# Sample Plugin: Server

The server component of this sample plugin is written in Go and [net/rpc](https://golang.org/pkg/net/rpc/). It relies on a configured `ChannelName` and `Username` in [plugin.json](../plugin.json) to implement each of the supported hooks. 

Each of the included files or folders is outlined below.

## [go.mod](go.mod), [go.sum](go.sum)

These are metadata files managed by [vgo](https://github.com/golang/vgo) for dependency management. While vgo is currently in beta, it will launch as part of the standard Go 1.11 tooling and stabilize in subsequent releases. It was preferred for this project over [dep](https://github.com/golang/dep) since it does not require locating your plugin in the `$GOPATH`.

## [main.go](main.go)

This is the entry point of your plugin binary, that in turn invokes [plugin.ClientMain](https://godoc.org/github.com/mattermost/mattermost-server/plugin#ClientMain) to wire up RPC communication between your plugin and the Mattermost Server.

## [plugin\_id.go](plugin_id.go)

This is a file generated by the [build/manifest](../build/manifest) tool that captures the plugin id from [plugin.json](../plugin.json). It simplifies the need to hard-code the plugin id in multiple places by exporting a constant for use instead.

## [plugin.go](plugin.go)

This file defines the `Plugin` struct, embedding [plugin.MattermostPlugin](https://godoc.org/github.com/mattermost/mattermost-server/plugin#MattermostPlugin) to automatically handle the wiring up the [API](https://godoc.org/github.com/mattermost/mattermost-server/plugin#API) when the plugin starts. It contains public fields that are automatically unmarshalled from [plugin.json](../plugin.json) as part of the `OnConfiguration` hook in [configuration.go](configuration.go).

## [activate\_hooks.go](activate_hooks.go)

### OnActivate

This sample implementation logs a message to the sample channel whenever the plugin is activated.

### OnDeactivate

This sample implementation logs a debug message to the server logs whenever the plugin is activated.

## [configuration.go](configuration.go)

### OnConfigurationChange

This sample implementation ensures the configured sample user and channel are created for use
by the plugin.

## [channel\_hooks.go](channel_hooks.go)

### ChannelHasBeenCreated

This sample implementation logs a message to the sample channel whenever a channel is created.

### UserHasJoinedChannel

This sample implementation logs a message to the sample channel whenever a user joins a channel.

### UserHasLeftChannel

This sample implementation logs a message to the sample channel whenever a user leaves a channel.

## [command\_hooks.go](command_hooks.go)

### ExecuteCommand

This sample implementation responds to a `/sample_plugin` command, allowing the user to enable
or disable the sample plugin's hooks functionality (but leave the command and webapp enabled).

## [http\_hooks.go](http_hooks.go)

### ServeHTTP

This sample implementation sends back whether or not the plugin hooks are currently enabled. It
is used by the web app to recover from a network reconnection and synchronize the state of the
plugin's hooks.

## [message\_hooks.go](message_hooks.go)

### MessageWillBePosted

This sample implementation rejects posts in the sample channel, as well as posts that @-mention
the sample plugin user.

### MessageWillBeUpdated

This sample implementation rejects posts that @-mention the sample plugin user.

### MessageHasBeenPosted

This sample implementation logs a message to the sample channel whenever a message is posted,
unless by the sample plugin user itself.

### MessageHasBeenUpdated

This sample implementation logs a message to the sample channel whenever a message is updated,
unless by the sample plugin user itself.

## [team\_hooks.go](team.go)

### UserHasJoinedTeam

This sample implementation logs a message to the sample channel in the team whenever a user
joins the team.

### UserHasLeftTeam

This sample implementation logs a message to the sample channel in the team whenever a user
leaves the team.