The power of informal contracts

The "Principle of Informal Contracts" allows anyone to create useful mashups.

Before releasing elmcity as
an open source project,
it had to be reviewed by a team of Microsoft lawyers. They found no
patentable invention in the code and gave me the green light. Which is
funny in a way, because I’m sure I couldn’t ever create a patentable
software invention. I’m just not that talented as a programmer.
Writing code, for me, is mainly a way to explore ideas and illustrate
possibilities. In this case, it’s the idea that we can manage data
in a social way by participating in networks of syndicated feeds. And
it’s the possibility that a lone developer, modestly capable but
empowered by languages, libraries, tools, and cloud services, can
bring that idea to life.

What is innovative about my project, I claim, is the network-oriented
way of thinking and acting that it embodies and promotes. The
approach is based on a set of principles that we have yet to fully
articulate, never mind teach along with the proverbial three R’s.
Almost everybody learns the rules of reading, writing, and
arithmetic. But almost nobody learns the laws that govern the
structure and flow of information in networks, and that enable us to
make effective use of those networks.

We don’t need software innovation to solve the problem that the
elmcity project addresses. Our perpetual inability to merge personal
and public calendar data can’t be blamed on a lack of standard,
broadly-available software and services. We have all the stuff we
need, and have had for quite some time, and it all interoperates
pretty well. But we haven’t internalized why, and how, to
use it in a network-oriented way.

One of the crucial ingredients is something that I’ll call the
Principle of Informal Contracts. Here’s an example from the early
blogosphere: RSS auto-discovery. It’s the mechanism that associates the
pages of a website with a corresponding feed. Back in
2002 a remarkable collaboration brought it
into existence, summarized here by Mark Pilgrim who concluded:

Thank you to everyone who has been working on making this come
together in the past few days. It has been surprisingly painless and
friction-free. Together, we have come up with a new standard that is
useful, elegant, forward-thinking, and widely implemented. In 4 day.

Thanks to that consensus, it has ever since been easier to subscribe to
blogs. But what about before then? The blogosphere’s feed ecosystem was already
bootstrapped and thriving. RSS, implemented by various feed
publishers and feed readers, was the obvious enabler. But there was also an
informal contract. It went something like this:

My blog publishes a feed at a URL that I will tell you about one way
or another. Maybe I’ll use an orange icon, maybe I’ll use a subscribe
link, maybe both, maybe something else. By whatever means, I promise
to produce a flow of new items at that URL. The feed itself might be
one or another flavor of RSS. Whichever it is, your feed reader can count on
finding certain things in a predictable way: a title, a link, a

That was enough to get things started in a big way. Here’s a more contemporary
example: the contract that’s implied by choosing a tag at the beginning of a
conference. It says:

We, the organizers, promise to bind the online resources that we
produce for this conference to this tag. And we invite you, the
attendees, to do the same. We do not promise to collect all the
resources discoverable by means of this tag, dump them into a bucket,
and assert authority over (or assume liability for) the contents of the
bucket. We just want to be able to find all the stuff, yours and
ours, and use it as needed. We want you to be able to do the same.
And we think the virtual network routed by that tag can be valuable
to everybody.

Members of a certain tribe, which you most likely belong to if you’re
reading this, take that contract for granted. For you, the word “camp”
does not connote outdoor recreation, but rather a new kind of
conference that’s co-created by the organizers and by the attendees.
One of the organizers’ roles is to declare a tag for the conference.
I’ve watched newcomers to the tribe encounter this practice for the
first time, and then immediately adopt it. So I know the idea is
catching on.

But we haven’t yet spelled out the underlying principle of informal
contracts. And we’ve got to do that, because we’re living in a world
where networks of people and data can fruitfully use such contracts. They’re easy to
create if you know how and why. Here’s the contract for the ecosystem
of calendar feeds that I’m trying to bootstrap:

Anybody who wants to promote a series of public events agrees to
publish a feed that transmits certain facts about events in a
predictable way: the title, the starting date and time, a link back
to the authoritative source. Anybody who wants to curate a view of sets
of feeds made available in this way can do so by making
a list of them.

Within the project itself, there are some other contracts. Here’s one:

To make the lists of feeds that define these curated views,
we’ll agree to use the delicious social bookmarking service
in a particular way. The elmcity service will define the extensible set of
delicious accounts
used for this purpose. We’ll agree that
users of those accounts will follow certain practices that define the
settings for their instances of the service, and the lists of feeds they
trust to flow through their hubs.

That agreement in turn enables another. Because every action in
delicious is a database query that produces an RSS feed, the
acquisition of a new calendar feed by a curator sends a message on a
virtual channel that can be read and reacted to. The service that
reads and reacts, in this case, is FriendFeed. Here’s the contract:

Curators can subscribe to a project feed that’s aggregated by
an instance of the FriendFeed
service. Items flowing through its
Atom feed are
significant events in the life of the project. They include:

  • The posting of a forum message or reply.
  • The posting elsewhere of a tweet, blog item, or other resource bound to the
    project tag.
  • The discovery of a new (and trusted) iCalendar resource by any hub’s curator.

Like delicious, FriendFeed can support this kind of contract by empowering
users to define sets of online resources and share them as feeds.

With these kinds of contracts in place, interesting possibilities
arise. Here’s one that tickles me: The elmcity service doesn’t yet
need to implement its own system of user registration. If my approach
to decentralized event curation takes off, I might someday need to create a
registration system and require curators to use it. But for now it’s
trivial for me to bookmark a delicious account and tag it as one that
the service regards as authoritative for a hub.

Likewise, the folks who provide the feeds trusted by curators and
aggregated by hubs don’t yet have to register with the service. For
now, providers need only make feeds known to curators, one way or
another. And curators who deem those feeds worthy of inclusion need
only bookmark and tag them.

These are the kinds of workflows that can arise when informal
contracts are in place. They’re cheap to create and easy to evolve.
Here’s a final example. If you’re a curator who adds a new feed to a
hub, you naturally want to see your new events merged into the hub as soon
as possible. Normally you’d have to wait until the next aggregation
cycle, which might be as long as eight hours. So I had to come up with a way for
a curator to send an authenticated message to the service, telling it to
short-circuit the wait and gather new events right away.

My first thought was that here, finally, was the reason I’d need to build my
own user registration system and require curators to use it. My second
thought was,
hang on, I already trust their delicious accounts, why not use those accounts as
channels for authenticated messages? That’s doable, but I didn’t find
a graceful way to do it. My third thought was: What about Twitter?
Hence the Twitter contract:

Among the settings that a curator conveys to the elmcity service, by
way of a trusted delicious account, is the Twitter account to be used
in connection with that curator’s elmcity hub. The service will follow
the curator at that Twitter account. By doing so, it enables the
curator to send authentic messages to the service. The vocabulary used
by those messages will initially be just a single verb: start. When
the service receives the start message from a hub, it will reaggregate
the hub’s list of feeds.

In a companion how-to article on O’Reilly Answers, I
show how this piece of the service works. What’s relevant here is that
the code doesn’t have to do very much. That’s because the informal
contract makes it possible to reuse Twitter in a novel way, as a
channel for authenticated messages.

In a world full of services like delicious, FriendFeed, and Twitter —
services that can route feeds of data based on user-defined
vocabularies — you don’t have to be a programmer to create useful
mashups. You just have to understand, and find ways to apply, the
Principle of Informal Contracts.


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