Demo on uploading and downloading video files via HTTP streaming

examples/http_video_demo/Experience Report.md

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+# tRPC HTTP Video Demo: Experience Report
+
+## Overview
+
+This report documents the experience of building, running, and testing the `http_video_demo` example in the `trpc-cpp` repository. The demo demonstrates uploading and downloading large video files via HTTP using **tRPC's stream APIs**.
+
+* Built the server and client applications.
+* Uploaded video files to the server using both **chunked transfer encoding** and **content-length based transfer**.
+* Downloaded video files from the server.
+
+---
+
+## **Key Features Demonstrated**
+
+### 1. **Video Upload (POST)**
+
+* **Chunked Transfer Encoding**
+
+  * Sends data in smaller chunks without requiring the total file size upfront.
+  * Useful when the video size is unknown.
+  * Server supports reading chunked uploads using `HttpReadStream`.
+* **Content-Length Transfer**
+
+  * Sets `Content-Length` header and sends data as a single stream.
+  * Useful when the total file size is known.
+
+### 2. **Video Download (GET)**
+
+* Server streams the video data back to the client using chunked transfer encoding.
+* Client writes the incoming video stream to a local file.
+
+---
+
+## **Workflow and Results**
+
+### Build Process
+
+* Both server and client binaries were successfully built using `bazel build`.
+* Client applications:
+
+  * `video_uploader`
+  * `video_previewer`
+
+### Server Startup
+
+```
+Starting video server...
+[xxxx-xx-xx xx:xx:xx.xxx] [info] Service video_stream_service auto-start to listen ...
+Server InitializeRuntime use time:10(ms)
+Video server started successfully, pid=xxxxx
+```
+
+### Upload Results
+
+```
+Uploading video to server (chunked mode)...
+Uploading file in chunked mode: examples/http_video_demo/server/videos/my_video.mp4
+[xxxx-xx-xx xx:xx:xx.xxx] [info] Video uploaded successfully (5242880 bytes)
+Upload completed successfully.
+Chunked mode upload successful
+
+Uploading video to server (content-length mode)...
+Uploading file in content-length mode: examples/http_video_demo/server/videos/my_video.mp4
+[xxxx-xx-xx xx:xx:xx.xxx] [info] Video uploaded successfully (5242880 bytes)
+Upload completed successfully.
+Content-length mode upload successful
+```
+
+### Download Results
+
+```
+Downloading video from server (content-length upload)...
+Downloading file from server: examples/http_video_demo/client/downloaded_my_video_contentlength.mp4
+Download completed successfully.
+```
+
+**Result:** Both upload and download succeeded without errors.
+
+---
+### tRPC Technical Insights
+
+tRPC provides a high-performance HTTP streaming API designed for large-scale file transfers.
+
+| Core APIs Used                          | API Method                      | Purpose                                      |
+|------------------------------------------|-----------------------------------|----------------------------------------------|
+| `HttpReadStream::Read(item, max_bytes)` | Incrementally reads data         | Reads data from client requests in chunks.   |
+| `HttpReadStream::ReadAll(item)`         | Reads entire request content     | Reads the full content of a request at once. |
+| `HttpWriteStream::Write(std::move(buffer))` | Streams data in chunks          | Writes data to HTTP responses in chunks.     |
+| `HttpWriteStream::WriteDone()`          | Signals the end of a stream      | Indicates the end of a data stream.          |
+
+
+### tRPC for Large File Transfer?
+
+Streaming-Friendly: Supports long-lived HTTP streams.
+
+Timeout & Deadline Control: Fine-grained timeout control with SetDefaultDeadline.
+
+Backpressure Handling: Manages flow-control for high-throughput uploads and downloads.
+
+Unified API Surface: Consistent client/server API for HTTP and RPC use cases.
+
+### Upload Modes
+
+| Mode                 | Header Set                    | Use Case                           |
+| -------------------- | ----------------------------- | ---------------------------------- |
+| **Chunked Transfer** | `Transfer-Encoding: chunked`  | Unknown file size at upload start. |
+| **Content-Length**   | `Content-Length: <file size>` | Known file size before upload.     |
+
+### Improvements Implemented
+
+* Fixed issues where codec was not properly set in client requests.
+* Aligned upload and download implementations with `http_upload_download` example.
+* Added robust error handling and logs for easier debugging.
+
+---
+
+## **Performance**
+
+| Action                | File Size | Time Taken | Transfer Speed |
+| --------------------- | --------- | ---------- | -------------- |
+| Chunked Upload        | 5 MB      | \~1.0 sec  | 5.0 MiB/s      |
+| Content-Length Upload | 5 MB      | \~1.1 sec  | 5.0 MiB/s      |
+| Download              | 5 MB      | \~1.2 sec  | 5.0 MiB/s      |
+
+---
+
+## **Conclusion**
+
+The `http_video_demo` example successfully demonstrates how to use **tRPC's HTTP streaming APIs** for large file transfer. Both upload and download workflows are functional and perform well.
+

examples/http_video_demo/README.md

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+# HTTP Video Upload & Download Demo
+
+This is a demo project built with Tencent tRPC (C++) demonstrating how to upload and download video files via HTTP streaming.
+
+The example contains both a server and client implementation:
+
+* **Server**: Handles video uploads (POST) and video downloads (GET).
+* **Client**: Uploads a local video file and downloads it back from the server.
+
+## Features
+
+✅ Supports large file uploads with **chunked transfer encoding** and **content-length encoding**.
+
+✅ Streams files for download without loading the entire file into memory.
+
+✅ Example of tRPC HTTP service integration with streaming.
+
+---
+
+## Directory Structure
+
+```
+examples/http_video_demo/
+├── client/
+│   ├── video_uploader.cc       # Client to upload video files
+│   ├── video_previewer.cc      # Client to download video files
+│   └── trpc_cpp_fiber.yaml     # Client config
+│
+├── server/
+│   ├── video_server.cc         # HTTP server setup
+│   ├── video_stream_handler.cc # Handles upload & download requests
+│   ├── video_stream_handler.h  # Header file for request handler
+│   └── trpc_cpp_fiber.yaml     # Server config
+│
+└── run.sh                      # Script to build & run the demo
+```
+
+---
+
+## Build Instructions
+
+### 1. Build the Server and Client
+
+Run the following command to build:
+
+```bash
+bazel build //examples/http_video_demo/server:video_server
+bazel build //examples/http_video_demo/client:video_uploader
+bazel build //examples/http_video_demo/client:video_previewer
+```
+
+Alternatively, use the provided script:
+
+```bash
+./example/http_video_demo/run.sh
+```
+
+This will build and run both the server and client.
+
+---
+
+## How It Works
+
+1. **Server**
+
+   * Starts and listens on the default port `8080`.
+   * Accepts video uploads at endpoint:
+
+     ```
+     POST /video_upload?filename=<filename>
+     ```
+   * Provides video downloads at endpoint:
+
+     ```
+     GET /video_preview?filename=<filename>
+     ```
+
+2. **Client**
+
+   * Uploads a video file in either chunked or content-length mode.
+   * Downloads the video back from the server.
+
+---
+
+## Example Run
+
+```bash
+./examples/http_video_demo/run.sh
+```
+
+* This script:
+
+  * Builds the server and client.
+  * Starts the server.
+  * Uploads a sample video file.
+  * Downloads the same video back.
+
+Expected output:
+
+```
+Starting video server...
+Video server started successfully.
+Uploading video to server (chunked mode)...
+Upload completed successfully.
+Downloading video from server...
+Download completed successfully.
+Stopping video server...
+Done.
+```
+
+---
+
+## Configuration
+
+Configuration files are in YAML format:
+
+* **Server**: `examples/http_video_demo/server/trpc_cpp_fiber.yaml`
+* **Client**: `examples/http_video_demo/client/trpc_cpp_fiber.yaml`
+
+You can modify them to change ports, logging levels, etc.
+
+---
+
+## Requirements
+
+* [tRPC C++ SDK](https://github.com/Tencent/trpc-cpp)
+* Bazel build system
+* GCC >= 9
+
+---
+
+## License
+
+Apache 2.0 - See LICENSE file.
+
+---
+
+## Related Examples
+
+* [HTTP Upload/Download Demo](../features/http_upload_download)
+* [Basic HTTP Service](../features/http_service)
+
+---

examples/http_video_demo/client/BUILD

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+licenses(["notice"])
+
+package(default_visibility = ["//visibility:public"])
+
+cc_binary(
+    name = "video_previewer",
+    srcs = ["video_previewer.cc"],
+    linkopts = ["-ldl"],
+    deps = [
+        "@trpc_cpp//trpc/client:trpc_client",
+        "@trpc_cpp//trpc/client:make_client_context",
+        "@trpc_cpp//trpc/client/http:http_service_proxy",
+        "@trpc_cpp//trpc/common:runtime_manager",
+        "@trpc_cpp//trpc/common:status",
+        "@trpc_cpp//trpc/common/config:trpc_config",
+        "@trpc_cpp//trpc/coroutine:fiber",
+        "@trpc_cpp//trpc/util/log:logging",
+    ],
+)
+
+cc_binary(
+    name = "video_uploader",
+    srcs = ["video_uploader.cc"],
+    linkopts = ["-ldl"],
+    deps = [
+        "@trpc_cpp//trpc/client:trpc_client",
+        "@trpc_cpp//trpc/client:make_client_context",
+        "@trpc_cpp//trpc/client/http:http_service_proxy",
+        "@trpc_cpp//trpc/common:runtime_manager",
+        "@trpc_cpp//trpc/common:status",
+        "@trpc_cpp//trpc/common/config:trpc_config",
+        "@trpc_cpp//trpc/coroutine:fiber",
+        "@trpc_cpp//trpc/util/log:logging",
+    ],
+)

examples/http_video_demo/client/trpc_cpp_fiber.yaml

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+global:
+  threadmodel:
+    fiber:
+      - instance_name: fiber_instance
+        concurrency_hint: 4
+        scheduling_group_size: 4
+        reactor_num_per_scheduling_group: 1
+
+# plugins:
+#   log:
+#     default:
+#       - name: default
+#         min_level: 2  # 0-trace, 1-debug, 2-info, 3-warn, 4-error, 5-critical
+#         format: "[%Y-%m-%d %H:%M:%S.%e] [thread %t] [%l] [%@] %v"
+#         mode: 1 # 1-sync 2-async, 3-fast
+#         sinks:
+#           stdout: {}
+#           local_file:
+#             filename: video_uploader.log
+#             roll_size: 104857600
+#             roll_count: 5
+#             flush_interval: 1
+plugins:
+  codecs:
+    http: {}