Mix, Sew or Merge any Datasource — SitePoint







On this article, we’ll focus on the issue of tips on how to fetch knowledge from a number of sources whereas nonetheless protecting our frontend snappy, and a possible answer: utilizing a GraphQL Gateway.

As software program engineers, we’ve all confronted the problem of mixing knowledge from many techniques. Even a single web page requires knowledge from a number of providers to render.

Knowledge is in every single place, from CRMs to monetary techniques and SaaS platforms to databases. Each enterprise inevitably buys a plethora of SaaS platforms, then desires a unified enterprise view on high of all of them. We’ve to embrace this head on and combine all the things.

A GraphQL gateway combines the advantages of a standard API gateway with GraphQL.

We’ll begin by discussing the advantages of an API gateway, after which have a look at how GraphQL matches in. Stick round to the top of the article, the place we have a look at some frameworks for constructing our personal API gateway.

Desk of Contents

Advantages of an API Gateway

Securing our public-facing APIs towards hackers is a full-time job. Over time, organizations have advanced to create many APIs, from SOA to microservices. As a substitute of placing these APIs straight onto the Web, organizations want so as to add an additional layer of safety that sits in entrance of all these APIs and ensures that entry to knowledge at all times follows the identical authentication guidelines.

They do that with an API gateway.

Merchandise akin to Kong or Apigee expose inside APIs from a central location. They act as a reverse proxy with options like API key administration, charge limiting, and monitoring.

The API gateway permits us to regulate who and what has entry to every service, monitoring the connections and logging entry.

Extra not too long ago, apps have been required to mix knowledge from an API gateway and different exterior SaaS suppliers. Which means the previous centralized software — which ensured our guidelines had been adopted — is now bypassed frequently.

Think about we’re constructing an internet app for our firm. We’ve a activity to create the person profile web page. Throughout the login course of, we have to mix knowledge from many techniques:

  • Salesforce CRM: holds the final buyer knowledge akin to first and final title.
  • Orders: current orders are in an ordering system inside the group.
  • Notifications Service: the notification settings and up to date messages are in an app-specific database linked to a Node.js service.

The shopper would wish to make three separate requests to get the information, as represented within the picture under.

making three separate requests to get the data

Within the picture above, the online shopper sends three separate API requests after which has to mix the leads to frontend code. Sending a number of requests impacts the app’s efficiency, and mixing this knowledge will increase the complexity of the code. As well as, if there’s multiple app, now all apps have to pay attention to all backends, and a single API change in a single service can lead to updates to all of our purposes.

We will do higher. Ideally, we need to cut back the requests from three to a single fetch. We may create a brand new service to do this — a service that orchestrates requests to backend providers. This concept has a reputation: the BFF sample.

The Backend-for-frontend (BFF) structure sample permits a single request from the frontend.

However how does it work? Let’s have a look at this sample in additional element.

The Advantages of the BFF Sample

With the BFF sample, an software sends a single request to the API gateway. The BFF service then requests knowledge from every backend service and combines it. Lastly, the information is filtered, returning solely the information wanted for the entrance finish, decreasing the information despatched over the wire.

Representation of the BFF pattern

As illustrated within the picture above, we’ve launched an additional layer into the stack to orchestrate the request.

The person profile endpoint returns the information wanted for that app on the profile web page. Decreasing our three requests to a single request has fastened our earlier efficiency difficulty.

However we aren’t completed but.

The enterprise has determined to launch a cellular app. The cellular app additionally has a profile web page, however this display shows a lot much less profile data.

At this level, the cellular crew has two choices. The crew may reuse the online crew’s endpoint, which might imply we over-fetch the information (fetching extra knowledge than is required for the cellular app). The choice is that the cellular crew creates their very own BFF.

Not surprisingly, the cellular crew resolve to create their very own BFF, as they need good efficiency for his or her app.

Diagram showing the interaction of the two BFFs

As illustrated within the picture above, issues are beginning to get sophisticated, and we now have two new points:

  • Every crew has to create a brand new BFF service for every software they create, slowing every crew down and making it onerous to standardize.
  • Every BFF must be pen-tested to make sure it’s safe.

How can we clear up these points?

We’d like an answer the place every app can choose the information it wants, and it must be a single API utilized by all purposes within the firm.

As BFFs have matured, many builders have began experimenting with GraphQL as a substitute of REST.

Let’s have a look at how this know-how can assist.

The Advantages of GraphQL for a BFF

GraphQL has many strengths that make it a super know-how for a BFF:

  • Environment friendly Knowledge Fetching. GraphQL permits purchasers to request precisely the information they want and nothing extra. This improves efficiency by decreasing the information that’s transferred from the API.
  • Single Endpoint. As a substitute of exposing many endpoints through the gateway, GraphQL makes use of a single endpoint for all requests. This simplifies the upkeep and the necessity to model.
  • Versatile queries. Purchasers can assemble queries by combining fields and relationships right into a single request. This empowers frontend builders to optimize knowledge fetching, rising efficiency. As well as, if the necessities for the frontend change, it may be up to date to fetch completely different knowledge with out altering the backend in any method.

Frontends can now choose solely the information they want for every request.

We will now join each our apps to the identical GraphQL server, decreasing the necessity for a second BFF service.

Diagram showing how a GraphQL BFF works

We will now share the BFF for any app within the group. We even have a single endpoint that must be pen-tested.

However once more, we’ve launched a brand new downside! We nonetheless should handle two techniques — the API gateway and the GraphQL BFF.

What if we mixed the 2 right into a GraphQL gateway?

Subsequent, let’s have a look at how a GraphQL gateway works.

What’s a GraphQL Gateway?

A GraphQL gateway combines an API gateway with a GraphQL API to get the perfect of each applied sciences.

Let’s recap the advantages:

  • Builders have a single API endpoint to request knowledge from. This reduces over- or under-fetching, as every software selects solely the information it wants.
  • The GraphQL gateway is shared by many apps inside the group. This implies now we have decreased our safety publicity to a single API endpoint.
  • We solely have a single service to handle, now that the BFF is mixed with the gateway.

The diagram under exhibits how the person profile API request works with a GraphQL gateway.

how the user profile API request works with a GraphQL gateway

Within the picture above, the shopper sends a single request to the GraphQL gateway, requesting the information it wants. The gateway makes particular person requests to every service and combines the outcomes. We now solely have a single service to handle and deploy.

Hopefully, you’re prepared to do that for your self. Subsequent, let’s have a look at how we are able to construct a GraphQL gateway.

Constructing a GraphQL Gateway

When selecting a gateway framework, we need to search for some key options:

  • A number of Sources. The gateway should hook up with many knowledge sources — from databases to SaaS — and we should always have the ability to create our connections.
  • Routing. The gateway ought to have the ability to request knowledge from the underlying providers straight.
  • Batching. A number of queries to the identical service are despatched in a batch, decreasing the variety of requests.
  • Safety. Authentication and authorization ought to management who can entry the linked knowledge.
  • Cross Datasource Filtering. Highly effective filters must be obtainable to not over-fetch the information wanted by the shopper.
  • Extensible. Builders ought to have the ability to lengthen the code with middleware or capabilities to suit their wants.

There are lots of frameworks to select from, however listed below are the highest three that I like to recommend exploring additional.


Hasura has gained reputation through the years, initially as a GraphQL-over-Postgres server. Nevertheless, it has added the flexibility to connect with exterior techniques.

We will join a “Distant Schema”, which mixes GraphQL from different servers.

There are some downsides to this strategy. The primary is that we have to create and handle our distant schema in a separate service, and this service have to be a GraphQL endpoint. This results in the second difficulty: we are able to’t join the information supply straight.

As well as, Hasura doesn’t enable us to filter knowledge in a single knowledge supply primarily based on the values in one other. This may sound tutorial, nevertheless it’s really fairly frequent that we need to specific one thing like, “Give me orders the place the shopper title is ‘ABC’.”

This presents flexibility, however on the expense of operating a number of providers. Let’s have a look at an possibility that may join straight.


StepZen permits us to connect with the information supply straight from the GraphQL server. This reduces the necessity to run a number of providers to create a gateway.

To attach Stepzen to a knowledge supply, we create a GraphQL schema file like this:

sort Question {
  something(message: String): JSON
  @relaxation (
    endpoint: "https://httpbin.org/something"
    methodology: POST
    headers: [
      {name: "User-Agent", value: "StepZen"}
      {name: "X-Api-Key", value: "12345"}
    postbody: """
        "person": {
          "id": "1000",
          "title": "The Person"

On this instance, we’re connecting the server to a database utilizing the customized schema.

There’s another choice that you could be want, and that may be a code-only strategy. Let’s have a look at that subsequent.


For the previous few years, I’ve been engaged on an open-source product referred to as Graphweaver, which can be utilized as a GraphQL gateway.

It connects on to our knowledge sources and creates an instantaneous GraphQL API. This API consists of all of the CRUD operations we’d count on to create, learn, replace, and delete. It auto-generates filters, sorting, and pagination arguments, saving time. We will lengthen the built-in operations with our code for full flexibility.

Graphweaver has out-of-the-box knowledge connectors for databases akin to Postgres and Mysql and SaaS suppliers like Xero and Contentful.

Making modifications or connecting knowledge sources includes writing Typescript code, giving us full customization.

When you’re focused on creating your individual GraphQL API, I extremely advocate you check out the Graphweaver GitHub code.


On this article, we’ve checked out tips on how to change our present API gateway and BFF sample with a single GraphQL gateway.

We’ve checked out the advantages of an API gateway and why organizations use them. Model management, charge limiting and entry administration are among the causes.

We additionally seemed on the BFF sample and the way it orchestrates API requests for frontend apps.

Lastly, we checked out GraphQL and the way this can be a useful know-how for BFFs.

In the end, this led us to making a GraphQL gateway, and we checked out three choices for creating our personal: Hasura, StepZen, and the product I’ve been engaged on, Graphweaver.

I hope this text has satisfied you to strive a GraphQL gateway of your individual, and if that’s the case, that you simply’ll contemplate giving Graphweaver a strive.


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