Apollo server II
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This document provides an overview of GraphQL basics and compares it to REST APIs. It discusses that GraphQL allows fetching multiple resources with a single query, while REST typically requires multiple requests. GraphQL also avoids over-fetching and under-fetching of data, and provides built-in type checking and documentation. The document outlines topics that will be covered in the next session, including GraphQL schemas, resolvers, and introspection.
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Apollo server II
- 1. Basics of Apollo Server II (GraphQL) - By Sumit
- 2. 2 NodeXperts Topics - Why we use GraphQL? - Before GraphQL. - After GraphQL. - Problems in REST? - GraphQL in the logical architecture. - Next Session Topic
- 3. 3 NodeXperts Why we use GraphQL? In our last session we have learnt that GraphQL is use to create API. There are three operations in GraphQL to create API. - Query - Mutation - Subscription. But we have ways to create API before GraphQL. Let's look into that.
- 4. 4 NodeXperts Before GraphQL? Before GraphQL we create API’s using REST method in which we have HTTP method like - - GET - POST - PUT - DELETE So, we have all the operations required to query or manipulate the data from database, then why we need GraphQL? Let’s look on GraphQL now.
- 5. 5 NodeXperts After GraphQL? Now we know that GraphQL has three operations, let’s look explore its operations. - Query is same as we have GET request in HTTP. - Mutation is same as we have POST, PUT, DELETE request in HTTP. - Subscription this is new introduced in GraphQL. So, now we know that what Query and Mutation is, but we have a new entry here, Subscription. What is that? Let’s explore it.
- 6. 6 NodeXperts The team structure of each DAN POD is optimised per set hierarchy After GraphQL So, before GraphQL when we have REST API if there is any change in data in database the client is unaware of that. So, how client will get the new data. - If the page is reloaded then it will send the request to the server and in response server returns the new data. - Second method is implement websocket to get the new data. As client gets the real-time data in websocket but it takes time to implement the websocket. To get the new data on client using REST API either we need to reload the page or implement websocket. Here comes Subscription in picture, it ensures client that it will keep client updated on any data change.
- 7. 7 NodeXperts Query Complexity - Fetching multiple resources require making multiple calls to the server. With GraphQL query we can do that in a single query. As we can see in diagram, if I want user we make on request, if I want all the posts related to user we make another request to fetch that. Problems in REST
- 8. 8 NodeXperts Problems in REST Over Fetching and Under Fetching - In REST Api we end up with getting lot of extra data or incomplete data for which we have make extra calls to get complete data. Using graphQL we get the exact data what we want in a single request. In the image we can see that we want only the picture of user we get name and location along with that, it is called over fetching.
- 9. 9 NodeXperts Problems in REST Validation and type Checking - In REST Api we do not have any method for type checking or if we want that then we need to implement typescript in that. Apart from that Typescript is also implements check until compile time. In GraphQL we have type check available at run time. So, client knows in well advance that what is available for the query. Autogenerating API Documentation - In REST we spend lot of time in documentation, we use tools like swagger to document API. In GraphQL the API documentation is automatically done with each changes in the schema. We will see that when we are writing the schema.
- 10. 10 NodeXperts GraphQL in the logical Architecture Before graphQL if we want data to be fetched from multiple resources we use to process and aggregate the data on client which increase the complexity on client. After graphQL now we can get the data on graphQL and process data and send it to client. So client receives only that data which it requires to show to the end user.
- 11. 11 NodeXperts Next Session Topics: - Schema - Resolvers - Introspection in graphQL.