A Super High Level Description

When GraphQL was first announced as OSS software from Facebook in 2015 I remember briefly looking at it and thought it made sense for Facebook use case and similar other use cases. To expand on this a bit more, here is a concrete example. When I am browsing through my friend’s list I am proably interested in snapshot of each friend as follow :


If I were to use pure REST approach to this problem, I would have to to make following few API calls

  • /friends to get a list of my friends’ ids
  • /friends/id to get a detail of each friend such as profile_pic_url, birthday
  • /locations/id to get details of locations.

and more than likely data these APIs return will have more attribues than I need because for a given entity friend the server has lots more attributes. So a logical optimization would be to introduce query parameters such as view=list, view=details, include_location=true, include_friends=true As you can imagine this opens lots of permuations and combinations on entities and their relationships. In a nutshell a client is at mercy of server to figure out how to get what it needs.

On the other hand, the GraphQL approach would be that client knows what it wants so server should give exactly that – no more, no less. In essence, you construct your request by defining the resources you want. You send this via a POST to a server, and the response matches the format of your request. It’s server’s responsibilities to stitch different entities together regardless of how data are stored in its datastore. This sounds super exciting from a API consumer perspective. Clients do not have to know how different entities are tied together, don’t have to make 10s of API calls just for one view.

A tiny project to look under the hood

Recenlty I dug a little bit more to understand pros and cons of GraphQL and what it would take to expose this service on top of existing data infrastructure. I have created a small project, graphql-rails using GraphQL-Ruby project. The graphql ruby gem saved me from adding a bunch of boiler plate code you see at https://github.com/prabhatjha/graphql-rails/tree/master/app/graphql but I still had to describe my ojects/models in GraphQL’s type system as you can see here .

Pros and Cons

I then played with the UI tool called GraphiQL and following pros and cons stick out. The lens I have put is for the entire API lifecycle – from design, deployment, documentation, monitoring, performance and common tools in this space.

  • Because you have to describe types, see end_users, you get the documentation for “free” and more importantly documentation is always consistent with actual implementation.
  • The HTTP status code server returns is either 200 or 500. To return more granualar status codes and error messages you would have to implement that yourself. It’s possible that there are tools and wrappers which make it easier for implementation but IMHO it’s a big gap, for it means that most of API monitoring tools you rely on currently are useless in this context.
  • From a client perspective there is one URL to hit. From a server perspective any advanced API analytics tools which give you a view of resources usage breakdown will be of no value.
  • URL based routing that you often see on load balancers and API Gateway also are of no use.
  • Well understood concepts such as Authorization (eg OAuth), Paginations are harder to implement.
  • If your datastore is relational then traditional schema of normalized tables, relationship between tables may get in the way of performance. You might have to switch your datastore to optimize for the GraphQL like query.

I have not done lots of research on tools and frameworks in this space but it seems that it’s an evolving space. Few prominent offerings are listed here.

In essence, you should approach using GraphQL for the use case it’s built for, not just to look cool and to ditch REST apis. Picking a new framework is more than about just the framework itself. Some well known use cases are listed here. I think the most pragmatic approach to expose this capability at your organzation would be to first expose it as a wrapper atop your existing REST apis instead of starting from scratch and get a feel of what you lack. For a brand new project I suggest to build a small project with complete SDLC which includes CI/CD process and monitoring so that you identify gaps in all different dimensions namely people, product, process and infrastructure.