Actually all these wargames are as much to horn the skills of the participants' military as they are commercial show for their products.
Since I don't think China could sell their J-11 or Su-30 to third country, there really is no need to showcase these weaponries, especially in front of the Russian. However J-10 is a product that might be interested in many parties, so by showcasing these weapons and letting other see what the J-10 can do, it might attract more interest and ultimately generate some sales figures.
So today's wargame is many folds.
1) train soldiers
2) For diplomatic purposes especially with friendly nations.
3) A show of might, so that people will not take the participants lightly.
4) Commerical reasons (to showcase equipments you wanted to sell, and to shop around for equipments being showcased.)
Great analysis Rhino! However I also want to know whether the J-10 will participate in mock dog-fights with the Russian Flankers (perhaps in secret). Could this also be intended as a sort of "take that" to the naval exercises in the Yellow Sea as well?