travisjeffery / trvseventsource

Server-sent events EventSource client using NSURLSession

TRVSEventSource

Server-sent events EventSource implementation in ObjC for iOS and OS X using NSURLSession.

Usage

TRVSEventSource *eventSource = [[TRVSEventSource alloc] initWithURL:URL];
eventSource.delegate = self;

[eventSource addListenerForEvent:@"message" usingEventHandler:^(TRVSServerSentEvent *event, NSError *error) {
    NSDictionary *JSON = [NSJSONSerialization JSONObjectWithData:event.data options:0 error:NULL];
    Message *message = [Message messageWithJSON:JSON];
}];

[eventSource open];

Local test server

Run the following to have a local server streaming events named message:

node TRVSEventSourceTests/server.js

❯ curl 127.0.0.1:8000
event: message
data: {"id": 1, "body":"1381466575460", "author_id": 1, "conversation_id": 1}

event: message
data: {"id": 2, "body":"1381466577463", "author_id": 1, "conversation_id": 1}

trvseventsource's Issues

Support custom http header

Would be nice to provide interface to support http header.

Update Cocoapod to the latest

Thanks for creating this library!

It'd be awesome if you can update the cocoa pod to use the latest in the master branch.

Incompatibility with W3C specification

Specification can be found here: http://www.w3.org/TR/eventsource/

Most importantly the library ignores empty strings that are delimiters between messages.

TRVSEventSource merges everything that it finds into one message.
So next three server events will produce one TRVSServerSentEvent:

data: This is the first message.

data: This is the second message, it
data: has two lines.

data: This is the third message.

There are lot more incompatibilities anyway.

Bad access on [stream propertyForKey:]

I get data from event source for few minute and this error occur.

#pragma mark - NSStreamDelegate

- (void)stream:(NSStream *)stream handleEvent:(NSStreamEvent)eventCode {
    switch (eventCode) {
        case NSStreamEventHasSpaceAvailable: {
            //bad access on this line
            NSData *data = [stream propertyForKey:NSStreamDataWrittenToMemoryStreamKey];
            NSError *error = nil;
            TRVSServerSentEvent *event = [TRVSServerSentEvent eventWithFields:TRVSServerSentEventFieldsFromData([data subdataWithRange:NSMakeRange(self.offset, [data length] - self.offset)], &error)];
            self.offset = [data length];

            if (error) {
                [self transitionToFailedWithError:error];
            }
            else {
                if (event) {
                    [[self.listenersKeyedByEvent objectForKey:event.event] enumerateKeysAndObjectsUsingBlock:^(id _, TRVSEventSourceEventHandler eventHandler, BOOL *stop) {
                        eventHandler(event, nil);
                    }];

                    if ([self.delegate respondsToSelector:@selector(eventSource:didReceiveEvent:)]) {
                        [self.delegate eventSource:self didReceiveEvent:event];
                    }
                }
            }
            break;
        }
        case NSStreamEventErrorOccurred: {
            [self transitionToFailedWithError:self.outputStream.streamError];
            break;
        }
        default: break;
    }
}

The pending pull request should be reviewed and merged. As it fixes few critical issues.

Return http status code if event source failed

We are using this client for long running streaming data. (2000 messages per sec). And a lot of times event source failed with error set to be nil. Sometimes it is due to authentication failure to establish streaming. Sometime server restarts and connection is broken. Sometimes it is due to time out. Sometimes server closes the connection with a http status code.

So a lot of time we want to know what is causing the failure. So that we can either reconnect, or re-authenticate, or just let it fail. It would be super nice to have http status code returned in the failure callback so we have more info to determine what is going wrong.

Max number of connections

Hi,

I am curious how many concurrent clients you were able to connect to your server. I wrote a express.js (Node) server supporting event source streams and could get up to 3000 clients without optimizations, which seems not that high to me. Also the CPU is maxed out with 3000 clients.

Did you benchmarked yours? How does it perform?

Delegate methods are not called at the right time

The delegate's -eventSourceDidOpen: method is called when -open: is called on the event source, not when the connection is actually established, and is called even if the connection fails.

Similarly, -eventSourceDidClose: is called only when -close: is called on the event source, not when the connection actually closes, and not if there is a network error or the remote host unexpectedly closes the connection.