Frequent Ask Questions

Question: There were many products in the market that was purposed to provide load balancing, then why we still need Opera?
Question: How Opera makes it's topologically load distribution decision?
Question: What html pages should I include in my website when I use the OPERA?
Question: How do OPERA know the URL of my website?
Question: How to auto detect what media player have been installed in the user 's PC?
Question: Why I just can use the media detector in Netscape but not in Internet Explorer?
Question: Is there any demo site to tell me how to use the DetectPlayer() function?

There were many products in the market that was purposed to provide load balancing, then why we still need Opera?

In general, many vendor specific products have suggest several ideas on load balancing and service distribution issue. The following were the common approaches:
1) DNS based approach.
2) Dispatcher based approach.
3) HTTP Session Redirector approaches.

All the above, although were using different approaches, but the pre-requisites is that full replication of server content is need. It is because the above application where all server level approaches which means that the basic assumption behind were services server where replicated in exactly the same content. Also, vendor specific product increases difficulties in merging existing networking equipment.

Benefit of OPERA, provides features that overcome the drawback discussed above plus many other advanced options. All were listed below:

There were many products in the market that was purposed to provide load balancing, then why we still need OPERA?

The first phase of Opera topological load distribution function was work by making static mapping of range of IP address to geographical location. Such that data file will be prepared and store as configuration file.

Second phase of Opera will provide dynamic updated route topology table by making use of the BGP & IGP in network infrastructure. Currently the data file only support IP redirection of Taiwan, Singapore and Hong Kong.

The information were retrieved and processed from the following sources:
1) APNIC
2) Taiwan exchange center
3) Singapore exchange center
4) Hong Kong exchange center
5) WHOIS services from RADB database

The idea of our product is that when a UMRL request were received, the location of the client (Client's IP address) will be known by the matching of it's IP to the predefined range. In case of unable to find a match, client will be redirected to a server that is configurable by the Services Provider
The location of client will be one of the metrics in choosing server for providing services. Other metrics will include server loading, services availability, etc. The weight of those will be configurable.

Second phase of redirection was still undergoing development. More information will be updated as it's going to release.

What html pages should I include in my website when I use the OPERA?

When you use OPERA, you may need to prepare about 4 html pages. These pages are: l umrl_setup.html - where the user can set the preference to store on the cookie l umrl_notfound.html - tell the user whether the video successfully delivery or not l umrl_result.html - just the page to go after the user setup the preference l umrl_popup.cgi - after the video delivery, show the information of it With these pages in your website, you can let your web users to setup his own watching video preference with different language, different player format and different bandwidth. Also, the user can know that rather the video can successfully delivery or not when using OPERA. If the videos can successfully delivery, a popup window can show the information about the video.

How do OPERA know the URL of my website?

There is a configure file in the Multimedia Name System (MNS) of OPERA called mns_config_file. Using these configure file, MNS can know the information of your website and it can redirect to your page correctly.

How to auto detect what media player have been installed in the user 's PC?

You can include a JavaScript file called detector.js in OPERA and use the function on it. First add a line on your auto detect player web page:

Then you can write some JavaScript with the function DetectPlayer() in the file detector.js such that u can detect which media player the user has been installed. You can take a look in our OPERA demo site to learn how to use the function.

Why I just can use the media detector in Netscape but not in Internet Explorer?

Yes, when you use JavaScript with DetectPlayer() function on your html page, you just can detect the media player only when the user is using Netscape browser. It is because this function just detects the mime-type of the user's browser. However, I.E. doesn't support this function call such that we can't detect which player have been installed when the user is using I.E.

In the near future, we believe that we can also detect in I.E. Now we have solution to detect Window Media Player and Real Player but not QuickTime yet. The next version of OPERA maybe included.

Is there any demo site to tell me how to use the DetectPlayer() function?

Yes, you can go to our OPERA demo site to see how to use this JavaScript function. http://www.hkcl.org/opera/auto.html
The following simple code also can help you: