Cloud Foundry Java Client V2

Ben Hale <bhale@...>

As many of you are aware, the Cloud Foundry Java Client has been a bit neglected lately. There are various reasons for this, but today I’m pleased to announce that we’ve begun a V2 effort and that progress is swift.

We on the Cloud Foundry Java Experience team have been aware for some time that the current implementation of the Java Client is less than ideal. Among the most common complaints were the lack of separation between interface and implementation, the subpar network performance, and the requirement that users understand how to orchestrate common concepts like `push` on their own. (For a more in-depth treatment of issues we identified, please see the stellar work done by Scott Fredrick[1].) V2 aims to address all of these issues with a ground-up redesign of the client.

To address the issue of a lack of separation between interface and implementation, we’ve broken out the API into a project containing no implementation. This project (`cloudfoundry-client`) consists of a collection of interfaces and immutable datatypes. There is only a single dependency, and it isn’t Spring! The intent here was to create an API that could be implemented with multiple strategies, but requiring the minimal amount of code for each of those implementations. The API itself is now reactive (the single dependency is on Reactive Streams, the precursor to reactive support in Java 9) which we believe will more closely align with the trends towards non-blocking network communication. We will be providing a single implementation of this API, based on Spring (`cloudfoundry-client-spring`) but welcome additional implementations. We believe we’ve created a good environment for alternatives and would be happy to hear suggestions on how to improve if that turns out not to be the case.

In V1, the coverage of the APIs[2] was incomplete (about half, if I had to guess). Our commitment is to deliver a complete API and implementation in V2, including all 300+ documented APIs. We’ve observed that this API might not actually be the right level of abstraction for many users though. Knowing that you need to create an application, create a package, stage a droplet, create and start a process, etc. for `push` is quite a burden on many users of the project. So, we’re also providing a `cloudfoundry-operations` project that builds on the `cloudfoundry-client` API but instead of mapping onto the low-level REST API, we’re going to map roughly onto the `cf` CLI API. We suspect that nearly all users will want to `cloudFoundryOperations.push()` instead of the low-level alternative, so both choices are useful. This API and implementation will only depend on `cloudfoundry-client` allowing any implementation of that API to be used. Finally, we’ll be bringing the build-system plugins up to date with the systems that they are built for and ensuring that they cover a breadth of useful functionality at build time.

This leaves the question about what will happen to V1. We have a commitment to fixing up the bugs that have been identified in the code-base, but we’re not going to be doing any work that involves adding APIs. We feel that users who need those APIs are better served moving to V2. I’ll be feeding open issues from the backlog into the V2 stream of work to ensure that we aren’t seeing any resource starvation and you can expect future releases out of the `1.x` branch.

I hope that this comes as welcome news to the community and look forward to the feedback. I highly encourage users to keep an eye Pivotal Tracker[3] to see our progress and submit requests through GitHub[4].

-Ben Hale
Cloud Foundry Java Experience


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