Modify SSE config for server:

- rename to Kotlin style guide
- remove NPE
- manage paths clearly

Author: Mr3zee

src/main/kotlin/io/modelcontextprotocol/kotlin/sdk/server/McpKtorServerPlugin.kt

@@ -10,45 +10,57 @@ import io.ktor.util.collections.*
 
 private val logger = KotlinLogging.logger {}
 
+public val Mcp: ApplicationPlugin<Unit> = createApplicationPlugin("Mcp") {
+    application.install(SSE)
+}
+
+public fun Routing.mcp(path: String, block: () -> Server) {
+    route(path) {
+        mcp(block)
+    }
+}
+
 /**
  * Configures the Ktor Application to handle Model Context Protocol (MCP) over Server-Sent Events (SSE).
  */
-public fun Application.MCP(block: () -> Server) {
+public fun Routing.mcp(block: () -> Server) {
     val servers = ConcurrentMap<String, Server>()
 
-    install(SSE)
-    routing {
-        sse("/sse") {
-            val transport = SSEServerTransport("/message", this)
-            logger.info { "New SSE connection established with sessionId: ${transport.sessionId}" }
+    sse {
+        val transport = SSEServerTransport("", this) // same endpoint
+        logger.info { "New SSE connection established with sessionId: ${transport.sessionId}" }
 
-            val server = block()
+        val server = block()
 
-            servers[transport.sessionId] = server
-            logger.debug { "Server instance created and stored for sessionId: ${transport.sessionId}" }
+        servers[transport.sessionId] = server
+        logger.debug { "Server instance created and stored for sessionId: ${transport.sessionId}" }
 
-            server.onCloseCallback = {
-                logger.info { "Server connection closed for sessionId: ${transport.sessionId}" }
-                servers.remove(transport.sessionId)
-            }
-
-            server.connect(transport)
-            logger.debug { "Server connected to transport for sessionId: ${transport.sessionId}" }
+        server.onCloseCallback = {
+            logger.info { "Server connection closed for sessionId: ${transport.sessionId}" }
+            servers.remove(transport.sessionId)
         }
 
-        post("/message") {
-            val sessionId: String = call.request.queryParameters["sessionId"]!!
-            logger.debug { "Received message for sessionId: $sessionId" }
+        server.connect(transport)
+        logger.debug { "Server connected to transport for sessionId: ${transport.sessionId}" }
+    }
 
-            val transport = servers[sessionId]?.transport as? SSEServerTransport
-            if (transport == null) {
-                logger.warn { "Session not found for sessionId: $sessionId" }
-                call.respond(HttpStatusCode.NotFound, "Session not found")
+    post {
+        val sessionId: String = call.request.queryParameters["sessionId"]
+            ?: run {
+                call.respond(HttpStatusCode.BadRequest, "sessionId query parameter is not provided")
                 return@post
             }
 
-            transport.handlePostMessage(call)
-            logger.trace { "Message handled for sessionId: $sessionId" }
+        logger.debug { "Received message for sessionId: $sessionId" }
+
+        val transport = servers[sessionId]?.transport as? SSEServerTransport
+        if (transport == null) {
+            logger.warn { "Session not found for sessionId: $sessionId" }
+            call.respond(HttpStatusCode.NotFound, "Session not found")
+            return@post
         }
+
+        transport.handlePostMessage(call)
+        logger.trace { "Message handled for sessionId: $sessionId" }
     }
 }