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Comet is a web application model that used to “push” data to web page(browser), which can be used in applications like Web Chat, News Feed, Stock Market, even Web Game.

There are many opensourced comet servers, but most big companies develope their own comet server. As we know, Facebook’s comet server is built on Mochiweb, an opensourced Erlang Web server.

Nginx’s module nginx-push-stream is another solution, but it is suitable for small system, it can not handle 100K+ connections, according to our experiences. A comet should be able to handle 1 million connections.

Many companies develope their own comet server, for performance, and for integration with existing systems.

Writing a comet server is very easy with libevent, the famous network library. The simple C comet server is only 150 lines of code, can be down load from here: https://github.com/ideawu/icomet

SSDB now provided flushdb command, which is used to delete all data in SSDB server. This command is dangerous, so you need to type ‘yes’ on command prompt. This command is implemented via ssdb-cli.

You can flush only kv, hash, or zset data, with flushdb kv, flushdb hash, flushdb zset.

There is no need to recompile or restart the SSDB server.

Many command-line application ask the user to type in every character of the word “quit” and press Enter to quit the application. But I want to ask the reason why? Why can’t I just type in only the character ‘q’ and press Enter, or press ESC key to quit?

Actually, many cli application like redis-cli said it received a bad command when user type in ‘q’ and press Enter. So, the ‘q’ command doesn’t map to any other operation. So it is available to map ‘q’ to the quit operation.

As for the convienience of users, ssdb-cli allow user to type in ‘q’ to quit the application.

The WebRTC project included a voice engine(GIPS, Global IP Solutions), here is an example to show how you can use the voice engine to record audio from microphone.

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include "webrtc/modules/audio_device/include/audio_device.h"
#include "webrtc/common_audio/resampler/include/resampler.h"
#include "webrtc/modules/audio_processing/aec/include/echo_cancellation.h"

class AudioTransportImpl: public webrtc::AudioTransport
{
private:
    
public:
    AudioTransportImpl(webrtc::AudioDeviceModule* audio){
    }
    
    ~AudioTransportImpl(){
    }

    virtual int32_t RecordedDataIsAvailable(
        const void* audioSamples,
        const uint32_t nSamples,
        const uint8_t nBytesPerSample,
        const uint8_t nChannels,
        const uint32_t samplesPerSec,
        const uint32_t totalDelayMS,
        const int32_t clockDrift,
        const uint32_t currentMicLevel,
        const bool keyPressed,
        uint32_t& newMicLevel)
    {
        printf("record %d %d %d %d %d %d %d %d\n", nSamples,
            nBytesPerSample, nChannels,
            samplesPerSec, totalDelayMS,
            clockDrift, currentMicLevel, keyPressed);
        // now you have the audioSamples...
        return 0;
    }
};


int main(int argc, char **argv){
    webrtc::AudioDeviceModule *audio;
    audio = webrtc::CreateAudioDeviceModule(0, webrtc::AudioDeviceModule::kPlatformDefaultAudio);
    assert(audio);
    audio->Init();
    
    int num;
    int ret;
    
    num = audio->RecordingDevices();
    printf("Input devices: %d\n", num);
    for(int i=0; i<num; i++){
        char name[webrtc::kAdmMaxDeviceNameSize];
        char guid[webrtc::kAdmMaxGuidSize];
        int ret = audio->RecordingDeviceName(i, name, guid);
        if(ret != -1){
            printf("    %d %s %s\n", i, name, guid);
        }
    }
    
    audio->SetRecordingDevice(0);
    audio->InitRecording();
    
    AudioTransportImpl callback(audio);
    audio->StartRecording();

    getchar();
}

For more webrtc demos, visit: https://github.com/ideawu/webrtc-demo

The new detailed SSDB PHP Client API Documentation is now available. It is at this link: http://www.ideawu.com/ssdb/docs/php/.

The document looks like this

zsize

Description

Return the number of pairs of a zset.

Parameters

    name - The name of the zset

Return Value

false on error, otherwise an integer of the zset, 0 if the zset does not exist.

Example

$ssdb->zsize('z');

The document is also available in github repository.