Level 7 will check up backend servers’ status automatically. If Level 7 doesn’t receive server’s feedback for a certain while, it will identify this server as unavailable and won’t forward request to it any more.
3.In traditional Memcache, all the users share one LRU link; this would cause interference between user data exchange, like A’s data might be replaced by B’s. So we need to install different Memcache instances to keep these distinct LRU links.
3.Domain supported. Different domains have distinct memory limit and LRU. Developers can set up memory limit according to data importance, and these data LRU links won’t be interfered by each other.
For data service, SAE mainly uses replication to ensure the high reliability. SAE’s data storage service adopts two kinds of replication, the active and the passive. For instance, the synchronization between master and slave Binlog on SAE is typical passive replication: User’s task request is read into the master database, and be synchronized to the slave by backend process. Once the master was down, the slave would be quickly switched as master. In addition, some of SAE’s service use active replication (double-write) to ensure the HA, like Cron. When developers set up a Cron in configuration file, appconfig.yaml, the information of this timing task will be double-written into several persistent databases for later execution.
Besides developers need to enhance our own cyber-security awareness and strengthen the computer security, SAE also provides a security code protection mechanism. First, SAE will check the security code’s login IP; validate the cell phone number for IP from another region. Second, if users want a higher level security, you can apply for SAE cell phone dynamic password as a replace of security code.
DefferedJob is for developers to configure an off-line task execution schedule. It is not limited by HTTP longest execution time, which is the main difference from TaskQueue. This is because DefferedJob is executed at system level language so there is no time limit; while TaskQueue is triggered by HTTP methods.
SAE has many multiplex backbone network (China Telecom, China Unicom, China Mobile and Education network line) CDN nodes covering nearly all China’s big cities. Now these nodes are opened for clients to use this high quality CDN service.
After enable CDN service, data in Storage will be pushed to every CDN nodes. Users will receive data from the nearest nodes when try to fetch it and this will greatly improve the access performance.
SINA Short Message Service is a comprehensive message service supported by SINA Wireless. Users can send short message via China Mobile, China Unicom or China Telecom network, and the arrival rate is above 90%.
Geo. Location service is usually used in the situation of searching routine, bus lines, IP location and maps.
Chinese Word Segmentation means divide certain sequence of Chinese characters into one-by-one words. It is the basis of text mining. Segmentation with higher accuracy for certain Chinese paragraph would help computers understand what those really mean. SAE’s word segmentation is the Chinese sentence analysis system developed based on Hidden Markov Model, which mainly includes Chinese word segmentation, part-of-speech tagging, named entity recognition and new word identification.