Update Seaweed-Message-Queue.md

Seaweed-Message-Queue.md

@@ -1,15 +1,21 @@
 # Introduction
 
-Seaweed Message Queue has 
+Seaweed Message Queue (SMQ) is a distributed messaging system built on top of SeaweedFS. It provides:
+
 * Structured message : all messages need to have a schema
 * Streamed publishing with async acknowledgements
-* Messages are stored in Parquet files, for both streaming and batch reading.
-* Unlimited storage.
-* Scalable stateless message brokers.
+* Messages are stored in Parquet files, for both streaming and batch reading
+* Disaggregated storage
+* Scalable stateless message brokers
 
 # Architecture
 
-The structured messages are published to message brokers, persisted in SeaweedFS, and consumed by message subscribers. To simplify client libraries, a messaging agent with gRPC APIs is introduced, enabling easier client libraries for message publishing and subscribing.
+The system consists of three main components:
+
+1. **Message Queue Agent**: A gRPC server that provides a simplified interface for clients
+2. **Message Queue Brokers**: Stateless brokers that handle message routing and storage
+3. **SeaweedFS**: The underlying storage system that persists messages in Parquet format
+
 ```
   Publishers => gRPC Publish APIs => Agent => Brokers => Agent => gRPC Subscribe APIs => Subscribers
                                                  ^
@@ -21,15 +27,132 @@ The structured messages are published to message brokers, persisted in SeaweedFS
 The Agent can be run either on the server side, or as a sidecar on each client.
 
 # Features
-* Structured Messages: SeaweedFS is used to store unstructured data files, while Seaweed Message Queue is used to store structured messages.
-* Messages stored in SeaweedFS can be converted into Parquet files, saving disk space with more efficient columnar compression. 
-* The messages in Parquet files can be streamed via Seaweed messaging brokers.
-* The Parquet files can be read in batches directly from SeaweedFS.
 
-## Features on Publishing
-* Messages published successfully are acknowledged asynchronously.
+## Core Features
+* Structured Messages: SeaweedFS is used to store unstructured data files, while Seaweed Message Queue is used to store structured messages
+* Messages stored in SeaweedFS can be converted into Parquet files, saving disk space with more efficient columnar compression
+* The messages in Parquet files can be streamed via Seaweed messaging brokers
+* The Parquet files can be read in batches directly from SeaweedFS
 
-## Features on Subscribing
-* Message consume offsets are tracked and persisted.
-* Consumer APIs can process messages in multiple threads while still ensuring serial processing of messages with the same key.
+## Publishing Features
+* Messages published successfully are acknowledged asynchronously
+* Partition-based message routing
+* Schema validation for message structure
+
+## Subscribing Features
+* Message consume offsets are tracked and persisted on the server side
+* Consumer APIs can process messages in parallel while still ensuring serial processing of messages with the same key
+* Configurable sliding window for concurrent message processing
+* Ability to start consuming from specific timestamps or offsets
+
+# Usage Examples
+
+## Starting the Services
+
+1. Start a Message Queue Broker:
+```bash
+weed mq.broker -port=17777 -master=localhost:9333
+```
+
+2. Start a Message Queue Agent:
+```bash
+weed mq.agent -port=16777 -broker=localhost:17777
+```
+
+## Defining Message Schema
+
+Messages in SMQ must have a defined schema. Here's an example of defining a message type:
+
+```go
+type MyRecord struct {
+    Key    []byte
+    Field1 []byte
+    Field2 string
+    Field3 int32
+    Field4 int64
+    Field5 float32
+    Field6 float64
+    Field7 bool
+}
+
+func MyRecordType() *schema_pb.RecordType {
+    return schema.RecordTypeBegin().
+        WithField("key", schema.TypeBytes).
+        WithField("field1", schema.TypeBytes).
+        WithField("field2", schema.TypeString).
+        WithField("field3", schema.TypeInt32).
+        WithField("field4", schema.TypeInt64).
+        WithField("field5", schema.TypeFloat).
+        WithField("field6", schema.TypeDouble).
+        WithField("field7", schema.TypeBoolean).
+        RecordTypeEnd()
+}
+```
+
+## Publishing Messages
+
+```go
+// Create a publish session
+session, err := agent_client.NewPublishSession(
+    "localhost:16777",  // agent address
+    schema.NewSchema("my_namespace", "my_topic", MyRecordType()),
+    6,                  // partition count
+    "publisher1",       // client name
+)
+
+// Publish a message
+myRecord := &MyRecord{
+    Key:    []byte("key1"),
+    Field1: []byte("value1"),
+    Field2: "string value",
+    Field3: 123,
+    Field4: 456,
+    Field5: 1.23,
+    Field6: 4.56,
+    Field7: true,
+}
+
+err := session.PublishMessageRecord(myRecord.Key, myRecord.ToRecordValue())
+```
+
+## Subscribing to Messages
+
+```go
+// Create a subscribe session
+session, err := agent_client.NewSubscribeSession(
+    "localhost:16777",  // agent address
+    &agent_client.SubscribeOption{
+        ConsumerGroup:           "my-group",
+        ConsumerGroupInstanceId: "consumer1",
+        Topic:                   topic.NewTopic("my_namespace", "topmy_topicic"),
+        OffsetType:              schema_pb.OffsetType_RESUME_OR_EARLIEST,
+        MaxSubscribedPartitions: 3,  // maximum number of partitions this consumer instance can subscribe
+        SlidingWindowSize:       16, // concurrently process up-to 16 messages with different message key
+    },
+)
+
+// Subscribe to messages
+session.SubscribeMessageRecord(
+    func(key []byte, recordValue *schema_pb.RecordValue) {
+        record := FromRecordValue(recordValue)
+        fmt.Printf("Received: %+v\n", record)
+    },
+    func() {
+        fmt.Println("Subscription completed")
+    },
+)
+```
+
+# Configuration
+
+## Broker Configuration
+* `-port`: gRPC server port (default: 17777)
+* `-master`: comma-separated master servers
+* `-filerGroup`: share metadata with other filers in the same group
+* `-dataCenter`: prefer volumes in this data center
+* `-rack`: prefer volumes in this rack
+
+## Agent Configuration
+* `-port`: gRPC server port (default: 16777)
+* `-broker`: comma-separated message queue brokers