RSSCloud Vs. PubSubHubbub: Why The Fat Pings Win


Editor’s note: With all of the debate lately between RSSCloud versus PubSubHubbub, we wanted to hear from a developer who could actually tell us which one might be better and why. The following guest post is written by Josh Fraser, the co-founder of EventVue, who is an active contributor to PubSubHubbub in his free time.  He has contributed several client libraries for PubSubHubbub including a WordPress plugin. Guess which side of the debate he falls on.

In the past few months, a lot of attention has been given to the rise of the real-time web.  The problem is that the web wasn’t designed with real-time in mind.  There is a huge need for the tech community to get behind new protocols that will power this fundamental shift in how web applications work.  Today I want to take a look at two of the leading protocols that enable real-time notifications on the web.  While there are older protocols that enable real-time notifications like XEP-0060, PubSubHubbub (PuSH) and rssCloud are two new protocols which show a lot of promise of gaining adoption.

Both PuSH and rssCloud address a fundamental flaw in the way web applications work today.  Currently, getting updates on the web requires constant polling.  Subscribers are forced to act like nagging children asking, “Are we there yet?”  Subscribers must constantly ping the publisher to ask if there are new updates even if the answer is “no” 99% of the time.  This is terribly inefficient, wastes resources, and makes it incredibly hard to find new content in as soon as it appears.  Both protocols flip the current model on its head so that updates are event driven rather than request driven.  By that I mean that both protocols eliminate the need for polling by essentially telling subscribers, “Don’t ask us if there’s anything new.  We’ll tell you.”

Dave Winer deserves the credit for coming up with the idea long before anyone else.  In fact, the <cloud> element was added to the RSS 2.0 specification in 2001, but has only recently been revived (largely in response to the interest in PuSH).  rssCloud made major progress this week with the announcement that WordPress was adding rssCloud support for all 7.5 million blogs on In contrast, PuSH is currently enabled for well over 100 million feeds with adopters including Friendfeed, Blogger, Google Reader, LiveJournal, Google Alerts and FeedBurner. I expect to see many more services adopt these new protocols soon.

But if you find yourself confused about how they are different, you’re not alone.

Conceptually, both protocols are very similar.   Both add a simple declaration to a feed that tells a subscriber which hub/cloud has been delegated the responsibility of handling subscriptions.  Both protocols have a centralized hub that notifies subscribers when new content is published.  Both protocols are HTTP based.

The subtle differences in implementation are important to understand, however.  And in my opinion, PuSH is the better protocol for now. There are basically three things that make PuSH a more robust protocol:

First, PuSH doesn’t just tell you that something changed, it actually sends you the new content (also known as a “fat ping.”) This is an important feature that is missing from rssCloud.  Not only do fat pings make integration simpler for subscribers, they also eliminate the danger of inadvertent denial of service attacks as thousands of subscribers respond to the ping notification and request the updated feed at exactly the same time.  This problem is well known in computer science and is often referred to as “the thundering herd problem.”  While this would be relatively simple to fix in rssCloud, it has yet to be addressed.

Second, PuSH allows variable callbacks (custom URL’s for where the notification is sent) which rssCloud does not.  The rssCloud specification states “Notifications are sent to the IP address the request came from. You can not request notification on behalf of another server.”  This is highly limiting since you cannot separate the servers which are handling subscriptions from the servers which are receiving the ping notifications.

Third, PuSH has a more friendly policy for handling unsubscribes.  In rssCloud, every feed is automatically unsubscribed after 25 hours.  In PuSH, there is an explicit unsubscribe function with the option to automatically unsubscribe after a given amount of time.  Again, this small detail matters a lot when you’re operating at scale.  With rssCloud, RSS readers will be responsible for resubscribing millions of feeds every night – which is far less efficient than sending subscribe/unsubscribe requests only when something changes.

This isn’t to say that there aren’t benefits to rssCloud.  It is far easier to implement an RSS cloud than it is to implement a PuSH hub.  By design, PuSH hubs are not simple to implement.

There are other small differences, but these are the issues that matter most.  Everything else boils down to semantics.

I want to address a couple of misconceptions that are floating around about both protocols.  For example, many people think that rssCloud is simply about building a distributed alternative to Twitter.  This is largely due to Dave Winer’s stated goal for rssCloud to create “a loosely-coupled Twitter-like network of people and 140-character status messages.”  While that is certainly an interesting use-case, it promotes a very narrow view of the protocol and what it enables.  I think rssCloud has far more potential than Dave gives it credit for.

The biggest misconception about PuSH is that it is somehow owned and controlled by Google.  This simply isn’t true.  Not only are there plenty of independent developers like me working on PuSH, there are also other PuSH hubs like SuperFeedr which aren’t controlled by Google. Brett Slatkin points out:

Our spec development process is completely transparent. You can see every code check-in since August 5th 2008. All discussion is on the public mailing list (there is no Google-internal one). The whole point of this spec is to be open, decentralized, and not in control of any company.

Overall, I believe that both PubSubHubbub and rssCloud represent a huge step forward for the web. While I personally believe that PuSH is a better choice, competition is always good and will make both protocols stronger.

(Photo credit: Flickr/Libertinus)

More TechCrunch

Zen Educate, an online marketplace that connects schools with teachers, has raised $37 million in a Series B round of funding. The raise comes amid a growing teacher shortage crisis…

Zen Educate raises $37M and acquires Aquinas Education as it tries to address the teacher shortage

“When I heard the released demo, I was shocked, angered and in disbelief that Mr. Altman would pursue a voice that sounded so eerily similar to mine.”

Scarlett Johansson says that OpenAI approached her to use her voice

A new self-driving truck — manufactured by Volvo and loaded with autonomous vehicle tech developed by Aurora Innovation — could be on public highways as early as this summer.  The…

Aurora and Volvo unveil self-driving truck designed for a driverless future

The European venture capital firm raised its fourth fund as fund as climate tech “comes of age.”

ETF Partners raises €284M for climate startups that will be effective quickly — not 20 years down the road

Copilot, Microsoft’s brand of generative AI, will soon be far more deeply integrated into the Windows 11 experience.

Microsoft wants to make Windows an AI operating system, launches Copilot+ PCs

Hello and welcome back to TechCrunch Space. For those who haven’t heard, the first crewed launch of Boeing’s Starliner capsule has been pushed back yet again to no earlier than…

TechCrunch Space: Star(side)liner

When I attended Automate in Chicago a few weeks back, multiple people thanked me for TechCrunch’s semi-regular robotics job report. It’s always edifying to get that feedback in person. While…

These 81 robotics companies are hiring

The top vehicle safety regulator in the U.S. has launched a formal probe into an April crash involving the all-electric VinFast VF8 SUV that claimed the lives of a family…

VinFast crash that killed family of four now under federal investigation

When putting a video portal in a public park in the middle of New York City, some inappropriate behavior will likely occur. The Portal, the vision of Lithuanian artist and…

NYC-Dublin real-time video portal reopens with some fixes to prevent inappropriate behavior

Longtime New York-based seed investor, Contour Venture Partners, is making progress on its latest flagship fund after lowering its target. The firm closed on $42 million, raised from 64 backers,…

Contour Venture Partners, an early investor in Datadog and Movable Ink, lowers the target for its fifth fund

Meta’s Oversight Board has now extended its scope to include the company’s newest platform, Instagram Threads, and has begun hearing cases from Threads.

Meta’s Oversight Board takes its first Threads case

The company says it’s refocusing and prioritizing fewer initiatives that will have the biggest impact on customers and add value to the business.

SeekOut, a recruiting startup last valued at $1.2 billion, lays off 30% of its workforce

The U.K.’s self-proclaimed “world-leading” regulations for self-driving cars are now official, after the Automated Vehicles (AV) Act received royal assent — the final rubber stamp any legislation must go through…

UK’s autonomous vehicle legislation becomes law, paving the way for first driverless cars by 2026

ChatGPT, OpenAI’s text-generating AI chatbot, has taken the world by storm. What started as a tool to hyper-charge productivity through writing essays and code with short text prompts has evolved…

ChatGPT: Everything you need to know about the AI-powered chatbot

SoLo Funds CEO Travis Holoway: “Regulators seem driven by press releases when they should be motivated by true consumer protection and empowering equitable solutions.”

Fintech lender SoLo Funds is being sued again by the government over its lending practices

Hard tech startups generate a lot of buzz, but there’s a growing cohort of companies building digital tools squarely focused on making hard tech development faster, more efficient and —…

Rollup wants to be the hardware engineer’s workhorse

TechCrunch Disrupt 2024 is not just about groundbreaking innovations, insightful panels, and visionary speakers — it’s also about listening to YOU, the audience, and what you feel is top of…

Disrupt Audience Choice vote closes Friday

Google says the new SDK would help Google expand on its core mission of connecting the right audience to the right content at the right time.

Google is launching a new Android feature to drive users back into their installed apps

Jolla has taken the official wraps off the first version of its personal server-based AI assistant in the making. The reborn startup is building a privacy-focused AI device — aka…

Jolla debuts privacy-focused AI hardware

The ChatGPT mobile app’s net revenue first jumped 22% on the day of the GPT-4o launch and continued to grow in the following days.

ChatGPT’s mobile app revenue saw its biggest spike yet following GPT-4o launch

Dating app maker Bumble has acquired Geneva, an online platform built around forming real-world groups and clubs. The company said that the deal is designed to help it expand its…

Bumble buys community building app Geneva to expand further into friendships

CyberArk — one of the army of larger security companies founded out of Israel — is acquiring Venafi, a specialist in machine identity, for $1.54 billion. 

CyberArk snaps up Venafi for $1.54B to ramp up in machine-to-machine security

Founder-market fit is one of the most crucial factors in a startup’s success, and operators (someone involved in the day-to-day operations of a startup) turned founders have an almost unfair advantage…

OpenseedVC, which backs operators in Africa and Europe starting their companies, reaches first close of $10M fund

A Singapore High Court has effectively approved Pine Labs’ request to shift its operations to India.

Pine Labs gets Singapore court approval to shift base to India

The AI Safety Institute, a U.K. body that aims to assess and address risks in AI platforms, has said it will open a second location in San Francisco. 

UK opens office in San Francisco to tackle AI risk

Companies are always looking for an edge, and searching for ways to encourage their employees to innovate. One way to do that is by running an internal hackathon around a…

Why companies are turning to internal hackathons

Featured Article

I’m rooting for Melinda French Gates to fix tech’s broken ‘brilliant jerk’ culture

Women in tech still face a shocking level of mistreatment at work. Melinda French Gates is one of the few working to change that.

2 days ago
I’m rooting for Melinda French Gates to fix tech’s  broken ‘brilliant jerk’ culture

Blue Origin has successfully completed its NS-25 mission, resuming crewed flights for the first time in nearly two years. The mission brought six tourist crew members to the edge of…

Blue Origin successfully launches its first crewed mission since 2022

Creative Artists Agency (CAA), one of the top entertainment and sports talent agencies, is hoping to be at the forefront of AI protection services for celebrities in Hollywood. With many…

Hollywood agency CAA aims to help stars manage their own AI likenesses

Expedia says Rathi Murthy and Sreenivas Rachamadugu, respectively its CTO and senior vice president of core services product & engineering, are no longer employed at the travel booking company. In…

Expedia says two execs dismissed after ‘violation of company policy’