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some more doc fixes

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Signed-off-by: Sebastian Malton <sebastian@malton.name>
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Sebastian Malton 2021-05-21 14:55:48 -04:00
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docs/extensions/guides/ipc.md
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# Inter Process Communication # Inter Process Communication
A Lens Extension can utilize IPC to send information between its `LensRendererExtension` and its `LensMainExtension`. A Lens Extension can utilize IPC to send information between the `renderer` and `main` processes.
This is useful when wanting to communicate directly within your extension. This is useful when wanting to communicate directly within your extension.
For example, if a user logs into a service that your extension is a facade for and `main` needs to know some information so that you can start syncing items to the `Catalog`, this would be a good way to send that information along. For example, if a user logs into a service that your extension is a facade for and `main` needs to know some information so that you can start syncing items to the `Catalog`, this would be a good way to send that information along.
IPC channels are blocked off per extension. IPC channels are sectioned off per extension.
Meaning that each extension can only communicate with itself. Meaning that each extension can only communicate with itself.
## Types of Communication ## Types of Communication
@ -14,22 +15,22 @@ There are two flavours of communication that are provided:
- Event based (IPC) - Event based (IPC)
- Request based (RPC) - Request based (RPC)
### Event Based IPC ### Event Based or IPC
This is the same as an [Event Emitter](https://nodejs.org/api/events.html#events_class_eventemitter) but is not limited to just one Javascript process. This is the same as an [Event Emitter](https://nodejs.org/api/events.html#events_class_eventemitter) but is not limited to just one Javascript process.
This is a good option when you need to report that something has happened but you don't need a response. This is a good option when you need to report that something has happened but you don't need a response.
This is a fully two-way form of communication. This is a fully two-way form of communication.
Both `LensMainExtension` and `LensRendererExtension` can do this sort of IPC. Both `main` and `renderer` can do this sort of IPC.
### Request Based IPC ### Request Based or RPC
This is more like a Remote Procedure Call (RPC). This is more like a Remote Procedure Call (RPC) or Send-Receive-Reply (SRR).
With this sort of IPC the caller waits for the result from the other side. With this sort of communication the caller needs to wait for the result from the other side.
This is accomplished by returning a `Promise<T>` which needs to be `await`-ed. This is accomplished by `await`-int the returned `Promise<any>`.
This is a unidirectional form of communication. This is a unidirectional form of communication.
Only `LensRendererExtension` can initiate this kind of request, and only `LensMainExtension` can and respond this this kind of request. Only `renderer` can initiate this kind of request, and only `main` can and respond this this kind of request.
## Registering IPC Handlers and Listeners ## Registering IPC Handlers and Listeners
@ -75,7 +76,7 @@ function onInitialize(event: Types.IpcMainEvent, id: string) {
``` ```
In other files, it is not necessary to pass around any instances. In other files, it is not necessary to pass around any instances.
It should be able to just call `getInstance()` everywhere in your extension as needed. It should be able to just call `IpcMain.getInstance()` anywhere it is needed in your extension.
--- ---
@ -109,13 +110,16 @@ It is necessary to create child classes of these `abstract class`'s in your exte
--- ---
As this example shows: the channel names *must* be the same. As this example shows: the channel names *must* be the same.
It should also be noted that "listeners" and "handlers" are specific to either `LensRendererExtension` and `LensMainExtension`. It should also be noted that "listeners" and "handlers" are specific to either `renderer` or `main`.
There is no behind the scenes transfer of these functions. There is no behind the scenes transfer of these functions.
If you want to register a "handler" you would call `IpcMain.getInstance().handle(...)` instead. To register a "handler" call `IpcMain.getInstance().handle(...)`.
The cleanup of these handlers is handled by Lens itself. The cleanup of these handlers is handled by Lens itself.
Calling either `IpcRenderer.getInstance().broadcast(...)` or `IpcMain.getInstance().broadcast(...)` sends an event to all renderer frames and to main. The `listen()` methods on `Ipc.Main` and `Ipc.Renderer` return a `Disposer`, or more specifically, a `() => void`.
This can be optionally called to remove the listener early.
Calling either `IpcRenderer.getInstance().broadcast(...)` or `IpcMain.getInstance().broadcast(...)` sends an event to all `renderer` frames and to `main`.
Because of this, no matter where you broadcast from, all listeners in `main` and `renderer` will be notified. Because of this, no matter where you broadcast from, all listeners in `main` and `renderer` will be notified.
### Allowed Values ### Allowed Values
@ -123,6 +127,6 @@ Because of this, no matter where you broadcast from, all listeners in `main` and
This IPC mechanism utilizes the [Structured Clone Algorithm](developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm) for serialization. This IPC mechanism utilizes the [Structured Clone Algorithm](developer.mozilla.org/en-US/docs/Web/API/Web_Workers_API/Structured_clone_algorithm) for serialization.
This means that more types than what are JSON serializable can be used, but not all the information will be passed through. This means that more types than what are JSON serializable can be used, but not all the information will be passed through.
## Using RPC ## Using Request Based Communication
If you are meaning to do a request based call from `renderer`, you should do `const res = await IpcRenderer.getInstance().invoke(<channel>, ...<args>));` instead. If you are meaning to do a request based call from `renderer`, you should do `const res = await IpcRenderer.getInstance().invoke(<channel>, ...<args>));` instead.