As described in this document(https://developers.google.com/protocol-buffers/docs/reference/java/com/google/protobuf/Message.Builder.html#buildPartial--) Like MessageLite.Builder.build(), but does not throw an exception if the message is missing required fields. Instead, a partial message is returned
I guess that's a legacy API from proto2? since required keyword is removed in proto3, but they're not marking this API as deprecated, then in which case we should use this?
This allows to easily supply class instance to the unit test environment. Allowing to avoid complex mocking/class construction.
I'm trying to marshal an interface to another thread.
Windows provides the convenient CoMarshalInterThreadInterfaceInStream helper function to take care of the boilerplate code associated with using CoMarshalInterface directly.
const Guid CLSID_Widget = "{F8383852-FCD3-11d1-A6B9-006097DF5BD4}";
const Guid IID_IWidget = "{EBBC7C04-315E-11D2-B62F-006097DF5BD4}";
//Create our widget
HRESULT hr = CoCreateInstance(CLSID_Widget, null,
CLSCTX_INPROC_SERVER | CLSCTX_LOCAL_SERVER,
IID_IWidget, out widget);
OleCheck(hr);
//Marshall the interface into an IStream
IStream stm;
hr = CoMarshalInterThreadInterfaceInStream(IID_IWidget, widget, out stm);
OleCheck(hr);
Except that the call to CoMarshalThreadInterfaceInStream fails with:
REGDB_E_IIDNOTREG (0x80040155)
Interface not registered
Go directly to CoMarshalInterface
The COM API function CoMarshalInterThreadInterfaceInStream provides a simple wrapper around CreateStreamOnHGlobal and CoMarshalInterface, as shown here:
// from OLE32.DLL (approx.)
HRESULT CoMarsha1InterThreadInterfaceInStream(
REFIID riid, IUnknown *pItf, IStream **ppStm)
{
HRESULT hr = CreateStreamOnHGlobal(0, TRUE, ppStm);
if (SUCCEEDED(hr))
hr = CoMarshalInterface(*ppStm, riid, pItf,
MSHCTX_INPROC, 0, MSHLFLAGS_NORMAL);
return hr;
}
So we can try ourselves.
IStream stm = new Stream()
hr = CoMarshallInterface(stm, IID_IWidget, widget,
MSHCTX_INPROC, // destination context is in-process/same host
NULL, // reserved, must be null
MSHLFLAGS_NORMAL // marshal once, unmarshal once
);
OleCheck(hr);
But that fails with:
REGDB_E_IIDNOTREG (0x80040155)
Interface not registered
Use standard marshaling
My class does not implement IMarhsal interface. This is right and normal.
By default, when CoMarshalInterface is first called on an object, the object is asked whether it wishes to handle its own cross-apartment communications. This question comes in the form of a QueryInterface request for the IMarshal interface. Most objects do not implement the IMarshal interface and fail this
QueryInterface request, indicating that they are perfectly happy to let COM
handle all communications via ORPC calls. Objects that do implement the
IMarshal interface are indicating that ORPC is inappropriate and that the object implementor would prefer to handle all cross-apartment communications
via a custom proxy. When an object implements the IMarshalinterface all references to the object will be custom marshaled.
When an object does not implement the IMarshal interface, all references to the object will be standard marshaled. Most objects elect to use standard marshaling.
So the the question becomes why is the standard COM marshaler having so much problems? What is the source of the error Interface not registered?
The interface is, in fact, not registered
The requires for COM are undocumented, but i can tell you that my interface GUID does not exist in:
HKEY_CLASSES_ROOT\Interface\{EBBC7C04-315E-11D2-B62F-006097DF5BD4}
The reason for this will be explained at the end.
I know that Windows provides you the CoRegisterPSClsid function that allows you to register an interface inside your process, so that the standard marshaler will be able to marshal it:
Enables a downloaded DLL to register its custom interfaces within its running process so that the marshaling code will be able to marshal those interfaces.
HRESULT CoRegisterPSClsid(
_In_ REFIID riid,
_In_ REFCLSID rclsid
);
Parameters:
riid [in]: A pointer to the IID of the interface to be registered.
rclsid [in]: A pointer to the CLSID of the DLL that contains the proxy/stub code for the custom interface specified by riid.
Which i can try calling, but what clsid do i use?
CoRegisterPSClsid(IID_IWidget, ???);
What is the CLSID of the DLL that contains the proxy/stub code for the custom interface specified by riid? Do i use my class itself?
CoRegisterPSClsid(IID_IWidget, CLSID_Widget);
That doesn't sound right; but i don't understand the COM standard marshaler well enough. Doesn't that CLSID have to be one of the standard COM marsharling classes; implementing IPSFactoryBuffer?
Either way, it doesn't work. I still get the error "Interface not registered".
Register the interface
I of course can register my interface in the registry:
HKEY_CURRENT_USER\Software\Classes\Interface\{EBBC7C04-315E-11D2-B62F-006097DF5BD4}
(default) = "IWidget"
But that doesn't fix it. Spelunking through the Interface registry keys, i notice that many specify a ProxyStubClsid32 entry.
When a new interface is requested on an object, the proxy and stub managers
must resolve the requested IID onto the CLSID of the interface marshaler.
Under Windows NT 5.0, the class store maintains these mappings in the NT
directory, and they are cached at each host machine in the local registry. The
machine-wide IID-to-CLSID mappings are cached at
HKEY_CLASSES_ROOT\Interface
and the per-user mappings are cached at
HKEY_CURRENT_USER\Software\Classes\Interface
One or both of these keys will contain a subkey for each known interface. If the interface has an interface marshaler installed, there will be an additional
subkey (ProxyStubClsid32) that indicates the CLSID of the interface
marshaler.
Except what class implements marshaling? I don't have a marshaler.
Can COM automatically marshal based on a TypeLibrary
Is it possible that if i register a Type Library with my Interface, that COM's standard marshaler will be able to bootstrap a proxy class on the fly?
I registered my interface above. Now i manually include the TypeLibrary:
HKEY_CURRENT_USER\Software\Classes\Interface\{EBBC7C04-315E-11D2-B62F-006097DF5BD4}\TypeLib
(default) = "{38D528BD-4948-4F28-8E5E-141A51090580}"
And if i monitor the registry during the call to CoMarshalInterface i see that it attempts, and does find, my Interface IID:
Operation: RegOpenKey
Path: HKCR\WOW6432Node\Interface\{EBBC7C04-315E-11D2-B62F-006097DF5BD4}
Result: SUCCESS
It then tries to look for a ProxyStubClsid32, and fails:
Operation: RegOpenKey
Path: HKCR\WOW6432Node\Interface\{668790E3-83CC-47E0-907F-A44BA9A99C8D}\ProxyStubClsid32
Result: NAME NOT FOUND
My hope would then be that the standard COM marshaler attempts to look for:
Operation: RegOpenKey
Path: HKCR\WOW6432Node\Interface\{668790E3-83CC-47E0-907F-A44BA9A99C8D}\TypeLib
But it doesn't.
The OLE Automation marshaler
According to Don Box, the Ole Automation marshaler (PSOAInterface - {00020424-0000-0000-C000-000000000046}) is able to build a stub/proxy out of a type library:
The Type Library Marshaler
When these specially annotated interfaces are encountered by RegisterTypeLib (or LoadTypeLib in legacy mode), COM adds ProxyStubClsid32 entries for the interface with the value {00020424-0000-0000-C0000-000000000046}. This GUID corresponds to the class PSOAInterface that is registered as living in OLEAUT32.DLL, the OLE automation DLL. Because of the DLL that it lives in, this marshaler is sometimes called the [oleautomation] marshaler, although it is also called the type library marshaler or the universal marshaler. I'll refer to it as the type library marshaler, since it really has very little to do with IDispatch. (In fact, it is common to use the [oleautomation] attribute on interfaces that don't derive from IDispatch directly or indirectly.)
The class factory for the type library marshaler does something very tricky in its CreateProxy and CreateStub routines. Rather than return a statically compiled vtable (which is impossible given the fact that the requested interface didn't exist when OLEAUT32.DLL was built as part of the OS), the type library marshaler actually builds an /Oicf-style proxy and stub based on the type library for the interface. Because there is no efficient way to find the ITypeInfo for an arbitrary interface, the LIBID and version of the interface's type library must be stored under the:
HKCR\Interface\{XXX}\TypeLib
registry key.
I tried to set PSOAInterface as my interface's ProxyStub class:
Register standard COM class PSOAInterface as our proxy stub clsid
HKEY_CURRENT_USER\Software\Classes\Interface\{EBBC7C04-315E-11D2-B62F-006097DF5BD4}\ProxyStubClsid32
(default) = "{00020424-0000-0000-C0000-000000000046}"
Register our type library for our interface
HKEY_CURRENT_USER\Software\Classes\Interface\{EBBC7C04-315E-11D2-B62F-006097DF5BD4}\TypeLib
(default) = "{38D528BD-4948-4F28-8E5E-141A51090580}"
Version = "1.0"
The type library itself is already registered:
HKEY_CURRENT_USER\Software\TypeLib\{38D528BD-4948-4F28-8E5E-141A51090580}\1.0\0\win32
(default) = "D:\Junk\ComLibraryProxyTest\Win32\Project1.dll"
But it still fails.
it reads HKCR\Interface\[IID_IWidget]
it reads HKCR\Interface\[IID_IWidget]\ProxyStubClsid32
But it:
never reads: HKCR\Interface\[IID_IWidget]\TypeLib
So it fails to proxy the object.
Questions
Is it possible for the standard COM "Ole Automation" marshaler to build a proxy class out of a Type Library at runtime?
Is it possible for me to build a proxy class out of a Type Library at runtime?
Background
CoMarshalInterface takes an interface pointer on input and writes the
serialized representation of the pointer to a caller-provided byte stream. This byte stream can then be passed to another apartment, where the
CoUnmarshalInterface API function uses the byte stream to return an interface
pointer that is semantically equivalent to the original object yet can be
legally accessed in the apartment that executes the CoUnmarshalInterface
call. When calling CoMarshalInterface, the caller must indicate how far away
the importing apartment is expected to be. COM defines an enumeration for
expressing this distance:
enum MSHCTX {
MSHCTX_INPROC = 4, // in-process/same host
MSHCTX_LOCAL = 0, // out-of-process/same host
MSHCTX_NOSHAREDMEM = 1, //16/32 bit/same host
MSHCTX_DIFFERENTMACHINE = 2, // off-host
};
It is legal to specify a greater distance than required, but it is more efficient
to use the correct MSHCTX when possible. CoMarshalInterface also allows
the caller to specify the marshaling semantics using the following marshal flags:
enum MSHLFLAGS {
MSHLFLAGS_NORMAL, // marshal once, unmarshal once
MSHLFLAGS_TABLESTRONG, // marshal once, unmarshal many
MSHLFLAGS_TABLEWEAK, // marshal once, unmarshal many
MSHLFlAGS_NOPING = 4 // suppress dist. garbage collection
Normal marshaling (sometimes called call marshaling) indicates that the
marshaled object reference must be unmarshaled only once, and if additional
proxies are needed, additional calls to CoMarshalInterface are required. Table
marshaling indicates that the marshaled object reference may be unmarshaled
zero or more times without requiring additional calls to CoMarshalInterface.
I think that all COM object type libraries, when compiled by MIDL, can automatically create a proxy/stub factory. But in my case:
if the COM standard marshaler can't find a proxy/stub factory for an interface, it returns the error REGDB_E_IIDNOTREG.
It may be the case that i have to either:
use CreateProxyFromTypeInfo and CreateStubFromTypeInfo to create my own proxy
let the standard COM marshaler automatically create a proxy/stub if there's a typeinfo chunk associated with the interface GUID.
Bonus Reading
Old New Thing: What are the rules for CoMarshalInterThreadInterfaceInStream and CoGetInterfaceAndReleaseStream?
Old New Thing: Why do I get the error REGDB_E_IIDNOTREG when I call a method that returns an interface?
Old New Thing: Why do I get E_NOINTERFACE when creating an object that supports that interface?
Don Box - MSJ: Standard Marshalling in COM (archive)
Mysterious disappearing acts by samples from Microsoft SDKs
What CoMarshalInterface actually needs is IMarshal implementation (pointer) for the given interface, so that API could request the marshaling magic from it and, in particular, request IMarshal::GetUnmarshalClass in order to obtain information who is going to do the reverse magic afterwards:
This method is called indirectly, in a call to CoMarshalInterface, by whatever code in the server process is responsible for marshaling a pointer to an interface on an object. This marshaling code is usually a stub generated by COM for one of several interfaces that can marshal a pointer to an interface implemented on an entirely different object.
You don't have IMarshal implemented on your widget, so you are going to get it somewhere from.
As you started your question mentioning that you "want to marshal an interface to another thread" and the code comment says "Create our widget" there is a chance that you can utilize IMarhsal implementation of free threaded marshaler. The question does not provide information to tell whether it is possible and/or acceptable solution.
Back to the challenge of obtaining a marshaler, you are trying to work this around by utilizing a "standard" marshaler by "registering the interface":
why is the standard COM marshaler having so much problems
[...]
I of course can register my interface in the registry
Well, this is not how things actually work.
Interface registration is not just a registry key that "okay, this IID has its own key in the registry". The purpose of such registration is to point where to look for proxy/stub pair for this interface. Your manual creating of registry entries cannot help here if you don't have a proxy/stub DLL for the interface in question. If you had it, you would just regsvr32 it the usual way to create the registry keys.
So called standard marshaler, your next try, is not supposed to marshal any interface and your IWidget in particular. OLE supplies so called "PSOAInterface" marshaler, which is capable of supplying proxy/stub pairs for OLE Automation compatible interfaces. Just for them! The marshaler does not have so much problems, it actually has just one: your IWidget is unlikely to be compatible or you would not have the problem in first place.
If your IWidget was compatible, had an associated type library, where it was marked as [oleautomation], the type library registration process would have automatically created the registry keys referencing PSOAInterface and supplying ProxyStubClsid32. Then marshaling API would have picked PSOAInterface for your widget, it would have picked up the registered type library, load details of the interface, then provided standard proxy/stub pair for it and that's it. Standard marshaler works just within these contraints and not just for any interface pointed to.
That is, your options are:
implement IMarshal on the widget server
make IWidget OLE Automation compatible, with type library, so that type library registration process activates "standard marshaler" PSOAInterface for your interface
build, if possible and applicable, proxy/stub implementation for your interface automatically generated by MIDL complier (you can check standard ATL DLL project, created from Visual Studio template on how it can be done - it creates additional project with "PS" suffix, for a supplementary proxy/stub DLL)
implement separately IMarshal in a standalone DLL, and register it with the registry and your IWidget interface, so that marshaling API would pick it up when it attempts to marshal the interface pointer (I suppose it's the only option here if your IWidget is OLE incompatible and you have reasons to not alter the original implementation)
use free threaded marshaler in the widget server if its restrictions are acceptable
Oh wait, hold on - there is another weird one. If you don't want or cannot afford, or you are reluctant to change the COM server (widget, that is) but you can modify client side code as you like, you can create a thin wrapper that implements two interfaces IWidget (all methods forward calls to real server) and IMarshal on client side, and pass its IWidget to the CoMarshalInterThreadInterfaceInStream API. This will force COM to use your marshaling without altering the original server. You are on your own, of course, to do the actual marshaling afterwards. It is unlikely that it matches your actual need, and it is just an abstract note to the discussion (which mostly consists of attempts to do impossible without details on interface itself and available options on modification of server implementation).
TL;DR: Actual questions:
Is it possible for the standard COM "Ole Automation" marshaler to build a proxy class out of a Type Library at runtime?
Short answer: yes.
Is it possible for me to build a proxy class out of a Type Library at runtime?
Short answer: yes, with the type library marshaler and IPSFactoryBuffer. Or if you're willing to use the undocumented CreateProxyFromTypeInfo and CreateStubFromTypeInfo.
I wonder why you'd want to this.
This question is riddled with red herrings.
I'm trying to marshal an interface to another thread.
(...) the call to CoMarshalThreadInterfaceInStream fails with:
REGDB_E_IIDNOTREG (0x80040155)
Interface not registered
A useful error code, in this case.
Go directly to CoMarshalInterface
(...) that fails with:
REGDB_E_IIDNOTREG (0x80040155)
Interface not registered
It's not by switching API calls that do essentially the same thing that you could solve your issue.
Use standard marshaling
My class does not implement IMarhsal interface.
Can you confirm it doesn't implement INoMarshal, IStdMarshalInfo and IAgileObject either, just to be exhaustive?
The interface is, in fact, not registered
This was expected.
I know that Windows provides you the CoRegisterPSClsid
(...)
Which i can try calling, but what clsid do i use?
CoRegisterPSClsid(IID_IWidget, ???);
If you don't have a proxy/stub, why would you go through this?
But to answer this question, a standard marshalers' CLSID is usually the same GUID as the first IID found in an IDL file.
Register the interface
I of course can register my interface in the registry:
HKEY_CURRENT_USER\Software\Classes\Interface\{EBBC7C04-315E-11D2-B62F-006097DF5BD4}
(default) = "IWidget"
But that doesn't fix it. Spelunking through the Interface registry keys, i notice that many specify a ProxyStubClsid32 entry.
You should read the documentation, instead of relying on what other registry entries contain.
(...) I don't have a marshaler.
This should be the actual problem. If this object is yours, how do you intend to marshal it? Please see the bottom section of my answer.
Can COM automatically marshal based on a TypeLibrary
This is clearly rhetoric. Why would you think of a type library just now, instead of to begin with? The rest of your question corroborates.
Now i manually include the TypeLibrary:
HKEY_CURRENT_USER\Software\Classes\Interface\{EBBC7C04-315E-11D2-B62F-006097DF5BD4}\TypeLib
(default) = "{38D528BD-4948-4F28-8E5E-141A51090580}"
You mention this twice.
But it:
never reads: HKCR\Interface[IID_IWidget]\TypeLib
The type library marshaler has its own cache of interface->type library. To clear the cache, try recreating the registry entries, logging off and logging on, or ultimately, reboot.
The object may implement IProvideClassInfo, I don't know if the type library marshaler actually cares to QueryInterface for this to fetch a runtime ITypeInfo to work with.
These are the main types of marshalers:
Standard marshalers, which are usually compiled into a DLL from C/C++ source code generated by MIDL (which consists mainly of declarations on how to marshal types)
The type library marshaler, which can marshal types at runtime based on automation-compatible type information
The free-threaded marshaler aggregated with CoCreateFreeThreadedMarshaler, which avoids marshaling between threads within the same process
Custom marshalers, which do whatever the developer wants, most commonly to implement marshal-by-value, or a free-threaded marshaler back when CoCreateFreeThreadedMarshaler didn't exist
The standard marshalers generated by MIDL consist mainly of declarations on how to marshal types in and out, so the way they work is in the same vein as the type library marshaler. According to Don Box, the result is very similar.
However, the actual declarations are very different. The type library marshaler works on type information that is meant to work in VB6 and (excluding certain things, such as user-defined types) scripting languages (mainly VBScript and JScript) and is intended to be consumed by IDEs (e.g. VB6, VBA, Delphi, OleView) and interop code generators (e.g. VC++ #import, tlbimp.exe, Delphi's "Import Type Library", Lisp 1 2), etc.
Is it possible to get an instance of java.lang.reflect.Method by using the new method reference feature of Java 8?
That way I would have a compile time check and refactoring would be also easier. Also, I wouldn't need to catch the exceptions (which shouldn't been thrown after all).
Short answer: No.
You will get a lambda of that method, not a java.lang.reflect.Method. You do not know the name of the method. Just as you can not have a reference to a "property" of a java bean.
You can have a reference to the getter or setter but that is also a lambda and you do not know the actual name.
In any case you'd have to provide the name as a String and that can't be checked by the compiler. I also tried this but failed. It simply can't be done unless you write something that checks the javacode/bytecode. But there are tools that do that.
Maybe the Criteria API could be used for that, but it depends on the requirements.
http://docs.oracle.com/javaee/6/tutorial/doc/gjitv.html
There you'd have a SingularAttribute or similar field on a "metamodel" and then the regular java compiler can check the (generic) type of it.
I'm having some serious troubles getting a Windows Phone 7.5 class library to load into the WP Unit Test Framework. It internally calls GetExportedTypes() on my assembly which throws a ReflectionTypeLoadException that doesn't contain any details. Its message is "ReflectionTypeLoadException" and its LoaderExceptions is null ("Could not evaluate expression"). The assembly is not using any 3rd party assemblies. If I create a separate WP7 app and do the same thing, I get the same results. I'm a very experienced Reflection user, but the lack of any detailed errors has brought my research to a complete halt. Just for completeness, it's the Windows Phone version of Fluent Assertions.
What about the Types array on the exception? Does it contain values? If so, does it also contain nulls? If so, you can find out which classes failed to load: You know all classes in the assembly and you know which classes loaded correctly. Those that are missing are the classes that couldn't be loaded. Maybe this info gives some clues.
This answer is based on the documentation, especially these bits:
From the Remarks of the LoaderExceptions property:
The LoaderExceptions property retrieves an array of type Exception that is parallel to the Types array. This array will contain null values whenever reflection cannot load a class.
And from the documentation of the Types property:
An array of type Type containing the classes that were defined in the module and loaded. This array can contain some null values.
I've found it! #GeertvanHorrik pointed me at a blog post he recently wrote. I was using an covariant interface (using the out parameter) which the runtime (!) doesn't support. Why the compiler does not protect me from that is a big mystery (and a huge disappointment) to me
I'm throwing this out in case someone has encountered this before.
When creating DesignData for use within the WPF designer, I get one of two errors:
Object does not match target type.
at System.Reflection.RuntimeMethodInfo.CheckConsistency(Object
target)
(SNIP)
at Microsoft.Expression.DesignModel.InstanceBuilders.ClrObjectInstanceBuilder. UpdateProperty(IInstanceBuilderContext
context, ViewNode viewNode, IProperty
propertyKey, DocumentNode valueNode)
The other one is a little more informative:
The value "_.di0.MyProjectLol.MyType"
is not of type "MyProjectLol.MyType"
and cannot be used in this generic
collection.
at
System.ThrowHelper.ThrowWrongValueTypeArgumentException(Object
value, Type targetType)
(SNIP)
at Microsoft.Expression.DesignModel.InstanceBuilders.ClrObjectInstanceBuilder.
InstantiateChildren(IInstanceBuilderContext
context, ViewNode viewNode,
DocumentCompositeNode compositeNode,
Boolean isNewInstance)
When debugging, I can see that there is a dynamic assembly that is loaded with proxy-ish types that look like mine but, obviously, are not. This assembly is called Blend_RuntimeGeneratedTypeAssembly(Guid goes here). When attempting to load types in this assembly, it throws a type load exception for a number of them. So, some types get proxied, some types are left as God and I intended, and when they mix unnatural acts occur.
For example, the type "Foo" might get a proxy created, but no other types do (TypeLoadExceptions). Then the designer tries to hand one of my real types the proxy (helped by the fact that xaml serialization likes to cast collections to IList, thus shitting on type safety) and you get one of the above exceptions.
I have spent half a week trying to fix this. I've tried a hundred different things, but I can't figure out exactly what is causing it to fail. Suggestions are welcome, TIA.
Solution in two parts:
1) Ensure VS is fully updated. At this point, it means installing the Silverlight 4 tools for Visual Studio 2010. They include the latest updates to the WPF designer. If you're reading this off in the distant future, ignore this one.
2) Hit the properties for your design data files. Clear out "Custom Tool", and set the "Build Action" to either "DesignData" or "DesignTimeDataWithDesignTimeCreatableTypes".
DesignData means that your types cannot be deserialized from xaml directly (due to dependencies or the such), so the designer attempts to create mocks for those types and presents the mocks to your design surface.
DesignTimeDataWithDesignTimeCreatableTypes means that the designer will load your assemblies and deserialize the xaml directly into your types without creating mocks.
This can also be caused by a certain combination of situations that, when combined, cause deserialization to fail.
Essentially if you have
A custom collection, or a collection that doesn't implement IList
That is exposed as a property on your type
Which is defined in a different assembly
you can get this error message as well.
It is very important that your collection property types implement IList (the non-generic one) if you want to serialize them to and from xaml!