# Wildcard Subscriptions

There is no special code to subscribe with a [wildcard subject](/nats-concepts/subjects.md#wildcards). Wildcards are a normal part of the subject name. However, it is a common technique to use the subject provided with the incoming message to determine what to do with the message.

For example, you can subscribe using `*` and then act based on the actual subject.

{% tabs %}
{% tab title="Go" %}

```go
nc, err := nats.Connect("demo.nats.io")
if err != nil {
    log.Fatal(err)
}
defer nc.Close()

// Use a WaitGroup to wait for 2 messages to arrive
wg := sync.WaitGroup{}
wg.Add(2)

// Subscribe
if _, err := nc.Subscribe("time.*.east", func(m *nats.Msg) {
    log.Printf("%s: %s", m.Subject, m.Data)
    wg.Done()
}); err != nil {
    log.Fatal(err)
}

// Wait for the 2 messages to come in
wg.Wait()
```

{% endtab %}

{% tab title="Java" %}

```java
Connection nc = Nats.connect("nats://demo.nats.io:4222");

// Use a latch to wait for 2 messages to arrive
CountDownLatch latch = new CountDownLatch(2);

// Create a dispatcher and inline message handler
Dispatcher d = nc.createDispatcher((msg) -> {
    String subject = msg.getSubject();
    String str = new String(msg.getData(), StandardCharsets.UTF_8);
    System.out.println(subject + ": " + str);
    latch.countDown();
});

// Subscribe
d.subscribe("time.*.east");

// Wait for messages to come in
latch.await();

// Close the connection
nc.close();
```

{% endtab %}

{% tab title="JavaScript" %}

```javascript
nc.subscribe("time.us.*", (_err, msg) => {
    // converting timezones correctly in node requires a library
    // this doesn't take into account *many* things.
    let time;
    switch (msg.subject) {
      case "time.us.east":
        time = new Date().toLocaleTimeString("en-us", {
          timeZone: "America/New_York",
        });
        break;
      case "time.us.central":
        time = new Date().toLocaleTimeString("en-us", {
          timeZone: "America/Chicago",
        });
        break;
      case "time.us.mountain":
        time = new Date().toLocaleTimeString("en-us", {
          timeZone: "America/Denver",
        });
        break;
      case "time.us.west":
        time = new Date().toLocaleTimeString("en-us", {
          timeZone: "America/Los_Angeles",
        });
        break;
      default:
        time = "I don't know what you are talking about Willis";
    }
    t.log(subject, time);
});
```

{% endtab %}

{% tab title="Python" %}

```python
nc = NATS()

await nc.connect(servers=["nats://demo.nats.io:4222"])

# Use queue to wait for 2 messages to arrive
queue = asyncio.Queue()
async def cb(msg):
  await queue.put_nowait(msg)

await nc.subscribe("time.*.east", cb=cb)

# Send 2 messages and wait for them to come in
await nc.publish("time.A.east", b'A')
await nc.publish("time.B.east", b'B')

msg_A = await queue.get()
msg_B = await queue.get()

print("Msg A:", msg_A)
print("Msg B:", msg_B)
```

{% endtab %}

{% tab title="C#" %}

```csharp
// dotnet add package NATS.Net
using NATS.Net;

await using var client = new NatsClient();

var count = 0;
await foreach (var msg in client.SubscribeAsync<string>("time.*.east"))
{
    Console.WriteLine($"Received {++count}: {msg.Subject}: {msg.Data}");
    
    if (count == 2)
    {
        break;
    }
}

Console.WriteLine("Done");

// Output:
// Received 1: time.us.east: 2024-10-21T22:11:24 America/New_York (-04)
// Received 2: time.eu.east: 2024-10-22T04:11:24 Europe/Warsaw (+02)
// Done
```

{% endtab %}

{% tab title="Ruby" %}

```ruby
require 'nats/client'
require 'fiber'

NATS.start(servers:["nats://127.0.0.1:4222"]) do |nc|
  Fiber.new do
    f = Fiber.current

    nc.subscribe("time.*.east") do |msg, reply|
      f.resume Time.now
    end

    nc.publish("time.A.east", "A")
    nc.publish("time.B.east", "B")

    # Use the response
    msg_A = Fiber.yield
    puts "Msg A: #{msg_A}"

    msg_B = Fiber.yield
    puts "Msg B: #{msg_B}"

  end.resume
end
```

{% endtab %}

{% tab title="C" %}

```c
static void
onMsg(natsConnection *conn, natsSubscription *sub, natsMsg *msg, void *closure)
{
    printf("Received msg: %s - %.*s\n",
           natsMsg_GetSubject(msg),
           natsMsg_GetDataLength(msg),
           natsMsg_GetData(msg));

    // Need to destroy the message!
    natsMsg_Destroy(msg);
}


(...)

natsConnection      *conn = NULL;
natsSubscription    *sub  = NULL;
natsStatus          s;

s = natsConnection_ConnectTo(&conn, NATS_DEFAULT_URL);
if (s == NATS_OK)
    s = natsConnection_Subscribe(&sub, conn, "time.*.east", onMsg, NULL);

(...)


// Destroy objects that were created
natsSubscription_Destroy(sub);
natsConnection_Destroy(conn);
```

{% endtab %}
{% endtabs %}

or do something similar with `>`:

{% tabs %}
{% tab title="Go" %}

```go
nc, err := nats.Connect("demo.nats.io")
if err != nil {
    log.Fatal(err)
}
defer nc.Close()

// Use a WaitGroup to wait for 4 messages to arrive
wg := sync.WaitGroup{}
wg.Add(4)

// Subscribe
if _, err := nc.Subscribe("time.>", func(m *nats.Msg) {
    log.Printf("%s: %s", m.Subject, m.Data)
    wg.Done()
}); err != nil {
    log.Fatal(err)
}

// Wait for the 4 messages to come in
wg.Wait()

// Close the connection
nc.Close()
```

{% endtab %}

{% tab title="Java" %}

```java
Connection nc = Nats.connect("nats://demo.nats.io:4222");

// Use a latch to wait for 4 messages to arrive
CountDownLatch latch = new CountDownLatch(4);

// Create a dispatcher and inline message handler
Dispatcher d = nc.createDispatcher((msg) -> {
    String subject = msg.getSubject();
    String str = new String(msg.getData(), StandardCharsets.UTF_8);
    System.out.println(subject + ": " + str);
    latch.countDown();
});

// Subscribe
d.subscribe("time.>");

// Wait for messages to come in
latch.await();

// Close the connection
nc.close();
```

{% endtab %}

{% tab title="JavaScript" %}

```javascript
let nc = NATS.connect({
    url: "nats://demo.nats.io:4222"
});

nc.subscribe('time.>', (msg, reply, subject) => {
    // converting timezones correctly in node requires a library
    // this doesn't take into account *many* things.
    let time = "";
    switch (subject) {
        case 'time.us.east':
            time = new Date().toLocaleTimeString("en-us", {timeZone: "America/New_York"});
            break;
        case 'time.us.central':
            time = new Date().toLocaleTimeString("en-us", {timeZone: "America/Chicago"});
            break;
        case 'time.us.mountain':
            time = new Date().toLocaleTimeString("en-us", {timeZone: "America/Denver"});
            break;
        case 'time.us.west':
            time = new Date().toLocaleTimeString("en-us", {timeZone: "America/Los_Angeles"});
            break;
        default:
            time = "I don't know what you are talking about Willis";
    }
    t.log(subject, time);
});
```

{% endtab %}

{% tab title="Python" %}

```python
nc = NATS()

await nc.connect(servers=["nats://demo.nats.io:4222"])

# Use queue to wait for 4 messages to arrive
queue = asyncio.Queue()
async def cb(msg):
  await queue.put(msg)

await nc.subscribe("time.>", cb=cb)

# Send 2 messages and wait for them to come in
await nc.publish("time.A.east", b'A')
await nc.publish("time.B.east", b'B')
await nc.publish("time.C.west", b'C')
await nc.publish("time.D.west", b'D')

for i in range(0, 4):
  msg = await queue.get()
  print("Msg:", msg)

await nc.close()
```

{% endtab %}

{% tab title="C#" %}

```csharp
// dotnet add package NATS.Net
using NATS.Net;

await using var client = new NatsClient();

var count = 0;
await foreach (var msg in client.SubscribeAsync<string>("time.>"))
{
    Console.WriteLine($"Received {++count}: {msg.Subject}: {msg.Data}");
    
    if (count == 4)
    {
        break;
    }
}

Console.WriteLine("Done");

// Output:
// Received 1: time.us.east: 2024-10-21T22:11:24 America/New_York (-04)
// Received 2: time.us.east.atlanta: 2024-10-21T22:11:24 America/New_York (-04)
// Received 3: time.eu.east: 2024-10-22T04:11:24 Europe/Warsaw (+02)
// Received 4: time.eu.east.warsaw: 2024-10-22T04:11:24 Europe/Warsaw (+02)
// Done
```

{% endtab %}

{% tab title="Ruby" %}

```ruby
require 'nats/client'
require 'fiber'

NATS.start(servers:["nats://127.0.0.1:4222"]) do |nc|
  Fiber.new do
    f = Fiber.current

    nc.subscribe("time.>") do |msg, reply|
      f.resume Time.now.to_f
    end

    nc.publish("time.A.east", "A")
    nc.publish("time.B.east", "B")
    nc.publish("time.C.west", "C")
    nc.publish("time.D.west", "D")

    # Use the response
    4.times do 
      msg = Fiber.yield
      puts "Msg: #{msg}"
    end
  end.resume
end
```

{% endtab %}

{% tab title="TypeScript" %}

```typescript
await nc.subscribe('time.>', (err, msg) => {
    // converting timezones correctly in node requires a library
    // this doesn't take into account *many* things.
    let time = "";
    switch (msg.subject) {
        case 'time.us.east':
            time = new Date().toLocaleTimeString("en-us", {timeZone: "America/New_York"});
            break;
        case 'time.us.central':
            time = new Date().toLocaleTimeString("en-us", {timeZone: "America/Chicago"});
            break;
        case 'time.us.mountain':
            time = new Date().toLocaleTimeString("en-us", {timeZone: "America/Denver"});
            break;
        case 'time.us.west':
            time = new Date().toLocaleTimeString("en-us", {timeZone: "America/Los_Angeles"});
            break;
        default:
            time = "I don't know what you are talking about Willis";
    }
    t.log(msg.subject, time);
});
```

{% endtab %}

{% tab title="C" %}

```c
static void
onMsg(natsConnection *conn, natsSubscription *sub, natsMsg *msg, void *closure)
{
    printf("Received msg: %s - %.*s\n",
           natsMsg_GetSubject(msg),
           natsMsg_GetDataLength(msg),
           natsMsg_GetData(msg));

    // Need to destroy the message!
    natsMsg_Destroy(msg);
}


(...)

natsConnection      *conn = NULL;
natsSubscription    *sub  = NULL;
natsStatus          s;

s = natsConnection_ConnectTo(&conn, NATS_DEFAULT_URL);
if (s == NATS_OK)
    s = natsConnection_Subscribe(&sub, conn, "time.>", onMsg, NULL);

(...)


// Destroy objects that were created
natsSubscription_Destroy(sub);
natsConnection_Destroy(conn);
```

{% endtab %}
{% endtabs %}

The following example can be used to test these two subscribers. The `*` subscriber should receive at most 2 messages, while the `>` subscriber receives 4. More importantly the `time.*.east` subscriber won't receive on `time.us.east.atlanta` because that won't match.

{% tabs %}
{% tab title="Go" %}

```go
nc, err := nats.Connect("demo.nats.io")
if err != nil {
    log.Fatal(err)
}
defer nc.Close()

zoneID, err := time.LoadLocation("America/New_York")
if err != nil {
    log.Fatal(err)
}
now := time.Now()
zoneDateTime := now.In(zoneID)
formatted := zoneDateTime.String()

nc.Publish("time.us.east", []byte(formatted))
nc.Publish("time.us.east.atlanta", []byte(formatted))

zoneID, err = time.LoadLocation("Europe/Warsaw")
if err != nil {
    log.Fatal(err)
}
zoneDateTime = now.In(zoneID)
formatted = zoneDateTime.String()

nc.Publish("time.eu.east", []byte(formatted))
nc.Publish("time.eu.east.warsaw", []byte(formatted))
```

{% endtab %}

{% tab title="Java" %}

```java
Connection nc = Nats.connect("nats://demo.nats.io:4222");
ZoneId zoneId = ZoneId.of("America/New_York");
ZonedDateTime zonedDateTime = ZonedDateTime.ofInstant(Instant.now(), zoneId);
String formatted = zonedDateTime.format(DateTimeFormatter.ISO_ZONED_DATE_TIME);

nc.publish("time.us.east", formatted.getBytes(StandardCharsets.UTF_8));
nc.publish("time.us.east.atlanta", formatted.getBytes(StandardCharsets.UTF_8));

zoneId = ZoneId.of("Europe/Warsaw");
zonedDateTime = ZonedDateTime.ofInstant(Instant.now(), zoneId);
formatted = zonedDateTime.format(DateTimeFormatter.ISO_ZONED_DATE_TIME);
nc.publish("time.eu.east", formatted.getBytes(StandardCharsets.UTF_8));
nc.publish("time.eu.east.warsaw", formatted.getBytes(StandardCharsets.UTF_8));

nc.flush(Duration.ZERO);
nc.close();
```

{% endtab %}

{% tab title="JavaScript" %}

```javascript
nc.publish('time.us.east');
nc.publish('time.us.central');
nc.publish('time.us.mountain');
nc.publish('time.us.west');
```

{% endtab %}

{% tab title="Python" %}

```python
nc = NATS()

await nc.connect(servers=["nats://demo.nats.io:4222"])

await nc.publish("time.us.east", b'...')
await nc.publish("time.us.east.atlanta", b'...')

await nc.publish("time.eu.east", b'...')
await nc.publish("time.eu.east.warsaw", b'...')

await nc.close()
```

{% endtab %}

{% tab title="C#" %}

```csharp
// dotnet add package NATS.Net
// dotnet add package NodaTime
using NATS.Net;
using NodaTime;

await using var client = new NatsClient();

Instant now = SystemClock.Instance.GetCurrentInstant();

{
    DateTimeZone zone = DateTimeZoneProviders.Tzdb["America/New_York"];
    string formatted = now.InZone(zone).ToString();
    await client.PublishAsync("time.us.east", formatted);
    await client.PublishAsync("time.us.east.atlanta", formatted);
}

{
    DateTimeZone zone = DateTimeZoneProviders.Tzdb["Europe/Warsaw"];
    string formatted = now.InZone(zone).ToString();
    await client.PublishAsync("time.eu.east", formatted);
    await client.PublishAsync("time.eu.east.warsaw", formatted);
}
```

{% endtab %}

{% tab title="Ruby" %}

```ruby
NATS.start do |nc|
   nc.publish("time.us.east", '...')
   nc.publish("time.us.east.atlanta", '...')

   nc.publish("time.eu.east", '...')
   nc.publish("time.eu.east.warsaw", '...')

   nc.drain
end
```

{% endtab %}

{% tab title="TypeScript" %}

```typescript
nc.publish('time.us.east');
nc.publish('time.us.central');
nc.publish('time.us.mountain');
nc.publish('time.us.west');
```

{% endtab %}
{% endtabs %}


---

# Agent Instructions: 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://docs.nats.io/using-nats/developer/receiving/wildcards.md?ask=<question>
```

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.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.