networking with rx

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<div class="footer"><div class="flexcontainer"><span>.body[[https://kirkshoop.github.io/norawthread/rxnetts.html](https://kirkshoop.github.io/norawthread/rxnetts.html)]</span><span>.center[C++Now 2017]</span><span>.body[© 2017 Kirk Shoop ([github](http://github.com/kirkshoop) [twitter](http://twitter.com/kirkshoop))]</span></div></div>

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# Networking TS w/Algorithms

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# Networking TS Workshop

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![](content/networkingworkshop.png)
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[sched](https://cppnow2017.sched.com/event/A8Ie/networking-ts-workshop-part-1-of-2)

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# http get request

```
auto host = "www.boost.org"s;
auto service = "http"s;
auto request = "GET / HTTP/1.0\r\n"
                "Host: www.boost.org\r\n"
                "Accept: */*\r\n"
                "Connection: close\r\n\r\n"s;

auto boostorg = `rx_connect`(io_context, host, service) |
    rxo::concat_map([=](connected c){
        return rxs::just(request) | 
                `rx_send`(c); 
    }) |
    rxo::concat_map([=](connected c){
        return `rx_read`(c);
    }) |
    // share chunks
    rxo::publish() |
    rxo::ref_count();
```

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# derive results from the shared chunks

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## break out http headers]

```
auto headers = boostorg |
    split("\r\n", Split::RemoveDelimiter) |
    rxo::take_while([] (const string& s){
        return !s.empty();
    });
```

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## accumulate count of bytes read]

```
auto size = boostorg |
    rxo::scan(0, [] (int total, const string& chunk){
        return total + int(chunk.size());
    });
```

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# combine the data sources

```
auto responseupdates = boostorg |
    rxo::map([](const string&){return "response"s;});

headers.
    concat(rxs::just("END HEADERS"s), responseupdates).
    with_latest_from(size | rxo::start_with(0)).
```

```
    subscribe(rxu::apply_to([](const string& s, int size){
        cout << s << " : " << size << endl;
    }), [](exception_ptr ex){
        cerr << rxu::what(ex) << endl;
    }, [](){
        cout << endl;
    });
```

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# try it out

```sh
$ c++ -std=c++14 -I ../netts/include/ -I rxcpp/Rx/v2/src/ rx.cpp 
$ ./a.out
HTTP/1.1 200 OK : 0
Date: Thu, 18 May 2017 14:03:57 GMT : 0
Server: Apache/2.2.15 (CentOS) : 0
Accept-Ranges: bytes : 0
Connection: close : 0
Content-Type: text/html : 0
END HEADERS : 0
response : 8192
response : 12288
response : 16384
response : 20480
response : 24576
response : 28672
response : 32768
response : 36864

close
```

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# echo

```
auto echo = rx_connect(io_context, host, service) |
    rxo::concat_map([=](connected c){
        return rx_read(c) | 
                rx_send(c); 
    }) |
    rxo::subscribe<connected>();
```

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# code

The code was a 1day minimal solution. more work is needed to build a fully general adaption.

[https://github.com/kirkshoop/networkingts](https://github.com/kirkshoop/networkingts)

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# see more of these algorithms

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## No raw std::thread! - Live Tweet Analysis in C++]

> * ### friday
> * ### 2:30pm

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