diff --git a/mobile/src/main/java/io/github/marktony/espresso/data/source/PackagesRepository.java b/mobile/src/main/java/io/github/marktony/espresso/data/source/PackagesRepository.java
index e736f86..32f8a37 100644
--- a/mobile/src/main/java/io/github/marktony/espresso/data/source/PackagesRepository.java
+++ b/mobile/src/main/java/io/github/marktony/espresso/data/source/PackagesRepository.java
@@ -217,25 +217,18 @@ public void accept(Package aPackage) throws Exception {
      */
     @Override
     public Observable<Package> refreshPackage(@NonNull final String packageId) {
-        return packagesRemoteDataSource
-                .refreshPackage(packageId)
-                .flatMap(new Function<Package, ObservableSource<Package>>() {
-                    @Override
-                    public ObservableSource<Package> apply(Package p) throws Exception {
-                        return Observable
-                                .just(p)
-                                .doOnNext(new Consumer<Package>() {
-                                    @Override
-                                    public void accept(Package aPackage) throws Exception {
-                                        Package pkg = cachedPackages.get(aPackage.getNumber());
-                                        if (pkg != null) {
-                                            pkg.setData(aPackage.getData());
-                                            pkg.setReadable(true);
-                                        }
-                                    }
-                                });
-                    }
-                });
+        return packagesRemoteDataSource.refreshPackage(packageId)
+                                       .doOnNext(new Consumer<Package>() {
+                                           @Override
+                                           public void accept(Package aPackage) throws Exception {
+                                               Package pkg = cachedPackages.get(aPackage.getNumber());
+                                               if (pkg != null) {
+                                                   pkg.setData(aPackage.getData());
+                                                   pkg.setReadable(true);
+                                               }
+                                           }
+
+                                       });
     }
 
     /**
diff --git a/mobile/src/main/java/io/github/marktony/espresso/data/source/local/CompaniesLocalDataSource.java b/mobile/src/main/java/io/github/marktony/espresso/data/source/local/CompaniesLocalDataSource.java
index b6d2b31..19428fd 100644
--- a/mobile/src/main/java/io/github/marktony/espresso/data/source/local/CompaniesLocalDataSource.java
+++ b/mobile/src/main/java/io/github/marktony/espresso/data/source/local/CompaniesLocalDataSource.java
@@ -20,11 +20,14 @@
 import android.support.annotation.Nullable;
 
 import java.util.List;
+import java.util.concurrent.Callable;
 
 import io.github.marktony.espresso.data.Company;
 import io.github.marktony.espresso.data.source.CompaniesDataSource;
 import io.github.marktony.espresso.realm.RealmHelper;
 import io.reactivex.Observable;
+import io.reactivex.ObservableSource;
+import io.reactivex.functions.Function;
 import io.realm.Case;
 import io.realm.Realm;
 import io.realm.Sort;
@@ -52,18 +55,27 @@ public static CompaniesLocalDataSource getInstance() {
 
     @Override
     public Observable<List<Company>> getCompanies() {
-        Realm rlm = RealmHelper.newRealmInstance();
-        return Observable
-                .fromIterable(rlm.copyFromRealm(rlm.where(Company.class).findAllSorted("alphabet", Sort.ASCENDING)))
-                .toList()
-                .toObservable();
+        return Observable.fromCallable(new Callable<List<Company>>() {
+            @Override
+            public List<Company> call() throws Exception {
+                Realm rlm = RealmHelper.newRealmInstance();
+                return rlm.copyFromRealm(rlm.where(Company.class)
+                                            .findAllSorted("alphabet", Sort.ASCENDING));
+            }
+        });
     }
 
     @Override
-    public Observable<Company> getCompany(@NonNull String companyId) {
-        Realm rlm = RealmHelper.newRealmInstance();
-        return Observable
-                .just(rlm.copyFromRealm(rlm.where(Company.class).equalTo("id", companyId).findFirst()));
+    public Observable<Company> getCompany(@NonNull final String companyId) {
+        return Observable.fromCallable(new Callable<Company>() {
+            @Override
+            public Company call() throws Exception {
+                Realm rlm = RealmHelper.newRealmInstance();
+                return rlm.copyFromRealm(rlm.where(Company.class)
+                                            .equalTo("id", companyId)
+                                            .findFirst());
+            }
+        });
     }
 
     @Override
@@ -718,21 +730,25 @@ public void initData() {
     }
 
     @Override
-    public Observable<List<Company>> searchCompanies(@NonNull String keyWords) {
-        Realm rlm = RealmHelper.newRealmInstance();
-        List<Company> results = rlm.copyFromRealm(
-                rlm.where(Company.class)
-                        .like("name","*" + keyWords + "*", Case.INSENSITIVE)
-                        .or()
-                        .like("tel", "*" + keyWords + "*", Case.INSENSITIVE)
-                        .or()
-                        .like("website", "*" + keyWords + "*", Case.INSENSITIVE)
-                        .or()
-                        .like("alphabet", "*" + keyWords + "*", Case.INSENSITIVE)
-                        .findAllSorted("alphabet", Sort.ASCENDING));
-        return Observable.fromIterable(results)
-                .toList()
-                .toObservable();
+    public Observable<List<Company>> searchCompanies(@NonNull final String keyWords) {
+
+        return Observable.fromCallable(new Callable<List<Company>>() {
+            @Override
+            public List<Company> call() throws Exception {
+                Realm rlm = RealmHelper.newRealmInstance();
+                return rlm.copyFromRealm(rlm.where(Company.class)
+                                            .like("name", "*" + keyWords + "*", Case.INSENSITIVE)
+                                            .or()
+                                            .like("tel", "*" + keyWords + "*", Case.INSENSITIVE)
+                                            .or()
+                                            .like("website", "*" + keyWords + "*", Case.INSENSITIVE)
+                                            .or()
+                                            .like("alphabet",
+                                                    "*" + keyWords + "*",
+                                                    Case.INSENSITIVE)
+                                            .findAllSorted("alphabet", Sort.ASCENDING));
+            }
+        });
     }
 
 }
\ No newline at end of file
diff --git a/mobile/src/main/java/io/github/marktony/espresso/data/source/local/PackagesLocalDataSource.java b/mobile/src/main/java/io/github/marktony/espresso/data/source/local/PackagesLocalDataSource.java
index e646803..47a14a0 100644
--- a/mobile/src/main/java/io/github/marktony/espresso/data/source/local/PackagesLocalDataSource.java
+++ b/mobile/src/main/java/io/github/marktony/espresso/data/source/local/PackagesLocalDataSource.java
@@ -20,6 +20,7 @@
 import android.support.annotation.Nullable;
 
 import java.util.List;
+import java.util.concurrent.Callable;
 
 import io.github.marktony.espresso.data.Package;
 import io.github.marktony.espresso.data.source.PackagesDataSource;
@@ -64,10 +65,14 @@ public static void destroyInstance() {
      */
     @Override
     public Observable<List<Package>> getPackages() {
-        Realm rlm = RealmHelper.newRealmInstance();
-
-        return Observable.just(rlm.copyFromRealm(rlm.where(Package.class)
-                .findAllSorted("timestamp", Sort.DESCENDING)));
+        return Observable.fromCallable(new Callable<List<Package>>() {
+            @Override
+            public List<Package> call() throws Exception {
+                Realm rlm = RealmHelper.newRealmInstance();
+                return rlm.copyFromRealm(rlm.where(Package.class)
+                                            .findAllSorted("timestamp", Sort.DESCENDING));
+            }
+        });
     }
 
     /**
@@ -78,11 +83,16 @@ public Observable<List<Package>> getPackages() {
      * @return The observable package from database.
      */
     @Override
-    public Observable<Package> getPackage(@NonNull String packNumber) {
-        Realm rlm = RealmHelper.newRealmInstance();
-        return Observable.just(rlm.copyFromRealm(rlm.where(Package.class)
-                .equalTo("number", packNumber)
-                .findFirst()));
+    public Observable<Package> getPackage(@NonNull final String packNumber) {
+        return Observable.fromCallable(new Callable<Package>() {
+            @Override
+            public Package call() throws Exception {
+                Realm rlm = RealmHelper.newRealmInstance();
+                return rlm.copyFromRealm(rlm.where(Package.class)
+                                            .equalTo("number", packNumber)
+                                            .findFirst());
+            }
+        });
     }
 
     /**
@@ -206,20 +216,26 @@ public void updatePackageName(@NonNull String packageId, @NonNull String name) {
     }
 
     @Override
-    public Observable<List<Package>> searchPackages(@NonNull String keyWords) {
-        Realm rlm = RealmHelper.newRealmInstance();
-        return Observable.fromIterable(rlm.copyFromRealm(
-                rlm.where(Package.class)
-                        .like("name", "*" + keyWords + "*", Case.INSENSITIVE)
-                        .or()
-                        .like("companyChineseName", "*" + keyWords + "*", Case.INSENSITIVE)
-                        .or()
-                        .like("company", "*" + keyWords + "*", Case.INSENSITIVE)
-                        .or()
-                        .like("number", "*" + keyWords + "*", Case.INSENSITIVE)
-                        .findAll()))
-                .toList()
-                .toObservable();
+    public Observable<List<Package>> searchPackages(@NonNull
+                                                    final String keyWords) {
+
+        return Observable.fromCallable(new Callable<List<Package>>() {
+            @Override
+            public List<Package> call() throws Exception {
+                Realm rlm = RealmHelper.newRealmInstance();
+                return rlm.copyFromRealm(rlm.where(Package.class)
+                                            .like("name", "*" + keyWords + "*", Case.INSENSITIVE)
+                                            .or()
+                                            .like("companyChineseName",
+                                                    "*" + keyWords + "*",
+                                                    Case.INSENSITIVE)
+                                            .or()
+                                            .like("company", "*" + keyWords + "*", Case.INSENSITIVE)
+                                            .or()
+                                            .like("number", "*" + keyWords + "*", Case.INSENSITIVE)
+                                            .findAll());
+            }
+        });
     }
 
 }