Dart SDK for Dapr.

Last update: Sep 7, 2022

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Overview

Dapr dart sdk

Welcome to the dart-sdk for dapr. This repository aims to provide and maintain the dart packages required to interact with dapr sidecar.

What is Dapr?

Dapr is an API to build & maintain, portable and reliable microservices. It allows developers to build microservices that can inteface with a plethora of external services, through a set of standardised APIs. Using Dapr allows developers to focus on the core business logic instead of dealing with the SDKs required to connect with theses external services.

Dapr enables this interfacing by defining a set of standard components namely building blocks each of which handle different core logic that a microservice would require to handle. This is achieved using a sidecar architecture in which the sidecar runs alongside your service or web app and enables interacting with external services through this sidecar.

To learn more about Dapr head over to docs section at https://dapr.io/

What does this SDK offer?

The Dart-sdk offers two main packages namely dapr_client and dapr_server which provides api's to interact with a dapr_sidercar.

When using Dapr there are two main use cases.

An application interacting with the Dapr sidecar to invoke, publish or retrieve state.
- dapr_client eases this process by providing a unified api to interact with all the building blocks a sidecar offers.
An application which can be invoked by external services, which listens to a published message to take corresponding action.
- dapr_server eases this process by providing APIs to write daperised services which confirm to the required specification.

The image below depicts both these use cases.

Comments

Daprdocs - Initiate Daprdocs for dart-sdk
Description

Initiate Daprdocs for dart-sdk, in order to allow dapr.io site to render docs related to dart-sdk.

Checklist

Please make sure you've completed the relevant tasks for this PR, out of the following list:

[x] Code compiles correctly

[ ] Created/updated tests

[x] Extended the documentation
opened by Abhilash-Chandran 0
Pubsub route matching and routing messages

In its current form the pub module is dapr_server supports only simple routing based on the route parameter.

However, there is feature to perform route matchin introduced in v1.5 of Dapr.

This needs to be incorporated in to the current api.

Current documentation of this feature is available here.

https://docs.dapr.io/developing-applications/building-blocks/pubsub/howto-route-messages/
enhancement dapr_server pubsub

opened by Abhilash-Chandran 0
Multiple subscribers for same topic, possible?

In the current form both go-sdk and js-sdk allows registering multiple subscriber callbacks for the same topic, when the communication protocol is http, meanig the server is an http server.

However in grpc server since the map of subscribing callback is built using only the pubsub name and topic name, only one subscriber callback is mapped to the combination of pubsubname and topic name.

This means a service can register only one subscriber for a topic in the grpc format and multiple subscriber in the http format.

This needs to be verified which is the correct approach.
help wanted question dapr_server

opened by Abhilash-Chandran 0
Subscription is passed the cloud event data in the form for string.

In the current form subscribe method under HttpServerPubsub passes the cloud event data to the callback as a string.

This could be enhanced by passing the decoded cloud event to the callback.

Decision needs to be made whether this should be decoded into a CloudEvent object before passing it to the callback.

This needs to be done only if the rawEvents argument is set to false.
bug dapr_server pubsub

opened by Abhilash-Chandran 0
Define Exception base/implementation classes
In order to clearly pass on the information from the API to the user, it is important to define the known Exceptions and Errors. This needs to be defined as a set of abstract and concrete classes in order to be used across the API and tested.

TODO:

[ ] Define a base Dapr exception class

[ ] Derive a base Dapr HTTP and GRPC exception class for client implementations.

Note: The server api is not planned as of now. In future in might evolve into a separate package within this project if necessary.

enhancement good first issue dapr_client
opened by Abhilash-Chandran 0