I am making an xmpp webchat application in Grails. I have a message listener that can log the recieved messages in console. But how can I do this dinamycally in a website ? I am new to webapp development so please dont down vote. I am guessing Ajax but not sure.
My listener:
private MessageListener messageListener = new MessageListener() {
#Override
public void processMessage(Chat chat, Message message) {
// 'from' and 'to' fields contains senders ids, e.g.
// 17792-1028#chat.quickblox.com/mac-167
// 17744-1028#chat.quickblox.com/Smack
String from = message.getFrom().split("#")[0];
String to = message.getTo().split("#")[0];
org.jivesoftware.smack.packet.Message.Type type = message.getType();
String tajp = type.toString();
println String.format(">>> Message received (from=%s, to=%s, type=%s): %s", from, to, tajp, message.getBody())
if (onMessageReceivedListener != null) {
onMessageReceivedListener.onMessageReceived(message);
}
}
}
I suggest you to take a look on the Events Push plugin. With that you can propagate your messages and notify your clients.
You will need:
Service that notify a new message
Controller method to call this service
Ajax request to the controller, sending the user message
JavaScript to handle incoming messages
I am new to webapp development
Web development is pretty different from desktop, so I suggest you to slow down to something more easy. There's other topics on StackOverflow that will introduce you to Grails.
Also, for webdev, it's essential to know about JavaScript, CSS and HTML for your front end.
Related
I have Developed ASP.net Core Web API & Web APP Which are in the same solution but different projects.
in the API I have some validations/checking as you may call.
e.g: if user email already exists, the API returns 'Email alreday in use' like this
bool EmailExists = dbContext.Users.Any(u => u.Email == user.Email);
if (EmailExists)
{
return new JsonResult("Email Address already taken!, Try a differen Email");
}
and so on. in some cases I may need to check multiple columns one a time, (eg: UserName, Email, TellNum)
This is an example of calling the API in the MVC
using (var client = new HttpClient())
{
client.BaseAddress = new Uri(_baseAPIUrl);
client.DefaultRequestHeaders.Clear();
client.DefaultRequestHeaders.Accept.Add(
new MediaTypeWithQualityHeaderValue("application/json"));
HttpResponseMessage Res = await client.PostAsJsonAsync("Users", user);
if (Res.IsSuccessStatusCode)
{
//in here I want check the `Res` and if it contains the returned messages, I want to display them by assigning it to `TempData[infoMsg]`
// else some something(register user)
}
// Check the returned JsonResult messages here if statusCode is ultered eg: BadRequest
}
My Question is how can I display these types of response messages in razor view in the MVC(Web App). in PostMan its workin, returning the response messages in body.
I did a lot of research about this but couldn't come to conclusion. I also cantacted some Devs I know(not .NET) and they said use JavaScript to call your API, which means I have to change almost everything I have done so far.
I aslo tried ultereing the statuCode to something like BadRequest in the API(if Email exists) in which case it will be checked outside the if (Res.IsSuccessStatusCode) of the Httpclient.
any help or direction is highly appreciated.
You should return a http error and a body containing some data about it eg field and message to your mvc controller. That could be a 422 error or whatever you like really since it's effectively internal and just coming back to the mvc controller.
The controller can then add any such error to modelstate and you can use the razor model "client" validation mechanism to show the error associated with a field.
This is therefore using the same mechanism used for attribute validation in the controller where you'd do
if (!ModelState.IsValid)
This is air code but will hopefully give you the idea.
[HttpPost]
public ActionResult PostUpdate(User u)
{
// call service and await response
var response = await httpClient.PostAsJsonAsync(posturi, u);
var returnContent = await response.Content.ReadAsAsync<ReturnContent>();
if (response.Result != HttpStatusCode.OK)
{
ModelState.AddModelError(returnContent.FieldName,returnContent.Error);
return Page();
}
// etc
You will want a more sophisticated checking on errors of course and check you get the body you're expecting.
Maybe you just hard code the field and error message if there's only one possibility. Maybe work with an array of fields and errors if there could be numerous validation fails.
I'm publishing messages into RabbitMQ and I would like to track the errors when RabbitMQ is down, for this I added one RetryTemplate with the recovery callback, but the recovery callback only provides this method getLastThrowable() and I'm not sure how to provide the details of the messages that failed when RabbitMQ is down. (as per documentation "The RecoveryCallback is somewhat limited in that the retry context only contains the
lastThrowable field. For more sophisticated use cases, you should use an external
RetryTemplate so that you can convey additional information to the RecoveryCallback via
the context’s attributes") but I don't know how to do that, if anyone could help me with one example that will be awesome.
Rabbit Template
public RabbitTemplate rabbitMqTemplate(RecoveryCallback publisherRecoveryCallback) {
RabbitTemplate r = new RabbitTemplate(rabbitConnectionFactory);
r.setExchange(exchangeName);
r.setRoutingKey(routingKey);
r.setConnectionFactory(rabbitConnectionFactory);
r.setMessageConverter(jsonMessageConverter());
RetryTemplate retryTemplate = new RetryTemplate();
ExponentialBackOffPolicy backOffPolicy = new ExponentialBackOffPolicy();
backOffPolicy.setInitialInterval(500);
backOffPolicy.setMultiplier(10.0);
backOffPolicy.setMaxInterval(10000);
retryTemplate.setBackOffPolicy(backOffPolicy);
r.setRetryTemplate(retryTemplate);
r.setRecoveryCallback(publisherRecoveryCallback);
return r;
}
Recovery Callback
#Component
public class PublisherRecoveryCallback implements RecoveryCallback<AssortmentEvent> {
#Override
public AssortmentEvent recover(RetryContext context) throws Exception {
log.error("Error publising event",context.getLastThrowable());
//how to get message details here??
return null;
}
}
AMQP Outbound Adapter
return IntegrationFlows.from("eventsChannel")
.split()
.handle(Amqp.outboundAdapter(rabbitMqTemplate)
.exchangeName(exchangeName)
.confirmCorrelationExpression("payload")
.confirmAckChannel(ackChannel)
.confirmNackChannel(nackChannel)
)
.get();
The isn't possible because the function RabbitTemplate.execute() is already not aware about message you send, because it may be performed from any other method, where we might not have messages to deal:
return this.retryTemplate.execute(
(RetryCallback<T, Exception>) context -> RabbitTemplate.this.doExecute(action, connectionFactory),
(RecoveryCallback<T>) this.recoveryCallback);
What I suggest you to do is like storing message to the ThreadLocal before send and get it from there from your custom RecoveryCallback.
I am using apache camel netty4 in grails and I have declared mycustom ServerInitializerFactory as follows
public class MyServerInitializerFactory extends ServerInitializerFactory {
private int maxLineSize = 1048576;
NettyConsumer nettyConsumer
public MimacsServerInitializerFactory() {}
#Override
protected void initChannel(Channel channel) throws Exception {
ChannelPipeline pipeline = channel.pipeline()
pipeline.addLast("logger", new LoggingHandler(LogLevel.INFO))
pipeline.addLast("framer", new LengthFieldBasedFrameDecoder(ByteOrder.LITTLE_ENDIAN, maxLineSize, 2, 2, 6, 0, false))
pipeline.addLast("decoder", new MfuDecoder())
pipeline.addLast("encoder", new MfuEncoder())
pipeline.addLast("handler", new MyServerHandler())
}
}
I have a route which I setup as follows in my routebuilder.
from('netty4:tcp://192.168.254.3:553?serverInitializerFactory=#sif&keepAlive=true&sync=true&allowDefaultCodec=false').to('activemq:queue:Tracking.Queue')
My Camel Context is setup in the BootStrap.groovy as follows
def serverInitializerFactory = new MyServerInitializerFactory()
SimpleRegistry registry = new SimpleRegistry()
registry.put("sif", serverInitializerFactory)
CamelContext camelContext = new DefaultCamelContext(registry)
camelContext.addComponent("activemq", activeMQComponent.activeMQComponent("failover:tcp://localhost:61616"))
camelContext.addRoutes new TrackingMessageRoute()
camelContext.start()
When I run my app, my route is started and my framer, decoder, handler and encoders are all invoked but messages do not reach the Tracking. Queue and responses do not get back to the client.
If I do not use serverInitializerFactory in the netty url and user encoders and decoders instead, My messages are hitting the queue but I lose control of the acknowledgement that I want to sent for each type of message that I receive. It seems activemq tries to sent its own response which is rejected by my encoder.
Am I supposed to then write code to send again or is there something I am missing?
You need to add a handler with the consumer so it can be routed, see the unit test how its done:
https://github.com/apache/camel/blob/master/components/camel-netty4/src/test/java/org/apache/camel/component/netty4/NettyCustomPipelineFactoryAsynchTest.java#L112
I managed to get around that problem. In my channelRead0 method. I added the following lines
Exchange exchange = this.consumer.getEndpoint().createExchange(ctx, msg);
where ctx is the ChannelContextHandler and msg is the Message Object, the two are both parameters of the channelRead0 method.
I also added the following lines
this.consumer.createUoW(exchange);
and after my handling code I inserted the following line
this.consumer.doneUoW(exchange);
and everything works like a charm.
I am using SingalR for my Chat Application. Wanted to play with Redis
and SignalR but I cannot find an working example where i can send msg to
specific connectionId. Below Code that works for a single server instance.
But when i make it a Web Garden with 3 process it stops working as my
server instance that gets the message cannot find the connectionId
for that destination UserId to send the message.
private readonly static ConnectionMapping<string> _connections = new ConnectionMapping<string>();
public void Send(string sendTo, string message, string from)
{
string fromclientid = Context.QueryString["clientid"];
foreach (var connectionId in _connections.GetConnections(sendTo))
{
Clients.Client(connectionId).send(fromclientid, message);
}
Clients.Caller.send(sendTo, "me: " + message);
}
public override Task OnConnected()
{
int clientid = Convert.ToInt32(Context.QueryString["clientid"]);
_connections.Add(clientid.ToString(), Context.ConnectionId);
}
I have used the example below to setup my box and code but none of
them have examples for sending from one client to specific client or
group of specific clients.
http://www.asp.net/signalr/overview/performance-and-scaling/scaleout-with-redis
https://github.com/mickdelaney/SignalR.Redis/tree/master/Redis.Sample
The ConnectionMapping instance in your Hub class will not synced across different SignalR server instances. You need to use permanent external storage such as a database or a Windows Azure table. Refer to this link for more details:
http://www.asp.net/signalr/overview/hubs-api/mapping-users-to-connections
We are currently implementing private messaging in our asp.net mvc app and we have come to the conclusion that we would like to make it work like github does... meaning we would like the user to receive the message both through our site and to his email inbox(this is somewhat easy to achieve with mvcmailer nuget).. but we would also like the option to have the user reply to the email (through his email client) and have that email be sent to our app (if you have used guthubs private messaging you should know what I mean)..... what is a common approach to implementing this feature?
See my comment regarding how to read emails from a mailbox.
I would use a message bus so that you are not limited to just internal and email notifications, for example you may wish to add SMS notifications in the future.
You may want to check out MassTransit or NServiceBus although for something like this it may be easier to just create your own.
public class Message {
public string Title {get;set;}
public string Body {get;set;}
}
public interface IMessageBus {
void Send(Message message);
}
public interface IMessageHandler {
void Handle(Message message);
}
public class InternalMessageHander : IMessageHandler {
public void Handle(Message message) {
// send internal message
}
}
public class EmailMessageHandler : IMessageHandler {
public void Handle(Message message) {
// send email
}
}
Your IMessageBus implementation would need to locate all the handlers (I would use an IoC container for this).
If you need to process large volumes of messages then I would recommend handing these off to a queue and processing these asynchronously (both MassTransit and NServiceBus support message queues but you could just as easily use a simple database table).
As far as reading emails, I would have background task that connects to the mailbox, downloads emails, parses them and updates your content.
Usually you put either something in the subject line or at the end of the body to track the email. Any UID will do.
Hope that helps.