diff --git a/scm-clients/scm-client-api/src/main/java/sonia/scm/client/ScmClient.java b/scm-clients/scm-client-api/src/main/java/sonia/scm/client/ScmClient.java
index 8fd24be788..e83e834b18 100644
--- a/scm-clients/scm-client-api/src/main/java/sonia/scm/client/ScmClient.java
+++ b/scm-clients/scm-client-api/src/main/java/sonia/scm/client/ScmClient.java
@@ -35,6 +35,9 @@ package sonia.scm.client;
 
 //~--- non-JDK imports --------------------------------------------------------
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import sonia.scm.util.ServiceUtil;
 
 /**
@@ -47,6 +50,9 @@ public class ScmClient
   /** Field description */
   private static volatile ScmClientProvider provider = null;
 
+  /** the logger for ScmClient */
+  private static final Logger logger = LoggerFactory.getLogger(ScmClient.class);
+
   //~--- methods --------------------------------------------------------------
 
   /**
@@ -91,8 +97,10 @@ public class ScmClient
    *
    *
    * @return
+   *
+   * @throws ScmClientException
    */
-  private static ScmClientProvider getProvider()
+  private static ScmClientProvider getProvider() throws ScmClientException
   {
     if (provider == null)
     {
@@ -105,6 +113,16 @@ public class ScmClient
       }
     }
 
+    if (provider == null)
+    {
+      throw new ScmClientException("could not find a ScmClientProvider");
+    }
+    else if (logger.isInfoEnabled())
+    {
+      logger.info("create ScmClient with provider {}",
+                  provider.getClass().getName());
+    }
+
     return provider;
   }
 }
diff --git a/scm-clients/scm-client-api/src/main/java/sonia/scm/client/ScmUrlProvider.java b/scm-clients/scm-client-api/src/main/java/sonia/scm/client/ScmUrlProvider.java
index eff6ad029c..28c3e40d8e 100644
--- a/scm-clients/scm-client-api/src/main/java/sonia/scm/client/ScmUrlProvider.java
+++ b/scm-clients/scm-client-api/src/main/java/sonia/scm/client/ScmUrlProvider.java
@@ -33,6 +33,11 @@
 
 package sonia.scm.client;
 
+//~--- non-JDK imports --------------------------------------------------------
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 /**
  *
  * @author Sebastian Sdorra
@@ -52,6 +57,10 @@ public class ScmUrlProvider
   /** Field description */
   public static final String URLPART_REPOSITORY = "repositories/";
 
+  /** the logger for classVar */
+  private static final Logger logger =
+    LoggerFactory.getLogger(ScmUrlProvider.class);
+
   //~--- constructors ---------------------------------------------------------
 
   /**
@@ -70,6 +79,11 @@ public class ScmUrlProvider
     {
       this.baseUrl = baseUrl;
     }
+
+    if (logger.isDebugEnabled())
+    {
+      logger.debug("create new url provider with baseurl {}", this.baseUrl);
+    }
   }
 
   //~--- get methods ----------------------------------------------------------
@@ -141,7 +155,14 @@ public class ScmUrlProvider
    */
   public String getResourceUrl(String urlPart)
   {
-    return baseUrl.concat(urlPart).concat(extension);
+    String resourceUrl = baseUrl.concat(urlPart).concat(extension);
+
+    if (logger.isTraceEnabled())
+    {
+      logger.trace("return resourceurl {}", resourceUrl);
+    }
+
+    return resourceUrl;
   }
 
   //~--- set methods ----------------------------------------------------------
diff --git a/scm-clients/scm-client-impl/src/main/java/sonia/scm/client/JerseyClientProvider.java b/scm-clients/scm-client-impl/src/main/java/sonia/scm/client/JerseyClientProvider.java
index 9d3d3df09b..b5b15e6d96 100644
--- a/scm-clients/scm-client-impl/src/main/java/sonia/scm/client/JerseyClientProvider.java
+++ b/scm-clients/scm-client-impl/src/main/java/sonia/scm/client/JerseyClientProvider.java
@@ -35,6 +35,9 @@ package sonia.scm.client;
 
 //~--- non-JDK imports --------------------------------------------------------
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import org.sonatype.spice.jersey.client.ahc.config.DefaultAhcConfig;
 
 import sonia.scm.ScmState;
@@ -58,6 +61,12 @@ import javax.ws.rs.core.MultivaluedMap;
 public class JerseyClientProvider implements ScmClientProvider
 {
 
+  /** the logger for JerseyClientProvider */
+  private static final Logger logger =
+    LoggerFactory.getLogger(JerseyClientProvider.class);
+
+  //~--- methods --------------------------------------------------------------
+
   /**
    * Method description
    *
@@ -71,12 +80,24 @@ public class JerseyClientProvider implements ScmClientProvider
    * @throws ScmClientException
    */
   @Override
-  public ScmClientSession createSession(String url, String username,
+  public JerseyClientSession createSession(String url, String username,
           String password)
           throws ScmClientException
   {
     AssertUtil.assertIsNotEmpty(url);
 
+    if (logger.isInfoEnabled())
+    {
+      String user = "anonymous";
+
+      if (Util.isNotEmpty(username))
+      {
+        user = username;
+      }
+
+      logger.info("create new session for {} with username {}", url, user);
+    }
+
     ScmUrlProvider urlProvider = new ScmUrlProvider(url);
     DefaultAhcConfig config = new DefaultAhcConfig();
     Client client = Client.create(config);
@@ -85,6 +106,11 @@ public class JerseyClientProvider implements ScmClientProvider
 
     if (Util.isNotEmpty(username) && Util.isNotEmpty(password))
     {
+      if (logger.isDebugEnabled())
+      {
+        logger.debug("try login for {}", username);
+      }
+
       MultivaluedMap<String, String> formData = new MultivaluedMapImpl();
 
       formData.add("username", username);
@@ -94,11 +120,21 @@ public class JerseyClientProvider implements ScmClientProvider
     }
     else
     {
+      if (logger.isDebugEnabled())
+      {
+        logger.debug("try anonymous login");
+      }
+
       response = resource.get(ClientResponse.class);
     }
 
     if (response.getStatus() == 401)
     {
+      if (logger.isWarnEnabled())
+      {
+        logger.warn("server returned 401 unauthorized");
+      }
+
       throw new UnauthorizedAccessException();
     }
 
@@ -106,6 +142,11 @@ public class JerseyClientProvider implements ScmClientProvider
 
     if (!state.isSuccess())
     {
+      if (logger.isWarnEnabled())
+      {
+        logger.warn("server returned state failed");
+      }
+
       throw new ScmClientException("create ScmClientSession failed");
     }
 
diff --git a/scm-clients/scm-client-impl/src/main/java/sonia/scm/client/JerseyClientSession.java b/scm-clients/scm-client-impl/src/main/java/sonia/scm/client/JerseyClientSession.java
index f2335f6e56..6d035c9a61 100644
--- a/scm-clients/scm-client-impl/src/main/java/sonia/scm/client/JerseyClientSession.java
+++ b/scm-clients/scm-client-impl/src/main/java/sonia/scm/client/JerseyClientSession.java
@@ -35,6 +35,9 @@ package sonia.scm.client;
 
 //~--- non-JDK imports --------------------------------------------------------
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
 import sonia.scm.ScmState;
 import sonia.scm.group.Group;
 import sonia.scm.repository.Repository;
@@ -53,6 +56,12 @@ import java.io.IOException;
 public class JerseyClientSession implements ScmClientSession
 {
 
+  /** the logger for JerseyClientSession */
+  private static final Logger logger =
+    LoggerFactory.getLogger(JerseyClientSession.class);
+
+  //~--- constructors ---------------------------------------------------------
+
   /**
    * Constructs ...
    *
@@ -80,6 +89,11 @@ public class JerseyClientSession implements ScmClientSession
   @Override
   public void close() throws IOException
   {
+    if (logger.isInfoEnabled())
+    {
+      logger.info("close client session");
+    }
+
     client.destroy();
   }