I'm in over my head.
At the broadest level, I'm trying to expose an Odata interface to an existing pool of data exposed by a service written using Mule. When my Mule service is invoked, if I detect that the URL is Odata format, I want to delegate processing down to something written in Java and then feed the response from that component back to my caller.
I found the Olingo and OData4j libraries. My problem is that these start from building a Web service. But that's too far upstream for me. I have a Web service. What I need to understand are what components I need to implement in order to pass the URL (which I have in hand) onward to an Odata parser which will, in turn, invoke a data provider.
I'm a bit lost with this technology. Can someone point me to a very basic tutorial that clearly delineates this. Or, can they give me a couple steps like: "You have to implement A, B & C and then pass your URL into C.foo()"?
I've tried the Getting Started doc for both libraries but they both start with "first we'll implement a Web service" and don't clearly delineate (to me, at least) where that leaves off and pure Odata sets in.
Thanks.
The following is the code that will help you to get started for using data from a service exposing via OData.(using Apache Olingo).
URL url=new URL(/*your url*/);
HttpURLConnection conn=(HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setRequestProperty(HttpHeaders.ACCEPT,HttpContentType.APPLICATION_XML);
conn.connect();
InputStream content=conn.getInputStream();
Edm edm = EntityProvider.readMetadata(content, false);
After this you can use static methods of EntityProvider class for carrying out various operations like read,update,write
If you are using odata4j go with the following code
ODataConsumer demo_consumer= ODataConsumers.create(/*your URL*/);
Enumerable<EntitySetInfo> demo_entitySetList = demo_consumer.getEntitySets();
for (EntitySetInfo entitySet : entitySetList) {
System.out.println(entitySet.getHref());
}
this sounds very like how we read rss or other data feeds
Since you have a url, this can be read by a Http Connector or even a polling http connector.
The data can be streamed using a Java input stream the default behavior or converted to a string (object to string).
A simple java component using (OData4j) can process your content .. it sounds like 2 simple components on a mule flow.
R
Related
I'm trying to utilise com.google.cloud.dialogflow.v2.WebhookResponse to interact with my dialogflow agent. But I'm having trouble responding back to the agent during fulfillment.
The response created doesn't follow the specifications required i.e the agent expect the json to be fulfillmentText: "something" but the builder builds it in the format of fulfillment_text. There's not enough documentation on how to use API client correctly
Anyone has experience doing this in java/kotlin?
val response = WebhookResponse
.newBuilder()
.setFulfillmentText("Hello")
.build()
println(response)
println(Gson().toJson(response))
Output:
fulfillment_text: "Hello"
{"bitField0_":0,"fulfillmentText_":"Hello","fulfillmentMessages_":
[],"source_":"","outputContexts_":[],"memoizedIsInitialized":1,"unknownFields":{"fields":{}},"memoizedSize":-1,"memoizedHashCode":0}
I'm using 'com.google.cloud:google-cloud-dialogflow:0.75.1-alpha' from https://cloud.google.com/dialogflow-enterprise/docs/reference/libraries/java
The library you're using is primarily designed as a client library, letting you send text to Dialogflow and having it determine the Intent and parameters (and possibly a response) from that text.
It sounds like you're trying to use this on the other end - in a webhook to handle fulfillment. It just isn't designed for that. The Class was automatically generated from the ProtoBuf definition, which does not serialize to JSON, and isn't designed to represent things that way.
You will need to build the JSON for the response yourself.
I've looked through the examples at https://doc.akka.io/docs/akka-http/current/introduction.html for Akka HTTP routing and strangely for something built on top of Akka Streams none of the examples connect to a stream.
Can somebody show a simple example of creating a Java DSL flow (not Scala please), and then connecting a Route directly to that flow?
Or am I missing the point and it's not possible but requires some CompletionStage code within the Route to wait for a result of glue code that calls a Flow?
Edit: to clarify the flow can do something like append a string to a posted request body.
Using akka streams to complete a route is definitely possible. It involves either:
a web socket route, see examples in the docs, or
a chunked http response (since you typically do not know the size of the response if it's fed from a stream). You can create a Chunked Entity from an akka stream Source of ByteStrings
you can also use other response types if the response size is known in advance, see docs for HttpEntity about their specifics
Edit: to clarify the flow can do something like append a string to a posted request body.
Michał's answer contains good links, so please give them a read. Akka HTTP is by default and always streaming with its data -- e.g. the entities. So for example to do a streaming "echo" which at the same time adds a suffix, you could do something like this:
path("test", () ->
// extract the request entity, it contains the streamed entity as `getDataBytes`
extractRequestEntity(requestEntity -> {
// prepare what to add as suffix to the incoming entity stream:
Source<ByteString, NotUsed> suffixSource =
Source.single(ByteString.fromString("\n\nADDS THIS AFTER INCOMING ENTITY"))
// concat the suffix stream to the incoming entity stream
Source<ByteString, Object> replySource = requestEntity.getDataBytes()
.concat(suffixSource);
// prepare and return the entity:
HttpEntity.Chunked replyEntity = HttpEntities.create(ContentTypes.TEXT_PLAIN_UTF8, replySource);
return complete(StatusCodes.OK, replyEntity);
})
);
Having that said, there is numerous ways to make use of the streaming capabilities, including framed JSON Streaming and more. You should also give the docs page about implications of streaming a read.
I am loading model in apache jena using function FileManager.get().loadModel(url).And I also know that there may be some URLs in HTTP Response Link Header .I want to load model also from the links(URLs) in link header.How to do that ? Is there any inbuilt fuctionality to get access to header and process link header in Response header?
FileManager.get().loadModel(url) packages up reading a URL and parsing the results into a model. It is packing up a common thing to do; it is not claiming to be comprehensive. It is quite an old interface.
If you wanted detailed control over the HTTP handling, see if HttpOp (a lower level) mechanism helps, otherwise do the handling in the application and hand the input stream for the response directly to the parser.
You may also find it useful to look at the code in RDFDataMgr.process for help with content negotiation.
I don't think that this is supported by Jena. I don't see any reason in doing so. The HTTP request is done to get the data and maybe also to get the response type. If you want to get the URLs in some header fields, why not simply use plain old Java:
URL url = new URL("http://your_ontology.owl");
URLConnection conn = url.openConnection();
Map<String, List<String>> map = conn.getHeaderFields();
I Am serving an authenticated image using django. The image is behind a view which require login, and in the end I have to check more things than just the authentication.
Because of a reason to complicated to explain here, I cannot use the real url to the image, but I Am serving it with a custom url leading to the authenticated view.
From java the image must be reachable, to save or display. For this part I use Apache httpclient.
In Apacahe I tried a lot of things (every example and combination of examples...) but can't seem to get it working.
For other parts of the webapp I use django-rest-framwork, which I succesfully connected to from java (and c and curl).
I use the login_reuired decorator in django, which makes the attempt to get to the url redirect to a login page first.
Trying the link and the login in a webviewer, I see the 200 code (OK) in the server console.
Trying the link with the httpclient, I get a 302 Found in the console.... (looking up 302, it means a redirect..)
this is what I do in django:
in urls.py:
url(r'^photolink/(?P<filename>.*)$', 'myapp.views.photolink',name='photolink'),
in views.py:
import mimetypes
import os
#login_required
def photolink(request, filename):
# from the filename I get the image object, for this question not interesting
# there is a good reason for this complicated way to reach a photo, but not the point here
filename_photo = some_image_object.url
base_filename=os.path.basename(filename_photo)
# than this is the real path and filename to the photo:
path_filename=os.path.join(settings.MEDIA_ROOT,'photos',mac,base_filename)
mime = mimetypes.guess_type(filename_photot)[0]
logger.debug("mimetype response = %s" % mime)
image_data = open(path_filename, 'rb').read()
return HttpResponse(image_data, mimetype=mime)
by the way, if i get this working i need another decorator to pass some other tests....
but i first need to get this thing working....
for now it's not a secured url.... plain http.
in java i tried a lot of things... using apache's httpclient 4.2.1
proxy, cookies, authentication negociation, with follow redirects... and so on...
Am I overlooking some basic thing here?...
it seems the login of the website client is not suitable for automated login...
so the problem can be in my code in django....or in the java code....
In the end the problem was, using HTTP authorization.
Which is not by default used in the login_required decorator.
adding a custom decorator that checks for HTTP authorization did the trick:
see this example: http://djangosnippets.org/snippets/243/
I'm refactoring legacy C++ system to SOA using gSoap. We have some performance issues (very big XMLs) so my lead asked me to take a look at protocol buffers. I did, and it looks very cool (We need C++ and Java support). However protocol buffers are solution just for serialization and now I need to send it to Java front-end. What should I use from C++ and Java perspective to send those serialized stuff over HTTP (just internal network)?
PS. Another guy tries to speed-up our gSoap solution, I'm interested in protocol buffers only.
You can certainly send even a binary payload with an HTTP request, or in an HTTP response. Just write the bytes of the protocol buffer directly into the request/response, and make sure to set the content type to "application/octet-stream". The client, and server, should be able to take care of the rest easily. I don't think you need anything more special than that on either end.
ProtoBuf is a binary protocol. It doesn't mix well with SOAP. I suggest you either stick with gSOAP or convert to ProtoBuf entirely.
With protoBuf, you define your protocol in a special format like this,
message Product {
required string id = 1;
required string description = 2;
required int32 quantity = 3;
optional bool discontinued = 4;
}
The protoc tool can generate code in C++/Java/Python so you can serialize it on one end and deserialize on another.
As you can see, ProtoBuf is designed to serialize individual object. It doesn't provide all the facilities provided by SOAP, like headers. To get around this issue, we use ProtoBuf inside ProtoBuf. We define an Envelope like this,
message Envelope {
enum Type {
SEARCH = 1;
SEARCH_RESPONSE = 2;
RETRIEVE = 3;
RETRIEVE_RESPONSE = 4;
}
required Type type = 1;
required bytes encodedMessage = 2;
message Header {
required string key = 1;
required bytes value = 2;
}
repeated Header headers = 3;
}
The encodedMessage is another serialized ProtoBuf message. All the stuff in SOAP header now goes to headers.
Google frontends prefer application/protobuf.
The ProtocolBufferModel of the Google API client uses application/x-protobuf.
You can serialize/de-serialize protobuf encoded data to/from strings. Send the serialized string as the body of an HTTP POST to Java and de-serialize it. That is one approach. Another way is to make use of the protobuf Service interface. Protobuf allows you to define a service interface in a .proto file and the protocol buffer compiler will generate service interface code and stubs in your chosen language. You only need to implement the protobuf::RpcChannel and protobuf::RpcController classes to get a complete RPC framework. Probably you can write an HTTP wrapper for these classes. See the following links for more information:
http://code.google.com/apis/protocolbuffers/docs/proto.html#services
http://code.google.com/apis/protocolbuffers/docs/reference/cpp-generated.html#service
http://code.google.com/apis/protocolbuffers/docs/reference/cpp/google.protobuf.service.html
To my knowledge protocol buffers support is available in both C++ and Java, you should be able to exchange protocol buffer serialized data between both systems.
That said, it seems your real question is "How do I send stuff over HTTP between a C++ backend and Java client"
It sound like you need to learn how to use gSOAP, read the docs.
Alternatively you could host a RESTful web server from your C++ app: Look at this: https://stackoverflow.com/questions/298113/how-can-i-implement-a-restful-webservice-using-c++
Next you would need to access the data hosted on your new C++ RESTful server: Look at this: Rest clients for Java?