diff --git a/.gitmodules b/.gitmodules
index 9fa5939f53..a02a5fe232 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -271,6 +271,10 @@
 	path = Sming/Libraries/UPnP
 	url = https://github.com/mikee47/Sming-UPnP
 	ignore = dirty
+[submodule "Sming/Libraries/UPnP-Schema"]
+	path = Sming/Libraries/UPnP-Schema
+	url = https://github.com/mikee47/UPnP-Schema
+	ignore = dirty
 [submodule "Libraries.VT100"]
 	path = Sming/Libraries/VT100
 	url = https://github.com/mikee47/VT100
diff --git a/Sming/Core/Data/Stream/MemoryDataStream.cpp b/Sming/Core/Data/Stream/MemoryDataStream.cpp
index 88f26fcaea..03d700ff0a 100644
--- a/Sming/Core/Data/Stream/MemoryDataStream.cpp
+++ b/Sming/Core/Data/Stream/MemoryDataStream.cpp
@@ -21,6 +21,10 @@ MemoryDataStream::MemoryDataStream(String&& string) noexcept
 bool MemoryDataStream::ensureCapacity(size_t minCapacity)
 {
 	if(capacity < minCapacity) {
+		if(minCapacity > maxCapacity) {
+			debug_e("MemoryDataStream too large, requested %u limit is %u", minCapacity, maxCapacity);
+			return false;
+		}
 		size_t newCapacity = minCapacity;
 		if(capacity != 0) {
 			// If expanding stream, increase buffer capacity in anticipation of further writes
@@ -30,6 +34,7 @@ bool MemoryDataStream::ensureCapacity(size_t minCapacity)
 		// realloc can fail, store the result in temporary pointer
 		auto newBuffer = (char*)realloc(buffer, newCapacity);
 		if(newBuffer == nullptr) {
+			debug_e("MemoryDataStream realloc(%u) failed", newCapacity);
 			return false;
 		}
 
diff --git a/Sming/Core/Data/Stream/MemoryDataStream.h b/Sming/Core/Data/Stream/MemoryDataStream.h
index f8e7016df1..75a1f06607 100644
--- a/Sming/Core/Data/Stream/MemoryDataStream.h
+++ b/Sming/Core/Data/Stream/MemoryDataStream.h
@@ -26,7 +26,9 @@
 class MemoryDataStream : public ReadWriteStream
 {
 public:
-	MemoryDataStream() = default;
+	MemoryDataStream(size_t maxCapacity = UINT16_MAX) : maxCapacity(maxCapacity)
+	{
+	}
 
 	/**
 	 * @brief Stream takes ownership of String content using move semantics
@@ -103,8 +105,9 @@ class MemoryDataStream : public ReadWriteStream
 	}
 
 private:
-	char* buffer = nullptr; ///< Stream content stored here
-	size_t readPos = 0;		///< Offset to current read position
-	size_t size = 0;		///< Number of bytes stored in stream (i.e. the write position)
-	size_t capacity = 0;	///< Number of bytes allocated in buffer
+	char* buffer = nullptr;			///< Stream content stored here
+	size_t maxCapacity{UINT16_MAX}; ///< Limit size of stream
+	size_t readPos = 0;				///< Offset to current read position
+	size_t size = 0;				///< Number of bytes stored in stream (i.e. the write position)
+	size_t capacity = 0;			///< Number of bytes allocated in buffer
 };
diff --git a/Sming/Core/Data/Stream/ReadWriteStream.h b/Sming/Core/Data/Stream/ReadWriteStream.h
index 8672f0d76c..0cdef21026 100644
--- a/Sming/Core/Data/Stream/ReadWriteStream.h
+++ b/Sming/Core/Data/Stream/ReadWriteStream.h
@@ -24,6 +24,8 @@ class ReadWriteStream : public IDataSourceStream
 		return write(&charToWrite, 1);
 	}
 
+	using Print::write;
+
 	/** @brief  Write chars to stream
      *  @param  buffer Pointer to buffer to write to the stream
      *  @param  size Quantity of chars to write
diff --git a/Sming/Libraries/HueEmulator b/Sming/Libraries/HueEmulator
index 015fc4bab6..20553f6e9e 160000
--- a/Sming/Libraries/HueEmulator
+++ b/Sming/Libraries/HueEmulator
@@ -1 +1 @@
-Subproject commit 015fc4bab6830b24c0d84a04bb70125160aa5513
+Subproject commit 20553f6e9e223588595e626fc7aa060847df57eb
diff --git a/Sming/Libraries/RapidXML b/Sming/Libraries/RapidXML
index c8106482bc..0b56a775b7 160000
--- a/Sming/Libraries/RapidXML
+++ b/Sming/Libraries/RapidXML
@@ -1 +1 @@
-Subproject commit c8106482bc4665ebb7dceb06f8b7d3ada1d1b744
+Subproject commit 0b56a775b7b3603631734506be4984f094df3685
diff --git a/Sming/Libraries/SSDP b/Sming/Libraries/SSDP
index 357a95ea3e..835b7f68e3 160000
--- a/Sming/Libraries/SSDP
+++ b/Sming/Libraries/SSDP
@@ -1 +1 @@
-Subproject commit 357a95ea3ee1fca39b76405387ba37232e0bcfe5
+Subproject commit 835b7f68e33e6f809c0d8b66d98b7aa2b1ef7988
diff --git a/Sming/Libraries/UPnP b/Sming/Libraries/UPnP
index e231503b53..011f5a7679 160000
--- a/Sming/Libraries/UPnP
+++ b/Sming/Libraries/UPnP
@@ -1 +1 @@
-Subproject commit e231503b5398a408bfb8922c4d87a9ecd12f6db2
+Subproject commit 011f5a7679cc402fba8a357044cb7a53dcae067a
diff --git a/Sming/Libraries/UPnP-Schema b/Sming/Libraries/UPnP-Schema
new file mode 160000
index 0000000000..6ec36bfd4d
--- /dev/null
+++ b/Sming/Libraries/UPnP-Schema
@@ -0,0 +1 @@
+Subproject commit 6ec36bfd4d0e9b945f0997a2c15643e0da7ae619
diff --git a/Sming/Wiring/FIFO.h b/Sming/Wiring/FIFO.h
index 2ea887d19c..a86a35d9a9 100644
--- a/Sming/Wiring/FIFO.h
+++ b/Sming/Wiring/FIFO.h
@@ -73,8 +73,10 @@ template <typename T, int rawSize> bool FIFO<T, rawSize>::enqueue(T element)
 	}
 	numberOfElements++;
 	raw[nextIn] = element;
-	if(++nextIn >= rawSize) // advance to next index, wrap if needed
+	// advance to next index, wrap if needed
+	if(++nextIn >= rawSize) {
 		nextIn = 0;
+	}
 	return true;
 }
 
diff --git a/Sming/build.mk b/Sming/build.mk
index 532fd7bac9..7eec599237 100644
--- a/Sming/build.mk
+++ b/Sming/build.mk
@@ -249,14 +249,30 @@ define IsSubDir
 $(if $(subst $(1:/=),,$(2:/=)),$(findstring $(1:/=),$2),)
 endef
 
+# List sub-directories recursively for a single root directory
+# Results are sorted and without trailing path separator
+# Sub-directories with spaces are skipped
+# $1 -> Root path
+define ListAllSubDirsSingle
+$(foreach d,$(dir $(wildcard $1/*/.)),$(if $(call IsSubDir,$1,$d),$(d:/=) $(call ListAllSubDirs,$(d:/=))))
+endef
+
 # List sub-directories recursively for a list of root directories
 # Results are sorted and without trailing path separator
 # Sub-directories with spaces are skipped
 # $1 -> Root paths
 define ListAllSubDirs
-$(foreach d,$(dir $(wildcard $1/*/.)),$(if $(call IsSubDir,$1,$d),$(d:/=) $(call ListAllSubDirs,$(d:/=))))
+$(foreach d,$1,$(call ListAllSubDirsSingle,$d))
 endef
 
+# Recursively search list of directories for matching files
+# $1 -> Directories to scan
+# $2 -> Filename filter
+define ListAllFiles
+$(wildcard $(foreach d,$(call ListAllSubDirs,$1),$d/$2))
+endef
+
+
 # Display variable and list values, e.g. $(call PrintVariable,LIBS)
 # $1 -> Name of variable containing values
 define PrintVariable
@@ -276,6 +292,11 @@ define PrintVariableRefs
 	$(foreach item,$(sort $($1)),$(info - $(item) = $(value $(item))) )
 endef
 
+#
+# Get directory without trailing separator
+# $1 -> List of directories
+dirx = $(patsubst %/,%,$(dir $1))
+
 # Extract commented target information from makefiles and display
 # Based on code from https://suva.sh/posts/well-documented-makefiles/
 define PrintHelp
diff --git a/Sming/building.rst b/Sming/building.rst
index 65fc2bdd65..611ed8c17b 100644
--- a/Sming/building.rst
+++ b/Sming/building.rst
@@ -468,6 +468,14 @@ These values are for reference only and should not be modified.
    This should be used if the Component provides any application code or targets to ensure it is
    built in the correct directory (but not by this makefile).
 
+   This value changes depending on the build variant.
+
+.. envvar:: COMPONENT_BUILD_BASE
+
+   This value does not change with build variant.
+
+   If the Component generates source code, for example, it can be placed here (in a sub-directory).
+
 .. envvar:: COMPONENT_LIBDIR
 
    Location to store created Component (shared) libraries
@@ -500,6 +508,11 @@ changed as required.
    If targets should be built for each application, use :envvar:`CUSTOM_TARGETS` instead.
    See :component:`spiffs` for an example.
 
+.. envvar:: COMPONENT_PREREQUISITES
+
+   These targets will be built before anything else. If your library generates source code,
+   for example, then it should be done by setting this value to the appropriate targets.
+
 .. envvar:: COMPONENT_RULE
 
    This is a special value used to prefix any custom targets which are to be built as
diff --git a/Sming/project.mk b/Sming/project.mk
index 7c3aaa844c..b7ee31eed9 100644
--- a/Sming/project.mk
+++ b/Sming/project.mk
@@ -160,9 +160,11 @@ COMPONENT_INCDIRS		:= include
 COMPONENT_NAME			:= $1
 COMPONENT_LIBNAME		:= $1
 CMP_$1_BUILD_BASE		:= $3/$1
+COMPONENT_BUILD_BASE	:= $$(CMP_$1_BUILD_BASE)
 COMPONENT_BUILD_DIR		:= $$(CMP_$1_BUILD_BASE)
 COMPONENT_VARS			:=
 COMPONENT_RELINK_VARS	:=
+COMPONENT_PREREQUISITES	:=
 COMPONENT_TARGETS		:=
 COMPONENT_DEPENDS		:=
 COMPONENT_PYTHON_REQUIREMENTS		:= $$(wildcard $2/requirements.txt)
@@ -184,6 +186,7 @@ LIBS					+= $$(EXTRA_LIBS)
 CMP_$1_LDFLAGS			:= $$(EXTRA_LDFLAGS)
 LDFLAGS					+= $$(CMP_$1_LDFLAGS)
 endif
+CMP_$1_PREREQUISITES	:= $$(COMPONENT_PREREQUISITES)
 CMP_$1_TARGETS			:= $$(COMPONENT_TARGETS)
 CMP_$1_BUILD_DIR		:= $$(COMPONENT_BUILD_DIR)
 CMP_$1_LIBNAME			:= $$(COMPONENT_LIBNAME)
@@ -266,7 +269,7 @@ $(foreach c,$(COMPONENTS),$(eval $(call ResolveDependencies,$c)))
 # $1 => Component name
 define CheckComponentMatches
 ifneq ($1,Sming)
-COMPONENT_MATCHES := $(filter %/$1,$(ALL_COMPONENT_DIRS))
+COMPONENT_MATCHES := $(sort $(filter %/$1,$(ALL_COMPONENT_DIRS)))
 ifeq ($$(words $$(COMPONENT_MATCHES)),0)
 $$(warning No matches found for Component '$1')
 else ifneq ($$(words $$(COMPONENT_MATCHES)),1)
@@ -362,6 +365,7 @@ $1-build: $(addsuffix -build,$(filter $(CMP_$1_DEPENDS),$(BUILDABLE_COMPONENTS))
 	+$(Q) $(MAKE) -r -R --no-print-directory -C $(CMP_$1_BUILD_DIR) -f $(SMING_HOME)/component-wrapper.mk \
 		COMPONENT_NAME=$1 \
 		COMPONENT_PATH=$(CMP_$1_PATH) \
+		COMPONENT_BUILD_BASE=$(CMP_$1_BUILD_BASE) \
 		COMPONENT_LIBDIR=$(CMP_$1_LIBDIR) \
 		COMPONENT_LIBNAME=$(CMP_$1_LIBNAME) \
 		COMPONENT_LIBHASH=$(CMP_$1_LIBHASH) \
@@ -432,9 +436,12 @@ checkdirs: | $(BUILD_BASE) $(FW_BASE) $(TOOLS_BASE) $(APP_LIBDIR) $(USER_LIBDIR)
 $(BUILD_BASE) $(FW_BASE) $(TOOLS_BASE) $(APP_LIBDIR) $(USER_LIBDIR):
 	$(Q) mkdir -p $@
 
+# Targets to be built before anything else (e.g. source code generators)
+PREREQUISITES := $(foreach c,$(COMPONENTS),$(CMP_$c_PREREQUISITES))
+
 # Build all Component (user) libraries
 .PHONY: components
-components: $(ALL_COMPONENT_TARGETS) $(CUSTOM_TARGETS)
+components: $(PREREQUISITES) $(ALL_COMPONENT_TARGETS) $(CUSTOM_TARGETS)
 
 ##@Cleaning
 
@@ -523,6 +530,7 @@ list-config: ##Print the contents of build variables
 	$(info ** Sming build configuration **)
 	$(info )
 	$(if $(V),$(call PrintVariable,MAKEFILE_LIST))
+	$(call PrintVariableSorted,PREREQUISITES)
 	$(call PrintVariableSorted,CUSTOM_TARGETS)
 	$(call PrintVariableSorted,LIBS)
 	$(call PrintVariableSorted,ARDUINO_LIBRARIES)