OSGi Cloud Ecosystems RFC 183 in public draft

Recently the OSGi Alliance has made an Early Access Draft available of many of the RFCs that are currently being worked on in the Enterprise Expert Group (EEG) and the Core Platform Expert Group (CPEG).

One of these is RFC 183: OSGi Cloud Ecosystems.
OSGi Cloud Ecosystems is about having a many OSGi frameworks co-operating in a Cloud or Cloud-like environment. Its about having multiple cloud nodes work together to provide a coherent logical function. This includes the ability to reconfigure your deployments to scale up when needed or scale down when possible. It also includes providing the ability to react to volatility in your Cloud environment, as nodes might die unexpectedly or may become unresponsive for some reason.

A large portion of RFC 183 is about how you discover things. How do I discover what OSGi frameworks are available in my environment? And what are the characteristics of those frameworks? What cloud or other environment are they running on and where? For certain applications knowing the actual country or region of your deployment is vital, so this is one of the pieces of information available.

When a cloud node appears it often appears on a dynamically assigned node. RFC 183 is about letting the other OSGi frameworks in the environment know that there is a new Framework available so that they can communicate with it. Information passed to other frameworks includes things as the IP address of the node, which is obviously vital in order to be able to communicate. Additionally information about the type of infrastructure the node is running on is made available. Typically the process that reacts to changes in the topology involves some of the following:

• If a new framework appears, it needs to be provisioned, meaning that an entity in the system needs to decide what artifacts need to be deployed on it.
• Once provisioned it needs to become part of the overall function of the system. This means that other entities on the various participating nodes must be wired up to use the new node.
• Similarly, when a VM is taken out of the environment, the interested other nodes are informed so that they can adjust to the situation.
• Other conditions may also require a change in the way the system is provisioned can be:
• when the load on a particular node gets too high - we need to find some quiet nodes that can take over some of the load.
• when the functionality offered by the application changes, maybe the user has changed the application configuration.
• when the system is quiet - we can give some resources back for consumption by other components.

RFC 183 aims at making it really easy to use OSGi services across Cloud nodes. This means that as a developer you're just writing OSGi services (which are really just Java POJOs) and that you can make these available across your Cloud Ecosystem to all the frameworks available. The mechanics are based on the OSGi Remote Services specs. The nice thing is that the Discovery piece takes care of wiring these services up, so you don't need to know where the service is running, you can simply find it in your local Service Registry and use it. If the service migrates to another VM, or another copy of it becomes available, Discovery will update the Service Registry in your framework so that it's up to date with what services are available in the ecosystem. The OSGi service model is already very much geared towards dynamicity of services, so the potential volatility of a cloud deployment fits here very well. Existing service component such as Declarative Services, Blueprint and others can work well with these Distributed Services while providing a very simple programming model at the same time.

RFC 183 is really about providing a base layer for dynamic applications that run in the cloud. It's minimal in the sense that it provides some primitives that allow you to create a dynamic, service-based cloud system in a way that is very familiar if you are used to OSGi services. It gives you all you need to write a provisioner that is part of the system, but it does not define a cloud deployment descriptor format or anything like that. At this stage you need to write your own provisioner that knows how to provision your application, although a more generic provisioning system could be written using the primitives provided.
Or maybe someone wants to create a PaaS that can take direct deployment of Blueprint beans or Declarative Service components. These too could also be modeled atop of what RFC 183 attempts to provide.

At the moment RFC 183 does not attempt to provide a standard mechanism for creating or shutting down compute nodes. There are already a number of projects that abstract over this and I think it would be best to utilize those right now, although it might make sense to describe at some point how these are integrated with the OSGi Service Registry.

It's still early days, this is the first EA draft that contains RFC 183, but from speaking with people who are using OSGi in a cloud environment, many solutions are moving into a similar direction, so it looks like things are converging.

You can find RFC 183 in the draft here: http://www.osgi.org/Download/File?url=/download/osgi-early-draft-2013-03.pdf

If you have any thoughts about it, let us know what you think at the osgi-dev mailing list or to create a bug around the topic in OSGi buzilla.

Additionally, I'll be talking about this topic at EclipseCon: http://www.eclipsecon.org/2013/sessions/osgi-cloud-ecosystems

New OSGi EEG Early Access Draft available

A new Early Access Draft has been published at OSGi that contains 3 RFCs that are currently being discussed in the Enterprise Expert Group.

Blueprint Transactions (RFC 164)
This RFC focuses on how to add declarative transaction support to the OSGi Blueprint standard.

Portable Java Contracts (RFC 180)
OSGi has always been very outspoken about versioning Java packages (for more info see the Semantic Versioning white paper: http://www.osgi.org/wiki/uploads/Links/SemanticVersioning.pdf) however, what version to use for APIs defined by JavaEE has been unclear. While many people have been talking about these APIs in terms of the JavaEE versions (e.g. Servlet 2.5, Servlet 3.0) these version numbers don't always match with the Semantic Versioning ideas that OSGi promotes. For example, with Semantic Versioning you would only increase the major version if you are breaking backward compatibility. When Servlet 3.0 came out of the JCP it did actually not break compatibility with 2.5, but still the major version was increased. In the end the various OSGi-enabled application server implementors used different versioning schemes for JavaEE packages, which made it unclear how to use these in a portable way from OSGi. This RFC aims at addressing this issue in a way that is both natural to people familiar with the JavaEE version numbers as well as being able to cope with the various package version numbers used in the OSGi capable Application Servers.

REST Management Interface (RFC 182)
In the context of Cloud Computing, REST is becoming the dominant way of accessing and controlling remote applications running in the cloud. This RFC defines a remote management interface for OSGi bundles over REST and defines both JSON as well as XML data bindings.

You can find the Early Access Draft here: http://www.osgi.org/News/20121011
Remember that these drafts are not final - if you have any feedback, let us know either via bugzilla (http://www.osgi.org/bugzilla) or via the osgi-dev mailing list: http://www.osgi.org/MailLists

Presenting about Cloud Ecosystems at OSGi Community Event 2012

Over the past few months I've been piloting what I started to call an OSGi Cloud Ecosystem. You can see the details on my technical blog <coderthoughts/>. I am coming to the conclusion that OSGi can provide a really interesting basis for a Platform as a Service that can support the fluidity of the cloud, where services migrate from one VM to another and systems can scale up and down as needed, without having to worry about getting swamped by configuring what runs where etc. Your OSGi system is based on a Service Oriented Architecture where your services are implemented and consumed using the widely supported OSGi services programming model. Your system is comprised for multiple cloud VMs each of which may take different roles over time. As the need arises you add or remove cloud VMs that contain some of your OSGi services, migrating services across VMs as needed. However as a consumer you simply use the OSGi Service Registry to find and use your services.

The postings on <coderthoughts/> show a pilot that implements these ideas and I'll be talking more about them (and showing a demo) at the OSGi Community Event 2012 (which is part of EclipseCon Europe 2012) on October 23-25 in Ludwigsburg, Germany. See here for the programme: http://www.osgi.org/CommunityEvent2012/Agenda for general conference information go here: http://www.osgi.org/CommunityEvent2012

Hope to see you there!

OSGi Cloud Workshop at EclipseCon/OSGiDevCon 2012

Many people are seeing how well OSGi fits conceptually with Cloud Computing. Its modularity is frugal on memory, and provides isolation. Additionally it focuses components on a particular task, which makes them better maintainable too. Furthermore, OSGi dynamicity makes it possible to create Cloud components that react to changes in the cloud environment in a natural way. They can be dynamically configured, reconfigured and an OSGi Framework can be dynamically provisioned and re-provisioned as well!

Over the past while the OSGi Cloud Working Group has been looking at how OSGi can be enhanced to provide additional support for Cloud Computing. This has resulted in a requirements document called RFP 133.

At this point in time we need to discuss which of these requirements should be tackled first? Is it Discovery in the Cloud? Or Metadata? Or Management or maybe something else?
At the same time we should embrace any existing standards in this area and certainly not attempt to reinvent the wheel!

This discussion is the topic of the Second OSGi Cloud Workshop which is held this year at the EclipsCon/OSGiDevCon venue on Thursday March 29 at 9am.

It is set to be a morning with some presentations (the lineup currently is: Paremus, JClouds, eBay and RedHat/JBoss), a demo, and a lot of time for discussion. Entrance is free - you don't need an EclipseCon pass, but you do need to register as numbers are limited (see here also for details on the location of the venue): http://osgi-cloudworkshop-2012.eventbrite.co.uk

Oh, and just to be sure: EclipseCon/OSGiDevCon 2012 has moved and is in Washington/Reston this year!

OSGi Cloud Computing RFP 133

I'm quite excited by the work that is being done in the OSGi Cloud Working Group recently. In this working group we are looking at what role OSGi standards can play in a Cloud Computing environment. Currently we're focusing on the possible requirements in RFP 133. Both OSGi Alliance members as well as non-members are involved in defining this document.

If you're interested, have a look at the RFP. It's available as an attachment to this bug in the public OSGi Bugzilla system: https://www.osgi.org/bugzilla/show_bug.cgi?id=114. Feel free to comment!

If you're interested in becoming more involved, join the OSGi Cloud Working Group mailing list: https://mail.osgi.org/mailman/listinfo/cloud-workshop.