I am attempting to use google cloud storage api to save image files.
It usually takes 1 to 3 seconds to send image insertion request and get the reply back from the google server per an image, but sometimes(like 1 per 1500 tries) it takes very long time, such as more than 10 minutes.(I checked that a case waits about 50 minutes from the request to retrieve the insertion result) Since google console doesn't provide delay logs, I cannot check anything about it.
This delay bothers my job to be finished in time. I want to know the reason for the delay.
I works with java, and the maximum size of an image is 2 mega bytes, and my code uses google providing api.
Also I checked the readTimeout is 20sec and connectTimeout is 20sec which are given by the provided class of google. But this delayed cases never provide any exception message, just make my program be blocked.
please give me any clue about it...
thank you.
maven :
<dependency>
<groupId>com.google.apis</groupId>
<artifactId>google-api-services-storage</artifactId>
<version>v1-rev82-1.22.0</version>
</dependency>
java code :
StorageObject objectMetadata = new StorageObject()
.setName(imgName)
.setAcl(Arrays.asList(new ObjectAccessControl()
.setEntity("allUsers")
.setRole("OWNER")));
ByteArrayContent byteArrayContent = new ByteArrayContent(null,imgBytes);
GoogleCredential credential = getMyCredential();
if (credential.createScopedRequired()) {
Collection<String> scopes = StorageScopes.all();
credential = credential.createScoped(scopes);
}
JsonFactory jsonFactory = JacksonFactory.getDefaultInstance();
Storage storage = new Storage.Builder(GoogleNetHttpTransport.newTrustedTransport(), jsonFactory, credential)
.setApplicationName(APPLICATION_NAME).build();
Storage.Objects.Insert insertRequest =
storage.objects().insert(bucketName,objectMetadata,byteArrayContent);
insertRequest.execute(); //delay occurs here
Related
I am building a bot for for Facebook Messenger using Microsoft Bot Framework. I am planning to use CosmosDB for State Management and also as my backend data store. (I am not stuck to CosmosBD and can use any other store if needed)
I need to send daily/weekly proactive messages(push notifications) to users based on their time preference. I will capturing their time preference when they first interact with the bot.
What is the best way to deliver these notifications?
As I will be storing these preferences in CosmosDB, I am thinking using ComosDB trigger of creating an Azure Function and schedule it based on the user time preference. This Azure function will make a call to my webhook which will deliver these messages. If requried, I will change Function schedule when a user changes his/her preference.
My questions are:
Is this a good approach?
Are there any other alternatives (Notifications Hub?)
I should be able to set specific times for notifications (like at the top of the hour or something like that), does it make sense to schedule an Azure Function to run at these hours rather than creating a function based on user preference (I can actually combine these two approaches too)
Thank you in advance.
First, I don't think there's any "right" answer to be given here; it's going to depend a lot on your domain's specific needs. Scale is going to play a major factor in the design of this. Will you have 100 users? 10000 users? 1mil users? I'm going to assume you want to design for maximum scale up front, but it could be overkill.
First, based on what you've described, I don't think a CosmosDB trigger is necessarily the solution to your problem because that's only going to fire when the preference data is created/updated. I assume that, from that point forward, your function needs to continuously fire at the time slot they've opted into, correct?
So let's pretend you let people choose from the 24hrs in the day. A naïve approach would be to simply use a scheduled trigger that fires up every hour, queries the CosmosDB for all the documents where the preference is set to that particular hour and then begins sending out notifications from there. The problem is how you scale from there and deal with issues of idempotency in the face of failures.
First off, a timer trigger only ever spins up one instance. If you were to just go query the CosmosDB documents and start processing them one by one in the scope of that single trigger, you'd hit a ceiling relatively quickly on how many notifications you can scale to. Instead what you'd want to do is use that timer trigger to fan out the notifications to as many "worker" function instances as possible. The timer trigger can act as the orchestrator in the sense that it can own the query against the CosmosDB and then turn each document result it finds for that particular notification time window into a message that it places on a queue to be processed by a separate function which will scale out on its own.
There are actually a couple ways you can accomplish this with Azure Functions, it really depends on how early an adopter of technology you are comfortable with being.
The first is what I would call the "manual" way which would be done by simply using the existing Azure Storage Queue extension by taking an IAsyncCollector<YourNotificationWorkerMessage> as a parameter to the timer function that's bound to the worker queue and then pumping out the messages through that. Then you write a second companion function which uses a QueueTrigger, bind it to that same queue, and it will take care of processing each message. This second function is where you get the scaling, enabling process all of the queued messages as quickly as possible based on whatever scaling parameters you choose to configure. This is the "simplest" approach
The second approach would be to adopt the newer Durable Functions extension. With that model, you don't have to directly think about creating a worker queue. You simply kick off a new instance of your orchestrator function from the timer function and the orchestrator fans out the work by invoking N "concurrent" calls to an action for each notification. Now, it happens to distribute those calls using queues under the covers, but that's an implementation detail that you need no longer maintain yourself. Additionally, if the work of delivering the notification requires more involved work and/or retry logic, you might actually consider using a sub-orchestration instead of a simple action. Finally, another added benefit of this approach, is that you can "fan back in" to your main orchestrator function once all the notifications are delivered to do some follow up work... even if that's simply some kind of event logging that the notification cycle has completed for this hour.
Now, the challenge with either of these approach is actually dealing with failure in initially fetching the candidates for notification from CosmosDB, paging through the results and making sure you actually fan all of them out in an idempotent manner. You need to deal with possible hiccups as you page and you need to deal with the fact that your whole function could be torn down and you might have to restart. Perhaps on the initial run of the 8AM notifications you got through page 273 out of 371 pages and then you got hit with a complete network connectivity fail or the VM your function was running on suffered a power failure. You could resume, but you'd need to know that you left off on page 273 and that you actually processed the 27th record out of that page and start from there. Otherwise, you risk sending double notifications to your users. Maybe that's something you can accept, maybe it's not. Maybe you're ok with the 27 notifications on that page being duplicated as long as the first 272 pages aren't. Again, this is something you need to decide for your domain, but if you want to avoid this issue your orchestrator function will need to track its progress to ensure that it doesn't send out dupes. Again I would say Durable Functions has a leg up here as it comes with the ability to configure retries. Maintaining the state of a particular run is left up to the author in either approach though.
I use pro-active dialog extensively with botframwork and messenger without any issue. During your facebook approval process you simply need to inform them you will be sending notifications trough messenger with your bot. Usually if you use it to inform your user and stay away from promotional content you should be fine.
I also use azure function to trigger the pro-active dialog from a custom controller endpoint.
Bellow sample code for azure function:
public static void Run(TimerInfo notificationTrigger, TraceWriter log)
{
try
{
//Serialize request object
string timerInfo = JsonConvert.SerializeObject(notificationTrigger);
//Create a request for bot service with security token
HttpRequestMessage hrm = new HttpRequestMessage()
{
Method = HttpMethod.Post,
RequestUri = new Uri(NotificationEndPointUrl),
Content = new StringContent(timerInfo, Encoding.UTF8, "application/json")
};
hrm.Headers.Add("Authorization", NotificationApiKey);
log.Info(JsonConvert.SerializeObject(hrm));
//Call service
using (var client = new HttpClient())
{
Task task = client.SendAsync(hrm).ContinueWith((taskResponse) =>
{
HttpResponseMessage result = taskResponse.Result;
var jsonString = result.Content.ReadAsStringAsync();
jsonString.Wait();
if (result.StatusCode != System.Net.HttpStatusCode.OK)
{
//Throw what ever problem as an exception with details
throw new Exception($"AzureFunction - ERRROR - HTTP {result.StatusCode}");
}
});
task.Wait();
}
}
catch (Exception ex)
{
//TODO log
}
}
Bellow sample code for starting the pro-active dialog:
public static async Task Resume<T, R>(string resumptionCookie) where T : IDialog<R>, new()
{
//Deserialize reference to conversation
ConversationReference conversationReference = JsonConvert.DeserializeObject<ConversationReference>(resumptionCookie);
//Generate message from bot to user
var message = conversationReference.GetPostToBotMessage();
var builder = new ContainerBuilder();
using (var scope = DialogModule.BeginLifetimeScope(Conversation.Container, message))
{
//From a cold start the service is not yet authenticated with dev bot azure services
//We thus must trust endpoint url.
if (!MicrosoftAppCredentials.IsTrustedServiceUrl(message.ServiceUrl))
{
MicrosoftAppCredentials.TrustServiceUrl(message.ServiceUrl, DateTime.MaxValue);
}
var botData = scope.Resolve<IBotData>();
await botData.LoadAsync(CancellationToken.None);
//This is our dialog stack
var task = scope.Resolve<IDialogTask>();
T dialog = scope.Resolve<T>(); //Resolve the dialog using autofac
try
{
task.Call(dialog.Void<R, IMessageActivity>(), null);
await task.PollAsync(CancellationToken.None);
}
catch (Exception ex)
{
//TODO log
}
finally
{
//flush dialog stack
await botData.FlushAsync(CancellationToken.None);
}
}
}
Your dialog needs to be registered in autofac.
Your resumptionCookie needs to be saved in your db.
You might want to check FB policy regarding proactive messages
There’s a 24h limit but it might not be totally screwed in your case
https://developers.facebook.com/docs/messenger-platform/policy/policy-overview#standard_messaging
I have written a plugin wherein I am trying to get an XML response.
This is my code :
// Set the Method property of the request to POST.
string strXMLServer = "xxx";
var request = (HttpWebRequest)WebRequest.Create(strXMLServer);
request.Method = "POST";
// Set the ContentType property of the WebRequest.
request.ContentType = "xyz";
// Assuming XML is stored in strXML
byte[] byteArray = Encoding.UTF8.GetBytes(strXML);
// Set the ContentLength property of the WebRequest.
request.ContentLength = byteArray.Length;
//(LINE 5) Get the request stream
Stream dataStream = request.GetRequestStream();
// Write the data to the request stream.
dataStream.Write(byteArray, 0, byteArray.Length);
// Close the Stream object.
dataStream.Close();
This code works fine when its written in a console application. But when I copy the same code to a class library(plugin) and tries to debug it using plugin profiler, the application gets stopped abruptly when it reaches (LINE 5)
i.e. At Stream dataStream = request.GetRequestStream();
request.GetRequestStream() function is not working with plugin, but works fine within a console.
Any help would be appreciated :)
Thanks in advance
Note: I am using Dynamics 365 online trial version
There are a couple of things to take into consideration when building a plugin with web requests. Firstly, you need to use WebClient as it's widely supported by Microsoft products.
Secondly, your URL needs to be a DNS name and not an IP address, as this is a hosted plugin in sandbox mode.
Example from Microsoft's website: https://msdn.microsoft.com/en-us/library/gg509030.aspx
Reading material: https://crmbusiness.wordpress.com/2015/02/05/understanding-plugin-sandbox-mode/
I have used cache2k with read through in a web application to load blog posts on demand. However, I am concerned about blocking for the read through feature. For example, if multiple threads (requests) ask the cache for the same key, is it possible for the read through method to be called multiple times to load the same key/value into the cache?
I get the impression from the documentation that the read through feature does block concurrent requests for the same key until the load has completed, but may I have mis-read the documentation. I just want to check that this is the behaviour.
The method which initializes the cache looks like this:
private void initializeURItoPostCache()
{
final CacheLoader<String, PostImpl> postFileLoader = new CacheLoader<String, PostImpl>(){
#Override public PostImpl load(String uri)
{
// Fetch the data and create the post object
final PostImpl post = new PostImpl();
//.. code omitted
return post;
}
};
// Initialize the cache with a read-through loader
this.cacheUriToPost = new Cache2kBuilder<String, PostImpl>(){}
.name("cacheBlogPosts")
.eternal(true)
.loader(postFileLoader)
.build();
}
The following method is used to request a post from the cache:
public Post getPostByURI(final String uri)
{
// Check with the index service to ensure the URI is known (valid to the application)
if(this.indexService.isValidPostURI(uri))
{
// We have a post associated with the given URI, so
// request it from the cache
return this.cacheUriToPost.get(uri);
}
return EMPTY_POST;
}
Many thanks in advance, and a happy and prosperous New Year to all.
When multiple requests to the same key will provoke a cache loader call, cache2k will only invoke the loader once. Other threads wait until the load is finished. This behavior is called blocking read through. To cite from the Java Doc:
Blocking: If the loader is invoked by Cache.get(K) or other methods that allow transparent access concurrent requests on the same key will block until the loading is completed. For expired values blocking can be avoided by enabling Cache2kBuilder.refreshAhead(boolean). There is no guarantee that the loader is invoked only for one key at a time. For example, after Cache.clear() is called load operations for one key may overlap.
This behavior is very important for caches, since it protects against the Cache stampede. An example: A high traffic website receives 1000 requests per second. One resource takes quite long to generate, about 100 milliseconds. When the cache is not blocking out the multiple requests when there is a cache miss, there would be at least 100 requests hitting the loader for the same key. "at least" is an understatement, since your machine will probably not handle 100 requests at the same speed then one.
Keep in mind that there is no hard guarantee by the cache. The loader must still be able to perform correctly when called for the same key at the same time. For example blocking read through and Cache.clear() lead to competing requirements. The Cache.clear() should be fast, which means we don't want to wait for ongoing load operations to finish.
I have a Play! Framework 2.3 project hosted on Heroku with the Postgres Addon.
It handles requests from mobile applications (Post a message).
For different reasons, I have duplicate (twice) rows (messages) in database :
the app might send the request twice in a short time ( less than 10ms )
I have multiple dynos that handle requests in parallel
Event if before writing in DB, I check the message does not exist yet. So I guess the first has still not been wrote when the second comes.
I also tried to write a message footprint in the memcache before handling the request (after form validation). But I still got twice messages sometimes.
The solutions I found are :
have a unique constraint on some database field (like a message timestamp client-side generated ?)
regularly check to remove duplicates
As I do not have means to update mobile apps I will script a regular check of duplicates.
Any other idea ?
What are the best practices to handle such concurrent requests ?
Attachement : my pseudo code
public static Result submit() {
User user = MySecured.getCurrentUser(ctx());
final Form<Message> filledForm = form(Message.class).bindFromRequest();
.... Some database pre-verification
if (filledForm.hasErrors()) {
ObjectNode error = Json.newObject();
error.put("error", filledForm.errorsAsJson());
return ok(error);
} else {
if(Cache.get(KEY_LOCK_FLASH_WRITING+filledForm.data().get("mail"))!=null){
return internalServerError();
}
//Verify this flash hasnt already been handled (requests can come twice from client)
Message sameMessage = Message.findSame(filledForm.get().mail, filledForm.get().message);
if(sameMessage!=null){
Logger.info("[Submit] message already exists" + sameMessage.id);
ObjectNode jsonResult = Json.newObject();
.... Processing a result ... no matter this does not happen.
return ok(jsonResult);
}
final Message flash = filledForm.get();
Cache.set(KEY_LOCK_FLASH_WRITING+flash.mail, "");
... some fields initializations like flash.author = new Author();
... Then some promises
return ok();
}
}
What I'm Trying To Do
I'm trying to create a solution of any kind that will run nightly on a Windows server, authenticate to a website, check a web page on the site for new links indicating a new version of a zip file, use new links (if present) to download a zip file, unzip the downloaded file to an existing folder on the server, use the unzipped contents (sql scripts, etc.) to build an instance of a database, and log everything that happens to a text file.
Forms App: The Part That Sorta Works
I created a Windows Forms app that uses a couple of WebBrowser controls, a couple of threads, and a few timers to do all that except the running nightly. It works great as a Form when I'm logged in and run it, but I need to get it (or something like it) to run on it's own like a Service or scheduled task.
My Service Attempt
So, I created a Windows Service that ticks every hour and, if the System.DateTime.Now.Hour >= 22, attempts to launch the Windows Forms app to do it's thing. When the Service attempts to launch the Form, this error occurs:
ActiveX control '8856f961-340a-11d0-a96b-00c04fd705a2' cannot be instantiated because the current thread is not in a single-threaded apartment.
which I researched and tried to resolve by either placing the [STAThread] attribute on the Main method of the Service's Program class or using some code like this in a few places including the Form constructor:
webBrowseThread = new Thread(new ThreadStart(InitializeComponent));
webBrowseThread.SetApartmentState(ApartmentState.STA);
webBrowseThread.Start();
I couldn't get either approach to work. In the latter approach, the controls on the Form (which would get initialized inside IntializeComponent) don't get initialized and I get null reference exceptions.
My Scheduled Task Attempt
So, I tried creating a nightly scheduled task using my own credentials to run the Form locally on my dev machine (just testing). It gets farther than the Service did, but gets hung up at the File Download Dialog.
Related Note: To send the key sequences to get through the File Download and File Save As dialogs, my Form actually runs a couple of vbscript files that use WScript.Shell.SendKeys. Ok, that's embarassing to admit, but I tried a few different things including SendMessage in Win32 API and referencing IWshRuntimeLibrary to use SendKeys inside my C# code. When I was researching how to get through the dialogs, the Win32 API seemed to be the recommended way to go, but I couldn't figure it out. The vbscript files was the only thing I could get to work, but I'm worried now that this may be the reason why a scheduled task won't work.
Regarding My Choice of WebBrowser Control
I have read about the System.WebClient class as an alternative to the WebBrowser control, but at a glance, it doesn't look like it has what I need to get this done. For example, I needed (or I think I needed) the WebBrowser's DocumentCompleted and FileDownload events to handle the delays in pages loading, files downloading, etc. Is there more to WebClient that I'm not seeing? Is there another class besides WebBrowser that is more Service-friendly and would do the trick?
In Summary
Geez, this is long. Sorry! It would help to even have a high level recommendation for a better way to do what I'm trying to do, because nothing I've tried has worked.
Update 10/22/09
Well, I think I'm closer, but I'm stuck again. I should end up with a decent-sized zip file with several files in it, but the zip file resulting from my code is empty. Here's my code:
// build post request
string targetHref = "http://wwwcf.nlm.nih.gov/umlslicense/kss/login.cfm";
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(targetHref);
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
// encoding to use
Encoding enc = Encoding.GetEncoding(1252);
// build post string containing authentication information and add to post request
string poststring = "returnUrl=" + fixCharacters(targetDownloadFileUrl);
poststring += getUsernameAndPasswordString();
poststring += "&login2.x=0&login2.y=0";
// convert to required byte array
byte[] postBytes = enc.GetBytes(poststring);
request.ContentLength = postBytes.Length;
// write post to request
Stream postStream = request.GetRequestStream();
postStream.Write(postBytes, 0, postBytes.Length);
postStream.Close();
// get response as stream
HttpWebResponse response = (HttpWebResponse)request.GetResponse();
Stream responseStream = response.GetResponseStream();
// writes stream to zip file
FileStream writeStream = new FileStream(fullZipFileName, FileMode.Create, FileAccess.Write);
ReadWriteStream(responseStream, writeStream);
response.Close();
responseStream.Close();
The code for ReadWriteStream looks like this.
private void ReadWriteStream(Stream readStream, Stream writeStream)
{
// taken verbatum from http://www.developerfusion.com/code/4669/save-a-stream-to-a-file/
int Length = 256;
Byte[] buffer = new Byte[Length];
int bytesRead = readStream.Read(buffer, 0, Length);
// write the required bytes
while (bytesRead > 0)
{
writeStream.Write(buffer, 0, bytesRead);
bytesRead = readStream.Read(buffer, 0, Length);
}
readStream.Close();
writeStream.Close();
}
The building of the post string is taken from my previous forms app that works. I compared the resulting values in poststring for both sets of code (my working forms app and this one) and they're identical.
I'm not even sure how to troubleshoot this further. Anyone see anything obvious as to why this isn't working?
Conclusion 10/23/09
I finally have this working. A couple of important hurdles I had to get over. I had some problems with the ReadWriteStream method code that I got online. I don't know why, but it wasn't working for me. A guy named JB in Claudio Lassala's Virtual Brown Bag meeting helped me to come up with this code which worked much better for my purposes:
private void WriteResponseStreamToFile(Stream responseStreamToRead, string zipFileFullName)
{
// responseStreamToRead will contain a zip file, write it to a file in
// the target location at zipFileFullName
FileStream fileStreamToWrite = new FileStream(zipFileFullName, FileMode.Create);
int readByte = responseStreamToRead.ReadByte();
while (readByte != -1)
{
fileStreamToWrite.WriteByte((byte)readByte);
readByte = responseStreamToRead.ReadByte();
}
fileStreamToWrite.Flush();
fileStreamToWrite.Close();
}
As Will suggested below, I did have trouble with the authentication. The following code is what worked to get around that issue. A few comments inserted addressing key issues I ran into.
string targetHref = "http://wwwcf.nlm.nih.gov/umlslicense/kss/login.cfm";
HttpWebRequest firstRequest = (HttpWebRequest)WebRequest.Create(targetHref);
firstRequest.AllowAutoRedirect = false; // this is critical, without this, NLM redirects and the whole thing breaks
// firstRequest.Proxy = new WebProxy("127.0.0.1", 8888); // not needed for production, but this helped in order to debug the http traffic using Fiddler
firstRequest.Method = "POST";
firstRequest.ContentType = "application/x-www-form-urlencoded";
// build post string containing authentication information and add to post request
StringBuilder poststring = new StringBuilder("returnUrl=" + fixCharacters(targetDownloadFileUrl));
poststring.Append(getUsernameAndPasswordString());
poststring.Append("&login2.x=0&login2.y=0");
// convert to required byte array
byte[] postBytes = Encoding.UTF8.GetBytes(poststring.ToString());
firstRequest.ContentLength = postBytes.Length;
// write post to request
Stream postStream = firstRequest.GetRequestStream();
postStream.Write(postBytes, 0, postBytes.Length); // Fiddler shows that post and response happen on this line
postStream.Close();
// get response as stream
HttpWebResponse firstResponse = (HttpWebResponse)firstRequest.GetResponse();
// create new request for new location and cookies
HttpWebRequest secondRequest = (HttpWebRequest)WebRequest.Create(firstResponse.GetResponseHeader("location"));
secondRequest.AllowAutoRedirect = false;
secondRequest.Headers.Add(HttpRequestHeader.Cookie, firstResponse.GetResponseHeader("Set-Cookie"));
// get response to second request
HttpWebResponse secondResponse = (HttpWebResponse)secondRequest.GetResponse();
// write stream to zip file
Stream responseStreamToRead = secondResponse.GetResponseStream();
WriteResponseStreamToFile(responseStreamToRead, fullZipFileName);
responseStreamToRead.Close();
sl.logScriptActivity("Downloading update.");
firstResponse.Close();
I want to underscore that setting AllowAutoRedirect to false on the first HttpWebRequest instance was critical to the whole thing working. Fiddler showed two additional requests that occurred when this was not set, and it broke the rest of the script.
You're trying to use UI controls to do something in a windows service. This will never work.
What you need to do is just use the WebRequest and WebResponse classes to download the contents of the webpage.
var request = WebRequest.Create("http://www.google.com");
var response = request.GetResponse();
var stream = response.GetResponseStream();
You can dump the contents of the stream, parse the text looking for updates, and then construct a new request for the URL of the file you want to download. That response stream will then have the file, which you can dump on the filesystem and etc etc.
Before you wonder, GetResponse will block until the response returns, and the stream will block as data is being received, so you don't need to worry about events firing when everything has been downloaded.
You definitely need to re-think your approach (as you've already begun to do) to eliminate the Forms-based application approach. The service you're describing needs to operate with no UI at all.
I'm not familiar with the details of System.WebClient, but since it
provides common methods for sending
data to and receiving data from a
resource identified by a URI,
it will probably be your answer.
At first glance, WebClient.DownloadFile(...) or WebClient.DownloadFileAsync(...) will do what you need.
The only thing I can add is that once you have scraped your screen and have the fully qualified name of the file you want to download, you could pass it along to the Windows/DOS command 'get' which will fetch files via HTTP. You can also script a command-line FTP client if desired. It's been a long time since I tried something like this in Windows, but I think you're almost there. Once you have fetched the correct file, building a batch file to do everything else should be pretty easy. If you are more comfortable with Unix, google "unix services for windows" just keep an eye on the services they start running (DHCP, etc). There are some nice utilities which will let your treat dos as a unix-like shell (ls -l, grep, etc) Finally, you could try another language like Perl or Python but I don't think that's the kind of advice you were looking for. :)