Add a way to select which transport is used when multiple exists

core/deployment/src/main/java/io/quarkiverse/mcp/server/deployment/McpBuildTimeConfig.java

@@ -0,0 +1,17 @@
+package io.quarkiverse.mcp.server.deployment;
+
+import java.util.Optional;
+
+import io.quarkus.runtime.annotations.ConfigPhase;
+import io.quarkus.runtime.annotations.ConfigRoot;
+import io.smallrye.config.ConfigMapping;
+
+@ConfigMapping(prefix = "quarkus.mcp.server")
+@ConfigRoot(phase = ConfigPhase.BUILD_TIME)
+public interface McpBuildTimeConfig {
+
+    /**
+     * If multiple transports extensions are on the classpath, select which one is used
+     */
+    Optional<String> transport();
+}

core/deployment/src/main/java/io/quarkiverse/mcp/server/deployment/McpServerProcessor.java

@@ -81,6 +81,33 @@
 
 class McpServerProcessor {
 
+    @BuildStep
+    SelectedTransportBuildItem selectTransport(McpBuildTimeConfig buildTimeConfig,
+            List<TransportCandidateBuildItem> transportCandidates) {
+        if (transportCandidates.isEmpty()) {
+            throw new IllegalStateException(
+                    "At least one MCP transport must be used. Consider adding the one of the 'quarkus-mcp-server-stdio', 'quarkus-mcp-server-sse' extensions");
+        }
+        if (transportCandidates.size() == 1) {
+            return new SelectedTransportBuildItem(transportCandidates.get(0).getName());
+        }
+        if (buildTimeConfig.transport().isPresent()) {
+            String selectedTransportName = buildTimeConfig.transport().get();
+            for (TransportCandidateBuildItem transportCandidate : transportCandidates) {
+                if (transportCandidate.getName().equals(selectedTransportName)) {
+                    return new SelectedTransportBuildItem(transportCandidate.getName());
+                }
+            }
+            throw new IllegalStateException(
+                    "Selected transport '" + selectedTransportName + "' does not correspond to any of the added extensions");
+        } else {
+            throw new IllegalStateException(
+                    "Multiple transport candidates were found, please select one by setting 'quarkus.mcp.server.transport' to one of the following values: "
+                            + transportCandidates.stream().map(TransportCandidateBuildItem::getName)
+                                    .collect(Collectors.joining(", ")));
+        }
+    }
+
     @BuildStep
     void addBeans(BuildProducer<AdditionalBeanBuildItem> additionalBeans) {
         additionalBeans.produce(AdditionalBeanBuildItem.unremovableOf("io.quarkiverse.mcp.server.runtime.ConnectionManager"));

core/deployment/src/main/java/io/quarkiverse/mcp/server/deployment/SelectedTransportBuildItem.java

@@ -0,0 +1,19 @@
+package io.quarkiverse.mcp.server.deployment;
+
+import io.quarkus.builder.item.SimpleBuildItem;
+
+/**
+ * The selected MCP transport
+ */
+public final class SelectedTransportBuildItem extends SimpleBuildItem {
+
+    private final String name;
+
+    public SelectedTransportBuildItem(String name) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+}

core/deployment/src/main/java/io/quarkiverse/mcp/server/deployment/TransportCandidateBuildItem.java

@@ -0,0 +1,19 @@
+package io.quarkiverse.mcp.server.deployment;
+
+import io.quarkus.builder.item.MultiBuildItem;
+
+/**
+ * Generated by MCP transport implementations to advertise their existence
+ */
+public final class TransportCandidateBuildItem extends MultiBuildItem {
+
+    private final String name;
+
+    public TransportCandidateBuildItem(String name) {
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+}

docs/modules/ROOT/pages/includes/quarkus-mcp-server-core.adoc

@@ -7,6 +7,23 @@ h|[.header-title]##Configuration property##
 h|Type
 h|Default
 
+a|icon:lock[title=Fixed at build time] [[quarkus-mcp-server-core_quarkus-mcp-server-transport]] [.property-path]##link:#quarkus-mcp-server-core_quarkus-mcp-server-transport[`quarkus.mcp.server.transport`]##
+
+[.description]
+--
+If multiple transports extensions are on the classpath, select which one is used
+
+
+ifdef::add-copy-button-to-env-var[]
+Environment variable: env_var_with_copy_button:+++QUARKUS_MCP_SERVER_TRANSPORT+++[]
+endif::add-copy-button-to-env-var[]
+ifndef::add-copy-button-to-env-var[]
+Environment variable: `+++QUARKUS_MCP_SERVER_TRANSPORT+++`
+endif::add-copy-button-to-env-var[]
+--
+|string
+|
+
 a| [[quarkus-mcp-server-core_quarkus-mcp-server-server-info-name]] [.property-path]##link:#quarkus-mcp-server-core_quarkus-mcp-server-server-info-name[`quarkus.mcp.server.server-info.name`]##
 
 [.description]

docs/modules/ROOT/pages/includes/quarkus-mcp-server-core_quarkus.mcp.adoc

@@ -7,6 +7,23 @@ h|[.header-title]##Configuration property##
 h|Type
 h|Default
 
+a|icon:lock[title=Fixed at build time] [[quarkus-mcp-server-core_quarkus-mcp-server-transport]] [.property-path]##link:#quarkus-mcp-server-core_quarkus-mcp-server-transport[`quarkus.mcp.server.transport`]##
+
+[.description]
+--
+If multiple transports extensions are on the classpath, select which one is used
+
+
+ifdef::add-copy-button-to-env-var[]
+Environment variable: env_var_with_copy_button:+++QUARKUS_MCP_SERVER_TRANSPORT+++[]
+endif::add-copy-button-to-env-var[]
+ifndef::add-copy-button-to-env-var[]
+Environment variable: `+++QUARKUS_MCP_SERVER_TRANSPORT+++`
+endif::add-copy-button-to-env-var[]
+--
+|string
+|
+
 a| [[quarkus-mcp-server-core_quarkus-mcp-server-server-info-name]] [.property-path]##link:#quarkus-mcp-server-core_quarkus-mcp-server-server-info-name[`quarkus.mcp.server.server-info.name`]##
 
 [.description]

docs/pom.xml

@@ -11,6 +11,10 @@
     <artifactId>quarkus-mcp-server-docs</artifactId>
     <name>Quarkus MCP Server - Documentation</name>
 
+    <properties>
+        <quarkus.mcp.server.transport>stdio</quarkus.mcp.server.transport> <!-- added just to have the build pass -->
+    </properties>
+
     <dependencies>
         <!-- Make sure the doc is built after the other artifacts -->
         <dependency>

transports/sse/deployment/src/main/java/io/quarkiverse/mcp/server/sse/deployment/SseMcpServerProcessor.java

@@ -2,6 +2,8 @@
 
 import static io.quarkus.deployment.annotations.ExecutionTime.RUNTIME_INIT;
 
+import io.quarkiverse.mcp.server.deployment.SelectedTransportBuildItem;
+import io.quarkiverse.mcp.server.deployment.TransportCandidateBuildItem;
 import io.quarkiverse.mcp.server.sse.runtime.SseMcpServerRecorder;
 import io.quarkiverse.mcp.server.sse.runtime.config.McpSseBuildTimeConfig;
 import io.quarkus.arc.deployment.SyntheticBeansRuntimeInitBuildItem;
@@ -21,12 +23,21 @@ FeatureBuildItem feature() {
         return new FeatureBuildItem("mcp-server-sse");
     }
 
+    @BuildStep
+    TransportCandidateBuildItem transportCandidate() {
+        return new TransportCandidateBuildItem("sse");
+    }
+
     @Record(RUNTIME_INIT)
     @Consume(SyntheticBeansRuntimeInitBuildItem.class)
     @BuildStep
-    void registerEndpoints(McpSseBuildTimeConfig config, HttpRootPathBuildItem rootPath, SseMcpServerRecorder recorder,
+    void registerEndpoints(SelectedTransportBuildItem selectedTransportCandidateBuildItem,
+            McpSseBuildTimeConfig config, HttpRootPathBuildItem rootPath, SseMcpServerRecorder recorder,
             BodyHandlerBuildItem bodyHandler,
             BuildProducer<RouteBuildItem> routes) {
+        if (!selectedTransportCandidateBuildItem.getName().equals("sse")) {
+            return;
+        }
         String mcpPath = rootPath.relativePath(config.rootPath());
 
         routes.produce(RouteBuildItem.newFrameworkRoute(mcpPath + "/" + "sse")

transports/stdio/deployment/src/main/java/io/quarkiverse/mcp/server/stdio/deployment/StdioMcpServerProcessor.java

@@ -2,6 +2,8 @@
 
 import static io.quarkus.deployment.annotations.ExecutionTime.RUNTIME_INIT;
 
+import io.quarkiverse.mcp.server.deployment.SelectedTransportBuildItem;
+import io.quarkiverse.mcp.server.deployment.TransportCandidateBuildItem;
 import io.quarkiverse.mcp.server.stdio.runtime.StdioMcpServerRecorder;
 import io.quarkus.arc.deployment.SyntheticBeansRuntimeInitBuildItem;
 import io.quarkus.deployment.annotations.BuildStep;
@@ -16,10 +18,18 @@ FeatureBuildItem feature() {
         return new FeatureBuildItem("mcp-server-stdio");
     }
 
+    @BuildStep
+    TransportCandidateBuildItem transportCandidate() {
+        return new TransportCandidateBuildItem("stdio");
+    }
+
     @Record(RUNTIME_INIT)
     @Consume(SyntheticBeansRuntimeInitBuildItem.class)
     @BuildStep
-    void initialize(StdioMcpServerRecorder recorder) {
+    void initialize(SelectedTransportBuildItem selectedTransportCandidateBuildItem, StdioMcpServerRecorder recorder) {
+        if (!selectedTransportCandidateBuildItem.getName().equals("stdio")) {
+            return;
+        }
         recorder.initialize();
     }