> For the complete documentation index, see [llms.txt](https://wamr.gitbook.io/document/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://wamr.gitbook.io/document/wamr-in-practice/features/socket_api/socket-api.md). # Example: Use Socket Api in WAMR This sample demonstrates how to use WAMR socket-api to develop wasm network applications. Two wasm applications are provided: tcp-server and tcp-client, and this sample demonstrates how they communicate with each other. ## Preparation Please install WASI SDK, download the [wasi-sdk release](https://github.com/WebAssembly/wasi-sdk/releases) and extract the archive to default path `/opt/wasi-sdk`. And install wabt, download the [wabt release](https://github.com/WebAssembly/wabt/releases) and extract the archive to default path `/opt/wabt` ## Build the sample ```bash mkdir build cd build cmake .. make ``` `iwasm` and the following Wasm modules (along with their corresponding native version) will be generated: * `addr_resolve.wasm`, `addr_resolve` * `send_recv.wasm`, `send_recv` * `socket_opts.wasm`, `socket_opts` * `tcp_client.wasm`, `tcp_client` * `tcp_server.wasm`, `tcp_server` * `udp_client.wasm`, `udp_client` * `udp_server.wasm`, `udp_server` > Note that iwasm is built with libc-wasi and lib-pthread enabled. ## Run workload ### TCP client/server Start the tcp server, which opens port 1234 and waits for clients to connect. ```bash cd build ./iwasm --addr-pool=0.0.0.0/15 tcp_server.wasm ``` Start the tcp client, which connects the server and receives message. ```bash cd build ./iwasm --addr-pool=127.0.0.1/15 tcp_client.wasm ``` The output of client is like: ```bash [Client] Create socket [Client] Connect socket [Client] Client receive [Client] 115 bytes received: Buffer received: Say Hi from the Server Say Hi from the Server Say Hi from the Server Say Hi from the Server Say Hi from the Server [Client] BYE ``` `send_recv.wasm` contains a thread as a server and a thread as a client. They send and receive data via 127.0.0.1:1234. ```bash $ ./iwasm --addr-pool=127.0.0.1/0 ./send_recv.wasm ``` The output is: ```bash Server is online ... Client is running... Start receiving. Start sending. Send 106 bytes successfully! Receive 106 bytes successfully! Data: The stars shine down It brings us light Light comes down To make us paths It watches us And mourns for us ``` ### Socket options `socket_opts.wasm` shows an example of getting and setting various supported socket options ```bash $ ./iwasm socket_opts.wasm ``` The output is: ```bash [Client] Create TCP socket [Client] Create UDP socket [Client] Create UDP IPv6 socket setsockopt SO_RCVTIMEO result is expected getsockopt SO_RCVTIMEO result is expected ... [Client] Close sockets ``` The `timeout_client.wasm` and `timeout_server.wasm` examples demonstrate socket send and receive timeouts using the socket options. Start the server, then start the client. ```bash $ ./iwasm --addr-pool=0.0.0.0/15 timeout_server.wasm ``` The output is: ```bash Wait for client to connect Client connected, sleeping for 10s Shutting down ``` ```bash $ ./iwasm --addr-pool=127.0.0.1/15 timeout_client.wasm ``` The output is: ```bash Waiting on recv, which should timeout Waiting on send, which should timeout Success. Closing socket ``` The `multicast_client` and `multicast_server` examples demonstrate receiving multicast packets in WASM. Start the client and then the server with a multicast IP address and port. ```bash $ ./iwasm --addr-pool=0.0.0.0/0,::/0 multicast_client.wasm $ ./iwasm --addr-pool=0.0.0.0/0,::/0 multicast_client.wasm 224.0.0.1 $ ./iwasm --addr-pool=0.0.0.0/0,::/0 multicast_client.wasm FF02:113D:6FDD:2C17:A643:FFE2:1BD1:3CD2 ``` The output should be ```bash Joined multicast group. Waiting for datagram... Reading datagram message...OK. The message from multicast server is: "Test message" ``` ```bash $ ./multicast_server $ ./multicast_server 224.0.0.1 $ ./multicast_server FF02:113D:6FDD:2C17:A643:FFE2:1BD1:3CD2 ``` The output should be ```bash Datagram sent ``` ### Domain name server resolution `addr_resolve.wasm` demonstrates the usage of resolving a domain name ``` $ ./iwasm --allow-resolve=*.com addr_resolve.wasm github.com ``` The command displays the host name and its corresponding IP address: ``` Host: github.com IPv4 address: 140.82.121.4 (TCP) ``` ### UDP client/server Start the UDP server, which opens port 1234 and waits for clients to send a message. ```bash cd build ./iwasm --addr-pool=0.0.0.0/15 udp_server.wasm ``` Start the tcp client, which sends a message to the server and waits for the response. ```bash cd build ./iwasm --addr-pool=127.0.0.1/15 udp_client.wasm ``` The output of client is like: ```bash [Client] Create socket [Client] Client send [Client] Client receive [Client] Buffer received: Hello from server [Client] BYE ``` The output of the server is like: ``` [Server] Create socket [Server] Bind socket [Server] Wait for clients to connect .. [Server] received 17 bytes from 127.0.0.1:60927: Hello from client ``` ## Documentation Refer to [socket api document](/document/wamr-in-practice/features/socket_api.md) for more details. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://wamr.gitbook.io/document/wamr-in-practice/features/socket_api/socket-api.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. 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