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IotWebConf hacking guide

IotWebConf comes with a lot of examples. These examples are intended to be easy to use, with clear goals. While IotWebConf is also ment to be developer friendly, providing lots of customization options.

This documentation will try to explain features where you can customize IotWebConf on your need, or where a feature explanation might be out of the scope of regular examples.

Please note, that header files are full of documentation, so please heavily consult IotWebConf.h header file while/beside reading this documentation.

Contents:

Using IotWebConf with PlatformIO

It is recommended to use PlatformIO instead of the Arduino environment.

With v3.0.0, a folder pio is provided with scripts that transforms examples to PlatformIO compatible format. You can use these as templates for your project. (On the other hand, these scripts creating soft-link loops, and having soft link loops in these folders might cause Arduino and other environment to fail. Just keep in mind, if something goes wrong with your IDE, then examples-pio is likely the corporate.)

Compile time configuration

IotWebConf includes a configuration file named IotWebConfSettings.h. This configuration file works on C pre-compiler mechanism. This means you cannot use it in Arduino environment, so I encourage everyone to switch to PlatformIO.

In the PlatformIO you can do configuration changes by adding lines to platformio.ini like this:

build_flags =
  -DIOTWEBCONF_DEFAULT_WIFI_CONNECTION_TIMEOUT_MS="60000"
  -DIOTWEBCONF_DEBUG_DISABLED

Note: You must not use #define IOTWEBCONF_CONFIG_START 20, or similar defines in your .ino file (e.g. before the includes). It will eventually just not work, as all .cpp files are compiled separately for each other. Thus, you must use the -D compiler flag for the job.

Groups and Parameters

With version 3.0.0 IotWebConf introduces individual parameter classes for each type, and you can organize your parameters into groups. You can also free to add groups into groups to make a tree hierarchy.

Optional and chained groups

With OptionalParameterGroup, the group you have defined will have a special appearance in the config portal, as the fieldset in which the group items are shown can be hidden (inactive) / shown (active).

E.g you want to create a group with property items, that are not mandatory, so you can hide these options in the config portal by default, and only reveal the contents, when it is strictly requested. There is a specific example covering this very feature under IotWebConf13OptionalGroup.

ChainedParameterGroups can be linked. One after another. The property sets will reveal on after another, when user requests is. The difference between OptionalParameterGroup and ChainedParameterGroup is that second group item in a chained list can only be added, when the first item is already visible. There is a specific example covering this very feature under IotWebConf14GroupChain.

Using system parameter-group

By default, you should add your own parameter group, that will appear as a new field-set on the Config Portal. However, there is a special group maintained by IotWebConf called the System group, where you are also allowed to add your own custom properties.

Example:

  iotWebConf.addSystemParameter(&stringParam);

You can directly access system-parameter group by calling getSystemParameterGroup().

Example:

  ParameterGroup* systemParameters = iotWebConf.getSystemParameterGroup();
  systemParameters.label = "My Custom Label";

There is another group "WiFi parameters" managed by IotWebConf, that can be retrieved by getWifiParameterGroup().

Alternative WiFi connection

With v3.0.0 you can set up multiple WiFi connection by utilizing the MultipleWifiAddition class can be found in IotWebConfMultipleWifi.h .

This class basically set up some handlers in iotWebConf to

  1. display optional WiFi settings in admin GUI,
  2. use these alternative settings in case previous WiFi connection attempts fails.

The maximal number of connection settings are determined compile-time, as we want to avoid any dynamic memory allocations in Arduino.

There is a complete example covering this topic, please visit example IotWebConf15MultipleWifi!

Accessing system properties

IotWebConf comes with some parameters, that are required for the basic functionality. You can retrieve these parameter by getters, e.g. getThingNameParameter(). You can directly modify these items as seen in the code block below.

There is a dedicated example covering this topic, so please visit example IotWebConf11AdvancedRuntime!

    // -- Update Thing name
    strncpy(
      iotWebConf.getThingNameParameter()->valueBuffer,
      "My changed name",
      iotWebConf.getThingNameParameter()->getLength());
    iotWebConf.saveConfig();

Here is list of some of the system parameter-acccessors, please consult IotWebConf.h for further details.

  • getSystemParameterGroup()
  • getThingNameParameter()
  • getApPasswordParameter()
  • getWifiParameterGroup()
  • getWifiSsidParameter()
  • getWifiPasswordParameter()
  • getApTimeoutParameter()

Use custom style

You can provide your own custom HTML template by updating default HTML format provider. For this you should utilize the setHtmlFormatProvider() method.

There is a complete example about this topic, so please visit example IotWebConf10CustomHtml!

Create your property class

With version 3.0.0 you are free to create your own property class. It is done by inheriting the iotwebconf::Parameter C++ class. You can use other property types e.g. PasswordProperty as a template for this.

Now, custom properties are mainly handy, when you would like to create some special HTML form item. But eventually you can change the whole behaviour of your parameter handling. E.g. by overriding storeValue() and loadValue() you can basically convert your internal data format to whatever you like. The Typed parameters approach is just an excellent example for this option.

You can also override ParameterGroup class in case you need some special group appearance.

There is a complete example about this topic, so please visit example IotWebConf12CustomParameterType!

Typed parameters (experimental)

A new parameter structure is introduced, where the parameters does not require a "valueBuffer" anymore. Storing the parameter is done in a native format, e.g. a 8-bit integers are stored in one byte of EEPROM.

This was achieved by utilizing the template technology of C++. While the result is spectacular, the template makes thing very complicated under the hood.

Builder pattern is also introduced for the typed parameters. See example IotWebConf03TypedParameters for details. Please compare example IotWebConf03TypedParameters and IotWebConf03TypedParameters for the difference in the usage of the two different approach.

Please note, that Typed Parameters are very experimental, and the interface might be a subject of change in the future.

UML diagram of the Typed Parameters approach. (This image was created by PlantUML, the source file is generate with command hpp2plantuml -i src/IotWebConfTParameter.h -o doc/TParameter.plantuml)

Control on WiFi connection status change

IotWebConf provides a feature to control WiFi connection events by defining your custom handler event handler.

With setWifiConnectionFailedHandler() you can set up a handler, that will be called, when a connection to a WiFi network failed (most likely timed out). Now, when you return with a new valid connection-info from your callback, IotWebConf will not fall back to AP mode, but try the connection you have just provided. With this method you can theoretically set up multiple WiFi networks for IotWebConf to try connect to after one-by-one if the previous one fails. Some days IotWebConf might also provide this feature out of the box.

There is a second method, where you can define a specific handler, this is the setWifiConnectionHandler(). Your method will be called when IotWebConf trying to establish connection to a WiFi network.

For details please consult IotWebConf.h header file!

Use alternative WebServer

There was an expressed need from your side for supporting specific types of Web servers. (E.g https web server or async web server.) So, with v3.0.0 there is an option to use web server of your choice. To achieve this, you will call IotWebConf constructor, that accepts a WebServerWrapper pointer. In the WebServerWrapper you have the implement all expected web server functionalities (as seen in the header file). You can use the StandardWebServerWrapper as a template for that.

Further more, you also need to provide your custom WebRequestWrapper instances when calling handleCaptivePortal(), handleConfig() and handleNotFound().

Unfortunately I currently do not have the time to implement solutions for Async Web Server os Secure Web Server. If you can do that with the instruction above, please provide me the pull request!