Telegram

Since Camel 2.18

The Telegram component provides access to the Telegram Bot API. It allows a Camel-based application to send and receive messages by acting as a Bot, participating in direct conversations with normal users, private and public groups or channels.

A Telegram Bot must be created before using this component, following the instructions at the Telegram Bot developers home. When a new Bot is created, the BotFather provides an authorization token corresponding to the Bot. The authorization token is a mandatory parameter for the camel-telegram endpoint.

In order to allow the Bot to receive all messages exchanged within a group or channel (not just the ones starting with a '/' character), ask the BotFather to disable the privacy mode, using the /setprivacy command.

Maven users will need to add the following dependency to their pom.xml for this component:

<dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-telegram</artifactId>
    <version>x.x.x</version>
    <!-- use the same version as your Camel core version -->
</dependency>

URI format

telegram:type/authorizationToken[?options]

You can append query options to the URI in the following format, ?option=value&option=value&…​

Options

The Telegram component supports 2 options, which are listed below.

Name Description Default Type

authorizationToken (security)

The default Telegram authorization token to be used when the information is not provided in the endpoints.

String

resolveProperty Placeholders (advanced)

Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders.

true

boolean

The Telegram endpoint is configured using URI syntax:

telegram:type/authorizationToken

with the following path and query parameters:

Path Parameters (2 parameters):

Name Description Default Type

type

Required The endpoint type. Currently, only the 'bots' type is supported.

String

authorizationToken

Required The authorization token for using the bot (ask the BotFather), eg. 654321531:HGF_dTra456323dHuOedsE343211fqr3t-H.

String

Query Parameters (24 parameters):

Name Description Default Type

proxyHost (common)

The proxyHost which could be used when sending out the message.

String

proxyPort (common)

The proxyPort which could be used when sending out the message.

Integer

bridgeErrorHandler (consumer)

Allows for bridging the consumer to the Camel routing Error Handler, which mean any exceptions occurred while the consumer is trying to pickup incoming messages, or the likes, will now be processed as a message and handled by the routing Error Handler. By default the consumer will use the org.apache.camel.spi.ExceptionHandler to deal with exceptions, that will be logged at WARN or ERROR level and ignored.

false

boolean

limit (consumer)

Limit on the number of updates that can be received in a single polling request.

100

Integer

sendEmptyMessageWhenIdle (consumer)

If the polling consumer did not poll any files, you can enable this option to send an empty message (no body) instead.

false

boolean

timeout (consumer)

Timeout in seconds for long polling. Put 0 for short polling or a bigger number for long polling. Long polling produces shorter response time.

30

Integer

exceptionHandler (consumer)

To let the consumer use a custom ExceptionHandler. Notice if the option bridgeErrorHandler is enabled then this option is not in use. By default the consumer will deal with exceptions, that will be logged at WARN or ERROR level and ignored.

ExceptionHandler

exchangePattern (consumer)

Sets the exchange pattern when the consumer creates an exchange.

ExchangePattern

pollStrategy (consumer)

A pluggable org.apache.camel.PollingConsumerPollingStrategy allowing you to provide your custom implementation to control error handling usually occurred during the poll operation before an Exchange have been created and being routed in Camel.

PollingConsumerPoll Strategy

chatId (producer)

The identifier of the chat that will receive the produced messages. Chat ids can be first obtained from incoming messages (eg. when a telegram user starts a conversation with a bot, its client sends automatically a '/start' message containing the chat id). It is an optional parameter, as the chat id can be set dynamically for each outgoing message (using body or headers).

String

synchronous (advanced)

Sets whether synchronous processing should be strictly used, or Camel is allowed to use asynchronous processing (if supported).

false

boolean

backoffErrorThreshold (scheduler)

The number of subsequent error polls (failed due some error) that should happen before the backoffMultipler should kick-in.

int

backoffIdleThreshold (scheduler)

The number of subsequent idle polls that should happen before the backoffMultipler should kick-in.

int

backoffMultiplier (scheduler)

To let the scheduled polling consumer backoff if there has been a number of subsequent idles/errors in a row. The multiplier is then the number of polls that will be skipped before the next actual attempt is happening again. When this option is in use then backoffIdleThreshold and/or backoffErrorThreshold must also be configured.

int

delay (scheduler)

Milliseconds before the next poll. You can also specify time values using units, such as 60s (60 seconds), 5m30s (5 minutes and 30 seconds), and 1h (1 hour).

500

long

greedy (scheduler)

If greedy is enabled, then the ScheduledPollConsumer will run immediately again, if the previous run polled 1 or more messages.

false

boolean

initialDelay (scheduler)

Milliseconds before the first poll starts. You can also specify time values using units, such as 60s (60 seconds), 5m30s (5 minutes and 30 seconds), and 1h (1 hour).

1000

long

runLoggingLevel (scheduler)

The consumer logs a start/complete log line when it polls. This option allows you to configure the logging level for that.

TRACE

LoggingLevel

scheduledExecutorService (scheduler)

Allows for configuring a custom/shared thread pool to use for the consumer. By default each consumer has its own single threaded thread pool.

ScheduledExecutor Service

scheduler (scheduler)

To use a cron scheduler from either camel-spring or camel-quartz2 component

none

ScheduledPollConsumer Scheduler

schedulerProperties (scheduler)

To configure additional properties when using a custom scheduler or any of the Quartz2, Spring based scheduler.

Map

startScheduler (scheduler)

Whether the scheduler should be auto started.

true

boolean

timeUnit (scheduler)

Time unit for initialDelay and delay options.

MILLISECONDS

TimeUnit

useFixedDelay (scheduler)

Controls if fixed delay or fixed rate is used. See ScheduledExecutorService in JDK for details.

true

boolean

Spring Boot Auto-Configuration

When using Spring Boot make sure to use the following Maven dependency to have support for auto configuration:

<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-telegram-starter</artifactId>
  <version>x.x.x</version>
  <!-- use the same version as your Camel core version -->
</dependency>

The component supports 3 options, which are listed below.

Name Description Default Type

camel.component.telegram.authorization-token

The default Telegram authorization token to be used when the information is not provided in the endpoints.

String

camel.component.telegram.enabled

Enable telegram component

true

Boolean

camel.component.telegram.resolve-property-placeholders

Whether the component should resolve property placeholders on itself when starting. Only properties which are of String type can use property placeholders.

true

Boolean

Message Headers

Name Description

CamelTelegramChatId

This header is used by the producer endpoint in order to resolve the chat id that will receive the message. The recipient chat id can be placed (in order of priority) in message body, in the CamelTelegramChatId header or in the endpoint configuration (chatId option). This header is also present in all incoming messages.

CamelTelegramMediaType

This header is used to identify the media type when the outgoing message is composed of pure binary data. Possible values are strings or enum values belonging to the org.apache.camel.component.telegram.TelegramMediaType enumeration.

CamelTelegramMediaTitleCaption

This header is used to provide a caption or title for outgoing binary messages.

CamelTelegramParseMode

This header is used to format text messages using HTML or Markdown (see org.apache.camel.component.telegram.TelegramParseMode).

Usage

The Telegram component supports both consumer and producer endpoints. It can also be used in reactive chat-bot mode (to consume, then produce messages).

Producer Example

The following is a basic example of how to send a message to a Telegram chat through the Telegram Bot API.

in Java DSL

from("direct:start").to("telegram:bots/123456789:insertYourAuthorizationTokenHere");

or in Spring XML

<route>
    <from uri="direct:start"/>
    <to uri="telegram:bots/123456789:insertYourAuthorizationTokenHere"/>
<route>

The code 123456789:insertYourAuthorizationTokenHere is the authorization token corresponding to the Bot.

When using the producer endpoint without specifying the chat id option, the target chat will be identified using information contained in the body or headers of the message. The following message bodies are allowed for a producer endpoint (messages of type OutgoingXXXMessage belong to the package org.apache.camel.component.telegram.model)

Java Type Description

OutgoingTextMessage

To send a text message to a chat

OutgoingPhotoMessage

To send a photo (JPG, PNG) to a chat

OutgoingAudioMessage

To send a mp3 audio to a chat

OutgoingVideoMessage

To send a mp4 video to a chat

OutgoingDocumentMessage

To send a file to a chat (any media type)

byte[]

To send any media type supported. It requires the CamelTelegramMediaType header to be set to the appropriate media type

String

To send a text message to a chat. It gets converted automatically into a OutgoingTextMessage

Consumer Example

The following is a basic example of how to receive all messages that telegram users are sending to the configured Bot. In Java DSL

from("telegram:bots/123456789:insertYourAuthorizationTokenHere")
.bean(ProcessorBean.class)

or in Spring XML

<route>
    <from uri="telegram:bots/123456789:insertYourAuthorizationTokenHere"/>
    <bean ref="myBean" />
<route>

<bean id="myBean" class="com.example.MyBean"/>

The MyBean is a simple bean that will receive the messages

public class MyBean {

    public void process(String message) {
        // or Exchange, or org.apache.camel.component.telegram.model.IncomingMessage (or both)

        // do process
    }

}

Supported types for incoming messages are

Java Type Description

IncomingMessage

The full object representation of an incoming message

String

The content of the message, for text messages only

Reactive Chat-Bot Example

The reactive chat-bot mode is a simple way of using the Camel component to build a simple chat bot that replies directly to chat messages received from the Telegram users.

The following is a basic configuration of the chat-bot in Java DSL

from("telegram:bots/123456789:insertYourAuthorizationTokenHere")
.bean(ChatBotLogic.class)
.to("telegram:bots/123456789:insertYourAuthorizationTokenHere");

or in Spring XML

<route>
    <from uri="telegram:bots/123456789:insertYourAuthorizationTokenHere"/>
    <bean ref="chatBotLogic" />
    <to uri="telegram:bots/123456789:insertYourAuthorizationTokenHere"/>
<route>

<bean id="chatBotLogic" class="com.example.ChatBotLogic"/>

The ChatBotLogic is a simple bean that implements a generic String-to-String method.

public class ChatBotLogic {

    public String chatBotProcess(String message) {
        if( "do-not-reply".equals(message) ) {
            return null; // no response in the chat
        }

        return "echo from the bot: " + message; // echoes the message
    }

}

Every non-null string returned by the chatBotProcess method is automatically routed to the chat that originated the request (as the CamelTelegramChatId header is used to route the message).

Getting the Chat ID

If you want to push messages to a specific Telegram chat when an event occurs, you need to retrieve the corresponding chat ID. The chat ID is not currently shown in the telegram client, but you can obtain it using a simple route.

First, add the bot to the chat where you want to push messages, then run a route like the following one.

from("telegram:bots/123456789:insertYourAuthorizationTokenHere")
.to("log:INFO?showHeaders=true");

Any message received by the bot will be dumped to your log together with information about the chat (CamelTelegramChatId header).

Once you get the chat ID, you can use the following sample route to push message to it.

from("timer:tick")
.setBody().constant("Hello")
to("telegram:bots/123456789:insertYourAuthorizationTokenHere?chatId=123456")

Note that the corresponding URI parameter is simply chatId.

Customizing keyboard

You can customize the user keyboard instead of asking him to write an option. OutgoingTextMessage has the property ReplyKeyboardMarkup which can be used for such thing.

from("telegram:bots/123456789:insertYourAuthorizationTokenHere")
    .process(exchange -> {

        OutgoingTextMessage msg = new OutgoingTextMessage();
        msg.setText("Choose one option!");

        InlineKeyboardButton buttonOptionOneI = InlineKeyboardButton.builder()
                .text("Option One - I").build();

        InlineKeyboardButton buttonOptionOneII = InlineKeyboardButton.builder()
                .text("Option One - II").build();

        InlineKeyboardButton buttonOptionTwoI = InlineKeyboardButton.builder()
                .text("Option Two - I").build();

        ReplyKeyboardMarkup replyMarkup = ReplyKeyboardMarkup.builder()
                .keyboard()
                    .addRow(Arrays.asList(buttonOptionOneI, buttonOptionOneII))
                    .addRow(Arrays.asList(buttonOptionTwoI))
                    .close()
                .oneTimeKeyboard(true)
                .build();

        msg.setReplyKeyboardMarkup(replyMarkup);

        exchange.getIn().setBody(msg);
    })
    .to("telegram:bots/123456789:insertYourAuthorizationTokenHere");

If you want to disable it the next message must have the property removeKeyboard set on ReplyKeyboardMarkup object.

from("telegram:bots/123456789:insertYourAuthorizationTokenHere")
    .process(exchange -> {

        OutgoingTextMessage msg = new OutgoingTextMessage();
        msg.setText("Your answer was accepted!");

        ReplyKeyboardMarkup replyMarkup = ReplyKeyboardMarkup.builder()
                .removeKeyboard(true)
                .build();

        msg.setReplyKeyboardMarkup(replyMarkup);

        exchange.getIn().setBody(msg);
    })
    .to("telegram:bots/123456789:insertYourAuthorizationTokenHere");
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