NAME

Mojo::WebSocketProxy::Backend::ConsumerGroups - Class for communication with backend by sending messaging through redis streams.

VERSION

version 0.07

DESCRIPTION

Class for communication with backend by sending messaging through redis streams.

• Redis streams is used as channel for sending request to backend servers.
• Redis subscriptions is used as channel for receiving responses from backend servers.

NAME

Mojo::WebSocketProxy::Backend::ConsumerGroup

METHODS

new

Creates object instance of the class

• redis_uri - URI for Redis connection. Ignored if the redis argument is also given.

• redis - Redis client object (must be compatible with Mojo::Redis2). This argument will override the redis_uri argument.

• timeout - Request timeout, in seconds. If not set, uses the environment variable RPC_QUEUE_RESPONSE_TIMEOUT, or defaults to 30

• queue_separation_enabled - Boolean to specify if messages should be assigned to different queus based on their category or only general queue.

• category_timeout_config - A hash containing the timeout value for each request category.

    { general => 5, other => 120 }
  

loop

pending_requests

Returns hashref which is used as a storage for keeping requests which were sent. Stucture of the hash should be like:

• key - request id, which we'll get from redis after successful adding request to the stream
• value - future object, which will be done in case of getting response, of cancelled in case of timeout

redis

timeout

category_timeout_config

Hash containing the timeout value for each rpc call category.

{ general => 5, other => 120 }

queue_separation_enabled

Boolean specifying if category separation should be enabled.

whoami

Return unique ID of Redis which will be used by backend server to send response. Id is persistent for the object.

call_rpc

Makes a remote call to a process returning the result to the client in JSON format. Before, After and error actions can be specified using call backs. It takes the following arguments

• $c : Mojolicious::Controller
• $req_storage A hashref of attributes stored with the request. This routine uses some of the following named arguments:
  • method The name of the method at the remote end.
  • msg_type a name for this method; if not supplied method is used.
  • call_params a hashref of arguments on top of req_storage to send to remote method. This will be suplemented with $req_storage->{args} added as an args key and be merged with $req_storage->{stash_params} with stash_params overwriting any matching keys in call_params.
  • rpc_response_callback If supplied this will be run with args: Mojolicious::Controller instance, the rpc_response and $req_storage. Note: if rpc_response_callback is supplied the success and error callbacks are not used.
  • before_get_rpc_response arrayref of subroutines to be run before the remote response is received, with args: $c and req_storage
  • after_get_rpc_response arrayref of subroutines to be run after the remote response is received; called with args: $c and req_storage called only when there is an response from the remote call.
  • before_call arrayref of subroutines called before the request to the remote service is made.
  • rpc_failure_cb a subroutine reference to call if the remote call fails. Called with Mojolicious::Controller, the rpc_response and $req_storage
  • category - if supplied, the message will be assigned to the Redis channel with the corresponding name. The general channel will be used by default if either $msg_type is not provided or queue_separation_enabled is 0.

Returns undef.

request

Sends request to backend service. The method accepts following arguments:

• request_data - an arrayref containing data for the item which is going to be put into redis stream.
• $category_name - this will be passed to _send_request to specify which redis category this message belongs to.
• category_timeout - timeout value for this specific call (differs based on category)

Returns future. Which will be marked as done in case getting response from backend server. And it'll be marked as failed in case of request timeout or in case of error putting request to redis stream.

wait_for_messages

By using redis subscription, we subscribe on channel for receiving responses from backend server. We'll use uniq id generated by whoami as subscription channel. Subscription will be done only once within first request to backend server.

AUTHOR

DERIV [email protected]

COPYRIGHT AND LICENSE

This software is copyright (c) 2021 by Deriv Services Ltd.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.