diff --git a/CMakeLists.txt b/CMakeLists.txt
index 8c9cf983..f8f76c8c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -184,6 +184,7 @@ logic/ModList.h
 # network stuffs
 logic/net/DownloadJob.h
 logic/net/NetWorker.h
+logic/net/HttpMetaCache.h
 
 # legacy instances
 logic/LegacyInstance.h
@@ -251,6 +252,7 @@ logic/ModList.cpp
 # network stuffs - to be moved into a depend lib ~_~
 logic/net/NetWorker.cpp
 logic/net/DownloadJob.cpp
+logic/net/HttpMetaCache.cpp
 
 # legacy instances
 logic/LegacyInstance.cpp
diff --git a/logic/net/DownloadJob.cpp b/logic/net/DownloadJob.cpp
index 5c8ed4b9..b87d3dc9 100644
--- a/logic/net/DownloadJob.cpp
+++ b/logic/net/DownloadJob.cpp
@@ -143,10 +143,12 @@ void DownloadJob::partSucceeded ( int index )
 	{
 		if(num_failed)
 		{
+			qDebug() << "Download JOB failed: " << this;
 			emit failed();
 		}
 		else
 		{
+			qDebug() << "Download JOB succeeded: " << this;
 			emit succeeded();
 		}
 	}
@@ -157,14 +159,8 @@ void DownloadJob::partFailed ( int index )
 	num_failed++;
 	if(num_failed + num_succeeded == downloads.size())
 	{
-		if(num_failed)
-		{
-			emit failed();
-		}
-		else
-		{
-			emit succeeded();
-		}
+		qDebug() << "Download JOB failed: " << this;
+		emit failed();
 	}
 }
 
@@ -176,6 +172,7 @@ void DownloadJob::partProgress ( int index, qint64 bytesReceived, qint64 bytesTo
 
 void DownloadJob::start()
 {
+	qDebug() << "Download JOB started: " << this;
 	for(auto iter: downloads)
 	{
 		connect(iter.data(), SIGNAL(succeeded(int)), SLOT(partSucceeded(int)));
diff --git a/logic/net/HttpMetaCache.cpp b/logic/net/HttpMetaCache.cpp
new file mode 100644
index 00000000..87741dc9
--- /dev/null
+++ b/logic/net/HttpMetaCache.cpp
@@ -0,0 +1,131 @@
+#include "HttpMetaCache.h"
+#include <pathutils.h>
+#include <QFile>
+#include <qjsondocument.h>
+#include <qjsonarray.h>
+#include <qjsonobject.h>
+#include <qfileinfo.h>
+#include <qtemporaryfile.h>
+#include <qsavefile.h>
+
+HttpMetaCache::HttpMetaCache(QString path)
+{
+	m_index_file = path;
+}
+HttpMetaCache::~HttpMetaCache()
+{
+	Save();
+}
+
+void HttpMetaCache::addEntry ( QString base, QString resource_path, QString etag )
+{
+	// no base. no base path. can't store
+	if(!m_entries.contains(base))
+		return;
+	QString real_path = PathCombine(m_entries[base].base_path, resource_path);
+	QFileInfo finfo(real_path);
+	
+	// just ignore it, it's garbage if it's not a proper file
+	if(!finfo.isFile() || !finfo.isReadable())
+	{
+		// TODO: log problem
+		return;
+	}
+	
+	Save();
+}
+
+void HttpMetaCache::addBase ( QString base, QString base_root )
+{
+	// TODO: report error
+	if(m_entries.contains(base))
+		return;
+	// TODO: check if the base path is valid
+	EntryMap foo;
+	foo.base_path = base_root;
+	m_entries[base] = foo;
+}
+
+void HttpMetaCache::Load()
+{
+	QFile index(m_index_file);
+	if(!index.open(QIODevice::ReadOnly))
+		return;
+	
+	QJsonDocument json = QJsonDocument::fromJson(index.readAll());
+	if(!json.isObject())
+		return;
+	auto root = json.object();
+	// check file version first
+	auto version_val =root.value("version");
+	if(!version_val.isString())
+		return;
+	if(version_val.toString() != "1")
+		return;
+	
+	// read the entry array
+	auto entries_val =root.value("entries");
+	if(!version_val.isArray())
+		return;
+	QJsonArray array = json.array();
+	for(auto element: array)
+	{
+		if(!element.isObject());
+			return;
+		auto element_obj = element.toObject();
+		QString base = element_obj.value("base").toString();
+		if(!m_entries.contains(base))
+			continue;
+		auto & entrymap = m_entries[base];
+		auto foo = new MetaEntry;
+		foo->base = base;
+		QString path = foo->path = element_obj.value("path").toString();
+		foo->md5sum = element_obj.value("md5sum").toString();
+		foo->etag = element_obj.value("etag").toString();
+		foo->last_changed_timestamp = element_obj.value("last_changed_timestamp").toDouble();
+		entrymap.entry_list[path] = MetaEntryPtr( foo );
+	}
+}
+
+void HttpMetaCache::Save()
+{
+	QSaveFile tfile(m_index_file);
+	if(!tfile.open(QIODevice::WriteOnly | QIODevice::Truncate))
+		return;
+	QJsonObject toplevel;
+	toplevel.insert("version",QJsonValue(QString("1")));
+	QJsonArray entriesArr;
+	for(auto group : m_entries)
+	{
+		for(auto entry : group.entry_list)
+		{
+			QJsonObject entryObj;
+			entryObj.insert("base", QJsonValue(entry->base));
+			entryObj.insert("path", QJsonValue(entry->path));
+			entryObj.insert("md5sum", QJsonValue(entry->md5sum));
+			entryObj.insert("etag", QJsonValue(entry->etag));
+			entryObj.insert("last_changed_timestamp", QJsonValue(double(entry->last_changed_timestamp)));
+			entriesArr.append(entryObj);
+		}
+	}
+	toplevel.insert("entries",entriesArr);
+	QJsonDocument doc(toplevel);
+	QByteArray jsonData = doc.toJson();
+	qint64 result = tfile.write(jsonData);
+	if(result == -1)
+		return;
+	if(result != jsonData.size())
+		return;
+	tfile.commit();
+}
+
+
+MetaEntryPtr HttpMetaCache::getEntryForResource ( QString base, QString resource_path )
+{
+	if(!m_entries.contains(base))
+		return MetaEntryPtr();
+	auto & entrymap = m_entries[base];
+	if(!entrymap.entry_list.contains(resource_path))
+		return MetaEntryPtr();
+	return entrymap.entry_list[resource_path];
+}
diff --git a/logic/net/HttpMetaCache.h b/logic/net/HttpMetaCache.h
new file mode 100644
index 00000000..161483ad
--- /dev/null
+++ b/logic/net/HttpMetaCache.h
@@ -0,0 +1,36 @@
+#pragma once
+#include <QString>
+#include <QSharedPointer>
+#include <QMap>
+
+struct MetaEntry
+{
+	QString base;
+	QString path;
+	QString md5sum;
+	QString etag;
+	quint64 last_changed_timestamp = 0;
+};
+
+typedef QSharedPointer<MetaEntry> MetaEntryPtr;
+
+class HttpMetaCache
+{
+public:
+	// supply path to the cache index file
+	HttpMetaCache(QString path);
+	~HttpMetaCache();
+	MetaEntryPtr getEntryForResource(QString base, QString resource_path);
+	void addEntry(QString base, QString resource_path, QString etag);
+	void addBase(QString base, QString base_root);
+private:
+	void Save();
+	void Load();
+	struct EntryMap
+	{
+		QString base_path;
+		QMap<QString, MetaEntryPtr> entry_list;
+	};
+	QMap<QString, EntryMap> m_entries;
+	QString m_index_file;
+};
\ No newline at end of file