Add Saga pattern quickstart in Java

[skyao]

Description

This PR is to add a quickstart for saga pattern support in java.

The implementation of saga pattern is in lasted dapr-sdk-workflows v0.11.0-SNAPSHOT version which is not merged and released yet.

At this time, This PR is a preview edition:

• Saga pattern support is still a proposal and under review and discussion.
• This PR is to help to understand how to use saga (for solution saga-in-workflow)
• This PR is not a final version and will keep updating during the proposal review and discussion
• Don't merge this PR before the proposal is accepted and the design is finalized.

Issue reference

TBD: add issue here when the proposal is accepted, and the design is finalized.

Checklist

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

• The quickstart code compiles correctly
• You've tested new builds of the quickstart if you changed quickstart code
• You've updated the quickstart's README if necessary
• If you have changed the steps for a quickstart be sure that you have updated the automated validation accordingly. All of our quickstarts have annotations that allow them to be executed automatically as code. For more information see mechanical-markdown. For user guide with examples see Examples.

[skyao]

how to run this quickstart

Since the proposal of saga pattern support is still under review and discussion, the code of saga pattern implementation in dapr java sdk is in preview edition as described in PR dapr/java-sdk#956.

install dapr-sdk-workflows locally

To run this quickstart, we need to build and install dapr-sdk-workflows 0.11.0-SNAPSHOT dependency locally.

# clone the PR repo before it's merged
git clone git@github.com:skyao/java-sdk.git
cd java-sdk
# checkout to the saga branch
git checkout saga-in-workflow
# install dapr-sdk-workflows 0.11.0-SNAPSHOT locally
mvn clean install

run this quickstart

# clone the PR repo before it's merged
git clone git@github.com:skyao/quickstarts.git
cd quickstarts
# checkout to the saga branch
git checkout saga-in-workflow

cd workflow-saga/java/sdk

Then reference to the README.md file in workflow-saga/java/sdk folder.

[skyao]

@artursouza this PR can merge now.

[DavidEggen]

Are there any plans to make this available for C#/.net sdk?

[paulyuk]

Hey folks. I like this content, but it wasn't ready to be a quickstart, and I'm not sure we even want multiplier quickstarts like this (e.g. a matrix multiplier for Saga). As David's comment points out it also instantly created a "debt" to do this right for all languages, testing and so on.

@artursouza I'd ask you to revert this. @msfussell fyi. Then @skyao we should really talk about a proposal for something like this before coding the PR. Or you risk me asking you to back it out and redo it.

[paulyuk]

@skyao what do you think about taking your same content, but submitting it as an "example" under the Java sdk repo? The bar is very different for that, and we won't lose the good work here.

The very specific folder is right here: https://github.com/dapr/java-sdk/tree/master/examples/src/main/java/io/dapr/examples/workflows