ldsemerenko / simple-slack-api

Simple Slack API

This library allows an aplication to connect to Slack to receive and send messages from any channel as if it were a slack client.

The main purpose of this library is to build slack bots able to react to channel events without having to configure any web hook.

Maven/Gradle

You can add this library as a dependency to your Maven or Gradle project through JitPack.

Short example

Slack connection :

The connection is made through the SlackSessionFactory class :

Direct connection :

SlackSession session = SlackSessionFactory.
  createWebSocketSlackSession("authenticationtoken");
session.connect();

Through a proxy :

SlackSession session = SlackSessionFactory.
  createWebSocketSlackSession("authenticationtoken", Proxy.Type.HTTP, "myproxy", 1234);
session.connect();

Listening to messages :

Slack messages can be retrieved by attaching a SlackMessageListener to the session provided by the factory :

  session.addMessagePostedListener(new SlackMessagePostedListener()
  {
      @Override
      public void onEvent(SlackMessagePosted event, SlackSession session)
      {
          session.sendMessageOverWebSocket(session.findChannelByName("general"), "Message sent : " + event.getMessageContent(), null);
      }
  });

(Since v0.4.0, lambda friendly version)

session.addMessagePostedListener((e, s) 
  -> s.sendMessageOverWebSocket(s.findChannelByName("general"), "Message sent : " + e.getMessageContent(), null));

Message operation :

The SlackSession interface provides various methods to send/modify and delete messages on a given channel :

SlackMessageHandle sendMessage(SlackChannel channel, String message, SlackAttachment attachment);
SlackMessageHandle sendMessage(SlackChannel channel, String message, SlackAttachment attachment, SlackChatConfiguration chatConfiguration);
SlackMessageHandle updateMessage(String timeStamp, SlackChannel channel, String message);
SlackMessageHandle deleteMessage(String timeStamp, SlackChannel channel)

(Since v0.4.3, emoji reactions on channel messages)

The SlackSession interface provides a method to add an emoji reaction to a message on a given channel :

SlackMessageHandle addReactionToMessage(SlackChannel channel, String messageTimeStamp, String emojiCode);

Full example :

Here's a full example with an echoing bot using this library :

public class Example
{

  public static void main(String[] args) throws Exception
  {

    final SlackSession session = SlackSessionFactory.
      createWebSocketSlackSession("authenticationtoken", Proxy.Type.HTTP, "myproxy", 1234, true);
    session.addMessagePostedListener(new SlackMessagePostedListener()
    {
        @Override
        public void onEvent(SlackMessagePosted event, SlackSession session)
        {
          //let's send a message
          SlackMessageHandle handle = session.sendMessage(session.getChannel(),
                              event.getMessageContent(), null);
          try
          {
              Thread.sleep(2000);
          } catch (InterruptedException e)
          {
              e.printStackTrace();
          }
          //2 secs later, let's update the message (I can only update my own messages)
          session.updateMessage(handle.getSlackReply().getTimestamp(),session.getChannel(),
                                event.getMessageContent()+" UPDATED");
          try
          {
              Thread.sleep(2000);
          } catch (InterruptedException e)
          {
              e.printStackTrace();
          }
          //2 secs later, let's now delete the message (I can only delete my own messages)
          session.deleteMessage(handle.getSlackReply().getTimestamp(),session.getChannel())
        }
      });
    session.connect();

    while (true)
    {
      Thread.sleep(1000);
    }
  }
}

Features

Supported Slack commands

All these commands can be sent through the library provided your bot has the rights to (IE : the bot has to be a member of the group or the channel to post some messages on it)

• Post a message on a channel / private group / user
• Update a message
• Delete a message
• Join a channel
• Leave a channel / a private group
• Invite to a channel / a private group
• Archive a channel
• Open a direct message channel (since v0.5.0)
• Open a multiparty direct message channel (since v0.5.0)
• Get the presence status of a user
• Add a reaction emoji to a message
• Fetch the channel history (since v0.5.0) (needs full user credentials)
• Invite a user to Slack (since v0.5.0)

On top of these built-in features, it is now possible to send not yet implemented API calls by using the postGenericSlackCommand method :

postGenericSlackCommand(Map<String, String> params, String command);

Supported Slack events

All these events can be listen provided your bot has the rights to (IE : the bot has to be a member of the group or a channel to gets the message events related to it)

• message posted event
• message deleted event
• message updated event
• channel created event
• channel / private group deleted event
• channel / private group archived event
• channel / private group unarchived event
• channel / private group renamed event
• channel /private group joined event
• reaction added to message event (since v0.5.0)
• reaction removed from message event (since v0.5.0)

Thanks

Many thanks to everyone who has contributed to this library :

• Christian Sprecher
• Jan Vidar Krey
• David Seebacher
• Wouter Vernaillen
• Claudio Comandini
• Maxim Gurkin
• Ole Kozaczenko
• Georges Gomes
• François Valdy
• Harry Fox

(Let me know if I forgot someone, I'll fix that ASAP ;) )

License

This library is licensed under the Creative Commons CC0 1.0 Universal license with no warranty (expressed or implied) for any purpose.