What is the difference between Falcor and GraphQL?

Solution 1:

I have viewed the Angular Air Episode 26: FalcorJS and Angular 2 where Jafar Husain answers how GraphQL compares to FalcorJS. This is the summary (paraphrasing):

• FalcorJS and GraphQL are tackling the same problem (querying data, managing data).
• The important distinction is that GraphQL is a query language and FalcorJS is not.
• When you are asking FalcorJS for resources, you are very explicitly asking for finite series of values. FalcorJS does support things like ranges, e.g. genres[0..10]. But it does not support open-ended queries, e.g. genres[0..*].
• GraphQL is set based: give me all records where true, order by this, etc. In this sense, GraphQL query language is more powerful than FalcorJS.
• With GraphQL you have a powerful query language, but you have to interpret that query language on the server.

Jafar argues that in most applications, the types of the queries that go from client to server share the same shape. Therefore, having a specific and predictable operations like get and set exposes more opportunities to leverage cache. Furthermore, a lot of the developers are familiar with mapping the requests using a simple router in REST architecture.

The end discussion resolves around whether the power that comes with GraphQL outweighs the complexity.

Solution 2:

I have now written apps with both libraries and I can agree with everything in Gajus' post, but found some different things most important in my own use of the frameworks.

• Probably the biggest practical difference is that most of the examples and presumably work done up to this point on GraphQL has been concentrated on integrating GraphQL with Relay - Facebook's system for integrating ReactJS widgets with their data requirements. FalcorJS on the other hand tends to act separately from the widget system which means both that it may be easier to integrate into a non-React/Relay client and that it will do less for you automatically in terms of matching widget data dependencies with widgets.
• The flip side of FalcorJS being flexible in client side integrations is that it can be very opinionated about how the server needs to act. FalcorJS actually does have a straight up "Call this Query over HTTP" capability - although Jafar Husain doesn't seem to talk about it very much - and once you include those, the way the client libraries react to server information is quite similar except that GraphQL/Relay adds a layer of configuration. In FalcorJS, if you are returning a value for movie, your return value better say 'movie', whereas in GraphQL, you can describe that even though the query returns 'film', you should put that in the client side datastore as 'movie'. - this is part of the power vs complexity tradeoff that Gajus mentioned.
• On a practical basis, GraphQL and Relay seems to be more developed. Jafar Husain has mentioned that the next version of the Netflix frontend will be running at least in part on FalcorJS whereas the Facebook team has mentioned that they've been using some version of the GraphQL/Relay stack in production for over 3 years.
• The open source developer community around GraphQL and Relay seems to be thriving. There are a large number of well-attended supporting projects around GraphQL and Relay whereas I have personally found very few around FalcorJS. Also the base github repository for Relay (https://github.com/facebook/relay/pulse) is significantly more active than the github repository for FalcorJS (https://github.com/netflix/falcor/pulse). When I first pulled the Facebook repo, the examples were broken. I opened a github issue and it was fixed within hours. On the other hand, the github issue I opened on FalcorJS has had no official response in two weeks.

Solution 3:

Lee Byron one of the engineer behind GraphQL did an AMA on hashnode, here is his answer when asked this question:

• Falcor returns Observables, GraphQL just values. For how Netflix wanted to use Falcor, this makes a lot of sense for them. They make multiple requests and present data as it's ready, but it also means that the client developer has to work with the Observables directly. GraphQL is a request/response model, and returns back JSON, which is trivially easy to then use. Relay adds back in some of the dynamicism that Falcor presents while maintaining only using plain values.
• Type system. GraphQL is defined in terms of a type system, and that's allowed us to built lots of interesting tools like GraphiQL, code generators, error detection, etc. Falcor is much more dynamic, which is valuable in its own right but limits the ability to do this kind of thing.
• Network usage. GraphQL was originally designed for operating Facebook's news feed on low end devices on even lower end networks, so it goes to great lengths to allow you to declare everything you need in a single network request in order to minimize latency. Falcor, on the other hand, often performs multiple round trips to collect additional data. This is really just a tradeoff between the simplicity of the system and the control of the network. For Netflix, they also deal with very low end devices (e.g. Roku stick) but the assumption is the network will be good enough to stream video.

Edit: Falcor can indeed batch requests, making the comment about the network usage inaccurate. Thanks to @PrzeoR