Tutorial by Examples: channel

When it comes to adding/removing channels to/from your channel groups, you need to have must have the manage permission for those channel groups. But you should never grant clients the permission to manage the channel groups that they will subscribe to. If they did, then they could add any channel t...

With Stream Controller add-on enabled, you can use Channel Groups to subscribe to a 1000's of channels from a single client. You do this by creating a channel group and adding channels to the channel group. We'll assume pubnub variable has been initialized properly with your keys. Create a generic ...

Channels can be used to send data from one thread to another. Below is an example of a simple producer-consumer system, where the main thread produces the values 0, 1, ..., 9, and the spawned thread prints them: use std::thread; use std::sync::mpsc::channel; fn main() { // Create a channel...

In this example we create a goroutine (a function running in a separate thread) that accepts a chan parameter, and simply loops, sending information into the channel each time. In the main we have a for loop and a select. The select will block processing until one of the case statements becomes tru...

Channel uses a Buffer to read/write data. A buffer is a fixed sized container where we can write a block of data at once. Channel is a quite faster than stream-based I/O. To read data from a file using Channel we need to have the following steps- We need an instance of FileInputStream. FileInput...

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We can use Channel to copy file content faster. To do so, we can use transferTo() method of FileChannel . import java.io.File; import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.IOException; import java.nio.channels.FileChannel; public class FileCopier { ...

To write data to a file using Channel we need to have the following steps: First, we need to get an object of FileOutputStream Acquire FileChannel calling the getChannel() method from the FileOutputStream Create a ByteBuffer and then fill it with data Then we have to call the flip() method of ...

Often times you will have reason to catch when your program is being told to stop by the OS and take some actions to preserve the state, or clean up your application. To accomplish this you can use the os/signal package from the standard library. Below is a simple example of assigning all signals fr...

Arrow is, vaguely speaking, the class of morphisms that compose like functions, with both serial composition and “parallel composition”. While it is most interesting as a generalisation of functions, the Arrow (->) instance itself is already quite useful. For instance, the following function: sp...

If the file already exists, it will be overwritten! String fileName = "file.zip"; // name of the file String urlToGetFrom = "http://www.mywebsite.com/"; // URL to get it from String pathToSaveTo = "C:\\Users\\user\\"; // where to put it ...

core.async is about making processes that take values from and put values into channels. (require [clojure.core.async :as a]) Creating channels with chan You create a channel using the chan function: (def chan-0 (a/chan)) ;; unbuffered channel: acts as a rendez-vous point. (def chan-1 (a/chan...

In PubNub JavaScript v3, you could implement a unique callback for every channel that you subscribed to as long as you called the subscribe function for each channel and implemented the callback in that subscribe like this: var pubnub = new PubNub({ publishKey: "your-pub-key", s...

Overview Android Studio's built-in update mechanism can be set to receive updates through any one of these four channels: Canary: Bleeding edge, released about weekly. These are early previews released in order to obtain real-world feedback during development. The canary channel will always have...

By default communication over the channcels is sync; when you send some value there must be a receiver. Otherwise you will get fatal error: all goroutines are asleep - deadlock! as follows: package main import "fmt" func main() { msg := make(chan string) msg <- "He...

Channel adapter is one of message endpoints in Spring Integration. It is used for unidirectional message flow. There are two types of channel adapter: Inbound Adapter: input side of the channel. Listen or actively read message. Outbound Adapter: output side of the channel. Send message to Java cla...

In the Spring Integration Reference Docuement, it says: The outbound Channel Adapter is the inverse of the inbound: its role is to handle a message and use it to execute a SQL query. The message payload and headers are available by default as input parameters to the query... Java code p...

What Are Notification Channels? Notification channels enable us app developers to group our notifications into groups—channels—with the user having the ability to modify notification settings for the entire channel at once. For example, for each channel, users can completely block all notifications...