Introspection control in GraphQL - Step-by-Step Execution

Concept Flow - Introspection control

Client sends introspection query

↓

Server receives query

↓

Check introspection enabled?

No→Reject or block query

Yes↓

Server processes introspection query

↓

Server returns schema details

↓

Client receives schema info

The client sends an introspection query, the server checks if introspection is allowed, then either processes or blocks the query, returning schema details if allowed.

Execution Sample

GraphQL

query IntrospectionQuery {
  __schema {
    types {
      name
    }
  }
}

This query asks the server for the list of all types in the schema if introspection is enabled.

Execution Table

Step	Action	Introspection Enabled?	Result	Output
1	Client sends introspection query	Unknown	Query received by server	No output yet
2	Server checks introspection setting	Yes	Introspection allowed	Proceed to process query
3	Server processes __schema request	Yes	Fetch schema types	List of type names
4	Server sends response	Yes	Response sent to client	{"data":{"__schema":{"types":[{"name":"Query"},{"name":"User"},{"name":"String"}]}}}
5	Client receives response	Yes	Client can use schema info	Schema details available
6	Server checks introspection setting	No	Introspection blocked	Error or empty response
7	Server sends error response	No	Response sent to client	{"errors":[{"message":"Introspection disabled"}]}

💡 Execution stops after sending response or error depending on introspection setting.

Variable Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	Final
introspection_enabled	Unknown	Yes or No	Yes or No	Yes or No	Yes or No
query_received	No	Yes	Yes	Yes	Yes
response	None	None	Schema data or error	Sent to client	Sent to client

Key Moments - 2 Insights

Why does the server sometimes block introspection queries?

Because introspection_enabled is set to No (see execution_table rows 6 and 7), the server rejects introspection queries to prevent clients from seeing schema details.

What happens if introspection is enabled?

The server processes the introspection query and returns schema information (see execution_table rows 2 to 5).

Visual Quiz - 3 Questions

Look at the execution_table, at which step does the server decide if introspection is allowed?

A Step 1

B Step 2

C Step 4

D Step 6

💡 Hint

Check the 'Introspection Enabled?' column in execution_table row 2.

According to variable_tracker, what is the value of 'response' after step 3 if introspection is enabled?

A None

B Error message

C Schema data

D Query not received

💡 Hint

Look at 'response' variable values in variable_tracker after step 3.

If introspection_enabled is No, what output does the server send according to execution_table?

A Error message 'Introspection disabled'

B Schema details

C List of type names

D Empty response

💡 Hint

See execution_table rows 6 and 7 for output when introspection is blocked.

Concept Snapshot

Introspection control in GraphQL:
- Client sends introspection query
- Server checks if introspection is enabled
- If yes, server returns schema info
- If no, server blocks query with error
- Control protects schema details from unauthorized access

Full Transcript

In GraphQL, introspection control means the server decides if it allows clients to ask about the schema. When a client sends an introspection query, the server checks if introspection is enabled. If it is, the server processes the query and returns schema details like type names. If not, the server blocks the query and sends an error message. This protects the schema from being exposed when not desired. The execution table shows each step from receiving the query, checking settings, processing or blocking, and sending the response. The variable tracker shows how key variables like introspection_enabled and response change during execution.