This is the implementation of the Friends and Presence services, which are part of Lightbend Cloudstate Cloudstate Chat Sample. The code is written in Javascript and runs as a Node.js server. The screenshot below shows the user interface of the chat application:
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Friends is a stateful service. Using an Observed-Removed Set ORSet CRDT to store/retrieve the list of friends of an user.
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Presence is a stateful service. Using a Vote CRDT to store/retrieve the online status of an user.
The Friends and Presence services have no UI. In this repo, we build these services and test them using docker and grpcurl.
A detailed tutorial is described in Javascript implementation of the Friends service. As the design of these services is quite similar, it is not necessary to repeat for the Presence service.
This is at deployment time, when all the services collaborate together that we can really appreciate the true benefits of microservices. And in particular their stateful and serverless abilities. By using Cloudstate library and deploying on Kubernetes, your services store/retrieve state without requiring you to write any code nor manage any storage.
The deployment is described in details in the Cloudstate Chat Sample.
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Install nvm (node version manager)
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Check with
nvm --version, version 0.34.0+ recommended
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Install npm (node package manager)
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Check with
npm -v, version 6.14.3+ recommended
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Install the protobuf compiler.
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Check with
protoc --version, version 3.0.0+ recommended -
Mac OS X
brew install protobuf -
Linux
sudo apt install protobuf-compiler -
Or alternatively (src and bins)
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Install Docker
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Check with
docker version, version v19.03+ recommended
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The communication between the Cloudstate user-function uses the gRPC protocol. gRPCurl is a command-line tool allowing to query gRPC servers in the same fashion as curl with REST servers.
Install gRPCurl from brew if you are on MacOS or directly from binaries for other OS. If the installation is successful, you should be able to invoke grpcurl -version in a terminal:
$ grpcurl -version
grpcurl 1.6.0