Telegram Adapter

Step by step Guide.

• Framework
• Structure
• Used online sources

Framework

• Using Java-Telegram-Bot-API Framework from github user pengrad.
  • Easy access to Telegram API via TelegramBot-Objects
  • Well maintained repository (June 2017)

Structure

• Telegram Adapter is split in two basic classes:
  1. TelegramReceiveAdapter
  2. TelegramSendAdapter
• Receiving messages via webhook.

i. TelegramReceiveAdapter

• For receiving new messages from Users.

Using RESTEasy for HTTP Requests.

@Path("/telegram")
public class TelegramReceiveAdapter {

    @POST
    @Path("/getUpdates")
    public void getUpdates(final String msg) {}

    ...
}

ii. TelegramSendAdapter

• For sending new messages to Users.

Asynchronus Webhook verification.

SetWebhook webhook = new SetWebhook().url(properties.getProperty("WEB_URL") + properties.getProperty("TELEGRAM_WEBHOOK_URL"));

bot.execute(webhook, new Callback<SetWebhook, BaseResponse>() {
    @Override
    public void onResponse(final SetWebhook request, final BaseResponse response) {
        logger.debug("No errors while setting Telegram webhook.");
    }
    @Override
    public void onFailure(final SetWebhook request, final IOException e) {
        logger.warn("An Error occured while setting Telegram webhook. BOT_TOKEN: " + properties.getProperty("TELEGRAM_BOT_TOKEN") + " - WEBHOOK_URL: " + properties.getProperty("WEB_URL") + properties.getProperty("TELEGRAM_WEBHOOK_URL"));
    }
});

Send Text Request.

private void sendMessage(final Long senderId, final String message) {
        SendMessage request = new SendMessage(senderId, message);
        SendResponse sendResponse = bot.execute(request);
        logger.debug("Send de.bht.chatbot.message: " + sendResponse.isOk());
    }

Send Audio Request.

private void sendAudio(final BotMessage botMessage){
    SendAudio request;

    // check and send each attachement
    for (Attachment attachment : botMessage.getAttachements()) {
        request = new SendAudio(botMessage.getSenderID(), attachment.getFileURI());

        if (attachment.getCaption() != null)
            request.caption(attachment.getCaption());

        SendResponse sendResponse = bot.execute(request);
        logger.debug("Send Audio: " + sendResponse.isOk());
    }
}

Used online sources

• Telegram API overview
• Java-Telegram-Bot-API (github - user: pengrad)