I have a subroutine in my Controller
<HttpPost>
Sub Index(Id, varLotsOfData)
'Point B.
'By the time it gets here - all the data has been accepted by server.
What I would like to do it capture the Id of the inbound POST and mark, for example, a database record to say "Id xx is receiving data"
The POST receive can take a long time as there is lots of data.
When execution gets to point B I can mark the record "All data received".
Where can I place this type of "pre-POST completed" code?
I should add - we are receiving the POST data from clients that we do not control - that is, it is most likely a client's server sending the data - not a webbrowser client that we have served up from our webserver.
UPDATE: This is looking more complex than I had imagined.
I'm thinking that a possible solution would be to inspect the worker processes in IIS programatically. Via the IIS Manager you can do this for example - How to use IIS Manager to get Worker Processes (w3wp.exe) details information ?
From your description, you want to display on the client page that the method is executing and you can show also a loading gif, and when the execution completed, you will show a message to the user that the execution is completed.
The answer is simply: use SignalR
here you can find some references
Getting started with signalR 1.x and Mvc4
Creating your first SignalR hub MVC project
Hope this will help you
If I understand your goal correctly, it sounds like HttpRequest.GetBufferlessInputStream might be worth a look. It allows you to begin acting on incoming post data immediately and in "pieces" rather than waiting until the entire post has been received.
An excerpt from Microsoft's documentation:
...provides an alternative to using the InputStream propertywhich waits until the whole request has been received. In contrast, the GetBufferlessInputStream method returns the Stream object immediately. You can use the method to begin processing the entity body before the complete contents of the body have been received and asynchronously read the request entity in chunks. This method can be useful if the request is uploading a large file and you want to begin accessing the file contents before the upload is finished.
So you could grab the beginning of the post, and provided your client-facing page sends the ID towards the beginning of its transmission, you may be able to pull that out. Of course, this would be reading raw byte data which would need to be decoded so you could grab the inbound post's ID. There's also a buffered one that will allow the stream to be read in pieces but will also build a complete request object for processing once it has been completely received.
Create a custom action filter,
Action Filters for executing filtering logic either before or after an action method is called. Action Filters are custom attributes that provide declarative means to add pre-action and post-action behavior to the controller's action methods.
Specifically you'll want to look at the
OnActionExecuted – This method is called after a controller action is executed.
Here are a couple of links:
http://www.infragistics.com/community/blogs/dhananjay_kumar/archive/2016/03/04/how-to-create-a-custom-action-filter-in-asp-net-mvc.aspx
http://www.asp.net/mvc/overview/older-versions-1/controllers-and-routing/understanding-action-filters-vb
Here is a lab, but I think it's C#
http://www.asp.net/mvc/overview/older-versions/hands-on-labs/aspnet-mvc-4-custom-action-filters
Related
I have a webapp created with Node.js/Express.js/Pug that runs a bash script(mostly an Nmap scan) and displays the results. I'd like to implement some sort of page in between the start and the results to signify the system is working on the task.
I tried to just add another res.render(...) at the beginning of the route that starts the scan, but I ran into the problem that HTTP cannot send headers twice. Effectively, I can't send two http responses for one request; please let me know if I'm wrong here.
I'm still not very familiar with this stuff; I'm working with a group and this job fell to me, any help is appreciated.
Typically the route handler would:
trigger the long running script asynchronously
return an "in progress" page
Then the "in progress" page would ask the server if it was done yet via:
Websocket
Ajax polling
Meta refresh polling
You'd need to have the callback to the original asynchronous process keep track of where the response should go to (possibly using a GUID that would be passed to it and also returned as data in the "in progress" page).
I am designing my first REST API.
Suppose I have a (SOAP) web service that takes MyData1 and returns MyData2.
It is a pure function with no side effects, for example:
MyData2 myData2 = transform(MyData myData);
transform() does not change the state of the server. My question is, what REST call do I use? MyData can be large, so I will need to put it in the body of the request, so POST seems required. However, POST seems to be used only to change the server state and not return anything, which transform() is not doing. So POST might not be correct? Is there a specific REST technique to use for pure functions that take and return something, or should I just use POST, unload the response body, and not worry about it?
I think POST is the way to go here, because of the sheer fact that you need to pass data in the body. The GET method is used when you need to retrieve information (in the form of an entity), identified by the Request-URI. In short, that means that when processing a GET request, a server is only required to examine the Request-URI and Host header field, and nothing else.
See the pertinent section of the HTTP specification for details.
It is okay to use POST
POST serves many useful purposes in HTTP, including the general purpose of “this action isn’t worth standardizing.”
It's not a great answer, but it's the right answer. The real issue here is that HTTP, which is a protocol for the transfer of documents over a network, isn't a great fit for document transformation.
If you imagine this idea on the web, how would it work? well, you'd click of a bunch of links to get to some web form, and that web form would allow you to specify the source data (including perhaps attaching a file), and then submitting the form would send everything to the server, and you'd get the transformed representation back as the response.
But - because of the payload, you would end up using POST, which means that general purpose components wouldn't have the data available to tell them that the request was safe.
You could look into the WebDav specifications to see if SEARCH or REPORT is a satisfactory fit -- every time I've looked into them for myself I've decided against using them (no, I don't want an HTTP file server).
I am uploading multiple files using javascript.
After I upload the files, I need to run several processing functions.
Because of the processing time that is required, I need a UI on the front telling the user the estimated time left of the entire process.
Basically I have 3 functions:
/upload - this is an endpoint for uploading the files
/generate/metadata - this is the next endpoint that should be triggered after /upload
/process - this is the last endpoint. SHould be triggered after /generate/metadata
This is how I expect the screen to look like basically.
Information such as percentage remaining and time left should be displayed.
However, I am unsure whether to allow server to supply the information or I do a hackish estimate solely using javascript.
I would also need to update the screen like telling the user messages such as
"currently uploading"
if I am at function 1.
"Generating metadata" if I am at function 2.
"Processing ..." if I am at function 3.
Function 2 only occurs after the successful completion of 1.
Function 3 only occurs after the successful completion of 2.
I am already using q.js promises to handle some parts of this, but the code has gotten scarily messy.
I recently come across Backbone and it allows structured ways to handle single page app behavior which is what I wanted.
I have no problems with the server-side returning back json responses for success or failure of the endpoints.
I was wondering what would be a good way to implement this function using Backbone.js
You can use a "progress" file or DB entry which stores the state of the backend process. Have your backend process periodically update this file. For example, write this to the file:
{"status": "Generating metadata", "time": "3 mins left"}
After the user submits the files have the frontend start pinging a backend progress function using a simple ajax call and setTimeout. the progress function will simply open this file, grab the JSON-formatted status info, and then update the frontend progress bar.
You'll probably want the ajax call to be attached to your model(s). Have your frontend view watch for changes to the status and update accordingly (e.g. a progress bar).
Long Polling request:
Polling request for updating Backbone Models/Views
Basically when you upload a File you will assign a "FileModel" to every given file. The FileModel will start a long polling request every N seconds, until get the status "complete".
I've spend days trying to find a solution the problem i'm going to try to describe, i've googled alot and even looked at the .NET 4 reference source for SendReply and InternalSendReply activity. But until now i'm stuck.
To make the life of our end customers simpler i want to replace the Receive and SendReply activities with custom activites and use bookmarks instead.
I'm implementing a central webservice which can route to a correct workflow instance, that workflow modifies the bookmark value and finaly it creates a new bookmark while returning the modified bookmark value. It's rather complex already with a WorkflowServiceHostFactory which adds Behaviours and Attach a DataContractResolver to the endpoint.
The endpoint is derived from WorkflowHostingEndpoint which resolves a bookmark created in a custom activity (instead of a receive). And i want another activity instead of a sendreply. Those 2 should correlate and the custom sendreply does send a response on the open channel through the endpoint while creating a new bookmark.
The problem is that i didn't find a way yet to access the endpoint responseContext from within my custom send activity. On the other side, at the workflowcreating endpoint side, it seems that i'm not able to be notified whenever the workflow becomes Idle and as well i don't seem to be able to access the WorkflowExtensions from the host. i'm missing something?
A possible solution i've in mind might be not using a WorkflowServiceHost, but then i loose alot of AppFabric functionaly.
The workflowapplication in platform update 1 has some extension methods called RunEpisode with an overload Func called idleEventCallback. There it's possible to hook into the OnIdle and get a workflowextension to get the object to send back as response.
To answer my own question, i ended up in a workaround using the servicebroker functionality of sql server. The SqlDependency class where the workflow listens for the event to be fired whenever the workflow reach the activity that creates a new bookmark in another state.
So, I've read a lot about using ExtJS's fileuploadfield to submit a form via an IFRAME. I understand that I'm supposed to reply with a JSON object indicating success or failure; fine. What I want to know is, how can I get more information back to the calling code? I don't want to simple send a file and say "yup, that worked fine" -- I want to submit a document, act on it, and return a result.
Say I have the user upload an XML document -- I might want to do a lookup or conversion based on it and update the contents of a form on my page accordingly. Is this even possible? I'd strongly prefer to avoid involving Flash or embedded applets if at all possible. If need be, I could even restrict this behavior to HTML5-compliant browsers...
I honestly thought I wasn't seeing the response I sent, but it was a server-side error. My success callback is now firing, with the full text of my server's response available as f.responseText (where f is the first argument to the success callback). My mistake!