fileserver

File handling

Serve Files with WSO2 MSF4J

You can serve files from the resource methods by returning a java.io.File, java.io.InputStream or by returning a javax.ws.rs.core.Response object with a java.io.File or java.io.InputStream entity. Streaming is supported by default for java.io.File and java.io.InputStream entities.

javax.ws.rs.core.StreamingOutput is also supported by MSF4J. This provides the service author more control over the chunk size.

See the following sample.

    @GET
    @Path("/{fileName}")
    public Response getFile(@PathParam("fileName") String fileName) {
        File file = Paths.get(MOUNT_PATH, fileName).toFile();
        if (file.exists()) {
            return Response.ok(file).build();
        }
        return Response.status(Response.Status.NOT_FOUND).build();
    }

Streaming (Chunked) HTTP Request Handling

With WSO2 MSF4J, you can handle chunked requests in two ways.

1. Handle requests using HttpStreamHandler

First way is to implement org.wso2.msf4j.HttpStreamHandler as shown in the below example to handle chunked http requests in a zero copy manner.

    @POST
    @Path("/stream")
    @Consumes("text/plain")
    public void stream(@Context HttpStreamer httpStreamer) {
        final StringBuffer sb = new StringBuffer();
        httpStreamer.callback(new HttpStreamHandler() {
            @Override
            public void chunk(ByteBuf request, HttpResponder responder) {
                sb.append(request.toString(Charsets.UTF_8));
            }

            @Override
            public void finished(ByteBuf request, HttpResponder responder) {
                sb.append(request.toString(Charsets.UTF_8));
                responder.sendString(HttpResponseStatus.OK, sb.toString());
            }

            @Override
            public void error(Throwable cause) {
                sb.delete(0, sb.length());
            }
        });
    }

In the above example when the request chunks arrive, chunk() method is called. When the last chunk is arrived the finished() method is called. error() method will be called if an error occurs while processing the request.

2. Handle requests by aggregating chunks

Second way of handling chunked requests is to implement a normal resource method to handle the request ignoring whether the requests is chunked as shown in the below example. In this case MSF4J internally aggregates all the chunks of the request and presents it as a full http request to the resource method.

    @POST
    @Path("/aggregate")
    @Consumes("text/plain")
    public String aggregate(String content) {
        return content;
    }

How to build the sample

From this directory, run

mvn clean package

How to run the sample

Use following command to run the application

java -jar target/fileserver-*.jar

How to test the sample

Run the following curl command to upload file

curl -v -X POST --data-binary @/testPng.png http://localhost:8080/filename.png

Here /testPng.png will be uploaded with the name filename.png

---

Run the following curl command to download the file:

curl -v -X GET http://localhost:8080/filename.png > result.png

Now the file will be downloaded as result.png to the current directory.

Alternatively, to see how streaming works with java.io.InputStream, run the following command:

curl -v -X GET http://localhost:8080/ip/filename.png > result-ipstream.png

To see how streaming works with javax.ws.rs.core.StreamingOutput , run the following command:

curl -v -X GET http://localhost:8080/op/filename.png > result-opstream.png