GraphQL is an open source server-side technology which was developed by Facebook to optimize RESTful API calls. It is an execution engine and a data query language. GraphQL structures data in the form of a graph with its powerful query syntax for traversing, retrieving, and modifying data. GraphQL is a specification that describes the behavior of a GraphQL server.
Why GraphQl?
GraphQl is more preferable because even though RESTful APIs follow clear and well-structured resource-oriented approach, the routes get longer when the data get more complex and sometimes, it’s impossible to fetch data with a simple request.However, GraphQl makes up for this by structuring data in form of a graph with its powerful query syntax for traversing, retrieving, and modifying data. The transport layer agnostics is another important concept of GraphQl. It can be used with any available network protocol like websocket or any other transport layer protocol. It’s also neutral to databases, therefore, it can be used with relational or NoSQL databases.
Advantages of GraphQl
a) GraphQL queries always return predictable results: Applications using GraphQL are fast and stable.
b) GraphQl always returns the exact results required unlike REST APIs eg:a business object Student with the attributes id, firstName, lastName and collegeName. Suppose a mobile application needs to fetch only the firstName and id.
c) Get many resources in a single request: GraphQL APIs fetch all the data your application need in a single request. Example: Let’s consider another business object, College which has the attributes: name and location. The Student business object has an association relationship with the College object.
Result: GraphQl fetches the details for both Student and College objects in a single request.
d) Describe what’s possible with a type system: GraphQL is strongly typed and the queries are based on fields and their associated data types. If there’s type mismatch in a GraphQL query, server applications return clear and helpful error messages which jelps in smooth debugging and easybug detection by client aplications.
e) GraphQL also provides client side libraries that can help in reducing explicit data conversion and parsing.
f) Move faster with powerful developer tools: GraphQL provides rich developer tools for documentation and testing queries.
Methods for deploying GraphQl server
• GraphQL server with connected database
• GraphQL server that integrates existing systems
• Hybrid approach
GraphQl components
• **Server-side Components**: Apollo Server is most commonly used implementation of GraphQL specification. Other server programming components include: Schema, Query,Resolver.
• **Client-side Components**: GraphiQl, ApoolloClient.
** Commonly Used GraphQl Data Types**
• Scalar
• Object
• Query
• Mutation
• Enum
GraphQl Schema: It describes the functionality available to the client applications that connect to it. We can use any programming language to create a GraphQL schema and build an interface around it.
GraphQl Resolver: Acts as a GraphQL query handler. Every resolver function in a GraphQL schema accepts four positional arguments viz: root, args, context, info.
GraphQl Query: A GraphQL operation can either be a read or a write operation. A GraphQL query is used to read or fetch values. GraphQL queries help to reduce over fetching of data. Unlike a Restful API, GraphQL allows a user to restrict fields that should be fetched from the server. This means smaller queries and lesser traffic over the network; which in turn reduces the response time.
Conclusion
GraphQl is a specification that describes the behaviour of a graphQl server. It is a et of guidelines on how requests and response should be handled like supported protocols, format of the data that can be accepted by the server, etc. Instead of loading multiple URLs while using RESTful APIs, it's better and less stressful to use GraphQl in retrieving associated business objects.