I have installed the Microsoft AsyncTargetingPack in order to use async/await in specific RIA invoke operations.
I also read a lot about the implementation and some articls about building extensions for RIA data source from Kyle McClellan & Oren Beeri[Using the new Async framework with RIA][1][1]: https://zormim.wordpress.com/2011/01/06/using-the-new-async-framework-with-ria/
I used his extension as follows:
This async method will await the RIA invoke method to return the result to the caller either true / false.
public async Task<bool> CheckAccountDuplicates(string name, string id)
{
bool ret = false;
Debug.WriteLine("In func");
ret = await Context.InvokeAsync(() => Context.AccountNameExists(name, id));
Debug.WriteLine(ret);
return ret;
}
The caller is another method as follows:
public bool SaveRecs(ObservableCollection<Acc> accList)
{
int i = 0;
foreach (Acc item in accList)
{
if (CheckAccountDuplicates(item.name, item.id)) continue;
item.id = MaxID + i;
Context.Accs.Add(item);
i++;
}
return Commit();
}
as you can see this method needs to make sure that Acc 'name' does not exist before attempting to add it to the context.
The problem is that the debug write the value "In Func" once and the application halts ...!!!
no response at all.
What am I doing wrong ??
Related
In the Flutter/Dart app that I am currently working on need to download large files from my servers. However, instead of storing the file in local storage what I need to do is to parse its contents and consume it one-off. I thought the best way to accomplish this was by implementing my own StreamConsumer and overriding the relvant methods. Here is what I have done thus far
import 'dart:io';
import 'dart:async';
class Accumulator extends StreamConsumer<List<int>>
{
String text = '';
#override
Future<void> addStream(Stream<List<int>> s) async
{
print('Adding');
//print(s.length);
return;
}
#override
Future<dynamic> close() async
{
print('closed');
return Future.value(text);
}
}
Future<String> fileFetch() async
{
String url = 'https://file.io/bse4moAYc7gW';
final HttpClientRequest request = await HttpClient().getUrl(Uri.parse(url));
final HttpClientResponse response = await request.close();
return await response.pipe(Accumulator());
}
Future<void> simpleFetch() async
{
String url = 'https://file.io/bse4moAYc7gW';
final HttpClientRequest request = await HttpClient().getUrl(Uri.parse(url));
final HttpClientResponse response = await request.close();
await response.pipe(File('sample.txt').openWrite());
print('Simple done!!');
}
void main() async
{
print('Starting');
await simpleFetch();
String text = await fileFetch();
print('Finished! $text');
}
When I run this in VSCode here is the output I get
Starting
Simple done!! //the contents of the file at https://file.io/bse4moAYc7gW are duly saved in the file
sample.txt
Adding //clearly addStream is being called
Instance of 'Future<int>' //I had expected to see the length of the available data here
closed //close is clearly being called BUT
Finished! //back in main()
My understanding of the underlying issues here is still rather limited. My expectation
I had thought that I would use addStream to accumulate the contents being downloaded until
There is nothing more to download at which point close would be called and the program would display exited
Why is addStream showing instance of... rather than the length of available content?
Although the VSCode debug console does display exited this happens several seconds after closed is displayed. I thought this might be an issue with having to call super.close() but not so. What am I doing wrong here?
I was going to delete this question but decided to leave it here with an answer for the benefit of anyone else trying to do something similar.
The key point to note is that the call to Accumulator.addStream does just that - it furnishes a stream to be listened to, no actual data to be read. What you do next is this
void whenData(List<int> data)
{
//you will typically get a sequence of one or more bytes here.
for(int value in data)
{
//accumulate the incoming data here
}
return;
}
function void whenDone()
{
//now that you have all the file data *accumulated* do what you like with it
}
#override
Future<void> addStream(Stream<List<int>> s) async
{
s.listen(whenData,onDone:whenDone);
//you can optionally ahandler for `onError`
}
When trying to run the code above I'm getting javax.naming.OperationNotSupportedException with the message:
[LDAP: error code 12 - 00000057: LdapErr: DSID-0C09079A, comment: Error processing control, data 0, v2580].
The first page is successfully retrieved and the exception is thrown only at second loop iteration.
public void pagedResults() {
PagedResultsCookie cookie = null;
SearchControls searchControls = new SearchControls();
searchControls.setSearchScope(SearchControls.SUBTREE_SCOPE);
int page = 1;
do {
logger.info("Starting Page: " + page);
PagedResultsDirContextProcessor processor = new PagedResultsDirContextProcessor(20, cookie);
List<String> lastNames = ldapTemplate.search("", initialFilter.encode(), searchControls, UserMapper.USER_MAPPER_VNT, processor);
for (String l : lastNames) {
logger.info(l);
}
cookie = processor.getCookie();
page = page + 1;
} while (null != cookie.getCookie());
}
However, when I remove Spring LDAP using pure implementation as above, it works!
try {
LdapContext ctx = new InitialLdapContext(env, null);
// Activate paged results
int pageSize = 5;
byte[] cookie = null;
ctx.setRequestControls(new Control[] { new PagedResultsControl(pageSize, Control.CRITICAL) });
int total;
do {
/* perform the search */
NamingEnumeration results = ctx .search("",
"(&(objectCategory=person)(objectClass=user)(SAMAccountName=vnt*))",
searchCtls);
/* for each entry print out name + all attrs and values */
while (results != null && results.hasMore()) {
SearchResult entry = (SearchResult) results.next();
System.out.println(entry.getName());
}
// Examine the paged results control response
Control[] controls = ctx.getResponseControls();
if (controls != null) {
for (int i = 0; i < controls.length; i++) {
if (controls[i] instanceof PagedResultsResponseControl) {
PagedResultsResponseControl prrc = (PagedResultsResponseControl) controls[i];
total = prrc.getResultSize();
if (total != 0) {
System.out.println("***************** END-OF-PAGE "
+ "(total : " + total
+ ") *****************\n");
} else {
System.out.println("***************** END-OF-PAGE "
+ "(total: unknown) ***************\n");
}
cookie = prrc.getCookie();
}
}
} else {
System.out.println("No controls were sent from the server");
}
// Re-activate paged results
ctx.setRequestControls(new Control[] { new PagedResultsControl(
pageSize, cookie, Control.CRITICAL) });
} while (cookie != null);
ctx.close();
} catch (NamingException e) {
System.err.println("PagedSearch failed.");
e.printStackTrace();
} catch (IOException ie) {
System.err.println("PagedSearch failed.");
ie.printStackTrace();
}
Any hints?
The bad thing about LDAP paged results is that they only work if the same underlying connection is used for all requests. The internals of Spring LDAP get a new connection for each LdapTemplate operation, unless you use the transactional support.
The easiest way to make sure the same connection will be used for a sequence of LDapTemplate operations is to use the transaction support, i.e. configure transactions for Spring LDAP and wrap the target method with a Transactional annotation.
I managed to make my example above work using SingleContextSource.doWithSingleContext approach.
However my scenario is different, my app is service oriented and the paged results as well as the cookie should be sent to an external client so that he decides to request next pages or not.
So as far as I can tell, spring-ldap does not support such case. I must use pure implementation so that I can keep track of the underlying connection during requests. Transaction support could help as well as SingleContextSource, but not among different requests.
#marthursson
Is there any plan in spring ldap to such support in the future?
I found I could use your first example (Spring) as long as I set the ignorePartialResultException property to true in my ldapTemplate configuration and put the #Transactional on my method as suggested.
you can replace ldapTemplate DirContext like this
ldapTemplate.setContextSource(new SingleContextSource(ldapContextSource().getReadWriteContext()));
Here is code that use this eval method in Dart platform.
This is done via reflection.
runtime/lib/mirrors_impl.dart
_getFieldSlow(unwrapped) {
// ..... Skipped
var atPosition = unwrapped.indexOf('#');
if (atPosition == -1) {
// Public symbol.
f = _eval('(x) => x.$unwrapped', null);
} else {
// Private symbol.
var withoutKey = unwrapped.substring(0, atPosition);
var privateKey = unwrapped.substring(atPosition);
f = _eval('(x) => x.$withoutKey', privateKey);
}
// ..... Skipped
}
static _eval(expression, privateKey)
native "Mirrors_evalInLibraryWithPrivateKey";
runtime/lib/mirrors.cc
DEFINE_NATIVE_ENTRY(Mirrors_evalInLibraryWithPrivateKey, 2) {
GET_NON_NULL_NATIVE_ARGUMENT(String, expression, arguments->NativeArgAt(0));
GET_NATIVE_ARGUMENT(String, private_key, arguments->NativeArgAt(1));
const GrowableObjectArray& libraries =
GrowableObjectArray::Handle(isolate->object_store()->libraries());
const int num_libraries = libraries.Length();
Library& each_library = Library::Handle();
Library& ctxt_library = Library::Handle();
String& library_key = String::Handle();
if (library_key.IsNull()) {
ctxt_library = Library::CoreLibrary();
} else {
for (int i = 0; i < num_libraries; i++) {
each_library ^= libraries.At(i);
library_key = each_library.private_key();
if (library_key.Equals(private_key)) {
ctxt_library = each_library.raw();
break;
}
}
}
ASSERT(!ctxt_library.IsNull());
return ctxt_library.Evaluate(expression);
runtime/vm/bootstrap_natives.h
V(Mirrors_evalInLibraryWithPrivateKey, 2) \
P.S.
I ask question here becuase I cannot ask it at Dart mail lists.
P.S.
As we can see it static private method in mirrors_impl.dart:
static _eval(expression, privateKey) native "Mirrors_evalInLibraryWithPrivateKey";
Does anyone want that this method should be public? (this is not a question but just a thought aloud).
According to the Dart FAQ a pure string eval like that is not likely to make it into the language, even though other dynamic features will likely be added:
So, for example, Dart isn’t likely to support evaluating a string as
code in the current context, but it may support loading that code
dynamically into a new isolate. Dart isn’t likely to support adding
fields to a value, but it may (through a mirror system) support adding
fields to a class, and you can effectively add methods using
noSuchMethod(). Using these features will have a runtime cost; it’s
important to us to minimize the cost for programs that don’t use them.
This area is still under development, so we welcome your thoughts on
what you need from runtime dynamism.
Is there anyway to know which user is calling the WCF Ria service on server side? Client side is siverlight, user has to be authenticated first in order to use the system.
I need to know which user is actually calling the service in my current task, thanks, i searched a lot, but seems no good findings.
Once the client side has successfully cleared your authentication challenge, the server can issue a token to the caller on the client side. In subsequent calls to the server, the client would send the token as one of the arguments and the server would verify the token and respond accordingly.
The token can contain a segment of information that identifies a given user, and implementing this will provide the functionality you are seeking.
The only guidelines for generating tokens is that they are unique, non-predictable and expirable. I have always encrypted my tokens so that they appear as gibberish, but step this is optional.
I've also done very much "googleing" and got a lot of headache before I got the solution.
I don't use RIA-Services - but it should be (hopefully) the same...:
The SL-Client sends a "login-request" to the server.
On the (WCF) server-side, I do the following (LoginData = Return-Info for SL-Client):
public LoginData LoginRequest() {
(...)
OperationContext context = OperationContext.Current;
System.ServiceModel.Channels.MessageProperties prp = context.IncomingMessageProperties;
System.ServiceModel.Channels.RemoteEndpointMessageProperty endPrp = prp[System.ServiceModel.Channels.RemoteEndpointMessageProperty.Name] as System.ServiceModel.Channels.RemoteEndpointMessageProperty;
(...)
try {
clientIP = endPrp.Address;
System.Net.IPAddress ipAddress = System.Net.IPAddress.Parse(clientIP);
System.Net.IPHostEntry ipHostEntry = System.Net.Dns.GetHostEntry(ipAddress);
(...)
If you want to check the users WindowsPrincipal, you can do the following (securityGroup = server-side setting, which users can login):
(...)
switch (securityGroup) {
case SecurityGroup.AllClientsCanAccess: {
clientCanLogin = true;
} break;
case SecurityGroup.UseWindowsCredentials: {
if (OperationContext.Current.ServiceSecurityContext != null && OperationContext.Current.ServiceSecurityContext.WindowsIdentity != null) {
if (OperationContext.Current.ServiceSecurityContext.WindowsIdentity.IsAuthenticated) {
if (subSecurityInfo1 == true) { // only clients in specific roles can log in
bool userRoleFound = false;
WindowsPrincipal userPrincipal = new WindowsPrincipal(OperationContext.Current.ServiceSecurityContext.WindowsIdentity);
if (userPrincipal == null)
break;
foreach (string userRoleToPass in subSecurityList) { // subSecurityList = settings, which roles can pass
loginError.ErrorInfo += string.Format("{0}\n", userRoleToPass);
if (userPrincipal.IsInRole(userRoleToPass)) {
clientCanLogin = userRoleFound = true;
break;
}
}
if (userRoleFound) {
loginError.ErrorInfo = string.Empty;
break;
}
else {
loginError.ErrorNo = LoginErrorCodeNoEnum.UserIsNotInRole;
}
}
(...)
Hope it helps...
I am looking for a Win32 API call to return the runtime context of my process. I want to be able to programmatically test if I am running as a service or am I running as standard application process.
Several ideas come to mind.... Since I always have service DAD.exe who runs SON.exe sometimes as his child and in service context --- and sometimes SON.exe is started not by DAD, and by a user.
SON.EXE would do API whoami() to learn which context he is running in.
Now DAD could create an environment var -- and then SON could test for this var -- and if found he knows he is a son of DAD and thus runnning as a service..... But this is weak...
Another idea would be to look at my SID or token and see if I could make this determination.... Again this looks at best more complex vs. a single API check...
The simple low-tech solution to this is to register your service to run with command line arguments that identify it as a service.
Another option is to use the Tool Help library. Using it, you take a snapshot of all the currently running processes and then you can walk through all the processes using the Process32First and Process32Next function. These return a structure (PROCESSENTRY32) that looks like:
typedef struct tagPROCESSENTRY32 {
DWORD dwSize;
DWORD cntUsage;
DWORD th32ProcessID;
ULONG_PTR th32DefaultHeapID;
DWORD th32ModuleID;
DWORD cntThreads;
DWORD th32ParentProcessID;
LONG pcPriClassBase;
DWORD dwFlags;
TCHAR szExeFile[MAX_PATH];
} PROCESSENTRY32, *PPROCESSENTRY32;
as you walk through all the processes, as soon as you find the one whose th32ProcessID matches the one for SON.exe (see GetCurrentProcessId or GetProcessId ). If the th32ParentProcessID of that structure matches that of DAD.exe, then you know you were launched from DAD.exe.
Edit:
Answering your comment, I guess you could go one step further and then see who the parent of DAD.exe is, if it's services.exe, then you're a service.
Reading the documentation, I think you could determine whether you're in an interactive session or service via:
GetProcessWindowStation
GetUserObjectInformation(UOI_FLAGS)
and then WSF_VISIBLE should tell you.
If you wanted to differentiate between a logged-in user session and one that's inactive (Fast User Switching), I guess you could use GetThreadDesktop and GetUserObjectInformation(UOI_IO).
The best and simplest way to tell from inside the service is to set a flag when ServiceMain is called. But you're testing a child process, so see above.
I found the following:
bool WinUtil::IsServiceUser(HANDLE hToken, bool *is_service) {
if (is_service == NULL) {
return false;
}
TOKEN_STATISTICS ts;
DWORD dwSize = 0;
// Use token logon LUID instead of user SID, for brevity and safety
if (!::GetTokenInformation(hToken, TokenStatistics,
(LPVOID)&ts, sizeof(ts), &dwSize)) {
return false;
}
// Compare LUID
const LUID SystemLuid = SYSTEM_LUID;
const LUID LocalServiceLuid = LOCALSERVICE_LUID;
const LUID NetworkServiceLuid = NETWORKSERVICE_LUID;
if (EqualLuid(SystemLuid, ts.AuthenticationId) ||
EqualLuid(LocalServiceLuid, ts.AuthenticationId) ||
EqualLuid(NetworkServiceLuid, ts.AuthenticationId)) {
*is_service = true;
return true;
}
// Not a service account
*is_service = false;
return true;
}
bool WinUtil::IsServiceProcess(bool *is_service) {
if (is_service == NULL) {
return false;
}
if (Util::IsVistaOrLater()) {
// Session 0 is dedicated to services
DWORD dwSessionId = 0;
if (!::ProcessIdToSessionId(::GetCurrentProcessId(), &dwSessionId) ||
(dwSessionId == 0)) {
*is_service = true;
return true;
}
}
// Get process token
HANDLE hProcessToken = NULL;
if (!::OpenProcessToken(::GetCurrentProcess(),
TOKEN_QUERY | TOKEN_QUERY_SOURCE,
&hProcessToken)) {
return false;
}
ScopedHandle process_token(hProcessToken);
// Process token is one for a service account.
if (!IsServiceUser(process_token.get(), is_service)) {
return false;
}
return true;
}
I think your looking for Topshelf http://topshelf-project.com/, it does the heavy lifting and makes it easier run as console or install as a service. Topshelf hosting application debugging in VS2010