#GET
#Path("/{id}/content")
#Produces({ "application/octet-stream" })
public Response getDocumentContentById(#PathParam("id") String docId) {
InputStream is = getDocumentStream(); // some method which gives stream
ResponseBuilder responseBuilder = Response.ok(is);
responseBuilder.header("Content-Disposition", "attachment; filename=" + fileName);
return responseBuilder.build();
}
Here how can I close the InputStream is ? If something(jax.rs) closes automatically. Please give me some information. Thank you.
When you're wanting to stream a custom response, the most reliable way I've found is to return an object that contains the InputStream (or which can obtain the stream in some other way at some point), and to define a MessageBodyWriter provider that will do the actual streaming at the right time.
For example, this code is part of Apache Taverna, and it streams back the zipped contents of a directory. All that the main code needs to do to use it is to return a ZipStream as the response (which can be packaged in a Response or not) and to ensure that it is dealing with returning the application/zip content type. The final point to note is that since this is dealing with CXF, you need to manually register the provider; unlike with Glassfish, they are not automatically picked up. This is a good thing in sophisticated scenarios, but it does mean that you need to do the registration.
Related
I am building a REST API and facing this issue: How can REST API pass very large JSON?
Basically, I want to connect to Database and return the training data. The problem is in Database I have 400,000 data. If I wrap them into a JSON file and pass through GET method, the server would throw Heap overflow exception.
What methods we can use to solve this problem?
DBTraining trainingdata = new DBTraining();
#GET
#Produces("application/json")
#Path("/{cat_id}")
public Response getAllDataById(#PathParam("cat_id") String cat_id) {
List<TrainingData> list = new ArrayList<TrainingData>();
try {
list = trainingdata.getAllDataById(cat_id);
Gson gson = new Gson();
Type dataListType = new TypeToken<List<TrainingData>>() {
}.getType();
String jsonString = gson.toJson(list, dataListType);
return Response.ok().entity(jsonString).header("Access-Control-Allow-Origin", "*").header("Access-Control-Allow-Methods", "GET").build();
} catch (SQLException e) {
logger.warn(e.getMessage());
}
return null;
}
The RESTful way of doing this is to create a paginated API. First, add query parameters to set page size, page number, and maximum number of items per page. Use sensible defaults if any of these are not provided or unrealistic values are provided. Second, modify the database query to retrieve only a subset of the data. Convert that to JSON and use that as the payload of your response. Finally, in following HATEOAS principles, provide links to the next page (provided you're not on the last page) and previous page (provided you're not on the first page). For bonus points, provide links to the first page and last page as well.
By designing your endpoint this way, you get very consistent performance characteristics and can handle data sets that continue to grow.
The GitHub API provides a good example of this.
My suggestion is no to pass the data as a JSON but as a file using multipart/form-data. In your file, each line could be a JSON representing a data record. Then, it would be easy to use a FileOutputStream to receive te file. Then, you can process the file line by line to avoid memory problems.
A Grails example:
if(params.myFile){
if(params.myFile instanceof org.springframework.web.multipart.commons.CommonsMultipartFile){
def fileName = "/tmp/myReceivedFile.txt"
new FileOutputStream(fileName).leftShift(params.myFile.getInputStream())
}
else
//print or signal error
}
You can use curl to pass your file:
curl -F "myFile=#/mySendigFile.txt" http://acme.com/my-service
More details on a similar solution on https://stackoverflow.com/a/13076550/2476435
HTTP has the notion of chunked encoding that allows you send a HTTP response body in smaller pieces to prevent the server from having to hold the entire response in memory. You need to find out how your server framework supports chunked encoding.
Can I return a file with my get request? I want to return a word document to calling angularJS service through REST GET method. Not sure if it is even possible.
You're a bit light on detail, so I'm gonna be a bit light on answer.
A REST request is just... a request. The REST side of things is more the way URLs are defined that what actually happens in the request process itself, which is all still vanilla HTTP.
So, same as with any GET request, if you want to return binary data, set the headers appropriately (<cfheader>), then return the file (<cfcontent>).
So this is how I did it, luckily I got this:
http://smithcustomdev.com/2010/10/20/download-file-to-browser-using-cfscript/
All I have to do was make the method remote and listen to REST service
<cfscript>
private void function serveFile(string filePath){
var fileContent = fileRead(expandPath(filePath));
var context = getPageContext();
context.setFlushOutput(false);
var response = context.getResponse().getResponse();
response.reset();
response.setContentType("text/csv");
response.setContentLength(len(fileContent));
response.setHeader("Content-Disposition","attachment; filename=#listLast(filePath,'\')#");
var out = response.getOutputStream();
out.write(ToBinary(ToBase64(fileContent)));
out.flush();
out.close();
}
</cfscript>
I am trying to consume a binary stream from a ServiceStack service, as described here:
How to consume a file with a ServiceStack client
I realize that I must use a custom WebClient, since I want direct access to the response stream. However, I would still like to avoid making this client by hand. Instead, I'd like to write something like,
var webClient = new JsonServiceClient(baseUrl)
.ConfigureWebClient(new MyRequestDto { Foo = "bar" }));
This way, I wouldn't have to assemble the URL and query string by hand; and when I change my request DTO, I wouldn't have to remember to change my custom WebClient setup code, either.
Is there a way to accomplish this, somehow ? I've looked at ServiceClientBase.PrepareWebRequest(...), and it does a whole lot of useful stuff that I don't feel like copy/pasting into my own code. I'd love to inherit ServiceClientBase and call that method directly, but it's private, so I can't. Anyone got any other ideas ?
All of ServiceStack's C# Service Clients have both a Global and a Local Request Filter allowing you to initialise the Request and Global and Local Response Filters allowing fine-grained access to the returned HttpWebResponse.
Initializing the WebRequest of all ServiceClients using a Global Request Filter:
ServiceClientBase.HttpWebRequestFilter = httpReq => ConfigureWebClient(httpReq);
Using the Local Request Filter:
var client = new JsonServiceClient(baseUrl) {
LocalHttpWebRequestFilter = httpReq => ConfigureWebClient(httpReq)
};
Although if you just want the binary response All Service Clients allow you to specify either a string, byte[], Stream or HttpWebResponse as your Generic Response type and it will return what was requested. See the Service Client wiki page for more examples of these.
Here's how you can retrieve binary responses:
byte[] responseBytes = client.Get<byte[]>("/poco/World");
var dto = responseBytes.FromUtf8Bytes().FromJson<PocoResponse>();
Or with a Stream:
using (Stream responseStream = client.Get<Stream>("/poco/World")) {
var dto = responseStream.ReadFully().FromUtf8Bytes().FromJson<PocoResponse>();
}
Or from the underlying HttpWebResponse:
HttpWebResponse webResponse = client.Get<HttpWebResponse>("/poco/World");
using (var stream = webResponse.GetResponseStream())
using (var sr = new StreamReader(stream)) {
var dto = sr.ReadToEnd().FromJson<PocoResponse>();
}
You can change Open Source Software, you don't have to work around it
ServiceStack is Open Source software, there's no need to look for hacks or try to work around something that's not accessible or not available, make a pull-request to change what you want and if it's a valid request for a common use-case it will likely be accepted. Otherwise feel free to take a fork of the Source code and customize it as you wish.
I have a fileUploader widget that I'm using to select an xml file. I then have a button that calls my handler in the viewImpl class when the user submits the selected file. If I understand things correctly, from there I do a submit from the formPanel and the file is on the server.
#UiHandler("calculateComplexityButton")
void onClickCalculateComplexity(ClickEvent e){
formPanel.submit();
//How do I get the inputStream back to here????
presenter.getTask(inputStream);
}
My problem is how do I get the inputStream off the server? I tried using an RPC call for all this, but when I try to get the inputStream I'm not pulling anything off the server. I tried:
inputStream = request.getInputStream();
but it appears to be empty. Any ideas on this?
I dropped the RPC code and used a simple HTTPRequest I found here. That gets me to the servlet, but the request doesn't have the file stream. When I reach this line in the code:
FileItemIterator iter = upload.getItemIterator(request); //Nothing is here in iter.
You can not make an upload via RPC, thats why you have to submit your form to a servlet.
final FormPanel form = new FormPanel();
form.setEncoding(FormPanel.ENCODING_MULTIPART);
form.setMethod(FormPanel.METHOD_POST);
form.setAction("/upload");
So, when you do form.submit() it will send your file to the Action(Servlet). In the server side you can use the lib form apache (commons-fileupload). You have many different way to get your file, you can save on disk, read on memory....
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. :)