diff --git a/samples/README.md b/samples/README.md index f831a74b..187402c7 100644 --- a/samples/README.md +++ b/samples/README.md @@ -13,6 +13,7 @@ For background on the protocol itself, see the [MCP documentation](https://model | [kotlin-mcp-server](./kotlin-mcp-server) | Server | STDIO, SSE | Tools, Resources, Prompts | | [weather-stdio-server](./weather-stdio-server) | Server | STDIO | Tools | | [kotlin-mcp-client](./kotlin-mcp-client) | Client | STDIO | Tool discovery & invocation | +| [roots-demo](./roots-demo) | Client + Server | In-memory | Roots | | [notebooks](./notebooks) | Client (Notebook) | Streamable HTTP | Tool discovery & invocation | ## Getting Started @@ -56,6 +57,12 @@ An interactive CLI client that connects to any MCP server over STDIO and routes Anthropic's Claude API, bridging MCP tools with LLM conversations. [Read more →](./kotlin-mcp-client) +### Roots Demo + +A minimal in-memory sample demonstrating the MCP Roots capability — how a client exposes +filesystem roots to a server, and how the server reacts when the root list changes. +[Read more →](./roots-demo) + ### MCP Client Notebook A Kotlin notebook that connects to a remote MCP server via Streamable HTTP and demonstrates ping, diff --git a/samples/roots-demo/README.md b/samples/roots-demo/README.md new file mode 100644 index 00000000..46f72ee7 --- /dev/null +++ b/samples/roots-demo/README.md @@ -0,0 +1,54 @@ +# Roots Demo + +A minimal sample demonstrating the MCP **Roots** capability using in-memory +[ChannelTransport](../../kotlin-sdk-testing/src/commonMain/kotlin/io/modelcontextprotocol/kotlin/sdk/testing/ChannelTransport.kt). + +## Overview + +[Roots](https://modelcontextprotocol.io/docs/concepts/roots) allow an MCP client to +expose filesystem locations to a server. The server can request the list of roots and +receive notifications when that list changes. + +This sample shows the full roots lifecycle: + +1. **Client declares roots capability** — the client advertises `roots` with + `listChanged = true` during initialization. +2. **Client registers roots** — `addRoot(uri, name)` adds roots that the server can + discover. +3. **Server queries roots** — `serverSession.listRoots()` sends a `roots/list` + request to the client. +4. **Client sends change notification** — after dynamically adding or removing roots, + the client calls `sendRootsListChanged()` so the server knows to re-fetch. +5. **Server reacts to changes** — the server listens for + `notifications/roots/list_changed` and re-queries the updated root list. + +## Prerequisites + +- JDK 17+ + +## Build & Run + +```shell +./gradlew run +``` + +The program connects a client and server in-process using `ChannelTransport` and +prints the roots exchange to the console. No external server or network is required. + +## MCP Capabilities + +### Client + +| Capability | Details | +|-----------|---------| +| `roots` | Advertised with `listChanged = true`. Registers project directories and notifies the server on changes. | + +### Server + +Demonstrates consuming the roots capability by calling `listRoots()` and listening for +`notifications/roots/list_changed`. + +## Additional Resources + +- [MCP Roots Specification](https://modelcontextprotocol.io/docs/concepts/roots) +- [Kotlin MCP SDK](https://github.com/modelcontextprotocol/kotlin-sdk) \ No newline at end of file diff --git a/samples/roots-demo/build.gradle.kts b/samples/roots-demo/build.gradle.kts new file mode 100644 index 00000000..f0342f86 --- /dev/null +++ b/samples/roots-demo/build.gradle.kts @@ -0,0 +1,27 @@ +plugins { + alias(libs.plugins.kotlin.jvm) + alias(libs.plugins.shadow) + application +} + +group = "org.example" +version = "0.1.0" + +application { + mainClass.set("io.modelcontextprotocol.sample.roots.MainKt") +} + +dependencies { + implementation(libs.mcp.kotlin.client) + implementation(libs.mcp.kotlin.server) + implementation(libs.mcp.kotlin.testing) + implementation(libs.slf4j.simple) +} + +tasks.test { + useJUnitPlatform() +} + +kotlin { + jvmToolchain(17) +} \ No newline at end of file diff --git a/samples/roots-demo/gradle.properties b/samples/roots-demo/gradle.properties new file mode 100644 index 00000000..25a97ca2 --- /dev/null +++ b/samples/roots-demo/gradle.properties @@ -0,0 +1,5 @@ +org.gradle.configuration-cache=true +org.gradle.parallel=true +org.gradle.caching=true + +#mcp.kotlin.overrideVersion=0.0.1-SNAPSHOT \ No newline at end of file diff --git a/samples/roots-demo/gradle/libs.versions.toml b/samples/roots-demo/gradle/libs.versions.toml new file mode 100644 index 00000000..4ad86c0a --- /dev/null +++ b/samples/roots-demo/gradle/libs.versions.toml @@ -0,0 +1,15 @@ +[versions] +kotlin = "2.3.21" +mcp-kotlin = "0.12.0" +shadow = "9.4.1" +slf4j = "2.0.17" + +[libraries] +mcp-kotlin-client = { group = "io.modelcontextprotocol", name = "kotlin-sdk-client", version.ref = "mcp-kotlin" } +mcp-kotlin-server = { group = "io.modelcontextprotocol", name = "kotlin-sdk-server", version.ref = "mcp-kotlin" } +mcp-kotlin-testing = { group = "io.modelcontextprotocol", name = "kotlin-sdk-testing", version.ref = "mcp-kotlin" } +slf4j-simple = { group = "org.slf4j", name = "slf4j-simple", version.ref = "slf4j" } + +[plugins] +kotlin-jvm = { id = "org.jetbrains.kotlin.jvm", version.ref = "kotlin" } +shadow = { id = "com.gradleup.shadow", version.ref = "shadow" } \ No newline at end of file diff --git a/samples/roots-demo/gradle/wrapper/gradle-wrapper.jar b/samples/roots-demo/gradle/wrapper/gradle-wrapper.jar new file mode 100644 index 00000000..b1b8ef56 Binary files /dev/null and b/samples/roots-demo/gradle/wrapper/gradle-wrapper.jar differ diff --git a/samples/roots-demo/gradle/wrapper/gradle-wrapper.properties b/samples/roots-demo/gradle/wrapper/gradle-wrapper.properties new file mode 100644 index 00000000..b52fb7e7 --- /dev/null +++ b/samples/roots-demo/gradle/wrapper/gradle-wrapper.properties @@ -0,0 +1,9 @@ +distributionBase=GRADLE_USER_HOME +distributionPath=wrapper/dists +distributionUrl=https\://services.gradle.org/distributions/gradle-9.5.0-bin.zip +networkTimeout=10000 +retries=0 +retryBackOffMs=500 +validateDistributionUrl=true +zipStoreBase=GRADLE_USER_HOME +zipStorePath=wrapper/dists diff --git a/samples/roots-demo/gradlew b/samples/roots-demo/gradlew new file mode 100755 index 00000000..b9bb139f --- /dev/null +++ b/samples/roots-demo/gradlew @@ -0,0 +1,248 @@ +#!/bin/sh + +# +# Copyright © 2015 the original authors. +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# https://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. +# +# SPDX-License-Identifier: Apache-2.0 +# + +############################################################################## +# +# Gradle start up script for POSIX generated by Gradle. +# +# Important for running: +# +# (1) You need a POSIX-compliant shell to run this script. If your /bin/sh is +# noncompliant, but you have some other compliant shell such as ksh or +# bash, then to run this script, type that shell name before the whole +# command line, like: +# +# ksh Gradle +# +# Busybox and similar reduced shells will NOT work, because this script +# requires all of these POSIX shell features: +# * functions; +# * expansions «$var», «${var}», «${var:-default}», «${var+SET}», +# «${var#prefix}», «${var%suffix}», and «$( cmd )»; +# * compound commands having a testable exit status, especially «case»; +# * various built-in commands including «command», «set», and «ulimit». +# +# Important for patching: +# +# (2) This script targets any POSIX shell, so it avoids extensions provided +# by Bash, Ksh, etc; in particular arrays are avoided. +# +# The "traditional" practice of packing multiple parameters into a +# space-separated string is a well documented source of bugs and security +# problems, so this is (mostly) avoided, by progressively accumulating +# options in "$@", and eventually passing that to Java. +# +# Where the inherited environment variables (DEFAULT_JVM_OPTS, JAVA_OPTS, +# and GRADLE_OPTS) rely on word-splitting, this is performed explicitly; +# see the in-line comments for details. +# +# There are tweaks for specific operating systems such as AIX, CygWin, +# Darwin, MinGW, and NonStop. +# +# (3) This script is generated from the Groovy template +# https://github.com/gradle/gradle/blob/3d91ce3b8caaf77ad09f381f43615b715b53f72c/platforms/jvm/plugins-application/src/main/resources/org/gradle/api/internal/plugins/unixStartScript.txt +# within the Gradle project. +# +# You can find Gradle at https://github.com/gradle/gradle/. +# +############################################################################## + +# Attempt to set APP_HOME + +# Resolve links: $0 may be a link +app_path=$0 + +# Need this for daisy-chained symlinks. +while + APP_HOME=${app_path%"${app_path##*/}"} # leaves a trailing /; empty if no leading path + [ -h "$app_path" ] +do + ls=$( ls -ld "$app_path" ) + link=${ls#*' -> '} + case $link in #( + /*) app_path=$link ;; #( + *) app_path=$APP_HOME$link ;; + esac +done + +# This is normally unused +# shellcheck disable=SC2034 +APP_BASE_NAME=${0##*/} +# Discard cd standard output in case $CDPATH is set (https://github.com/gradle/gradle/issues/25036) +APP_HOME=$( cd -P "${APP_HOME:-./}" > /dev/null && printf '%s\n' "$PWD" ) || exit + +# Use the maximum available, or set MAX_FD != -1 to use that value. +MAX_FD=maximum + +warn () { + echo "$*" +} >&2 + +die () { + echo + echo "$*" + echo + exit 1 +} >&2 + +# OS specific support (must be 'true' or 'false'). +cygwin=false +msys=false +darwin=false +nonstop=false +case "$( uname )" in #( + CYGWIN* ) cygwin=true ;; #( + Darwin* ) darwin=true ;; #( + MSYS* | MINGW* ) msys=true ;; #( + NONSTOP* ) nonstop=true ;; +esac + + + +# Determine the Java command to use to start the JVM. +if [ -n "$JAVA_HOME" ] ; then + if [ -x "$JAVA_HOME/jre/sh/java" ] ; then + # IBM's JDK on AIX uses strange locations for the executables + JAVACMD=$JAVA_HOME/jre/sh/java + else + JAVACMD=$JAVA_HOME/bin/java + fi + if [ ! -x "$JAVACMD" ] ; then + die "ERROR: JAVA_HOME is set to an invalid directory: $JAVA_HOME + +Please set the JAVA_HOME variable in your environment to match the +location of your Java installation." + fi +else + JAVACMD=java + if ! command -v java >/dev/null 2>&1 + then + die "ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. + +Please set the JAVA_HOME variable in your environment to match the +location of your Java installation." + fi +fi + +# Increase the maximum file descriptors if we can. +if ! "$cygwin" && ! "$darwin" && ! "$nonstop" ; then + case $MAX_FD in #( + max*) + # In POSIX sh, ulimit -H is undefined. That's why the result is checked to see if it worked. + # shellcheck disable=SC2039,SC3045 + MAX_FD=$( ulimit -H -n ) || + warn "Could not query maximum file descriptor limit" + esac + case $MAX_FD in #( + '' | soft) :;; #( + *) + # In POSIX sh, ulimit -n is undefined. That's why the result is checked to see if it worked. + # shellcheck disable=SC2039,SC3045 + ulimit -n "$MAX_FD" || + warn "Could not set maximum file descriptor limit to $MAX_FD" + esac +fi + +# Collect all arguments for the java command, stacking in reverse order: +# * args from the command line +# * the main class name +# * -classpath +# * -D...appname settings +# * --module-path (only if needed) +# * DEFAULT_JVM_OPTS, JAVA_OPTS, and GRADLE_OPTS environment variables. + +# For Cygwin or MSYS, switch paths to Windows format before running java +if "$cygwin" || "$msys" ; then + APP_HOME=$( cygpath --path --mixed "$APP_HOME" ) + + JAVACMD=$( cygpath --unix "$JAVACMD" ) + + # Now convert the arguments - kludge to limit ourselves to /bin/sh + for arg do + if + case $arg in #( + -*) false ;; # don't mess with options #( + /?*) t=${arg#/} t=/${t%%/*} # looks like a POSIX filepath + [ -e "$t" ] ;; #( + *) false ;; + esac + then + arg=$( cygpath --path --ignore --mixed "$arg" ) + fi + # Roll the args list around exactly as many times as the number of + # args, so each arg winds up back in the position where it started, but + # possibly modified. + # + # NB: a `for` loop captures its iteration list before it begins, so + # changing the positional parameters here affects neither the number of + # iterations, nor the values presented in `arg`. + shift # remove old arg + set -- "$@" "$arg" # push replacement arg + done +fi + + +# Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script. +DEFAULT_JVM_OPTS='"-Xmx64m" "-Xms64m"' + +# Collect all arguments for the java command: +# * DEFAULT_JVM_OPTS, JAVA_OPTS, and optsEnvironmentVar are not allowed to contain shell fragments, +# and any embedded shellness will be escaped. +# * For example: A user cannot expect ${Hostname} to be expanded, as it is an environment variable and will be +# treated as '${Hostname}' itself on the command line. + +set -- \ + "-Dorg.gradle.appname=$APP_BASE_NAME" \ + -jar "$APP_HOME/gradle/wrapper/gradle-wrapper.jar" \ + "$@" + +# Stop when "xargs" is not available. +if ! command -v xargs >/dev/null 2>&1 +then + die "xargs is not available" +fi + +# Use "xargs" to parse quoted args. +# +# With -n1 it outputs one arg per line, with the quotes and backslashes removed. +# +# In Bash we could simply go: +# +# readarray ARGS < <( xargs -n1 <<<"$var" ) && +# set -- "${ARGS[@]}" "$@" +# +# but POSIX shell has neither arrays nor command substitution, so instead we +# post-process each arg (as a line of input to sed) to backslash-escape any +# character that might be a shell metacharacter, then use eval to reverse +# that process (while maintaining the separation between arguments), and wrap +# the whole thing up as a single "set" statement. +# +# This will of course break if any of these variables contains a newline or +# an unmatched quote. +# + +eval "set -- $( + printf '%s\n' "$DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS" | + xargs -n1 | + sed ' s~[^-[:alnum:]+,./:=@_]~\\&~g; ' | + tr '\n' ' ' + )" '"$@"' + +exec "$JAVACMD" "$@" diff --git a/samples/roots-demo/gradlew.bat b/samples/roots-demo/gradlew.bat new file mode 100644 index 00000000..aa5f10b0 --- /dev/null +++ b/samples/roots-demo/gradlew.bat @@ -0,0 +1,82 @@ +@rem +@rem Copyright 2015 the original author or authors. +@rem +@rem Licensed under the Apache License, Version 2.0 (the "License"); +@rem you may not use this file except in compliance with the License. +@rem You may obtain a copy of the License at +@rem +@rem https://www.apache.org/licenses/LICENSE-2.0 +@rem +@rem Unless required by applicable law or agreed to in writing, software +@rem distributed under the License is distributed on an "AS IS" BASIS, +@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +@rem See the License for the specific language governing permissions and +@rem limitations under the License. +@rem +@rem SPDX-License-Identifier: Apache-2.0 +@rem + +@if "%DEBUG%"=="" @echo off +@rem ########################################################################## +@rem +@rem Gradle startup script for Windows +@rem +@rem ########################################################################## + +@rem Set local scope for the variables, and ensure extensions are enabled +setlocal EnableExtensions + +set DIRNAME=%~dp0 +if "%DIRNAME%"=="" set DIRNAME=. +@rem This is normally unused +set APP_BASE_NAME=%~n0 +set APP_HOME=%DIRNAME% + +@rem Resolve any "." and ".." in APP_HOME to make it shorter. +for %%i in ("%APP_HOME%") do set APP_HOME=%%~fi + +@rem Add default JVM options here. You can also use JAVA_OPTS and GRADLE_OPTS to pass JVM options to this script. +set DEFAULT_JVM_OPTS="-Xmx64m" "-Xms64m" + +@rem Find java.exe +if defined JAVA_HOME goto findJavaFromJavaHome + +set JAVA_EXE=java.exe +%JAVA_EXE% -version >NUL 2>&1 +if %ERRORLEVEL% equ 0 goto execute + +echo. 1>&2 +echo ERROR: JAVA_HOME is not set and no 'java' command could be found in your PATH. 1>&2 +echo. 1>&2 +echo Please set the JAVA_HOME variable in your environment to match the 1>&2 +echo location of your Java installation. 1>&2 + +"%COMSPEC%" /c exit 1 + +:findJavaFromJavaHome +set JAVA_HOME=%JAVA_HOME:"=% +set JAVA_EXE=%JAVA_HOME%/bin/java.exe + +if exist "%JAVA_EXE%" goto execute + +echo. 1>&2 +echo ERROR: JAVA_HOME is set to an invalid directory: %JAVA_HOME% 1>&2 +echo. 1>&2 +echo Please set the JAVA_HOME variable in your environment to match the 1>&2 +echo location of your Java installation. 1>&2 + +"%COMSPEC%" /c exit 1 + +:execute +@rem Setup the command line + + + +@rem Execute Gradle +@rem endlocal doesn't take effect until after the line is parsed and variables are expanded +@rem which allows us to clear the local environment before executing the java command +endlocal & "%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %GRADLE_OPTS% "-Dorg.gradle.appname=%APP_BASE_NAME%" -jar "%APP_HOME%\gradle\wrapper\gradle-wrapper.jar" %* & call :exitWithErrorLevel + +:exitWithErrorLevel +@rem Use "%COMSPEC%" /c exit to allow operators to work properly in scripts +"%COMSPEC%" /c exit %ERRORLEVEL% diff --git a/samples/roots-demo/settings.gradle.kts b/samples/roots-demo/settings.gradle.kts new file mode 100644 index 00000000..3bfee0f1 --- /dev/null +++ b/samples/roots-demo/settings.gradle.kts @@ -0,0 +1,25 @@ +rootProject.name = "roots-demo" + +plugins { + // Apply the foojay-resolver plugin to allow automatic download of JDKs + id("org.gradle.toolchains.foojay-resolver-convention") version "1.0.0" +} + +dependencyResolutionManagement { + repositories { + mavenLocal() + mavenCentral() + } + + versionCatalogs { + create("libs") { + val mcpKotlinVersion = providers.gradleProperty( + "mcp.kotlin.overrideVersion", + ).orNull + if (mcpKotlinVersion != null) { + logger.lifecycle("Using the override version $mcpKotlinVersion of MCP Kotlin SDK") + version("mcp-kotlin", mcpKotlinVersion) + } + } + } +} \ No newline at end of file diff --git a/samples/roots-demo/src/main/kotlin/io/modelcontextprotocol/sample/roots/Main.kt b/samples/roots-demo/src/main/kotlin/io/modelcontextprotocol/sample/roots/Main.kt new file mode 100644 index 00000000..3223dac0 --- /dev/null +++ b/samples/roots-demo/src/main/kotlin/io/modelcontextprotocol/sample/roots/Main.kt @@ -0,0 +1,108 @@ +package io.modelcontextprotocol.sample.roots + +import io.modelcontextprotocol.kotlin.sdk.ExperimentalMcpApi +import io.modelcontextprotocol.kotlin.sdk.client.Client +import io.modelcontextprotocol.kotlin.sdk.client.ClientOptions +import io.modelcontextprotocol.kotlin.sdk.server.Server +import io.modelcontextprotocol.kotlin.sdk.server.ServerOptions +import io.modelcontextprotocol.kotlin.sdk.server.ServerSession +import io.modelcontextprotocol.kotlin.sdk.testing.ChannelTransport +import io.modelcontextprotocol.kotlin.sdk.types.ClientCapabilities +import io.modelcontextprotocol.kotlin.sdk.types.Implementation +import io.modelcontextprotocol.kotlin.sdk.types.Method +import io.modelcontextprotocol.kotlin.sdk.types.RootsListChangedNotification +import io.modelcontextprotocol.kotlin.sdk.types.ServerCapabilities +import kotlinx.coroutines.CompletableDeferred +import kotlinx.coroutines.joinAll +import kotlinx.coroutines.launch +import kotlinx.coroutines.runBlocking +import kotlinx.coroutines.withTimeoutOrNull +import java.nio.file.Path + +@OptIn(ExperimentalMcpApi::class) +fun main() = runBlocking { + val (clientTransport, serverTransport) = ChannelTransport.createLinkedPair() + + val client = Client( + clientInfo = Implementation(name = "roots-demo-client", version = "1.0.0"), + ClientOptions( + capabilities = ClientCapabilities( + roots = ClientCapabilities.Roots(listChanged = true), + ), + ), + ) + + val server = Server( + Implementation(name = "roots-demo-server", version = "1.0.0"), + ServerOptions( + capabilities = ServerCapabilities(), + ), + ) + + val serverSession = CompletableDeferred() + listOf( + launch { client.connect(clientTransport) }, + launch { serverSession.complete(server.createSession(serverTransport)) }, + ).joinAll() + val session = serverSession.await() + + val firstNotification = CompletableDeferred() + val secondNotification = CompletableDeferred() + + session.setNotificationHandler( + Method.Defined.NotificationsRootsListChanged, + ) { _ -> + launch { + try { + val updatedRoots = session.listRoots() + println("\n[Server] Roots list changed — updated roots:") + updatedRoots.roots.forEach { root -> + println(" ${root.name ?: "(unnamed)"}: ${root.uri}") + } + } catch (e: Exception) { + println("[Server] Error fetching updated roots: ${e.message}") + } finally { + if (!firstNotification.isCompleted) { + firstNotification.complete(Unit) + } else if (!secondNotification.isCompleted) { + secondNotification.complete(Unit) + } + } + } + CompletableDeferred(Unit) + } + + try { + val homeDir = Path.of(System.getProperty("user.home")) + + client.addRoot(homeDir.resolve("projects/my-project").toUri().toString(), "My Project") + client.addRoot(homeDir.resolve("Documents").toUri().toString(), "Documents") + + val roots = session.listRoots() + println("Initial roots reported by client:") + roots.roots.forEach { root -> + println(" ${root.name ?: "(unnamed)"}: ${root.uri}") + } + + val sharedRootUri = homeDir.resolve("projects/shared").toUri().toString() + client.addRoot(sharedRootUri, "Shared Libraries") + client.sendRootsListChanged() + + val firstResult = withTimeoutOrNull(5000L) { firstNotification.await() } + if (firstResult == null) { + println("[Warning] Timed out waiting for server to process first roots change") + } + + println("\n[Client] Removing a root and sending list changed notification...") + client.removeRoot(sharedRootUri) + client.sendRootsListChanged() + + val secondResult = withTimeoutOrNull(5000L) { secondNotification.await() } + if (secondResult == null) { + println("[Warning] Timed out waiting for server to process second roots change") + } + } finally { + client.close() + server.close() + } +} \ No newline at end of file diff --git a/samples/roots-demo/src/main/resources/simplelogger.properties b/samples/roots-demo/src/main/resources/simplelogger.properties new file mode 100644 index 00000000..fada7ecf --- /dev/null +++ b/samples/roots-demo/src/main/resources/simplelogger.properties @@ -0,0 +1,7 @@ +# Level of logging for the ROOT logger: ERROR, WARN, INFO, DEBUG, TRACE (default is INFO) +org.slf4j.simpleLogger.defaultLogLevel=INFO +org.slf4j.simpleLogger.showThreadName=true +org.slf4j.simpleLogger.showDateTime=false + +# Log level for specific packages or classes +org.slf4j.simpleLogger.log.io.modelcontextprotocol=INFO \ No newline at end of file