diff --git a/core/CMakeLists.txt b/core/CMakeLists.txt
index 6c7a3b5..d3327c9 100644
--- a/core/CMakeLists.txt
+++ b/core/CMakeLists.txt
@@ -12,8 +12,6 @@ target_sources(squawk PRIVATE
   conference.h
   contact.cpp
   contact.h
-  networkaccess.cpp
-  networkaccess.h
   rosteritem.cpp
   rosteritem.h
   ${SIGNALCATCHER_SOURCE}
@@ -27,3 +25,4 @@ target_include_directories(squawk PRIVATE ${LMDB_INCLUDE_DIRS})
 add_subdirectory(handlers)
 add_subdirectory(storage)
 add_subdirectory(passwordStorageEngines)
+add_subdirectory(components)
diff --git a/core/account.cpp b/core/account.cpp
index 0cb159d..08321d3 100644
--- a/core/account.cpp
+++ b/core/account.cpp
@@ -285,7 +285,10 @@ void Core::Account::onPresenceReceived(const QXmppPresence& p_presence)
             emit addPresence(jid, resource, {
                 {"lastActivity", lastInteraction},
                 {"availability", p_presence.availableStatusType()},           //TODO check and handle invisible
-                {"status", p_presence.statusText()}
+                {"status", p_presence.statusText()},
+                {"capabilityNode", p_presence.capabilityNode()},
+                {"capabilityVer", p_presence.capabilityVer().toBase64()},
+                {"capabilityHash", p_presence.capabilityHash()}
             });
         }
         break;
@@ -594,7 +597,8 @@ void Core::Account::onDiscoveryItemsReceived(const QXmppDiscoveryIq& items)
 
 void Core::Account::onDiscoveryInfoReceived(const QXmppDiscoveryIq& info)
 {
-    if (info.from() == getServer()) {
+    QString from = info.from();
+    if (from == getServer()) {
         bool enableCC = false;
         qDebug() << "Server info received for account" << name;
         QStringList features = info.features();
@@ -613,7 +617,7 @@ void Core::Account::onDiscoveryInfoReceived(const QXmppDiscoveryIq& info)
 
         qDebug() << "Requesting account" << name << "capabilities";
         dm->requestInfo(getBareJid());
-    } else if (info.from() == getBareJid()) {
+    } else if (from == getBareJid()) {
         qDebug() << "Received capabilities for account" << name << ":";
         QList<QXmppDiscoveryIq::Identity> identities = info.identities();
         bool pepSupported = false;
@@ -626,10 +630,27 @@ void Core::Account::onDiscoveryInfoReceived(const QXmppDiscoveryIq& info)
         }
         rh->setPepSupport(pepSupported);
     } else  {
-        qDebug() << "Received info for account" << name << "about" << info.from();
-        QList<QXmppDiscoveryIq::Identity> identities = info.identities();
-        for (const QXmppDiscoveryIq::Identity& identity : identities) {
-            qDebug() << "    " << identity.name() << identity.category() << identity.type();
+        qDebug() << "Received info for account" << name << "about" << from;
+        QString node = info.queryNode();
+        if (!node.isEmpty()) {
+            QStringList feats = info.features();
+            std::list<Shared::Identity> identities;
+            std::set<QString> features(feats.begin(), feats.end());
+            QList<QXmppDiscoveryIq::Identity> idents = info.identities();
+            for (const QXmppDiscoveryIq::Identity& ident : idents) {
+                identities.emplace_back();
+                Shared::Identity& identity = identities.back();
+                identity.category = ident.category();
+                identity.language = ident.language();
+                identity.name = ident.name();
+                identity.type = ident.type();
+
+                qDebug() << "    " << identity.name << identity.category << identity.type;
+            }
+            for (const QString& feat : features) {
+                qDebug() << "    " << feat;
+            }
+            emit infoDiscovered(from, node, identities, features);
         }
     }
 }
diff --git a/core/account.h b/core/account.h
index 2c9ec70..5651ad9 100644
--- a/core/account.h
+++ b/core/account.h
@@ -29,6 +29,7 @@
 
 #include <map>
 #include <set>
+#include <list>
 
 #include <QXmppRosterManager.h>
 #include <QXmppCarbonManager.h>
@@ -42,10 +43,11 @@
 #include <QXmppVCardManager.h>
 #include <QXmppMessageReceiptManager.h>
 
-#include "shared/shared.h"
+#include <shared/shared.h>
+#include <shared/identity.h>
 #include "contact.h"
 #include "conference.h"
-#include "networkaccess.h"
+#include <core/components/networkaccess.h>
 
 #include "handlers/messagehandler.h"
 #include "handlers/rosterhandler.h"
@@ -118,6 +120,8 @@ public:
     void resendMessage(const QString& jid, const QString& id);
     void replaceMessage(const QString& originalId, const Shared::Message& data);
     void invalidatePassword();
+
+    void discoverInfo(const QString& address, const QString& node);
     
 public slots:
     void connect();
@@ -151,6 +155,7 @@ signals:
     void uploadFile(const QFileInfo& file, const QUrl& set, const QUrl& get, QMap<QString, QString> headers);
     void uploadFileError(const QString& jid, const QString& messageId, const QString& error);
     void needPassword();
+    void infoDiscovered(const QString& address, const QString& node, const std::list<Shared::Identity>& identities, const std::set<QString>& features);
     
 private:
     QString name;
diff --git a/core/components/CMakeLists.txt b/core/components/CMakeLists.txt
new file mode 100644
index 0000000..5faf837
--- /dev/null
+++ b/core/components/CMakeLists.txt
@@ -0,0 +1,6 @@
+target_sources(squawk PRIVATE
+  networkaccess.cpp
+  networkaccess.h
+  clientcache.cpp
+  clientcache.h
+)
diff --git a/core/components/clientcache.cpp b/core/components/clientcache.cpp
new file mode 100644
index 0000000..0259f9c
--- /dev/null
+++ b/core/components/clientcache.cpp
@@ -0,0 +1,55 @@
+// Squawk messenger. 
+// Copyright (C) 2019  Yury Gubich <blue@macaw.me>
+// 
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+// 
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+
+#include "clientcache.h"
+
+Core::ClientCache::ClientCache():
+    requested(),
+    cache("clients")
+{
+    cache.open();
+}
+
+Core::ClientCache::~ClientCache() {
+    cache.close();
+}
+
+void Core::ClientCache::open() {
+    cache.open();}
+
+void Core::ClientCache::close() {
+    cache.close();}
+
+
+bool Core::ClientCache::checkClient(const QString& node, const QString& ver, const QString& hash) {
+    QString id = node + "/" + ver;
+    if (requested.count(id) == 0 && !cache.checkRecord(id)) {
+        Shared::ClientInfo& info = requested.insert(std::make_pair(id, Shared::ClientInfo())).first->second;
+        info.capabilitiesNode = node;
+        info.capabilitiesVerification = ver;
+        info.capabilitiesHash = hash;
+        emit requestClientInfo(id);
+        return false;
+    }
+
+    return true;
+}
+
+
+bool Core::ClientCache::registerClientInfo(const QString& sourceFullJid, const QString& id, const Shared::Identity& identity, const std::set<QString>& features) {
+
+}
diff --git a/core/components/clientcache.h b/core/components/clientcache.h
new file mode 100644
index 0000000..78c7e84
--- /dev/null
+++ b/core/components/clientcache.h
@@ -0,0 +1,56 @@
+// Squawk messenger. 
+// Copyright (C) 2019  Yury Gubich <blue@macaw.me>
+// 
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+// 
+// You should have received a copy of the GNU General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+#ifndef CORE_CLIENTCACHE_H
+#define CORE_CLIENTCACHE_H
+
+#include <map>
+#include <set>
+
+#include <QObject>
+#include <QString>
+
+#include <core/storage/cache.h>
+#include <shared/clientinfo.h>
+#include <shared/identity.h>
+
+namespace Core {
+
+class ClientCache : public QObject {
+    Q_OBJECT
+public:
+    ClientCache();
+    ~ClientCache();
+
+    void open();
+    void close();
+
+signals:
+    void requestClientInfo(const QString& id);
+
+public slots:
+    bool checkClient(const QString& node, const QString& ver, const QString& hash);
+    bool registerClientInfo(const QString& sourceFullJid, const QString& id, const Shared::Identity& identity, const std::set<QString>& features);
+
+private:
+    std::map<QString, Shared::ClientInfo> requested;
+    Cache<Shared::ClientInfo> cache;
+};
+
+}
+
+
+#endif // CORE_CLIENTCACHE_H
diff --git a/core/networkaccess.cpp b/core/components/networkaccess.cpp
similarity index 100%
rename from core/networkaccess.cpp
rename to core/components/networkaccess.cpp
diff --git a/core/networkaccess.h b/core/components/networkaccess.h
similarity index 98%
rename from core/networkaccess.h
rename to core/components/networkaccess.h
index 6ddfa99..c94c22a 100644
--- a/core/networkaccess.h
+++ b/core/components/networkaccess.h
@@ -30,8 +30,8 @@
 
 #include <set>
 
-#include "storage/urlstorage.h"
-#include "shared/pathcheck.h"
+#include <core/storage/urlstorage.h>
+#include <shared/pathcheck.h>
 
 namespace Core {
 
diff --git a/core/squawk.cpp b/core/squawk.cpp
index 0f8fe9f..5edcf58 100644
--- a/core/squawk.cpp
+++ b/core/squawk.cpp
@@ -28,9 +28,10 @@ Core::Squawk::Squawk(QObject* parent):
     amap(),
     state(Shared::Availability::offline),
     network(),
-    isInitialized(false)
+    isInitialized(false),
+    clientCache(),
 #ifdef WITH_KWALLET
-    ,kwallet()
+    kwallet()
 #endif
 {
     connect(&network, &NetworkAccess::loadFileProgress, this, &Squawk::fileProgress);
@@ -67,6 +68,7 @@ void Core::Squawk::stop()
 {
     qDebug("Stopping squawk core..");
     network.stop();
+    clientCache.close();
 
     if (isInitialized) {
         QSettings settings;
@@ -115,6 +117,7 @@ void Core::Squawk::start()
     readSettings();
     isInitialized = true;
     network.start();
+    clientCache.open();
 }
 
 void Core::Squawk::newAccountRequest(const QMap<QString, QVariant>& map)
@@ -180,6 +183,8 @@ void Core::Squawk::addAccount(
     connect(acc, &Account::receivedVCard, this, &Squawk::responseVCard);
     
     connect(acc, &Account::uploadFileError, this, &Squawk::onAccountUploadFileError);
+
+    connect(acc, &Account::infoDiscovered, this, &Squawk::onAccountInfoDiscovered);
     
     QMap<QString, QVariant> map = {
         {"login", login},
@@ -314,6 +319,27 @@ void Core::Squawk::onAccountAddPresence(const QString& jid, const QString& name,
 {
     Account* acc = static_cast<Account*>(sender());
     emit addPresence(acc->getName(), jid, name, data);
+
+    QString node = data["capabilityNode"].toString();
+    QString ver = data["capabilityVer"].toString();
+    QString hash = data["capabilityHash"].toString();
+    if (!clientCache.checkClient(node, ver, hash)) {
+        acc->discoverInfo(jid + "/" + name, node + "/" + ver);
+    }
+}
+
+void Core::Squawk::onAccountInfoDiscovered(
+    const QString& address,
+    const QString& node,
+    const std::list<Shared::Identity>& identities,
+    const std::set<QString>& features)
+{
+    Account* acc = static_cast<Account*>(sender());
+
+    if (identities.size() != 1 || clientCache.registerClientInfo(address, node, identities.back(), features)) {
+        qDebug() << "Account" << acc->getName() << "received an ill-formed client discovery response from" << address << "about" << node;
+        return;
+    }
 }
 
 void Core::Squawk::onAccountRemovePresence(const QString& jid, const QString& name)
diff --git a/core/squawk.h b/core/squawk.h
index 3b8073b..ea17cdf 100644
--- a/core/squawk.h
+++ b/core/squawk.h
@@ -32,9 +32,10 @@
 #include "shared/message.h"
 #include "shared/global.h"
 #include "shared/clientinfo.h"
-#include "networkaccess.h"
 #include "external/simpleCrypt/simplecrypt.h"
-#include <core/storage/cache.h>
+
+#include <core/components/clientcache.h>
+#include <core/components/networkaccess.h>
 
 #ifdef WITH_KWALLET
 #include "passwordStorageEngines/kwallet.h"
@@ -137,7 +138,7 @@ private:
     Shared::Availability state;
     NetworkAccess network;
     bool isInitialized;
-    //Cache<Shared::ClientInfo> clientCache;
+    ClientCache clientCache;
 
 #ifdef WITH_KWALLET
     PSE::KWallet kwallet;
@@ -181,6 +182,8 @@ private slots:
     
     void onWalletOpened(bool success);
     void onWalletRejectPassword(const QString& login);
+
+    void onAccountInfoDiscovered(const QString& address, const QString& node, const std::list<Shared::Identity>& identities, const std::set<QString>& features);
     
 private:
     void readSettings();
diff --git a/core/storage/CMakeLists.txt b/core/storage/CMakeLists.txt
index 5d34b7c..2da3c67 100644
--- a/core/storage/CMakeLists.txt
+++ b/core/storage/CMakeLists.txt
@@ -1,10 +1,10 @@
 target_sources(squawk PRIVATE
     archive.cpp
     archive.h
-    storage.cpp
+    storage.hpp
     storage.h
     urlstorage.cpp
     urlstorage.h
-    cache.cpp
+    cache.hpp
     cache.h
 )
diff --git a/core/storage/cache.h b/core/storage/cache.h
index e5b1b88..5091561 100644
--- a/core/storage/cache.h
+++ b/core/storage/cache.h
@@ -18,6 +18,7 @@
 #define CORE_CACHE_H
 
 #include <map>
+#include <set>
 
 #include <QString>
 
@@ -39,12 +40,16 @@ public:
     void changeRecord(const QString& key, const T& value);
     void removeRecord(const QString& key);
     T getRecord(const QString& key) const;
+    bool checkRecord(const QString& key) const;
 
 private:
     Core::Storage<T> storage;
     std::map<QString, T>* cache;
+    std::set<QString>* abscent;
 };
 
 }
 
+#include "cache.hpp"
+
 #endif // CORE_CACHE_H
diff --git a/core/storage/cache.cpp b/core/storage/cache.hpp
similarity index 60%
rename from core/storage/cache.cpp
rename to core/storage/cache.hpp
index 71fe369..1604d66 100644
--- a/core/storage/cache.cpp
+++ b/core/storage/cache.hpp
@@ -14,21 +14,21 @@
 // You should have received a copy of the GNU General Public License
 // along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
+#ifndef CORE_CACHE_HPP
+#define CORE_CACHE_HPP
 #include "cache.h"
 
-#include <shared/clientinfo.h>
-
-template class Core::Cache<Shared::ClientInfo>;
-
 template <class T>
 Core::Cache<T>::Cache(const QString& name):
     storage(name),
-    cache(new std::map<QString, T> ()) {}
+    cache(new std::map<QString, T> ()),
+    abscent(new std::set<QString> ()) {}
 
 template <class T>
 Core::Cache<T>::~Cache() {
     close();
     delete cache;
+    delete abscent;
 }
 
 template <class T>
@@ -43,27 +43,60 @@ template <class T>
 void Core::Cache<T>::addRecord(const QString& key, const T& value) {
     storage.addRecord(key, value);
     cache->insert(std::make_pair(key, value));
+    abscent->erase(key);
 }
 
 template <class T>
 T Core::Cache<T>::getRecord(const QString& key) const {
     typename std::map<QString, T>::const_iterator itr = cache->find(key);
     if (itr == cache->end()) {
-        T value = storage.getRecord(key);
-        itr = cache->insert(std::make_pair(key, value)).first;
+        if (abscent->count(key) > 0) {
+            throw Archive::NotFound(key, storage.getName().toStdString());
+        }
+
+        try {
+            T value = storage.getRecord(key);
+            itr = cache->insert(std::make_pair(key, value)).first;
+        } catch (const Archive::NotFound& error) {
+            abscent->insert(key);
+            throw error;
+        }
     }
 
     return itr->second;
 }
 
+template<class T>
+bool Core::Cache<T>::checkRecord(const QString& key) const {
+    typename std::map<QString, T>::const_iterator itr = cache->find(key);
+    if (itr != cache->end())
+        return true;
+
+    if (abscent->count(key) > 0)
+        return false;
+
+    try {
+        T value = storage.getRecord(key);
+        itr = cache->insert(std::make_pair(key, value)).first;
+    } catch (const Archive::NotFound& error) {
+        return false;
+    }
+
+    return true;
+}
+
 template<typename T>
 void Core::Cache<T>::changeRecord(const QString& key, const T& value) {
-    storage.changeRecord(key, value);
+    storage.changeRecord(key, value);   //there is a non straightforward behaviour: if there was no element at the sorage it will be added
     cache->at(key) = value;
+    abscent->erase(key);                //so... this line here is to make it coherent with the storage
 }
 
 template<typename T>
 void Core::Cache<T>::removeRecord(const QString& key) {
     storage.removeRecord(key);
     cache->erase(key);
+    abscent->insert(key);
 }
+
+#endif //CORE_CACHE_HPP
diff --git a/core/storage/storage.h b/core/storage/storage.h
index 5942c0f..5d6dabc 100644
--- a/core/storage/storage.h
+++ b/core/storage/storage.h
@@ -43,6 +43,7 @@ public:
     void changeRecord(const QString& key, const T& value);
     void removeRecord(const QString& key);
     T getRecord(const QString& key) const;
+    QString getName() const;
     
     
 private:
@@ -54,4 +55,6 @@ private:
 
 }
 
+#include "storage.hpp"
+
 #endif // CORE_STORAGE_H
diff --git a/core/storage/storage.cpp b/core/storage/storage.hpp
similarity index 97%
rename from core/storage/storage.cpp
rename to core/storage/storage.hpp
index 99db8af..48e334d 100644
--- a/core/storage/storage.cpp
+++ b/core/storage/storage.hpp
@@ -15,16 +15,14 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
+#ifndef CORE_STORAGE_HPP
+#define CORE_STORAGE_HPP
 
 #include <QStandardPaths>
 #include <QDir>
 
 #include "storage.h"
 
-#include <shared/clientinfo.h>
-
-template class Core::Storage<Shared::ClientInfo>;
-
 template <class T>
 Core::Storage<T>::Storage(const QString& p_name):
     name(p_name),
@@ -202,3 +200,9 @@ void Core::Storage<T>::removeRecord(const QString& key)
         mdb_txn_commit(txn);
     }
 }
+
+template <class T>
+QString Core::Storage<T>::getName() const {
+    return name;}
+
+#endif //CORE_STORAGE_HPP
diff --git a/main/main.cpp b/main/main.cpp
index 3368e0a..086dbc0 100644
--- a/main/main.cpp
+++ b/main/main.cpp
@@ -19,6 +19,7 @@
 #include "shared/global.h"
 #include "shared/messageinfo.h"
 #include "shared/pathcheck.h"
+#include "shared/identity.h"
 #include "main/application.h"
 #include "core/signalcatcher.h"
 #include "core/squawk.h"
@@ -39,6 +40,9 @@ int main(int argc, char *argv[])
     qRegisterMetaType<Shared::VCard>("Shared::VCard");
     qRegisterMetaType<std::list<Shared::Message>>("std::list<Shared::Message>");
     qRegisterMetaType<std::list<Shared::MessageInfo>>("std::list<Shared::MessageInfo>");
+    qRegisterMetaType<std::list<Shared::MessageInfo>>("std::list<QString>");
+    qRegisterMetaType<std::list<Shared::MessageInfo>>("std::set<QString>");
+    qRegisterMetaType<std::list<Shared::MessageInfo>>("std::list<Shared::Identity>");
     qRegisterMetaType<QSet<QString>>("QSet<QString>");
     qRegisterMetaType<Shared::ConnectionState>("Shared::ConnectionState");
     qRegisterMetaType<Shared::Availability>("Shared::Availability");
diff --git a/shared/CMakeLists.txt b/shared/CMakeLists.txt
index 1e47618..5828bd4 100644
--- a/shared/CMakeLists.txt
+++ b/shared/CMakeLists.txt
@@ -20,4 +20,5 @@ target_sources(squawk PRIVATE
   pathcheck.h
   clientinfo.h
   clientinfo.cpp
+  identity.h
   )
diff --git a/shared/clientinfo.cpp b/shared/clientinfo.cpp
index 745bd54..3a2f441 100644
--- a/shared/clientinfo.cpp
+++ b/shared/clientinfo.cpp
@@ -23,8 +23,14 @@ Shared::ClientInfo::ClientInfo():
     capabilitiesNode(),
     capabilitiesVerification(),
     capabilitiesHash(),
+    specificPresence(),
     capabilitiesExtensions() {}
 
+QString Shared::ClientInfo::getId() const {
+    return capabilitiesNode + "/" + capabilitiesVerification;
+}
+
+
 QDataStream & Shared::ClientInfo::operator >> (QDataStream& stream) const {
     stream << name;
     stream << category;
diff --git a/shared/clientinfo.h b/shared/clientinfo.h
index 742e49a..55dd29f 100644
--- a/shared/clientinfo.h
+++ b/shared/clientinfo.h
@@ -29,6 +29,8 @@ class ClientInfo
 public:
     ClientInfo();
 
+    QString getId() const;
+
     QDataStream& operator << (QDataStream& stream);
     QDataStream& operator >> (QDataStream& stream) const;
 
@@ -39,6 +41,7 @@ public:
     QString capabilitiesNode;
     QString capabilitiesVerification;
     QString capabilitiesHash;
+    QString specificPresence;
     std::set<QString> capabilitiesExtensions;
 };
 
diff --git a/shared/identity.h b/shared/identity.h
new file mode 100644
index 0000000..6041e1a
--- /dev/null
+++ b/shared/identity.h
@@ -0,0 +1,35 @@
+/*
+ * Squawk messenger.
+ * Copyright (C) 2019  Yury Gubich <blue@macaw.me>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef SHARED_IDENTITY_H
+#define SHARED_IDENTITY_H
+
+#include <QString>
+
+namespace Shared {
+
+struct Identity {
+    QString category;
+    QString language;
+    QString name;
+    QString type;
+};
+
+}
+
+#endif //SHARED_IDENTITY_H