mirror of
https://github.com/taigrr/nats.docs
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185 lines
6.9 KiB
HTML
185 lines
6.9 KiB
HTML
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<div class="tab-wrap">
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<input type="radio" id="drain_sub_go" name="drain_sub" class="tab" checked>
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<label for="drain_sub_go" class="api-lang" data-language="go">Go</label>
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<input type="radio" id="drain_sub_java" name="drain_sub" class="tab">
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<label for="drain_sub_java" class="api-lang" data-language="java">Java</label>
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<input type="radio" id="drain_sub_js" name="drain_sub" class="tab">
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<label for="drain_sub_js" class="api-lang" data-language="js">JavaScript</label>
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<input type="radio" id="drain_sub_py" name="drain_sub" class="tab">
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<label for="drain_sub_py" class="api-lang" data-language="py">Python</label>
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<input type="radio" id="drain_sub_ruby" name="drain_sub" class="tab">
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<label for="drain_sub_ruby" class="api-lang" data-language="ruby">Ruby</label>
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<input type="radio" id="drain_sub_ts" name="drain_sub" class="tab">
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<label for="drain_sub_ts" class="api-lang" data-language="ts">TypeScript</label>
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<div class="tab__content">
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<pre id="drain_sub_go_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/go-nats-examples/blob/master/api-examples/drain_sub/main.go#L13-67"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-go">
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nc, err := nats.Connect("demo.nats.io")
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if err != nil {
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log.Fatal(err)
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}
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defer nc.Close()
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done := sync.WaitGroup{}
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done.Add(1)
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count := 0
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errCh := make(chan error, 1)
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msgAfterDrain := "not this one"
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// This callback will process each message slowly
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sub, err := nc.Subscribe("updates", func(m *nats.Msg) {
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if string(m.Data) == msgAfterDrain {
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errCh <- fmt.Errorf("Should not have received this message")
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return
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}
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time.Sleep(100 * time.Millisecond)
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count++
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if count == 2 {
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done.Done()
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}
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})
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// Send 2 messages
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for i := 0; i < 2; i++ {
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nc.Publish("updates", []byte("hello"))
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}
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// Call Drain on the subscription. It unsubscribes but
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// wait for all pending messages to be processed.
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if err := sub.Drain(); err != nil {
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log.Fatal(err)
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}
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// Send one more message, this message should not be received
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nc.Publish("updates", []byte(msgAfterDrain))
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// Wait for the subscription to have processed the 2 messages.
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done.Wait()
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// Now check that the 3rd message was not received
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select {
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case e := <-errCh:
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log.Fatal(e)
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case <-time.After(200 * time.Millisecond):
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// OK!
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}
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</code></pre>
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</div>
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<div class="tab__content">
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<pre id="drain_sub_java_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/java-nats-examples/blob/master/src/main/java/io/nats/examples/DrainSub.java#L16-43"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-java">Connection nc = Nats.connect("nats://demo.nats.io:4222");
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// Use a latch to wait for a message to arrive
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CountDownLatch latch = new CountDownLatch(1);
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// Create a dispatcher and inline message handler
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Dispatcher d = nc.createDispatcher((msg) -> {
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String str = new String(msg.getData(), StandardCharsets.UTF_8);
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System.out.println(str);
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latch.countDown();
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});
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// Subscribe
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d.subscribe("updates");
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// Wait for a message to come in
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latch.await();
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// Messages that have arrived will be processed
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CompletableFuture<Boolean> drained = d.drain(Duration.ofSeconds(10));
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// Wait for the drain to complete
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drained.get();
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// Close the connection
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nc.close();
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</code></pre>
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</div>
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<div class="tab__content">
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<pre id="drain_sub_js_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/node-nats-examples/blob/master/src/subscriber_samples.js#L232-252"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-javascript">let nc = NATS.connect({url: "nats://demo.nats.io:4222"});
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let inbox = createInbox();
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let counter = 0;
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let sid = nc.subscribe(inbox, () => {
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counter++;
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});
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nc.publish(inbox);
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nc.drainSubscription(sid, (err)=> {
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if(err) {
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t.log(err);
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}
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t.log('processed', counter, 'messages');
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});
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nc.flush(() => {
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nc.close();
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t.pass();
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resolve();
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});
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</code></pre>
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</div>
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<div class="tab__content">
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<pre id="drain_sub_py_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/asyncio-nats-examples/blob/master/drain_sub.py#L1-24"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-python">import asyncio
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from nats.aio.client import Client as NATS
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async def example(loop):
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nc = NATS()
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await nc.connect("nats://127.0.0.1:4222", loop=loop)
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async def handler(msg):
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print("[Received] ", msg)
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await nc.publish(msg.reply, b'I can help')
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# Can check whether client is in draining state
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if nc.is_draining:
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print("Connection is draining")
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sid = await nc.subscribe("help", "workers", cb=handler)
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await nc.flush()
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# Gracefully unsubscribe the subscription
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await nc.drain(sid)
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</code></pre>
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</div>
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<div class="tab__content">
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<pre id="drain_sub_ruby_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/ruby-nats-examples/blob/master/notapplicable.txt#L9-11"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-ruby"># There is currently no API to drain a single subscription, the whole connection can be drained though via NATS.drain
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</code></pre>
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</div>
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<div class="tab__content">
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<pre id="drain_sub_ts_content"><a class="toolbar-icons pull-right" target="_blank" href="https://github.com/nats-io/ts-nats-examples/blob/master/src/subscriber_samples.ts#L208-212"><i class="mdi mdi-github-circle" title="View on GitHub"></i></a><a class="toolbar-icons pull-right"><i class="mdi mdi-content-copy js-copy" title="Copy to Clipboard"></i></a><span class="copy-msg pull-right"></span><code class="language-javascript">let sub = await nc.subscribe('updates', (err, msg) => {
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t.log('worker got message', msg.data);
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}, {queue: "workers"});
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</code></pre>
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</div>
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</div>
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