Remove dependency on CIO engine (#223)

<!-- Provide a brief summary of your changes -->
Replace the CIO dependency with only server/client core dependency.

## Motivation and Context
<!-- Why is this change needed? What problem does it solve? -->
In order to minimize the size of package. There are probably other
existing engines like Netty/Tomcat(server) or Java/OkHttp/Apache(client)
in the classpath. So we can reuse existing infrastructure.

## How Has This Been Tested?
<!-- Have you tested this in a real application? Which scenarios were
tested? -->
I have run:
- kotlin-sdk-client: jvmTest, jsTest
- kotlin-sdk-test: jvmTest, jsTest
- kotlin-sdk-server: allTests
- All `build` of samples

I have an issue about `samples/kotlin-mcp-server`.
`io.modelcontextprotocol` is not found in `commonMain`.

## Breaking Changes
<!-- Will users need to update their code or configurations? -->
Yes. They need to `implementation` CIO engine manually if they use it in
their app.

## Types of changes
<!-- What types of changes does your code introduce? Put an `x` in all
the boxes that apply: -->
- [ ] Bug fix (non-breaking change which fixes an issue)
- [ ] New feature (non-breaking change which adds functionality)
- [x] Breaking change (fix or feature that would cause existing
functionality to change)
- [x] Documentation update

## Checklist
<!-- Go over all the following points, and put an `x` in all the boxes
that apply. -->
- [ ] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [ ] My code follows the repository's style guidelines
- [x] New and existing tests pass locally
- [ ] I have added appropriate error handling
- [ ] I have added or updated documentation as needed

## Additional context
<!-- Add any other context, implementation notes, or design decisions
-->

closes #111

---------

Co-authored-by: Konstantin Pavlov <[email protected]>

Author: MukjepScarlet

README.md

@@ -40,10 +40,23 @@ Add the dependency:
 
 ```kotlin
 dependencies {
-    // Use the badge above for the latest version
+    // See the badge above for the latest version
     implementation("io.modelcontextprotocol:kotlin-sdk:$mcpVersion")
 }
 ```
+MCP SDK uses [Ktor](https://ktor.io/), but does not come with a specific engine dependency.
+You should add [Ktor client](https://ktor.io/docs/client-dependencies.html#engine-dependency) 
+and/or [Ktor server](https://ktor.io/docs/client-dependencies.html#engine-dependency) dependency 
+to your project yourself, e.g.:
+```kotlin
+dependencies {
+    // for client:
+    implementation("io.ktor:ktor-client-cio:$ktorVersion")
+    // for server:
+    implementation("io.ktor:ktor-server-netty:$ktorVersion")
+    
+}
+```
 
 ## Quick Start
 

gradle/libs.versions.toml

@@ -39,10 +39,10 @@ kotlinx-collections-immutable = { group = "org.jetbrains.kotlinx", name = "kotli
 kotlin-logging = { group = "io.github.oshai", name = "kotlin-logging", version.ref = "logging" }
 
 # Ktor
-ktor-client-cio = { group = "io.ktor", name = "ktor-client-cio", version.ref = "ktor" }
+ktor-client-core = { group = "io.ktor", name = "ktor-client-core", version.ref = "ktor" }
 ktor-server-sse = { group = "io.ktor", name = "ktor-server-sse", version.ref = "ktor" }
 ktor-server-websockets = { group = "io.ktor", name = "ktor-server-websockets", version.ref = "ktor" }
-ktor-server-cio = { group = "io.ktor", name = "ktor-server-cio", version.ref = "ktor" }
+ktor-server-core = { group = "io.ktor", name = "ktor-server-core", version.ref = "ktor" }
 
 # Testing
 kotlinx-coroutines-test = { group = "org.jetbrains.kotlinx", name = "kotlinx-coroutines-test", version.ref = "coroutines" }
@@ -52,6 +52,8 @@ slf4j-simple = { group = "org.slf4j", name = "slf4j-simple", version.ref = "slf4
 kotest-assertions-json = { group = "io.kotest", name = "kotest-assertions-json", version.ref = "kotest" }
 
 # Samples
+ktor-client-cio = { group = "io.ktor", name = "ktor-client-cio", version.ref = "ktor" }
+ktor-server-cio = { group = "io.ktor", name = "ktor-server-cio", version.ref = "ktor" }
 mcp-kotlin = { group = "io.modelcontextprotocol", name = "kotlin-sdk", version.ref = "mcp-kotlin" }
 anthropic-java = { group = "com.anthropic", name = "anthropic-java", version.ref = "anthropic" }
 ktor-client-content-negotiation = { group = "io.ktor", name = "ktor-client-content-negotiation", version.ref = "ktor" }

kotlin-sdk-client/build.gradle.kts

@@ -33,7 +33,7 @@ kotlin {
         commonMain {
             dependencies {
                 api(project(":kotlin-sdk-core"))
-                api(libs.ktor.client.cio)
+                api(libs.ktor.client.core)
                 implementation(libs.kotlin.logging)
             }
         }
@@ -43,6 +43,7 @@ kotlin {
                 implementation(kotlin("test"))
                 implementation(libs.ktor.client.mock)
                 implementation(libs.kotlinx.coroutines.test)
+                runtimeOnly(libs.slf4j.simple)
             }
         }
     }

kotlin-sdk-core/build.gradle.kts

@@ -47,5 +47,11 @@ kotlin {
                 implementation(libs.kotest.assertions.json)
             }
         }
+
+        jvmTest {
+            dependencies {
+                runtimeOnly(libs.slf4j.simple)
+            }
+        }
     }
 }

kotlin-sdk-server/build.gradle.kts

@@ -11,7 +11,7 @@ kotlin {
         commonMain {
             dependencies {
                 api(project(":kotlin-sdk-core"))
-                api(libs.ktor.server.cio)
+                api(libs.ktor.server.core)
                 api(libs.ktor.server.sse)
                 implementation(libs.kotlin.logging)
             }
@@ -21,7 +21,12 @@ kotlin {
             dependencies {
                 implementation(kotlin("test"))
                 implementation(libs.kotlinx.coroutines.test)
-                implementation(libs.slf4j.simple)
+            }
+        }
+
+        jvmTest {
+            dependencies {
+                runtimeOnly(libs.slf4j.simple)
             }
         }
     }

kotlin-sdk-test/build.gradle.kts

@@ -13,17 +13,18 @@ kotlin {
             dependencies {
                 implementation(project(":kotlin-sdk"))
                 implementation(kotlin("test"))
-                implementation(libs.ktor.server.test.host)
-                implementation(libs.kotlinx.coroutines.test)
                 implementation(libs.kotest.assertions.json)
+                implementation(libs.kotlin.logging)
+                implementation(libs.kotlinx.coroutines.test)
+                implementation(libs.ktor.client.cio)
+                implementation(libs.ktor.server.cio)
+                implementation(libs.ktor.server.test.host)
             }
         }
         jvmTest {
             dependencies {
                 implementation(kotlin("test-junit5"))
-                implementation(libs.kotlin.logging)
-                implementation(libs.ktor.server.cio)
-                implementation(libs.ktor.client.cio)
+                runtimeOnly(libs.slf4j.simple)
             }
         }
     }

samples/kotlin-mcp-client/build.gradle.kts

@@ -13,8 +13,9 @@ version = "0.1.0"
 
 dependencies {
     implementation(libs.mcp.kotlin)
-    implementation(libs.slf4j.simple)
+    implementation(libs.ktor.client.cio)
     implementation(libs.anthropic.java)
+    implementation(libs.slf4j.simple)
 }
 
 tasks.test {

samples/kotlin-mcp-server/build.gradle.kts

@@ -44,6 +44,7 @@ kotlin {
     sourceSets {
         commonMain.dependencies {
             implementation(libs.mcp.kotlin)
+            implementation(libs.ktor.server.cio)
         }
         jvmMain.dependencies {
             implementation(libs.slf4j.simple)

samples/weather-stdio-server/build.gradle.kts

@@ -13,15 +13,17 @@ repositories {
     mavenCentral()
 }
 
-
 group = "org.example"
 version = "0.1.0"
 
 dependencies {
-    implementation(libs.mcp.kotlin)
-    implementation(libs.slf4j.simple)
     implementation(libs.ktor.client.content.negotiation)
     implementation(libs.ktor.serialization.kotlinx.json)
+    implementation(libs.mcp.kotlin)
+    implementation(libs.ktor.server.cio)
+    implementation(libs.ktor.client.cio)
+    implementation(libs.slf4j.simple)
+
     testImplementation(kotlin("test"))
     testImplementation(libs.kotlinx.coroutines.test)
 }