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BotIO

Apache-2.0 License Generic badge

Maven Central

https://central.sonatype.com/artifact/io.github.alexzhyshko/BotIO

Dependencies

(All corresponding rights belong to their respective owners)

Documentation

First of all, since this library relies on TelegramBots project, I recommend to check basics of it before moving on.

Bot Token configuration

There are 3 ways to configure a bot token:

  • Add an environment variable BOT_TOKEN;
  • Add a configuration property botio.botToken;
  • Create custom token provider class. For it just create a new bean which implements BotTokenProvider.

Create routes and transitions

Overall, flow structure in this library consists of so called "routes". A route is basically a state, to which a user will be directed upon each action. Each route has its own "view" - a message, set of buttons etc; and set of methods - actions which are to be executed on a certain user action.

As a first step, it is required to set up an Entrypoint route - the route which is equivalent to index.html in web apps - it is the landing route for our bot application. To do so, we need to:

  • create a class with a @Component;
  • add @Entrypoint - to declare an entrypoint - think of it as an index.html for a web app;
  • implement Route interface (empty by design).

Example below:

@Component
@Entrypoint
public class LandingRoute implements Route {

Other Routes just need to implement Route interface and have a @Component over them.

View Initialization

Every route, except the Entrypoint, can be configured to have a certain message to be displayed whenever the user is redirected to this route. View initializer can be created by declaring a method with @ViewInitializer within the route class. This method receives SendMessage.SendMessageBuilder builder as a parameter. This is a message builder ready to be customized with your own text, buttons, actions etc. Just modify it using builder methods and that's it (not recommended to call .build()).

@ViewInitializer
public ResponseList initView(UpdateWrapper wrapper) {
    var responseMessage = ..prepare some send message or other response..
    return ResponseList.builder()
        .response(responseMessage)
        .build();
}

Update handlers

Currently, bot supports handling of: Message, Callback, Edit Message, Document, Photo and Video types of updates. To create the logic itself, it is needed to specify inside the route class the handler methods with corresponding MessageMapping, CallbackMapping etc. Each method gets an UpdateWrapper instance as an input and should return a ResponseEntity:

@MessageMapping
public ResponseEntity helloWorld(UpdateWrapper wrapper, I18NLabelsWrapper i18NLabelsWrapper) {
    SendMessage sendMessage = SendMessage.builder()
            .chatId(wrapper.getChatId())
            .text("Hello World!")
            .build();
						
    return ResponseEntity.builder()
            .response(sendMessage)
            .build();
}

You can also specify the mapping for *Mapping annotations to specify which updates should be matched and handled to them. By default, if no value specified, it uses * matcher effectively matching any update of this type. For example, if you wish to route to method only MKV video documents, you should specify @DocumentMapping("video/x-matroska")

(similarly Callback handlers can be created)

Transitions to other routes

Routing logic is implemented out-of-the-box and it is enough to add a .nextRoute(<NextRouteClass>.class) into the ResponseEntity builder. Library will automatically invoke the view initializer and transition current state to the specified route.

    return ResponseEntity.builder()
            .response(sendMessage)
            .nextRoute(MenuRoute.class)
            .build();
}

In OOTB state management is using in-memory strategy. Future plans include to add Redis and DB support, until then, feel free to code your own implementation and override OOTB beans.

Filtering

Out-of-the-box there is an available functinality for using filters. To create a filter it is needed:

  • Create a filter class and put @Component over it;
  • Implement FilterAdapter interface and its method;
  • Add config property botio.filters with filter bean names to specify in which order filters have to be executed;
  • Use filterChain.doFilter() to trigger further flow, you can add any logic before anf after - it will be executed in the order of stack;
  • Use UpdateWrapper to get, check or modify any request-related information;
  • Use TelegramClient to execute any actions from within the filter;
  • To abort the filter flow - just throw a FilterException;
@Component
public class BlacklistCheckFilter implements FilterAdapter {
    @Override
    public void filter(FilterChain filterChain, UpdateWrapper wrapper, TelegramClient telegramClient) throws FilterException {
        //do something before request

        filterChain.doFilter();

        throw new FilterException("some error");
    }
}

Exception Handling

OOTB supports handling Exceptions using an @ExceptionHandler. Just create a new public method within a Route class, put an annotation, specify the wanted exception. Other stugg will be provided for you.

@ExceptionHandler(IllegalArgumentException.class)
    public ResponseEntity handleException(Exception e, UpdateWrapper wrapper) {
    
        return ResponseEntity.builder()
                .response(some response)
                .build();

    }

For better understanding of the place of filters in the general flow, at the end I will include a flowchart.

Session management

For now, OOTB uses in-memory session management. Plans include to add Redis support.

Session management is done as silently as possible, it is persisted in between requests, unless the server is restarted. To get and modify the session, in the handler method just use updateWrapper.getSession() method.

It is possible to get, set, delete and invalidate user session.

Internationalization

This library packs I18N functionality out of the box. By default it is disabled, however it can be enabled by adding a botio.i18nEnabled=true to the confifuration properties.

I18N is initialized under the hood and provides an easy access to labels without significant effort. Overall, to use the I18N you need:

  • Enable botio.i18nEnabled;
  • In view initializer method or handler method add second input parameter I18NLabelsWrapper i18NLabelsWrapper. This will be automatically constructed and injected for you;
  • Create message properties files under resources folder, default file is messages_en.properties, but you can add your own files for each locale you need;
  • In code, to get the label, call i18NLabelsWrapper.getLabel(key) (or i18NLabelsWrapper.getLabel(key, args) in case you have any custom parameters).

Multithreading

OOTB supports executing each update within a thread from a thread pool. Thread pool is of fixed size and can be configured. Defaults are:

spring:
  task:
    execution:
      pool:
        core-size: 10
        max-size: 25
        queue-capacity: 25
        keep-alive: "10s"
      thread-name-prefix: UpdateTask-
botio:
  multiThreadedUpdateConsumerEnabled: true

Per-user updates locking

To ensure the order or processing and decrease possible concurrency issues - OOTb supports locking updates for each user. By default it is enabled:

botio:
  perUserRequestLockingEnabled: true

This will lock execution of updates for single user, if they were submitted in a multithreaded way. Each user has their own lock.

Flowchart of processing steps:

image