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 # Class simulation\_framework::core::Topic

 Last update: 22.04.2026 

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**Definition**: `core/communication/topic.h` (line 38)

This is the concrete [Topic](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic) class that can be used for creation of a communication channel with given underlying message. As default type, DDS type will be applied. TopicId is globally unique and represents one single [Topic](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic). Different Topics can hold same underlying message type but they are different topics for communication.

Example:

```cpp
Topic<GenericBytesMessage> osi_topic_1("topic_1");
Topic<GenericBytesMessage> osi_topic_2("topic_2");

```

**Template parameters**:

- [typename](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic) [TopicMsgType](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic)

**Inherits from**:

- [simulation\_framework::core::ITopic](classsimulation__framework_1_1core_1_1ITopic.md#classsimulation__framework_1_1core_1_1ITopic)

## Members

- [AddPublisher](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic_1a9a3bdb1cc0fb2b885fbe528903abcb14)
- [AddSubscriber](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic_1a33882d851ffa66f8db5a83813969e48a)
- [ClearPubSub](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic_1ac366c5dd53e4c5770b1a5f40ae2c8956)
- [GetId](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic_1a6cef83adabcaab8aabd20cd3184dca3c)
- [GetPublishers](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic_1ac31691f84f68ad4a3aeda6074739676f)
- [GetSubscribers](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic_1ab0a3ea471d469cf2b0611b6548752298)
- [GetType](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic_1a6f459336816bf96dd43d4a827043485d)
- [PublisherCallback](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic_1a0f29e64e5b4720391091e07f6250e20a)
- [PublisherCount](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic_1a9056b30c90efc165ee8559b41e8a9064)
- [SubscriberCount](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic_1a71ce3df423a48cbc555cf9fb322726df)
- [SubscriberMessageCallback](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic_1a2c04396e41962b68a36c63f8a3c215f1)
- [Topic](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic_1a9ff71b7b23ec021c0f39891008c45e22)
- [TopicMessageType](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic_1aa28465d4f009835110d723ee902d17b4)
- [~ITopic](classsimulation__framework_1_1core_1_1ITopic.md#classsimulation__framework_1_1core_1_1ITopic_1ac3d4c1cecd1a0c394f8b5a308a0439b5)

## Public types

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### Typedef PublisherCallback

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**Definition**: `core/communication/topic.h` (line 41)

```cpp
using simulation_framework::core::Topic< TopicMsgType >::PublisherCallback =  std::function<TopicMsgType()>

```

**Return type**: std::function&lt; [TopicMsgType](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic)()&gt;

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### Typedef SubscriberMessageCallback

![](https://img.shields.io/badge/-public-brightgreen "public")

**Definition**: `core/communication/topic.h` (line 42)

```cpp
using simulation_framework::core::Topic< TopicMsgType >::SubscriberMessageCallback =  std::function<void(const TopicMsgType&)>

```

**Return type**: std::function&lt; [void](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic)([const](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic) [TopicMsgType](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic) &amp;)&gt;

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### Typedef TopicMessageType

![](https://img.shields.io/badge/-public-brightgreen "public")

**Definition**: `core/communication/topic.h` (line 43)

```cpp
using simulation_framework::core::Topic< TopicMsgType >::TopicMessageType =  TopicMsgType

```

**Return type**: [TopicMsgType](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic)

## Public functions

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### Function Topic

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```cpp
simulation_framework::core::Topic< TopicMsgType >::Topic(const TopicId &topic_id, const TopicType topic_type=TopicType::kRTIDDS)

```

**Parameters**:

- [const](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic) TopicId &amp; **topic\_id**
- [const](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic) TopicType **topic\_type** = TopicType::kRTIDDS

**Return type**:

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### Function GetId

![](https://img.shields.io/badge/-public-brightgreen "public")![](https://img.shields.io/badge/-const-lightblue "const")

```cpp
TopicId simulation_framework::core::Topic< TopicMsgType >::GetId() const override

```

**Returns**:

A unique ID of this topic

**Return type**: TopicId

**Reimplements**: [GetId](classsimulation__framework_1_1core_1_1ITopic.md#classsimulation__framework_1_1core_1_1ITopic_1ad4e077cd059e9c6f0ce9ad0df73ca3cd)

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### Function GetType

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```cpp
TopicType simulation_framework::core::Topic< TopicMsgType >::GetType() const override

```

**Returns**:

The type of this topic

**Return type**: TopicType

**Reimplements**: [GetType](classsimulation__framework_1_1core_1_1ITopic.md#classsimulation__framework_1_1core_1_1ITopic_1a461f8684a1e5190affbe69253f74fdb7)

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### Function AddPublisher

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```cpp
void simulation_framework::core::Topic< TopicMsgType >::AddPublisher(std::unique_ptr< IPublisher > pub_ptr) override

```

Add one publisher of this [Topic](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic). The max publisher count of a topic is limited to be one.

**Parameters**:

- **pub\_ptr**: The abstraction of publisher interface

**Parameters**:

- std::unique\_ptr&lt; IPublisher &gt; **pub\_ptr**

**Return type**: [void](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic)

**Reimplements**: [AddPublisher](classsimulation__framework_1_1core_1_1ITopic.md#classsimulation__framework_1_1core_1_1ITopic_1aadab7c49ae9beaa036d3fa9845aed85d)

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### Function AddSubscriber

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```cpp
void simulation_framework::core::Topic< TopicMsgType >::AddSubscriber(std::unique_ptr< ISubscriber > sub_ptr) override

```

Add one subscriber to this [Topic](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic)

**Parameters**:

- **sub\_ptr**: The abstraction of subscriber interface

**Parameters**:

- std::unique\_ptr&lt; ISubscriber &gt; **sub\_ptr**

**Return type**: [void](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic)

**Reimplements**: [AddSubscriber](classsimulation__framework_1_1core_1_1ITopic.md#classsimulation__framework_1_1core_1_1ITopic_1a612d64a1aca7a60a8efc7f07f4d28311)

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### Function SubscriberCount

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```cpp
std::size_t simulation_framework::core::Topic< TopicMsgType >::SubscriberCount() const override

```

**Returns**:

The number of subscriber which is listening to this topic

**Return type**: std::size\_t

**Reimplements**: [SubscriberCount](classsimulation__framework_1_1core_1_1ITopic.md#classsimulation__framework_1_1core_1_1ITopic_1a370ff9b0059ea1c200e6a5384671aac8)

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### Function PublisherCount

![](https://img.shields.io/badge/-public-brightgreen "public")![](https://img.shields.io/badge/-const-lightblue "const")

```cpp
std::size_t simulation_framework::core::Topic< TopicMsgType >::PublisherCount() const override

```

**Returns**:

The number of publisher which publishes message into this [Topic](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic). The max publisher count of a topic is limited to be one.

**Return type**: std::size\_t

**Reimplements**: [PublisherCount](classsimulation__framework_1_1core_1_1ITopic.md#classsimulation__framework_1_1core_1_1ITopic_1a469c0e1f5fd07f9829e93fd8a43bd6f7)

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### Function ClearPubSub

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```cpp
void simulation_framework::core::Topic< TopicMsgType >::ClearPubSub() override

```

Remove all publisher and subscriber which are asociated with this [Topic](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic)

**Return type**: [void](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic)

**Reimplements**: [ClearPubSub](classsimulation__framework_1_1core_1_1ITopic.md#classsimulation__framework_1_1core_1_1ITopic_1a470392793ee8cb2fc406b8b1e1b55d2d)

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### Function GetSubscribers

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```cpp
const Subscribers & simulation_framework::core::Topic< TopicMsgType >::GetSubscribers() const override

```

**Returns**:

The list of assigned subscriber which are listening to this [Topic](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic)

**Return type**: [const](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic) Subscribers &amp;

**Reimplements**: [GetSubscribers](classsimulation__framework_1_1core_1_1ITopic.md#classsimulation__framework_1_1core_1_1ITopic_1a52c9a4a95089eb1dfbc0606974d9a8d0)

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### Function GetPublishers

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```cpp
const Publishers & simulation_framework::core::Topic< TopicMsgType >::GetPublishers() const override

```

**Returns**:

The list of assigned publisher which are publishing message to this [Topic](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic)

**Return type**: [const](classsimulation__framework_1_1core_1_1Topic.md#classsimulation__framework_1_1core_1_1Topic) Publishers &amp;

**Reimplements**: [GetPublishers](classsimulation__framework_1_1core_1_1ITopic.md#classsimulation__framework_1_1core_1_1ITopic_1aa02ef4f55132426e2af9de01bde3bf4b)