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Plugins can be developed in a large variety, in process, out-of-process, out-of host, and each plugin can exploit a large scale over communication protocols, JSONRPC/COMRPC, MessagePackRPC.

In In-process, we can share the worker pool from the WPEFramework thread pool (it will be used a process which is light weight and does not require its own process space : lot of plugins are in-process (Device Info, RemoteControl, FirmwareControl, TraceControl etc)

Out-of-process is used to run a plugin which is required to handle in a separate process context (if by any action it can affect WPEFramework process, has to be run as out of process), for example BrowserPlugin (cobalt, webkit, spark, Netflix).
It will provide its own thread pool, then also it can communicate with the WPEFramework using COMRPC

OUT-of Host can be run outside the device and connect with the WPEFramework externally. COMRPC is used to communicate between process and it should be used if there is large data. Currently there is no existing plugin, only example plugin: https://github.com/WebPlatformForEmbedded/ThunderNanoServices/tree/master/examples/RemoteHostExample

COMRPC is used to communicate between the plugins (out of process) or to communicate for larger data
https://github.com/WebPlatformForEmbedded/ThunderNanoServices/tree/master/examples/COMRPCClient

JSONRPC is used to fetch/update info to or from plugins externally (most of the plugins provide this in interface, similar to ReST API)
also it can be used from applications : https://github.com/WebPlatformForEmbedded/ThunderNanoServices/tree/master/examples/JSONRPCClient
It will be used only for small data

Message pack also, similar to JSONRPC, we can have example at https://github.com/WebPlatformForEmbedded/ThunderNanoServices/tree/master/examples/JSONRPCClient plugin. But this feature is not exposed outside through the WPEFramework Process. It can implemented by using another application as like https://github.com/WebPlatformForEmbedded/ThunderNanoServices/blob/master/examples/JSONRPCPlugin/JSONRPCPlugin.h#L149

Steps involved in implementing new Thunder Plug-In

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