transaction stream step (#787)

Author: yuunlimm

apps/nextra/next.config.mjs

@@ -435,6 +435,12 @@ export default withBundleAnalyzer(
           "/en/build/indexer/indexer-sdk/documentation/connect-steps",
         permanent: true,
       },
+      {
+        source: "/indexer/indexer-sdk/documentation/transaction-stream",
+        destination:
+          "/en/build/indexer/indexer-sdk/documentation/transaction-stream",
+        permanent: true,
+      },
       {
         source: "/indexer/indexer-sdk/documentation/version-tracking",
         destination:

apps/nextra/pages/en/build/indexer/indexer-sdk/documentation/_meta.tsx

@@ -18,4 +18,7 @@ export default {
   "version-tracking": {
     title: "Version Tracking",
   },
+  "transaction-stream": {
+    title: "Transaction Stream",
+  },
 };

apps/nextra/pages/en/build/indexer/indexer-sdk/documentation/steps.mdx

@@ -101,7 +101,7 @@ To create a step with the SDK, follow these instructions:
 
 The SDK implements [several common steps](https://github.com/aptos-labs/aptos-indexer-processor-sdk/tree/main/aptos-indexer-processors-sdk/sdk/src/common_steps) that you can use in your processors. 
 
-1. `TransactionStreamStep` provides a stream of Aptos transactions to the processor
+1. `TransactionStreamStep` provides a stream of Aptos transactions to the processor. Read more about it [here](./transaction-stream.mdx).
 2. `TimedBufferStep` buffers a batch of items and periodically polls to release the items to the next step
 3. `VersionTrackerStep` tracks the progress of the processor and checkpoints the processor's progress. Read more about it [here](./version-tracking.mdx).
 4. `OrderByVersionStep` orders transaction contextx by their starting versions. It buffers ordered these contexts and releases them at every poll interval.

apps/nextra/pages/en/build/indexer/indexer-sdk/documentation/transaction-stream.mdx

@@ -0,0 +1,37 @@
+---
+title: "Transaction Stream Step"
+---
+
+# Transaction Stream Step
+
+The `TransactionStreamStep` is a foundational component in the transaction processing pipeline. It establishes a gRPC connection with the `TransactionStream` service, fetches transactions in batches, and outputs them for further processing. This step also manages connection retries and reconnections in case of transient failures. Typically, this is the initial step in a processor, responsible for streaming transactions for downstream steps.
+
+## Key Responsibilities
+
+1. **Fetch Transactions**: Retrieves transaction batches from a gRPC service.
+2. **Manage Connections**: Handles gRPC reconnections to ensure a resilient stream.
+3. **Provide Metadata**: Attaches contextual information like versions and timestamps to the transactions.
+
+## Struct Definition
+
+The `TransactionStreamStep` struct is defined as follows:
+
+```rust
+pub struct TransactionStreamStep
+where
+    Self: Sized + Send + 'static,
+{
+    transaction_stream_config: TransactionStreamConfig,
+    pub transaction_stream: Mutex<TransactionStreamInternal>,
+}
+```
+
+## How It Works
+
+- The `TransactionStreamStep` connects to the gRPC `TransactionStream` service.
+- It continuously polls for new transactions using the `poll` method.
+- Each batch is wrapped in a `TransactionContext`, which includes metadata such as:
+  - Start and end versions.
+  - Timestamps of transactions.
+  - Batch size in bytes.
+- If the connection is interrupted, it attempts to reconnect seamlessly.