Execution control for reliable outbound HTTP calls
A control layer to execute, regulate, observe and trace HTTP requests across systems.
What Sqalin is
Sqalin is an execution layer for HTTP requests.
When your systems need to call external services, legacy APIs, or internal systems under strict constraints, Sqalin sits in the middle and takes control of how those requests are executed.
How Sqalin works
A system sends an execution request to Sqalin
Sqalin decides execution mode: sync, async, or queued
Sqalin executes the request with proper controls
Sqalin stores the full execution trace
Sqalin optionally notifies the caller with results
Sqalin is not a message broker. It is not a workflow engine. It is not just a proxy.
It is a control layer purpose-built for executing outbound HTTP requests reliably.
The problems Sqalin solves
Concrete engineering problems that happen when systems need to communicate over HTTP
Legacy systems that cannot go async
PHP monoliths, legacy Java services, or any system that is synchronous by design but needs async execution without refactoring.
External APIs that break under concurrency
Third-party APIs with strict rate limits or fragile infrastructure that requires precise throttling and ordering.
Systems that need strict rate limiting or ordering
When requests must be executed one at a time, or with controlled concurrency to prevent overload or maintain sequence.
Lack of observability on outbound requests
When HTTP calls leave your system and disappear into the void, making debugging and auditing nearly impossible.
Difficult retries and failure handling
Implementing proper retry logic with exponential backoff, dead letter handling, and failure notifications is complex and error-prone.
Mixing business logic with infrastructure
When every service reimplements the same HTTP client logic, retry policies, and observability patterns.
Execution modes
All execution modes share the same execution model and full observability
Synchronous execution
Caller waits for the result. Sqalin executes immediately and returns the full response.
Use when: the caller needs the result immediately, such as user-facing requests or read operations.
Asynchronous execution
Caller returns immediately. Execution continues in the background. Sqalin stores the result and optionally sends it via callback.
Use when: the caller does not need to wait, such as notifications, background processing, or fire-and-forget integrations.
Queued / serialized execution
Requests are queued and executed respecting order and concurrency limits. Protects downstream systems from overload.
Use when: strict rate limiting is required, requests must be sequential, or downstream systems are fragile.
Observability by design
Sqalin stores the full execution history of every request
Every execution is stored with:
- Request payload, headers, and metadata
- Response payload and status code
- Timing information for each lifecycle stage
- Error details if the execution failed
- Correlation IDs to group related executions
This makes outbound HTTP traffic auditable, traceable, and debuggable.
No more invisible HTTP calls. No more guessing what happened. Query executions by ID, correlation, or status.
Use cases
Real scenarios where Sqalin provides immediate value
Protecting fragile third-party APIs
Route requests through Sqalin with queued execution to enforce rate limits and prevent overwhelming external systems.
Offloading outbound calls from monoliths
Let legacy systems delegate HTTP execution to Sqalin and immediately return to the user, avoiding timeout issues and blocking operations.
Centralizing integrations
Build a single execution layer for all outbound HTTP traffic across microservices, providing unified observability and control.
Regulating traffic between internal services
Control concurrency and ordering between internal systems that cannot handle high load or parallel requests.
Making async possible in synchronous systems
Give synchronous systems the ability to execute async operations without refactoring their architecture.
What Sqalin is not
Not a queue replacement
Sqalin is not RabbitMQ or Kafka. It does not replace message brokers for event streaming or pub/sub patterns.
Not a business workflow engine
Sqalin does not orchestrate complex multi-step business processes. It executes individual HTTP requests.
Not a cron system
Sqalin does not schedule recurring jobs. It executes requests when you tell it to.
Not tied to any specific language
Sqalin is language-agnostic. Any system that can make HTTP calls can use Sqalin.