/// <summary>
/// Create a new topic with the specified name and add it to the collection of active topics
/// </summary>
/// <param name="name">The desired name of the new topic</param>
/// <returns>The name and assigned unique ID of the new topic</returns>
protected NameIdPair CreateTopic(string name)
{
Guid id = Guid.NewGuid();
NameIdPair topicInfo = new NameIdPair(name, id);
topics[id] = new Topic(topicInfo);
return(topicInfo);
}
/// <summary>
/// Process a request received from the client and take action based on the request type
/// </summary>
/// <param name="request">The received request to process</param>
/// <returns>An appropriate response to the client's request</returns>
protected Response ProcessRequest(Request request)
{
Response response = new InfoResponse("Error: Unknown request");
if (request.Type == RequestType.CREATE_TOPIC)
{
// Create a new topic and send back the created topic's name and assigned unique ID
NameIdPair topicInfo = CreateTopic((request as CreateTopicRequest).TopicName);
response = new TopicCreatedResponse(topicInfo);
}
else if (request.Type == RequestType.LIST_TOPICS)
{
// Send back a list of active topics (without the topics' subscriber lists)
response = new ListTopicsResponse(GetClientTopicList());
}
else if (request.Type == RequestType.PUBLISH)
{
// Try to publish the received message
Message <string> message = (request as PublishRequest <string>).Message;
if (PublishMessage(message))
{
response = new InfoResponse("Message published to topic \"" + message.TopicInfo.Name + "\"");
}
else
{
// Send back an error message if the request was for a nonexistent topic
response = new InfoResponse("Message could not be published (Topic \"" + message.TopicInfo.Name + "\" does not exist)");
}
}
else if (request.Type == RequestType.SUBSCRIBE)
{
// Try to subscribe the client to the requested topic
if (Subscribe(request as SubscribeRequest))
{
response = new InfoResponse("Subscription added");
}
else
{
// Send back an error message if the request was for a nonexistent topic
response = new InfoResponse("Unable to add subscription (Topic does not exist)");
}
}
else if (request.Type == RequestType.UNSUBSCRIBE)
{
// Try to unsubscribe the client from the requested topic
if (Unsubscribe(request as UnsubscribeRequest))
{
response = new InfoResponse("Subscription removed");
}
else
{
// Send back an error message if the subscription couldn't be removed
response = new InfoResponse("Unable to remove subscription (Subscription may not exist)");
}
}
return(response);
}
/// <summary>
/// Construct a new publish request to publish the provided message to the specified topic
/// </summary>
/// <param name="topicInfo">The name and unique ID of the topic to publish to</param>
/// <param name="messageContent">The content of the message to publish</param>
/// <returns>A new publish request to publish the provided message to the specified topic</returns>
public PublishRequest <T> MakePublishRequest <T>(NameIdPair topicInfo, T messageContent)
{
Message <T> message = new Message <T>
{
Timestamp = DateTime.UtcNow,
PublisherInfo = new NameIdPair(Name, ID),
TopicInfo = topicInfo,
Content = messageContent
};
return(new PublishRequest <T>(message));
}
/// <summary>
/// Process a response received from the server and take action based on the response type
/// </summary>
/// <param name="response">The received response to process</param>
protected void ProcessResponse(Response response)
{
if (waitingForResponse)
{
// Handle responses to previous client requests
if (response.Type == ResponseType.TOPIC_CREATED)
{
// Add the new topic to the list of owned topics
NameIdPair topicInfo = (response as TopicCreatedResponse).TopicInfo;
OwnedTopics.Add(topicInfo);
Console.WriteLine("[Topic \"{0}\" has been created]", topicInfo.Name);
}
else if (response.Type == ResponseType.INFO)
{
// Show received information response
Console.WriteLine("[Info] {0}", (response as InfoResponse).Text);
}
waitingForResponse = false;
}
}
/// <summary>
/// Construct an UnsubscribeRequest for the specified topic
/// </summary>
/// <param name="subscriber">The name and ID of the subscriber client</param>
/// <param name="topicId">The ID of the topic to unsubscribe from</param>
public UnsubscribeRequest(NameIdPair subscriber, Guid topicId)
{
Type = RequestType.UNSUBSCRIBE;
Subscriber = subscriber;
TopicID = topicId;
}
/// <summary>
/// Construct a TopicCreatedResponse with the new topic's information
/// </summary>
/// <param name="topicInfo">The name and assigned unique ID of the created topic</param>
public TopicCreatedResponse(NameIdPair topicInfo)
{
Type = ResponseType.TOPIC_CREATED;
TopicInfo = topicInfo;
}
/// <summary>
/// Constructor to initialize a new topic and create its subscriber list
/// </summary>
public Topic(NameIdPair info)
{
Info = info;
Subscribers = new ConcurrentDictionary <Guid, string>();
}