What is Blynk?

Blynk is a platform with iOS and Android apps to control Arduino, Raspberry Pi and the likes over the Internet.
You can easily build graphic interfaces for all your projects by simply dragging and dropping widgets. If you need more information, please follow these links:

• Kickstarter.
• Blynk downloads, docs, tutorials
• Blynk community
• Facebook
• Twitter

Blynk server

Blynk Server is an Open-Source Netty based Java server, responsible for forwarding messages between Blynk mobile application and various microcontroller boards (i.e. Arduino, Raspberry Pi. etc). Take latest build here.

Requirements

Java 8 required. (OpenJDK, Oracle)

GETTING STARTED

Right now Blynk server uses 2 ports. 1 port is used for hardware and second one is used for the mobile apps. This is done due to the lack of security mechanism and low resources on microcontroller boards (e.g. Arduino UNO). By default, mobile application uses 8443 port and is based on SSL/TLS sockets. Default hardware port is 8442 and is based on plain TCP/IP sockets.

Quick local server setup

• Make sure you are using Java 8

    java -version
    Output: java version "1.8.0_40"
  

• Run the server on default 'hardware port 8442' and default 'application port 8443' (SSL port)

    java -jar server-{PUT_LATEST_VERSION_HERE}.jar
  

• Run the server on custom ports

    java -jar server-{PUT_LATEST_VERSION_HERE}.jar -hardPort 8442 -appPort 8443
  

Advanced local server setup

If you need more flexibility, you can extend server with more options by creating server.properties file in same folder as server.jar. Example could be found here. server.properties options:

• Application port

    server.ssl.port=8443
  

• Hardware port

    server.default.port=8442
  

• User profiles folder. Folder in which all users profiles will be stored. By default System.getProperty("java.io.tmpdir")/blynk used. Will be created if not exists

    data.folder=/tmp/blynk
  

• Folder for all application logs. Will be created if it doesn't exist.

    logs.folder=./logs
  

• Maximum allowed number of user dashboards. This value can be changed without restaring the server. ("Reloadable" below).

    user.dashboard.max.limit=10
  

• 100 Req/sec rate limit per user. Reloadable

    user.message.quota.limit=100
  

• In case user exceeds quota limit - response error returned only once in specified period (in Millis). Reloadable

    user.message.quota.limit.exceeded.warning.period=60000
  

• Maximum allowed user profile size. In Kb's. Reloadable

    user.profile.max.size=128
  

• In-memory storage limit for storing read values from hardware

    user.in.memory.storage.limit=1000
  

• Period for flushing all user DB to disk. In millis.

    profile.save.worker.period=60000
  

Behind wifi router

If you want to run Blynk server behind WiFi-router and want it to be accessible from the Internet, you have to add port-forwarding rule on your router. This is required in order to forward all of the requests that come to the router within the local network to Blynk server.

Performance

Currently server easly handles 40k req/sec hardware messages on VM with 2-cores of Intel(R) Xeon(R) CPU E5-2660 @ 2.20GHz. With high load - memory consumption could be up to 1 GB of RAM.

App Client (emulates Smartphone App)

• To emulate the Smartphone App client:

    java -jar client-${PUT_LATEST_VERSION_HERE}.jar -mode app -host localhost -port 8443
  

• In this client: register new user and/or login with the same credentials

    register username@example.com UserPassword
    login username@example.com UserPassword
  

• Save profile with simple dashboard

    saveProfile {"dashBoards":[{"id":1, "name":"My Dashboard", "boardType":"UNO"}]}
  

• Get the Auth Token for hardware (e.g Arduino)

    getToken 1
  

• Activate dashboard

    activate 1
  

• You will get server response similar to this:

    00:05:18.100 TRACE  - Incomming : GetTokenMessage{id=30825, command=GET_TOKEN, length=32, body='33bcbe756b994a6768494d55d1543c74'}
  

Where 33bcbe756b994a6768494d55d1543c74 is your Auth Token.

Hardware Client (emulates Hardware)

• Start new client and use received Auth Token to login

    java -jar client-${PUT_LATEST_VERSION_HERE}.jar -mode hardware -host localhost -port 8442
    login 33bcbe756b994a6768494d55d1543c74
  

You can run as many clients as you want.

Clients with the same credentials and Auth Token are grouped into one Session and can send messages to each other. All client’s commands are human-friendly, so you don't have to remember the codes.

Hardware Commands

Before sending any read/write commands to hardware, application must first send “init” command. "Init" command is a 'hardware' command which sets all the Pin Modes(pm). Here is an example of "init" command:

	hardware pm 1 in 13 out 9 out 8 in

// TODO: take description about pin modes from Blynk Arduino library readme // TODO Describe separation with Zeroes in pinmode command

In this example you set pin 1 and pin 8 to 'input’ PIN_MODE. This means this pins will read values from hardware (graph, display, etc). Pins 13 and 9 have 'output’ PIN_MODE. This means that these pins will we writable (button, slider).

List of hardware commands:

• Digital write:

    hardware dw 9 1
    hardware dw 9 0
  

• Digital read:

    hardware dr 9
    You should receive response: dw 9 <val>
  

• Analog write:

    hardware aw 14 123
  

• Analog read:

    hardware ar 14
    You should receive response: aw 14 <val>
  

• Virtual write:

    hardware vw 9 1234
    hardware vw 9 string
    hardware vw 9 item1 item2 item3
    hardware vw 9 key1 val1 key2 val2
  

• Virtual read:

    hardware vr 9
    You should receive response: vw 9 <values>
  

Registered users are stored locally in TMP dir of your system in "user.db" file. So, after the restart you won't need to re-register.

Licensing

MIT license