3 SERIAL NUMBER#",
        "version":1637112547,"timestamp":1326035399000},
    {"key":"shared.#DEVICE 3 SERIAL NUMBER#",
        "version":760504326,"timestamp":1326035397000},
    {"key":"schedule.#DEVICE 3 SERIAL NUMBER#",
        "version":-314552357,"timestamp":1326003402000},
    {"key":"track.#DEVICE 3 SERIAL NUMBER#",
        "version":-645931164,"timestamp":1326035531802}]}"

We’ve got three thermostats, so there are always three sets of subscription requests for each call to subscribe.

Using my iPad, I adjusted the set point for our second story (#DEVICE 2#) down one degree Fahrenheit (to 67°).

Within approximately a second, the most recent pending subscribe request returned with a far more interesting payload:

jQuery17108417355176061392_1326035646750(
    { "status": 200,
        "headers": {
            "X-nl-skv-key": "shared.#DEVICE 2 SERIAL NUMBER#",
            "X-nl-skv-version": 869022424,
            "X-nl-skv-timestamp": 1326038279000,
            "X-nl-service-timestamp": 1326038279825
        },
        "payload": {
            "current_temperature": 19.98,
            "hvac_fan_state": false,
            "name": "TWO", "hvac_heat_x2_state": false,
            "hvac_ac_state": false,
            "can_cool": true,
            "auto_away": 0,
            "compressor_lockout_enabled": false,
            "target_temperature_low": 16.66667,
            "target_temperature_high": 26.66667,
            "compressor_lockout_timeout": 0,
            "hvac_heater_state": false,
            "hvac_aux_heater_state": false,
            "target_temperature": 19.44444,
            "can_heat": true,
            "target_temperature_type": "heat",
            "target_change_pending": true
        }
    });

Everything above is needed to update the current state of the UI. As you can see, the current temperature (returned as Celsius apparently) is 19.98 (67.964°F). The current temperature as displayed on the thermostat and the web UI was 68.

Seeing these return values makes me think that they may be using Ruby and Rails (as the naming convention tends to follow Rails naming using underscores between words). I know for example, I wouldn’t name variables/columns that way when building a C#/JavaScript MVC project.

Rather than just a delta payload of what’s changed, they’ve currently opted for a full update of all information related to the thermostat state.

Several seconds later, a much larger payload was returned to a subscribe request:

"status": 200,
"headers": {
    "X-nl-skv-key": "device.#DEVICE 2 SERIAL NUMBER#",
    "X-nl-skv-version": -2086438581,
    "X-nl-skv-timestamp": 1326038378000,
    "X-nl-service-timestamp": 1326038379023
},
"payload": {
    "ob_orientation": "O",
    "upper_safety_temp": 1000.0,
    "forced_air": true,
    "creation_time": 1324142042019,
    "switch_preconditioning_control": false,
    "click_sound": "on",
    "leaf": false, "user_brightness": "auto",
    "learning_state": "steady",
    "heat_pump_comp_threshold": -1000.0,
    "local_ip": "10.0.0.205",
    "backplate_serial_number": "#SHOULD BE DEVICE 2 SERIAL NUMBER, BUT ISN'T?#",
    "capability_level": 1.03,
    "postal_code": "#POSTALCODE#",
    "upper_safety_temp_enabled": false,
    "heat_pump_aux_threshold": 10.0,
    "lower_safety_temp_enabled": true,
    "serial_number": "#DEVICE 2 SERIAL NUMBER#",
    "temperature_lock": false,
    "learning_time": 1002,
    "current_version": "1.0.4",
    "model_version": "Diamond-1.10",
    "backplate_bsl_info": "BSL",
    "auto_away_enable": true,
    "heat_pump_comp_threshold_enabled": false,
    "fan_mode": "auto",
    "range_enable": false,
    "temperature_scale": "F",
    "backplate_mono_info": "TFE (BP_DVT) 3.5.2 (ehs@ubuntu) 2011-11-05 12:00:00",
    "backplate_bsl_version": "1.1",
    "equipment_type": "gas",
    "range_mode": false,
    "lower_safety_temp": 7.0,
    "has_fan": true,
    "hvac_wires": "Heat,Cool,Fan,Common Wire,Rc",
    "learning_mode": true,
    "away_temperature_high": 32.0,
    "switch_system_off": false,
    "time_to_target": 1326039444,
    "away_temperature_low": 14.444444444444445,
    "current_humidity": 45,
    "mac_address": "#MACADDR#",
    "backplate_mono_version": "3.5.2",
    "has_aux_heat": false,
    "type": "TBD",
    "hvac_pins": "W1,Y1,C,Rc,G",
    "has_heat_pump": false,
    "heat_pump_aux_threshold_enabled": true,
    "battery_level": 3.945,
    "target_time_confidence": 1.0
}

A few things to note:

Next, a payload is returned with the new status:

"status": 200,
"headers": {
    "X-nl-skv-key": "shared.#DEVICE 2 SERIAL NUMBER#",
    "X-nl-skv-version": 1689916148,
    "X-nl-skv-timestamp": 1326038378000,
    "X-nl-service-timestamp": 1326038379151
},
"payload": {
    "hvac_fan_state": false,
    "name": "TWO",
    "hvac_heat_x2_state": false,
    "hvac_ac_state": false,
    "can_cool": true,
    "auto_away": 0,
    "compressor_lockout_enabled": false,
    "target_temperature_low": 16.66667,
    "current_temperature": 19.53,
    "target_temperature_high": 26.66667,
    "compressor_lockout_timeout": 0,
    "target_change_pending": false,
    "hvac_aux_heater_state": false,
    "target_temperature": 20.55556,
    "can_heat": true,
    "target_temperature_type": "heat",
    "hvac_heater_state": true
}

Here, the hvac_heater_state is set to true. The furnace is on.

A little while later, that value is set to false.

Occasionally, the payload includes the complete schedule for the thermostat. I’m not going to reproduce the entire payload here as it’s too large, and quite boring. Here’s a snippet of what it returns:

"schedule": {
    "#DEVICE 2 SERIAL NUMBER#": {
        "$version": 1187107985,
        "$timestamp": 1326005677000,
        "name": "One Current Schedule",
        "days": {
            "0": {
                "0": {
                    "type": "HEAT",
                    "temp": 14.445,
                    "time": 0,
                    "entry_type": "continuation"
                },
                "1": {
                    "type": "HEAT",
                    "temp": 14.445,
                    "time": 27900,
                    "entry_type": "setpoint"
                },
                "2": {
                    "type": "HEAT",
                    "temp": 20.556,
                    "time": 63000,
                    "entry_type": "setpoint"
                },
                "3": {
                    "type": "HEAT",
                    "temp": 14.445,
                    "time": 70200,
                    "entry_type": "setpoint"
                }
            },
            "1": {
                "0": {
                    "type": "HEAT",
                    "temp": 14.445,
                    "time": 0,
                    "entry_type": "continuation"
                },
                "1": {
                    "type": "HEAT",
                    "temp": 18.889,
                    "time": 20700,
                    "entry_type": "setpoint"
                },

It’s a basic table structure. The first set point of the day is at 0, and is a “continuation.” These don’t show up in the UI.

Here’s what the day 1 looks like on the Nest thermostat UI:

When changing a temperature setpoint, I’m a bit disappointed to see that the entire schedule is sent with every request apparently. I just wouldn’t have expected that given that the more setpoints that there are, the bigger the payload must be. The UI is often sluggish when rapidly making adjustments in the schedule, and this could be one of the factors.

In the example below (which I’ve snipped most of the payload sent again as a JSONP request), I’ve set the first set point to 57F.

    "payload": {
        "days": {
            "0": {
                "0": {
                    "type": "HEAT",
                    "temp": 14.685,
                    "time": 0,
                    "entry_type": "continuation"
                },
                "1": {
                    "type": "HEAT",
                    "temp": 15.000444444444444,
                    "time": 24300,
                    "entry_type": "setpoint"
                },

For the JSONP requests sent as “MAKE CHANGE” (easily could have been PUT), they each contained the following attributes as shown below. All JSONP requests are apparently routed on the web server using “headers” rather than a RESTful URL based system:

    },
    "headers": {
        "X-nl-client-timestamp": 1326041210566,
        "X-nl-session-id": "#SESSION ID#",
        "X-nl-protocol-version": 1,
        "Authorization": "Basic #BASIC AUTH#"
    },
    "path": "/v1/put/schedule.#DEVICE 2 SERIAL NUMBER#",
    "redir": "https://home.nest.com/post_jsonp",
    "jsonp": "4_"
}

It’s RESTful in spirit as there is a route (“path”), but it’s managed by some internal routing engine. (Now, I think that they’re not using Ruby and Rails).

For something simple, like changing the current temperature of a thermostat, the request is thankfully simple:

{
    "payload": {
        "shared": {
            "#DEVICE 2 SERIAL NUMBER#": {
                "target_temperature": 18.333333333333336
            }
        }
    },
    "headers": {
        "X-nl-client-timestamp": 1326041744556,
        "X-nl-session-id": "#SESSION ID#",
        "X-nl-protocol-version": 1,
        "Authorization": "Basic #BASIC AUTH#"
    },
    "path": "/v1/put",
    "redir": "https://home.nest.com/post_jsonp",
    "jsonp": "14_"
}

While, I haven’t taken the time to try to write a custom UI for this undocumented API yet, it looks like it should be relatively easy to do, especially as it relates to the schedule and current temperature settings. I know there’s been some Siri proxy stuff that’s been written – but I don’t have any interest in trying to get that to work.

As with most APIs like this, the trick is often getting authorization correct. For Nest, it appears that making a POST request to https://home.nest.com/accounts/login/ with username and password as form data, that the server responds with 2 cookies:

1. sessionid == used in X-nl-session-id in headers
2. cztoken == used as the Authorization in headers (prepended with the text “Basic “

I received a replacement thermostat earlier this week as promised by Nest Labs. I had time this afternoon to do a swap and reinstall. Nest had asked me to swap the thermostats between two floors experimentally to determine whether a temperature reading issue was related to the location or the thermostat. It was the thermostat.

As part of the swap, I had to reprogram the two thermostats.

I’d swapped the defective thermostat with one from the basement. Apparently, the base has the S/N on it of the thermostat and they’re intended to be “paired” so I decided to return the thermostat to the basement and install the new thermostat on the first floor (replacing the original defective unit).

I removed the old unit and replaced the wires. Depending on the type of wires you’re using, you may find that it’s far more difficult to do than you would expect. I ‘d forgotten how much I hated trying to stick the very stiff HVAC wires into the thermostat’s base!

I replaced everything and activated the unit. You can look at the installation experience post for more information about the general setup.

Past the wifi connection, rebooting, waiting, waiting, waiting, then “ERROR.” “No Rc or Rh” connection.

Crud. So, I popped the thermostat off the base and looked at the wires. They all appeared to be fine. So, I reseated the Rc connection and replaced the thermostat. Success! I find that a tiny tug on the wire after you believe it has been seated does the trick. The rest of the install went without issue.

The thermostat switched to the normal temperature display after a few more alerts. The only thing was – the temperature read 76F. Whaaaa? Given the reboot cycles, etc., I really hadn’t handled it much, not enough to cause the temperature to be that high. I waited about 5 minutes for it to start dropping and when it did not, I called Nest to speak with the person who’d handled the replacement, Mark. He was out apparently, so I ended up speaking with someone who went by “DK” for about 30 minutes about a few topics.

We decided the best course of action was to wait and see.

Thankfully, the new thermostat is now reading a temperature that I would expect, so for some reason, this new thermostat took quite a while to acclimate to the room temperature (much longer than the original three thermostats – around 45 minutes).

I started simple this time.

I wanted a PERSON class and a GIFT class.

A Person has been given gifts and may give gifts (and a few other common attributes).

class CreatePeople < ActiveRecord::Migration
  def change
    create_table :people do |t|
      t.string :first_name
      t.string :last_name
      t.date :date_of_birth
      t.string :email_address

      t.timestamps
    end
  end
end

One of the things that I can’t decide if I like is the automatic pluralization of words, especially People/Person. I would have been content with a Persons table, but when creating a model, by default (as I’m aware it can be overridden), a Person is mapped to a table called “People.”

The second table, Gifts is very simple:

class CreateGifts < ActiveRecord::Migration
  def change
    create_table :gifts do |t|
      t.string :description
      t.integer :from_person_id
      t.integer :to_person_id
      t.timestamps
    end
  end
end

As I thought I might want a richer structure for the Gift class in the future, I did not use the more standard “person_id” name for the foreign key column that maps a gift to a Person. I wanted the column name to be more obvious what it was. Additionally, I needed two columns that both mapped to a “Person", so I couldn’t have both be called “person_id” anyway.

By deviating from the normal pattern, there are a few expectations when defining the ActiveRecord class. It was these expectations that weren’t clear to me (especially with examples).

The Ruby class for Gift is defined like so:

class Gift < ActiveRecord::Base
  belongs_to :from_person, :class_name => "Person", :foreign_key => "from_person_id"
  belongs_to :to_person, :class_name => "Person", :foreign_key => "to_person_id"
end

and the Person:

class Person < ActiveRecord::Base
  has_many  :gifts_given , :class_name => "Gift", :foreign_key => "from_person_id"
  has_many  :gifts, :foreign_key => "to_person_id"
end

The key (and the ‘ah ha’ moment for me) was the use of the foreign_key parameter to the on the has_many and belongs_to associations.

In the Gift class, I included the belongs_to association macro. In this case, :from_person is the name of the rich accessor method (which looks like a property in other languages) that will be added to the Gift class. Using the symbol :class_name is like a class finding assistant. Without it, the Rails framework assumes that there would be a class named “FromPerson.” Of course, that would fail. By specifying “Person,” I’ve indicated to Rails that the class it should map to is called “Person” which I defined earlier. The :foreign_key symbol and value indicates which column in the backing table has the value which will map to an instance of a Person. In the SQL table, I added a “from_person_id” column and this points at that as the “from_person_id” column is the foreign key to the People table. (The same is true for :to_person.)

Looking at the Person class, it is using another common association macro, :has_many. :Has_many when used here, is indicating that a Person may have zero or more “gifts.” The new accessor method is named gifts (by using :gifts). Here, too, you’ll specify the name of the foreign_key. Again, repeat this for the :gifts_given automatically added accessor method. One interesting thing is that only :gifts_given requires the :class_name to be specified. The reason is that Rails automatically maps :gifts to the Gifts class (by way of naming). The :gifts_given cannot be automatically mapped, so you need to give (sigh) it a little help.

Here’s a little test:

>> jason = Person.find(1)
  Person Load (18.0ms)  SELECT "people".* FROM "people" WHERE "people"."id" = ? LIMIT 1  [["id", 1]]
#<Person id: 1, first_name: "Jason", last_name: "Bourne", date_of_birth: nil, email_address: nil, created_at: "2012-01-06 13:47:40", updated_at: "2012-01-07 03:10:29">
>> jason.gifts_given
  Gift Load (0.0ms)  SELECT "gifts".* FROM "gifts" WHERE "gifts"."from_person_id" = 1
[#<Gift id: 1, description: "Machine Gun", from_person_id: 1, to_person_id: 4, created_at: "2012-01-07 14:39:17", updated_at: "2012-01-07 14:39:17">]
>> jason.gifts_given[0].to_person.first_name
"Magnum"
  Person Load (0.0ms)  SELECT "people".* FROM "people" WHERE "people"."id" = 4 LIMIT 1
>> jason.gifts_given[0].to_person.gifts
  [#<Gift id: Gift Load (1.0ms)1  SELECT "gifts".* FROM "gifts" WHERE "gifts"."to_person_id" = 4
, description: "Machine Gun", from_person_id: 1, to_person_id: 4, created_at: "2012-01-07 14:39:17", updated_at: "2012-01-07 14:39:17">]
>> jason.gifts_given[0].to_person.gifts[0].from_person.first_name
  Person Load (0.0ms)  SELECT "people".* FROM "people" WHERE "people"."id" = 1 LIMIT 1
"Jason"

I added two people: Jason, and Magnum, and one gift before executing the code above. Jason, as you should be able to follow, gave a wonderful gift to Magnum. As you can see, by using the automatically added accessor methods by way of the association macros described above, I was able to traverse the database structure very easily when mapped to a few simple objects.

One plus of experimenting and testing with the console while using Rails/Ruby in this case is that the output includes the SQL commands that are executed when the various method calls are made. Here’s an example where I rolled multiple calls into one chained call:

>> jason = Person.find(1).gifts_given[0].to_person.first_name
  Person Load (19.0ms)  SELECT "people".* FROM "people" WHERE "people"."id" = ? LIMIT 1  [["id", 1]]
  Gift Load (0.0ms)  SELECT "gifts".* FROM "gifts" WHERE "gifts"."from_person_id" = 1
"Magnum"
  Person Load (0.0ms)  SELECT "people".* FROM "people" WHERE "people"."id" = 4 LIMIT 1