Loopback Address: A loopback address is a type of IP address that is used to test the communication or transportation medium on a local network card and/or for testing network applications. Data packets sent on a loopback address are re-routed back to the orginating node without any alteration or modification. Default route = 0.0.0.0/0; 127.0.0.0 = loopback address. Localhost = localhost as a hostname translates to an IPv4 address in the 127.0.0.0/8 (loopback) net block, usually 127.0.0.1, or::1 in IPv6. There are more special addresses. But you can learn about them later. See Reserved IP addresses. TCP/IP Protocol Layers TCP/IP data flow.
Overview
LoopBack is built on Express and implements Express' routing system. However, basic Express routing is limited only to a small portion of the functionality of LoopBack.A large part of LoopBack's features are implemented using its more detailed extension to the routing system.Understanding this system will help you understand LoopBack better and develop better LoopBack apps.
Summary of Express routing
Loopback 2 0 0 – Route Audio Between Applications Pdf Download
For those not familiar with routing in Express, here are some key points:
Routing refers to the rules for capturing requests to the server, and the subsequent passing through and handling of requests through a chain of middleware functions.
A middleware function accepts three objects, the request object (
req),the response object (res),and the next middleware in the chain (next); in that order.You load middleware either using
app.use()or by assigning it as the callback function of aroute definition.Multiple middleware can be matched to handle the requests to a route,these matched middleware make up the middleware chain for the request.The request will pass through each middleware in the order they were loaded, unless one of the middleware in the chain terminates the propagation.
Any middleware in the chain may terminate the request propagation by sending a response back to the client.
A middleware can send the response to the request using one of the response methods in the response objector pass on the request to the next middleware by calling
next().If a middleware sends the server response, conventionally the request does not propagate further in the middleware chain.Any call to
next()will likely result in an error.A middleware function can also take four arguments. In this case, it is an error handling middleware.The parameters to the function in their order are: the error object (
err),the request object (req), the response object (res),and the next middleware in the chain (next).
For more details about routing in Express, see http://expressjs.com/guide/routing.html.
LoopBack routing
LoopBack implements the middleware pattern of request routing, therefore the concept of middleware and routing is the same as in Express.However, the Express aspect of routing is contained within the modified middleware chain generated by LoopBack.The extended routing details in LoopBack is best understood by understanding the LoopBack middleware chain.
LoopBack middleware chain
The LoopBack middleware chain is composed of middleware added to the chain in the following order, and the request passes through them in the given order.
Note:
Except 14, 15, and 16, the listed items refer to LoopBack middleware phases.
- initial:before
- initial
- initial:after
- session:before
- session
- session:after
- auth:before
- auth
- auth:after
- parse:before
- parse
- parse:after
- routes:before
- routes
- routes:after
- files:before
- files
- files:after
- final:before
- final
- final:after
A middleware loaded earlier in the chain gets the prior opportunity to handle the request.If it happens to send a response or fail to call next(), the request will terminate at it, and not propagate any further.
As evident from the list above, LoopBack takes control of the loading order of the middleware in the app, and prioritizes its relevantmiddleware over those loaded using Express' interface app.use(), components, or boot scripts.
Loopback 2 0 0 – Route Audio Between Applications Pdf Reader
Note:
If you add middleware on the route or route:after phase, it will not execute after the route is matched.Instead, it will be ignored because the route was already matched.
The middleware to be loaded during the middleware phases are configured in the middleware.json file of the app.The order of the phases in the file are semantic, and cannot be listed randomly.
LoopBack also supports custom phases.Custom phases can be defined in any position of the middleware chain, and may be used to prioritize over LoopBack's built-in middleware phases.
As evident from the list above, LoopBack takes control of the loading order of the middleware in the app, and prioritizes its relevantmiddleware over those loaded using Express' interface app.use(), components, or boot scripts.
Loopback 2 0 0 – Route Audio Between Applications Pdf Reader
Note:
If you add middleware on the route or route:after phase, it will not execute after the route is matched.Instead, it will be ignored because the route was already matched.
The middleware to be loaded during the middleware phases are configured in the middleware.json file of the app.The order of the phases in the file are semantic, and cannot be listed randomly.
LoopBack also supports custom phases.Custom phases can be defined in any position of the middleware chain, and may be used to prioritize over LoopBack's built-in middleware phases.
Loopback 2 0 0 – Route Audio Between Applications Pdf File
Loading middleware
LoopBack middleware are declaratively loaded using the middleware.json file,or imperatively using the app.middleware() method.
Express middleware can be loaded in the server.js file using app.use()or a route definition.
Loopback 2 0 0 – Route Audio Between Applications Pdf Converter
LoopBack components can load middleware using the reference to the LoopBack application instance.
Boot scripts can load middleware using the reference to the LoopBack application instance.
Loopback makes it easy to pass audio between applications on your Mac. Create virtual audio devices to take the sound from applications and audio input devices, then send it to audio processing applications. Loopback gives you the power of a high-end studio mixing board, right inside your computer!
- Play Audio to All Your Podcast Guests - Combine your mic with audio sources like iTunes or QuickTime Player, then select your Loopback device as your source in Skype. Presto! Your guests all hear both your voice and your audio add-ons.
- Record Gameplay Videos - Making gameplay videos with great audio can often be very difficult. If you're using a device like Elgato's Game Capture hardware and you want to record both your microphone and the game's audio at once, Loopback can assist!
- Combine Hardware Devices - Apps like GarageBand, Logic, and Ableton Live only record from a single audio device at once. Thankfully, they offer recording from many channels. With Loopback, you can combine multiple input devices into one virtual device for easy recording.
- Create Top-Notch Screencasts - Screen recorders, including QuickTime Player, allow you to include your mic's audio. Some allow recording of system audio instead, but neither option is ideal. Create a virtual device that grabs just the mic and the app's audio to get exactly the audio you want.
- Route Audio For Broadcasts - Set a simple (pass-thru) device as the output at the end of an Audio Hijack chain, and then as the input source in Nicecast. Now listeners can tune in to a live stream of your podcast as you record it!
Features
- Combine Audio Sources - Configuring a virtual audio device from multiple sources is easy. Just add the applications and physical audio devices you want to include to the Audio Sources table to get started.
- Available System-Wide - Your Mac will show Loopback's virtual devices exactly like physical devices. Find them listed among other devices in System Preferences or select them as an input or output in any audio app.
- Send Audio Between Apps - Loopback can also create pass-thru devices, which send audio from one app to another. Set the Loopback device as the output in one app and the input in another to make audio flow directly between the applications.
- Works With Any Application - Make a virtual audio device with audio from the applications on your Mac, including production apps like Logic or Reason, as well as simple audio players, like iTunes or QuickTime.
- Works With Any Input Device - Pull audio from the physical audio devices connected to your Mac. Whether you've got simple USB microphones, or high-end studio mixers, Loopback can access it all.
- Combine Apps and Physical Devices - Of course, you can create a virtual audio device that includes audio from both apps and physical audio devices.
- Multichannel Audio - Your virtual audio devices can be configured to have up to 32 channels, providing tremendous power.
- Custom Channel Mapping - By default, Loopback sets up channel mapping automatically. If you want to manually configure things, though, you've got powerful options!
- Nested Devices - You can now nest one Loopback device inside another, allowing for easier configuration, as well as even more power and control.
