Request-Response Pattern

Synchronous communication where a client makes a request and waits for a response

The request-response pattern is one of the most fundamental integration approaches, where a client sends a request to a server and waits for the server to respond.

Request-Response Overview

The request-response pattern has several key characteristics:

Synchronous: The client typically waits for a response before proceeding
Direct communication: Clear sender and receiver relationship
Immediate feedback: Client receives immediate confirmation of success or failure
Simple mental model: Follows natural question-answer paradigm
Stateless: Each request-response pair is typically self-contained

When to Use Request-Response

Request-response is ideal for scenarios where:

Immediate answers are required
Operations must complete before proceeding
Simple, direct interactions are needed
Low latency is expected
The client needs confirmation of success/failure
Data lookups or validations are performed

Request-Response Variations

Synchronous Request-Response

The client waits (blocks) until the server responds:

Direct coupling: Client operation pauses until response arrives
Simple implementation: Straightforward to code and understand
Immediate results: No additional mechanisms needed to retrieve response
Timeout handling: May require timeout management for slow responses

# Synchronous API call
Set Variable [$url; Value: "https://api.example.com/customers/123"]
Set Variable [$options; Value: "-X GET -H \"Content-Type: application/json\""]

# Client blocks until response is received or times out
Insert From URL [Select; $result; $url; cURL options: $options]

# Process response immediately
If [JSONGetElement($result; "status") = "success"]
  # Handle successful response
  ...
Else
  # Handle error
  ...
End If

Asynchronous Request-Response

The client doesn't block, but checks for the response later:

Non-blocking: Client continues processing while waiting
Callback mechanism: Client is notified when response arrives
Correlation ID: Used to match responses to requests
Greater complexity: Requires additional mechanisms to handle responses

# Initiate asynchronous request
Set Variable [$requestID; Value: Get(UUID)]
Set Variable [$url; Value: "https://api.example.com/long-process"]
Set Variable [$payload; Value: JSONSetElement("{}";
  ["process"; "generate_report"; JSONString];
  ["parameters"; $parameters; JSONObject];
  ["callback_id"; $requestID; JSONString]
)]
Set Variable [$options; Value: "-X POST -H \"Content-Type: application/json\" --data " & Quote($payload)]

# Make request but don't wait for full processing
Insert From URL [Select; $initialResponse; $url; cURL options: $options]

# Store request ID for later checking
Set Field [RequestLog::request_id; $requestID]
Set Field [RequestLog::status; "pending"]
Set Field [RequestLog::timestamp; Get(CurrentTimestamp)]

Fire and Forget

A request with no expected response:

Simplest form: Client sends request and continues
No confirmation: Client doesn't know if request succeeded
Lowest overhead: Minimal resource usage
Use case: Non-critical notifications or logging

# Fire and forget notification
Set Variable [$url; Value: "https://api.example.com/log-event"]
Set Variable [$payload; Value: JSONSetElement("{}";
  ["event"; "user_login"; JSONString];
  ["user_id"; $userID; JSONString];
  ["timestamp"; Get(CurrentTimestamp); JSONString]
)]
Set Variable [$options; Value: "-X POST -H \"Content-Type: application/json\" --data " & Quote($payload)]

# Send without waiting for or checking response
Insert From URL [Select; $result; $url; cURL options: $options]

# Continue processing immediately

FileMaker as Request Sender

FileMaker offers several ways to implement request-response:

Insert From URL

The primary script step for making HTTP requests:

# Basic REST API request
Set Variable [$url; Value: "https://api.example.com/products?category=electronics"]
Set Variable [$options; Value: "-X GET -H \"Accept: application/json\""]

Insert From URL [Select; $result; $url; cURL options: $options]

# Parse JSON response
Set Variable [$products; Value: JSONGetElement($result; "products")]

cURL Options

Configure detailed request parameters:

# More complex request with authentication and data
Set Variable [$url; Value: "https://api.example.com/orders"]
Set Variable [$data; Value: JSONSetElement("{}";
  ["customer_id"; $customerID; JSONString];
  ["items"; $items; JSONArray];
  ["shipping_address"; $address; JSONObject]
)]
Set Variable [$options; Value: "-X POST -H \"Content-Type: application/json\" -H \"Authorization: Bearer " & $token & "\" --data " & Quote($data)]

Insert From URL [Select; $result; $url; cURL options: $options]

Handling Responses

Processing different response types:

# Response handling with error checking
Set Variable [$statusCode; Value: GetAsNumber(JSONGetElement($result; "status"))]

If [$statusCode >= 200 and $statusCode < 300]
  # Success - process data
  Set Variable [$data; Value: JSONGetElement($result; "data")]
  ...
Else If [$statusCode >= 400 and $statusCode < 500]
  # Client error - handle invalid request
  Set Variable [$errorMessage; Value: JSONGetElement($result; "message")]
  Show Custom Dialog ["Request Error"; $errorMessage]
Else If [$statusCode >= 500]
  # Server error - retry or notify
  Set Variable [$retryCount; Value: $retryCount + 1]
  If [$retryCount <= 3]
    # Retry request
    Perform Script [Self; Parameter: $retryCount]
  Else
    # Give up and notify
    Show Custom Dialog ["Server Error"; "The service is currently unavailable. Please try again later."]
  End If
End If