PaaS by Lineage

If you've ever wondered about what "Platform as a Service" (PaaS) really means, then you may find this analysis of mine useful.

The traditional NIST model of Cloud Computing shows three layers from a consumer's perspective:

Infrastructure as a Service refers to (shared and scalable) infrastructural capabilities such as compute power, storage and networking, as provided by a cloud vendor. The attributes "shared" (or "multi-tenanted") and "scalable" (or "elastic") distinguish cloud solutions from "terrestrial" alternatives. Amazon's EC2 (Elastic Compute Cloud) and S3 (Simple Storage Service) are examples of IaaS.

Software as a Service refers to applications that you don't have to install on your own computers but can consume through your browser. For an individual, Gmail is the best example of SaaS, while companies can relate to SalesForce.com.

But PaaS has always been a bit of a mystery. What is a "platform", exactly? This is a rather nebulous (pardon the cloudy adjective) area between IaaS and SaaS, and appears to be defined by what the other two are not. The market segment is also still in flux and yet to mature, and there are many players here, each staking out a piece of turf and attempting to define the segment to its own advantage.

I have a high-level, vendor-neutral view of this. [Disclosure: I'm currently working for one of the PaaS vendors, WSO2.]

My preferred categorisation of the PaaS landscape is by lineage. In other words, where did the various PaaS offerings evolve from? I think this is a useful way to look at PaaS because it indicates the traditional strengths of a vendor and therefore where their PaaS offering is likely to be stronger than its competitors. Potential consumers who are looking for a particular emphasis in their PaaS solution will know which vendors are likely to meet their requirements better.

In short, I think PaaS offerings have evolved from one of three directions.

IaaS vendors like VMWare (with their vCloud IaaS) have added DevOps capability to their traditional strength and are targeting organisations that want to develop and run generic applications on the cloud. Their version of PaaS is CloudFoundry.

SaaS vendors like SalesForce.com have made their application more generic and supportive of customisation. Organisations that want to build employee-oriented applications can do so through configuration rather than coding. Their version of PaaS, which is more oriented towards a vertical segment (employee-oriented applications), is called Force.com.

A third direction from which PaaS has evolved is from traditional "terrestrial" middleware (also known as Integration or SOA products). WSO2, which has a full stack of SOA middleware products collectively referred to as Carbon, has added cloud-native features (multi-tenancy, elasticity, etc.) to its suite of products to turn them into yet another version of horizontal PaaS called Stratos. Their DevOps tools have also been upgraded to be able to deploy applications to the cloud just like they do to terrestrial servers.

The diagram below that loosely follows the NIST layering, illustrates my analysis. There may be more versions of PaaS depending on where a vendor has traditionally been based, and I will update this model as more such examples appear.

Amazon Cloud Drive Tech Talk - Sydney, 10-10-2011

I attended the Amazon Cloud Drive Tech Talk today in Sydney. This was held on the 39th floor of the Citigroup building at 2 Park Street in the CBD. The views from the window are awesome, by the way.

That's Park Street stretching away towards King's Cross

Those red slugs are the new Metro double-buses

I reached the venue just after 1800, when registration was scheduled to begin. There were eats, bottles of beer and canned carbonated drinks in the room, but none suitable for a vegetarian teetotaller trying to lose a few calories, so I drank a glass of water instead and waited for the proceedings to begin.

The event kicked off promptly at 1830. John Scott of the Android Australia User Group made a short speech introducing Piragash Velummylum of Amazon, who had flown in from the US.


Then Piragash took the stage and spoke. I must say the Amazon Cloud Drive turned out to be more Amazon Recruitment Drive than anything else! Piragash and a colleague Brad (who spoke for half a minute) made no secret of the fact that they were in town to recruit developers for their Seattle office. The tech talk was like a campus recruitment talk - just enough data to pique the interest of developers wanting to work on cool technology.


The unofficial motto of the Amazon Cloud Drive service is "anything digital, securely stored, accessible anywhere". Piragash spoke a bit about Amazon CEO Jeff Bezos, who he projected to be a likeable nerd who listens to everybody and does the right thing. [Piragash must have a weird sense of humour. Just read this piece and the comments that follow. I wouldn't want to work for Jeff Bezos in a hundred years.]

Amazon Cloud Drive is meant to address three customer pain points:

• Multiple music downloads
• Moving files from one store to another
• Data loss

He said something about Amazon MP3, which seems to be similar to Apple's iTunes (Piragash sidestepped a question from the audience on a comparison with iTunes, saying they had a policy not to talk about competitors, but mentioned that the Amazon version allowed upload of customer content). I think the story might have begun with Amazon MP3 which catered to music files. Then Amazon Cloud Drive came along which was more general-purpose and catered to videos and other kinds of files as well. That's what I gathered.

He emphasised a few times that Amazon Cloud Drive is for customer content, not purchased content (also called studio content or catalog content). It's like DropBox, I guess. It's said to be free, but there was no mention about storage limits. Unlike DropBox, they don't do de-duplication of files (yet), and certainly not across users. They would need to sort out licensing before they did that sort of thing, and he made a statement to the effect that Amazon is DMCA-compliant.

They obviously leverage off their other technologies, i.e., AWS (Amazon Web Services). They currently use S3 (Scalable Storage Solution), not EC2 (Elastic Cloud Computing), but they may use that in future if required.

Amazon Cloud Drive has three layers. Storage is provided by S3. They've defined a hierarchical file system on top of that (which has long been a demand of S3 users). Finally, they have metadata on top that defines relationships and queries, making the file system much more useful.

These are some of the operations supported at each of those levels:

S3: Upload, download

Filesystem: Copy, move, delete, list, recycle, restore, create

Metadata: Select, get, put, delete (Aha, REST! But Select seems to have replaced Post. Puzzling.)

Piragash also talked about some of their technical challenges.

Scaling was the major one (and continues to be a major focus of research and innovation). The principles Amazon follows to ensure scalability are:

1. "Don't get in the way", i.e., let AWS and Akamai do the job they know best, don't interpose Amazon Cloud Drive between those systems and the user. Rather, allow Amazon Cloud Drive to be proxied by CDNs (Content Delivery Networks) like Akamai.

2. "Be flexible", i.e., be forward-thinking and don't prevent services like allowing a zipped set of files to be downloaded.

Security is another major concern. Content is meant to be private and personal. As part of their PaaS offering, Amazon provides an Identity and Access Management (IAM) system, and Amazon Cloud Drive uses IAM and AWS to control the generation of time-bound tokens. Delegated S3 access has an extra security token in the URL that expires after a certain period, so people can't pass content URLs around and have them accessible indefinitely to anyone who gets the URL. Can customers share their content with others, or is this purely private? Piragash's response: "Stay tuned".

Then Piragash briefly talked about the Kindle Fire, due for release in about a month. Incidentally, Kindle for iPad is said to use HTML5 throughout and to look like a native app.

There's also a new business called Amazon Fresh, currently only rolled out to the Seattle area. Order your groceries online at midnight, and have them delivered to your door by 6 am!

There was a little talk about version synchronisation strategies and rules for conflict resolution. They support multiple schemes for different domains. Sometimes they use automated algorithms, and at other times they let the customer resolve conflicts.

Asked about an API for Cloud Drive, Piragash would only say, "Stay tuned".

He mentioned that it was important to weed out "phantom requirements" and to concentrate on solving the customer's real problems.

A member of the audience remarked that Australia really needed an edge server located here to reduce latency. Piragash merely smiled acknowledgement. Someone else asked about the number of servers used by Amazon, but Piragash could not talk about that.

That was the end of the talk, and Piragash invited people to stay and talk to him and his colleagues. He called for CVs and said they'd be in Sydney the whole week, recruiting people to be based out of Seattle.

So if you like rain throughout the year and don't mind sharing a city with Microsoft, do apply to Amazon for a job.

[What was even more interesting than the technology talk was a nugget of cultural trivia that I've written about on my other blog.]