We begin to twitch as we review the first factor of Hasura's 3factor app, Realtime GraphQL, while Allen gets distrac … SQUIRREL!, Michael might own some bell bottoms, and Joe is stuck with cobalt.
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3factor app and the First Factor
3factor app
- The 3factor app is a modern architecture for full stack applications, described by the folks at Hasura.
- High feature velocity and scalability from the start:
- Real time GraphQL
- Reliable eventing
- Async serverless
- Kinda boils down to …
- Have an API gateway (for them, GraphQL).
- Store state in a (most likely distributed) store.
- Have services interact with state via an event system.
- Versus how did we used to do things using a REST API for each individual entity.
- Let's be honest though. We probably created a single very specialized REST API for a particular page all in the name of performance. But it was only used for that page.
- Related technologies:
- Web Sockets
- Serverless
- Lambda / Kappa – Types Streaming architectures
- Event based architectures
- Microservices
Factor 1 – Realtime GraphQL
Use Realtime GraphQL as the Data API Layer
- Must be low-latency.
- Less than 100 ms is ideal.
- Must support subscriptions.
- Allows the application to consume information from the GraphQL API in real-time.
Some Comparisons to Typical Backend API Calls
| Traditional application | 3factor application |
| Uses REST calls. | Uses GraphQL API. |
| May require multiple calls to retrieve all data (customer, order, order details) – OR a complex purpose built call that will return all three in one call. | Uses GraphQL query to return data needed in a single call defined by the caller. |
| Uses something like Swagger to generate API documentation. | GraphQL will auto-generate entire schema and related documents. |
| For realtime you'll set up WebSocket based APIs. | Use GraphQL's native subscriptions. |
| Continuously poll backend for updates. | Use GraphQL's event based subscriptions to receive updates. |
Major Benefits of GraphQL
- Massively accelerates front-end development speed because developers can get the data they want without any need to build additional APIs.
- GraphQL APIs are strongly typed.
- Don't need to maintain additional documenting tools. Using a UI like GraphiQL, you can explore data by writing queries with an Intellisense like auto-complete experience.
- Realtime built in natively.
- Prevents over-fetching. Sorta. To the client, yes. Not necessarily so though on the server side.
A Little More About GraphQL
- GraphQL is a Query Language for your API.
- It isn't tied to any particular database or storage engine.
- It's backed by your existing code and data.
- Queries are all about asking for specific fields on objects.
- The shape of your query will match the shape of the results.
- Queries allow for traversing relationships, so you can get all the data you need in a single request.
- Every field and nested object has its own set of arguments that can be passed.
- Many types are supported, including enums.
- Aliases
- GraphQL has the ability to alias fields to return multiple results of the same type but with different return names (think of aliasing tables in a database query).
- Fragments
- Fragments allow you to save a set of query fields to retrieve, allowing you to later reuse those fragments in simpler queries. This allows you to create complex queries with a much smaller syntax.
- There's even the ability to use variables within the fragments for further queries requiring more flexibility.
- Operations
- Three types of operations are supported: query, mutation, and subscription.
- Providing an operation name is not required, except for multi-operation documents, but is recommended to aid debugging and server side logging.
- Variables
- Queries are typically dynamic by way of variables.
- Supported variable types are scalars, enums, and input object types.
- Input object types must map to server defined objects.
- Can be optional or required.
- Default values are supported.
- Using variables, you can shape the results of a query.
- Mutations
- Mutations allow for modifying data.
- Nesting objects allows you to return data after the mutation occurs,
- Mutations, unlike queries, run sequentially, meaning
mutation1 will finish before mutation2 runs. - In contrast, queries run in parallel.
- Meta fields
- GraphQL also provides meta fields that you can use to inspect the schema that are part of the introspection system.
- These meta fields are preceded by a double underscore, like
__schema or __typename.
- GraphQL schema language
- Objects are the building blocks of a schema.
- Fields are properties that are available on the object.
- Field return types are defined as well – scalar, enum or objects.
- Scalar types: Int, Float, String Boolean, ID (special use case), or User Defined – must specify serializer, deserializer and validator.
- Fields can also be defined as non-nullable with an exclamation after the type like
String!. - This can be done on array types as well after the square brackets to indicate that an array will always be returned, with zero or more elements, like
[String]!.
- Each field can have zero or more arguments and those arguments can have default values.
- Lists are supported by using square brackets.
- GraphQL's type system supports interfaces.
- Complex objects can also be passed as input types, however, they are defined as
input rather than type.
Resources We Like
Tip of the Week
- From Google's Engineering Practices documentation: How to do a code review (GitHub.io).
- This is part of the larger Google Engineering Practices Documentation (GitHub.io).
- Use
CTRL+SHIFT+V to access Visual Studio's Clipboard Ring. - Take control of your tab usage in your browser with Workona.
- Theme your Chrome DevTools!
