What is Temporal?
Temporal is a scalable and reliable runtime for durable function executions called Temporal Workflow Executions.
Said another way, it's a platform that guarantees the Durable Execution of your application code.
It enables you to develop as if failures don't even exist. Your application will run reliably even if it encounters problems, such as network outages or server crashes, which would be catastrophic for a typical application. The Temporal Platform handles these types of problems, allowing you to focus on the business logic, instead of writing application code to detect and recover from failures.
The Temporal System
Durable Execution
Durable Execution in the context of Temporal refers to the ability of a Workflow Execution to maintain its state and progress even in the face of failures, crashes, or server outages. This is achieved through Temporal's use of an Event History, which records the state of a Workflow Execution at each step. If a failure occurs, the Workflow Execution can resume from the last recorded event, ensuring that progress isn't lost. This durability is a key feature of Temporal Workflow Executions, making them reliable and resilient. It enables application code to execute effectively once and to completion, regardless of whether it takes seconds or years.
What is the Temporal Platform?
The Temporal Platform consists of a Temporal Cluster and Worker Processes. Together these components create a runtime for Workflow Executions.
The Temporal Platform consists of a supervising software typically called a Temporal Cluster and application code bundled as Worker Processes. Together these components create a runtime for your application.
The Temporal Platform
A Temporal Cluster consists of the Temporal Server and a database.
Our software as a server (SaaS) offering, Temporal Cloud, offers an alternative to hosting a Temporal Cluster yourself.
Worker Processes are hosted and operated by you and execute your code. Workers run using one of our SDKs.
Basic component topology of the Temporal Platform
What is a Temporal Application?
A Temporal Application is a set of Temporal Workflow Executions. Each Temporal Workflow Execution has exclusive access to its local state, executes concurrently to all other Workflow Executions, and communicates with other Workflow Executions and the environment via message passing.
A Temporal Application can consist of millions to billions of Workflow Executions. Workflow Executions are lightweight components. A Workflow Execution consumes few compute resources; in fact, if a Workflow Execution is suspended, such as when it is in a waiting state, the Workflow Execution consumes no compute resources at all.
Reentrant Process
A Temporal Workflow Execution is a Reentrant Process. A Reentrant Process is resumable, recoverable, and reactive.
- Resumable: Ability of a process to continue execution after execution was suspended on an awaitable.
- Recoverable: Ability of a process to continue execution after execution was suspended on a failure.
- Reactive: Ability of a process to react to external events.
Therefore, a Temporal Workflow Execution executes a Temporal Workflow Definition, also called a Temporal Workflow Function, your application code, exactly once and to completion—whether your code executes for seconds or years, in the presence of arbitrary load and arbitrary failures.
What is a Temporal SDK?
A Temporal SDK is a language-specific library that offers APIs to do the following:
- Construct and use a Temporal Client
- Develop Workflow Definitions
- Develop Worker Programs
A Temporal SDK enables you to write your application code using the full power of the programming language, while the Temporal Platform handles the durability, reliability, and scalability of the application.
Temporal currently offers the following SDKs:
- Get started with the Go SDK
- Get started with the Java SDK
- Get started with the PHP SDK
- Get started with the Python SDK
- Get started with the TypeScript SDK
- .NET SDK API reference
Each SDK emits metrics which can be ingested into monitoring platforms. See the SDK metrics reference for a complete list.