##A simple android library to add Feature-Toggle capability in your app

###Philosophy

A feature toggle, is a technique in software development that helps alter the state of a feature in an application dynamically. For more information, check out this link.

###Example So say, you'd like to disable features like video (or analytics) for a certain group of users (based on api levels and devices) and enable them for the rest, you would need to do the following

####Step 1: Create a configuration file in the following json format and host it somewhere (on your server, S3, etc.)

{
"name": "myapp", "features":  [

{
"name":"video", "default": "enabled", "rules":[

 {
"state": "disabled", "value":

{
"apilevel_min": 21, "apilevel_max": 23, "device":[{
"manufacturer":"xiaomi","model":"mi3"
}
, {
"manufacturer":"samsung", "model":"s4"
}
]
}

}
,

  {
"state": "disabled", "value": {
"appversion_max": 13
}

}

]
}
,

{
"name":"crash_reporting", "rules":[

  {
"state": "disabled", "value":

 {
"appversion": 11, "buildtype": "false"
}

  
}

 ]

}
,

{
"name":"mixpanel","default": "enabled", "rules":[

 {
"state": "disabled", "value":

{
"device":[{
"model":"Google Nexus 5 - 5.1.0 - API 22 - 1080x1920"
}
, {
"manufacturer":"samsung", "model":"s4"
}
]
}

}

]
}
  ] 
}

This configuration file allows you to:

• disable the 'video' feature when all of the following get satisfied:
  • api level between 21 and 23
  • the device type is either a xiaomi mi3 or a samsung s4
• disable the 'video' feature if the app version is less than 13
• enable the 'video' feature otherwise (default: enabled)
• disable the 'mixpanel' feature if the device is a google nexus 5 or a samsung s4
• enable the 'mixpanel' feature otherwise (default: enabled)

You can find more information on the configuration parameters and how they work in the wiki here.

####Step 2: Download a new configuration You can download a new configuration in any of the following ways:

• By passing a url

Toggle.with(context).setConfig(myUrl);

• Downloading the config manually and then pass the same to Toggle as a String (in the Config JSON format)

String configInJson = ... // my custom code for downloading the config from my server and retrieving it as a json Toggle.with(context).setConfig(configInJson);

• Downloading the config manually and then pass the same to Toggle as a Config object

Config config = ... // my custom call (say Retrofit for example) for retrieving the Config object from my server Toggle.with(context).setConfig(config);

Once setConfig is called (in any form) the config is then cached locally, so you can always check for a feature later

####Step 3: Check for the state of a feature at any time (even if you are offline) You can check for a feature using the check method

Toggle.with(context).check("custom_network_component").defaultState(Toggle.ENABLED).start(new cc.soham.toggle.callbacks.Callback() {

 @Override

 public void onStatusChecked(CheckResponse checkResponse) {

  updateUiAfterResponse(checkResponse.featureName, checkResponse.state, checkResponse.featureMetaData, checkResponse.ruleMetadata, checkResponse.cached);

 
}

}
);

In case you used a URL in setConfig, you can also use the getLatest flag to get the latest config before making the callback

Toggle.with(context).check("custom_network_component").getLatest().defaultState(Toggle.ENABLED).start(new cc.soham.toggle.callbacks.Callback() {

 @Override

 public void onStatusChecked(CheckResponse checkResponse) {

  updateUiAfterResponse(checkResponse.featureName, checkResponse.state, checkResponse.featureMetaData, checkResponse.ruleMetadata, checkResponse.cached);

 
}

}
);

The state of the feature can be found in checkResponse.state along with other things present in the config like metadata

###Optional parameters when using check

• onError(ErrorCallback errorCallback): provide an optional callback in case any error is encountered in checking the state of the feature
• getLatest(): checks for the latest Config before returning the state (only valid for URL powered configs)
• defaultState(String defaultState): sets the default state of this request

For more information do check the implementation of CheckRequest.Builder

###Other resources You can find out more about Toggle in our wiki.

###Download

Get this via Gradle:

compile 'cc.soham:toggle:0.1'

or Maven:

<dependency>
<groupId>cc.soham</groupId>
<artifactId>toggle</artifactId>
<version>0.1</version> </dependency>

###ProGuard

If you are using ProGuard you might need to add the following option:

-dontwarn cc.soham.toggle.** 

###License

Copyright 2016 Soham Mondal  Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License. You may obtain a copy of the License at
  http://www.apache.org/licenses/LICENSE-2.0  Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.

###What's next These are the things that are coming up in Toggle

• custom rule-matchers/checks (beyond the usual api-level/app-version/date etc.) that you can define
• faster lookups in check (use hashmaps to look up the states)
• more tests
• multiple configs