add structures for kafka

@@ -23,3 +23,125 @@
 
 #include <srs_kafka_stack.hpp>
 
+using namespace std;
+
+SrsKafkaString::SrsKafkaString()
+{
+    size = -1;
+    data = NULL;
+}
+
+SrsKafkaString::~SrsKafkaString()
+{
+    srs_freep(data);
+}
+
+bool SrsKafkaString::null()
+{
+    return size == -1;
+}
+
+bool SrsKafkaString::empty()
+{
+    return size <= 0;
+}
+
+int SrsKafkaString::total_size()
+{
+    return 2 + (size == -1? 0 : size);
+}
+
+SrsKafkaBytes::SrsKafkaBytes()
+{
+    size = -1;
+    data = NULL;
+}
+
+SrsKafkaBytes::~SrsKafkaBytes()
+{
+    srs_freep(data);
+}
+
+bool SrsKafkaBytes::null()
+{
+    return size == -1;
+}
+
+bool SrsKafkaBytes::empty()
+{
+    return size <= 0;
+}
+
+int SrsKafkaBytes::total_size()
+{
+    return 4 + (size == -1? 0 : size);
+}
+
+SrsKafkaRequestHeader::SrsKafkaRequestHeader()
+{
+    size = 0;
+    api_key = api_version = 0;
+    correlation_id = 0;
+    client_id = new SrsKafkaString();
+}
+
+SrsKafkaRequestHeader::~SrsKafkaRequestHeader()
+{
+    srs_freep(client_id);
+}
+
+int SrsKafkaRequestHeader::header_size()
+{
+    return 2 + 2 + 4 + client_id->total_size();
+}
+
+int SrsKafkaRequestHeader::message_size()
+{
+    return size - header_size();
+}
+
+int SrsKafkaRequestHeader::total_size()
+{
+    return 4 + size;
+}
+
+SrsKafkaResponse::SrsKafkaResponse()
+{
+    correlation_id = 0;
+}
+
+SrsKafkaResponse::~SrsKafkaResponse()
+{
+}
+
+SrsKafkaMessage::SrsKafkaMessage()
+{
+    offset = 0;
+    message_size = 0;
+    
+    crc = 0;
+    magic_byte = attributes = 0;
+    key = new SrsKafkaBytes();
+    value = new SrsKafkaBytes();
+}
+
+SrsKafkaMessage::~SrsKafkaMessage()
+{
+    srs_freep(key);
+    srs_freep(value);
+}
+
+SrsKafkaMessageSet::SrsKafkaMessageSet()
+{
+}
+
+SrsKafkaMessageSet::~SrsKafkaMessageSet()
+{
+    vector<SrsKafkaMessage*>::iterator it;
+    for (it = messages.begin(); it != messages.end(); ++it) {
+        SrsKafkaMessage* message = *it;
+        srs_freep(message);
+    }
+    messages.clear();
+}
+

@@ -29,5 +29,212 @@
 */
 #include <srs_core.hpp>
 
+#include <vector>
+
+/**
+ * These types consist of a signed integer giving a length N followed by N bytes of content. 
+ * A length of -1 indicates null. string uses an int16 for its size, and bytes uses an int32.
+ * @see https://cwiki.apache.org/confluence/display/KAFKA/A+Guide+To+The+Kafka+Protocol#AGuideToTheKafkaProtocol-ProtocolPrimitiveTypes
+ */
+class SrsKafkaString
+{
+private:
+    int16_t size;
+    char* data;
+public:
+    SrsKafkaString();
+    virtual ~SrsKafkaString();
+public:
+    virtual bool null();
+    virtual bool empty();
+    virtual int total_size();
+};
+
+/**
+ * These types consist of a signed integer giving a length N followed by N bytes of content.
+ * A length of -1 indicates null. string uses an int16 for its size, and bytes uses an int32.
+ * @see https://cwiki.apache.org/confluence/display/KAFKA/A+Guide+To+The+Kafka+Protocol#AGuideToTheKafkaProtocol-ProtocolPrimitiveTypes
+ */
+class SrsKafkaBytes
+{
+private:
+    int32_t size;
+    char* data;
+public:
+    SrsKafkaBytes();
+    virtual ~SrsKafkaBytes();
+public:
+    virtual bool null();
+    virtual bool empty();
+    virtual int total_size();
+};
+
+/**
+ * the header of request, includes the size of request.
+ * @see https://cwiki.apache.org/confluence/display/KAFKA/A+Guide+To+The+Kafka+Protocol#AGuideToTheKafkaProtocol-Requests
+ */
+class SrsKafkaRequestHeader
+{
+private:
+    /**
+     * The MessageSize field gives the size of the subsequent request or response
+     * message in bytes. The client can read requests by first reading this 4 byte
+     * size as an integer N, and then reading and parsing the subsequent N bytes
+     * of the request.
+     */
+    int32_t size;
+private:
+    /**
+     * This is a numeric id for the API being invoked (i.e. is it 
+     * a metadata request, a produce request, a fetch request, etc).
+     * @remark MetadataRequest | ProduceRequest | FetchRequest | OffsetRequest | OffsetCommitRequest | OffsetFetchRequest
+     */
+    int16_t api_key;
+    /**
+     * This is a numeric version number for this api. We version each API and 
+     * this version number allows the server to properly interpret the request 
+     * as the protocol evolves. Responses will always be in the format corresponding 
+     * to the request version. Currently the supported version for all APIs is 0.
+     */
+    int16_t api_version;
+    /**
+     * This is a user-supplied integer. It will be passed back in
+     * the response by the server, unmodified. It is useful for matching
+     * request and response between the client and server.
+     */
+    int32_t correlation_id;
+    /**
+     * This is a user supplied identifier for the client application. 
+     * The user can use any identifier they like and it will be used
+     * when logging errors, monitoring aggregates, etc. For example,
+     * one might want to monitor not just the requests per second overall,
+     * but the number coming from each client application (each of
+     * which could reside on multiple servers). This id acts as a
+     * logical grouping across all requests from a particular client.
+     */
+    SrsKafkaString* client_id;
+public:
+    SrsKafkaRequestHeader();
+    virtual ~SrsKafkaRequestHeader();
+public:
+    /**
+     * the size of header, exclude the 4bytes size.
+     * @remark total_size = 4 + header_size + message_size.
+     */
+    virtual int header_size();
+    /**
+     * the size of message, the left bytes left after the header.
+     * @remark total_size = 4 + header_size + message_size.
+     */
+    virtual int message_size();
+    /**
+     * the total size of the request, 4bytes + size of header and message.
+     * @remark total_size = 4 + header_size + message_size.
+     */
+    virtual int total_size();
+};
+
+/**
+ * the common kafka response.
+ * The response will always match the paired request (e.g. we will 
+ * send a MetadataResponse in return to a MetadataRequest).
+ * @see https://cwiki.apache.org/confluence/display/KAFKA/A+Guide+To+The+Kafka+Protocol#AGuideToTheKafkaProtocol-Responses
+ */
+class SrsKafkaResponse
+{
+protected:
+    /**
+     * The server passes back whatever integer the client supplied as the correlation in the request.
+     */
+    int32_t correlation_id;
+public:
+    SrsKafkaResponse();
+    virtual ~SrsKafkaResponse();
+};
+
+/**
+ * the kafka message in message set.
+ * @see https://cwiki.apache.org/confluence/display/KAFKA/A+Guide+To+The+Kafka+Protocol#AGuideToTheKafkaProtocol-Messagesets
+ */
+struct SrsKafkaMessage
+{
+// metadata.
+public:
+    /**
+     * This is the offset used in kafka as the log sequence number. When the
+     * producer is sending messages it doesn't actually know the offset and
+     * can fill in any value here it likes.
+     */
+    int64_t offset;
+    /**
+     * the size of this message.
+     */
+    int32_t message_size;
+// message.
+public:
+    /**
+     * The CRC is the CRC32 of the remainder of the message bytes. 
+     * This is used to check the integrity of the message on the broker and consumer.
+     */
+    int32_t crc;
+    /**
+     * This is a version id used to allow backwards compatible evolution 
+     * of the message binary format. The current value is 0.
+     */
+    int8_t magic_byte;
+    /**
+     * This byte holds metadata attributes about the message.
+     * The lowest 2 bits contain the compression codec used
+     * for the message. The other bits should be set to 0.
+     */
+    int8_t attributes;
+    /**
+     * The key is an optional message key that was used for 
+     * partition assignment. The key can be null.
+     */
+    SrsKafkaBytes* key;
+    /**
+     * The value is the actual message contents as an opaque byte array.
+     * Kafka supports recursive messages in which case this may itself
+     * contain a message set. The message can be null.
+     */
+    SrsKafkaBytes* value;
+public:
+    SrsKafkaMessage();
+    virtual ~SrsKafkaMessage();
+};
+
+/**
+ * a set of kafka message.
+ * @see https://cwiki.apache.org/confluence/display/KAFKA/A+Guide+To+The+Kafka+Protocol#AGuideToTheKafkaProtocol-Messagesets
+ */
+class SrsKafkaMessageSet
+{
+private:
+    std::vector<SrsKafkaMessage*> messages;
+public:
+    SrsKafkaMessageSet();
+    virtual ~SrsKafkaMessageSet();
+};
+
+/**
+ * request the metadata from broker.
+ * This API answers the following questions:
+ *      What topics exist?
+ *      How many partitions does each topic have?
+ *      Which broker is currently the leader for each partition?
+ *      What is the host and port for each of these brokers?
+ * This is the only request that can be addressed to any broker in the cluster.
+ *
+ * Since there may be many topics the client can give an optional list of topic 
+ * names in order to only return metadata for a subset of topics.
+ *
+ * @see https://cwiki.apache.org/confluence/display/KAFKA/A+Guide+To+The+Kafka+Protocol#AGuideToTheKafkaProtocol-MetadataAPI
+ */
+class SrsKafkaTopicMetadataRequest
+{
+public:
+};
+
 #endif