TLDR: We made it better; GraphQL is coming; and we just released version
When I applied for a job at Stardog, after having several conversations with the leadership team and other engineers, my “homework” assignment was to do a code review of the stardog.js library.
I wrote a six or seven paragraph technical review, got the job, and never really thought about my review again.
The first and biggest issue was it wasn’t really compatible with modern
front-end tooling. The team was using webpack and ES6
import statements to
load stardog.js into a small React app. I was having trouble getting one of the
stardog.js calls to work correctly, so I started to litter stardog.js with
debugger statements. Not a single one of them was being hit when making XHR
requests back to the Stardog server. After 20 minutes of confusion, I realized
what was happening; we were using the “node side” of the library.
A quick look at the following lines of code revealed the issue:
var isNode = (typeof exports !== "undefined" && typeof module !== "undefined" && module.exports);
module.exports are always defined, so the code was
isNode path and using all the Node libraries instead of the
browser-based ones. Everything was functioning, but certainly not as intended.
Behind the scenes, stardog.js uses
restler for making HTTP calls in the Node
execution context. It was supposed to be using jQuery for XHR calls in the
The application we were building only leveraged the basic functionality provided by stardog.js. It worked well enough for that, but any non-trivial project would eventually run into bad times. Additionally, like it or not, pretty much every front-end project now uses some kind of bundler tooling so stardog.js has to work correctly in those contexts, too. With this as the catalyst, it was time to start a rewrite of stardog.js
Good thing I kept that technical review as it became a springboard for the work we needed to do to modernize stardog.js. Our three primary goals for the rewrite include:
fetch, the standard way to make XHR requests from the browser
The previous version of stardog.js achieved this by using feature detection,
module.exports. Detecting environments this way is unreliable and
should be avoided whenever possible. It is better to leverage tooling that
handles that for you.
The first thing we did was write the library for Node using standard CommonJS
require statements. This allowed us to structure the code in a much more
modular way. One catch of the Node-first approach was that we couldn’t use any
of Node’s core modules like
querystring because they don’t
exist in the browser. Any modules would have to be available via npm and be
Utility libraries like lodash, for example, are inherently universal because they don’t require any environment-specific features. Other libraries like form-data use a special, technically-not-spec-but-basically-spec field in package.json named “browser”.
polyfills and ponyfills. Both techniques are essentially fancy-talk for “if this
functionality exists in the current environment, use the native implementation,
otherwise, use the supplied code” This is how
fetch works, for example.
Promise-based way to make
XMLHttpRequest (XHR) requests. For many years
there have been many competing ways but nothing even as a de facto standard.
fetch. A first-class XHR request machine. At the time of this
writing, 75% of global browser usage
fetch implementation. For the other 25%, there exists
an excellent polyfill maintained by the fine
folks at GitHub.
There is a lot of code there to digest, so here are the salient bits. The first
thing the code does is check to see if
fetch is currently implemented in the
current environment (the browser in this case); if so, bail out and do nothing.
This causes all calls to the
fetch API to use the native implementation.
fetch isn’t implemented, it is reimplemented using
made globally available. This is an ideal setup because in your user-land code
you can always use
fetch and not worry about native or polyfill; to your
code, it is all the same.
Taking this one step further, we want to use
fetch on the browser, whether
it’s native or not, and use
fetch in Node,too. That is, we want a single
developer API that’s completely context agnostic. Thankfully, there is a
implementation that is spec compliant (mostly) written for Node
By combining all of these
fetch related concepts, stardog.js is able to use
fetch to make all of the requests to the Stardog HTTP server using the same
API and code regardless of the environment. If you look at the new code
currently in the “development” branch, you won’t see any branching logic trying
to guess how to make HTTP requests. It is just all
fetch all the way down.
So we wrote stardog.js with the intent of being universal, but the actual code
is littered with
require statements, which mean less than nothing in a
browser. While the code we wrote is environment agnostic, we still need to do
something so that it can function as expected in the browser.
In our case, rollup let us write stardog.js using the standard
CommonJS semantics we are used to, but then execute a build step to bundle all
of the dependencies into something a browser can execute.
And it’s during this build phase that the “browser” field in package.json comes
into play. When rollup follows a
require statement, if it’s an npm package,
and it has a specified “browser” field, that is the file that will be used to
Besides just flattening out
require statements and inlining dependencies,
rollup.js lets us use many es2015 features not available in some browsers like
Class, object destructuring, default arguments, and arrow functions. These
features are “transpiled” with babel down to ES5 which is what all modern
browsers natively support.
As you can see, in our package.json file, we’ve added a “browser” key pointing
to the built stardog.js file in the “dist” folder. So when you want to use
stardog.js in your project, just
import it in and you’ll be
communicating with the Stardog HTTP server faster than you can say SPARQL.
The stardog.js roadmap includes a mix of boring housekeeping tasks and some really exciting new features. Some of the housekeeping tasks include:
Typical housekeeping tasks. The interesting bits show up when we start talking about new features.
I’m going to let you in on a little secret…GraphQL is coming to the Stardog HTTP server. The existing Stardog REST API is going to be migrated to GraphQL.
First benefit of this move: re-using your existing GraphQL knowledge and skill set when building Stardog apps. Win.
Next, as this change is rolled out to the many (many) RESTful endpoints,
stardog.js is going to migrate along with it. Rather than pre-packaged URIs and
HTTP message bodies, it will become a collection of preconfigured GraphQL
queries and APIs for building GraphQL queries that can be dispatched using
Another benefit of moving to GraphQL is that developers will be able to query
whatever they want, provided it is exposed in the GraphQL schema. You won’t have
to wait for stardog.js to add a method to expose
new-feature-foo via a method
call on stardog.js; developers will be able to query against the GraphQL
endpoint directly for the information they need.
These changes add up to a better and more fun developer experience when programming against Stardog. We encourage pull requests of all kinds and welcome feedback and suggestions from the community.
Download Stardog today to start your free 30-day evaluation.