• High service speed

1. The program is ready to serve the requests immediately after it has got started. The check of storages integrity during the program's startup or reconfiguration procedure made in the background and does not detain processing of the customers' requests.

2. The elementary file system is chosen as a model for storing the objects cashed. I.e. the objects are not stored in separate files, but in one or several big files (storages), representing the file system within the file. Apart from the increase of access speed to the objects in such storage in comparison with the storage of "one object - one file" type, it allows to create storages on block devices. Unfortunately, it results in limitations on 32-bit systems, where the file size (to be more exact: offset in a file) is limited approximately to 2GB. It does not mean the impossibility to use storages with their capacity more than 2GB, just a necessity for use of several files will be faced in such systems. This problem will be fixed soon.

3. Objects in the storage are indexed. Index is b-tree database, which allows finding the objects with minimum time losses.

4. All operations on supporting storages (cleaning, expire), requiring blocking of access, are made in the background with less priority. If there is a request, the blocking is removed as fast as possible (the time of maximum delay can be configured and makes 1 second by default).

5. The program is written with the help of multithread technology. It certainly has both its advantages and disadvantages. The advantages are obvious: more simple program development, absence of the unforeseen blocking, capability to use several processors on multiprocessors machines with appropriate productivity increase. Disadvantages: the platforms having pthread's are just supported; some difficulties with debugging. It is necessary to take into account that threads become more and more popular paradigm of programming, so, I hope the disadvantages will absolutely disappear soon.

6. All the necessary operations are carried out within one program, no external demons (ftpget, dnsservers, unlinkd).

• Stability of work is gained by means of thorough testing and debugging. To find out the bugs of programming and memory leaks such means are used as "purify" and internal checker of debugger dbx.
• Supported protocols: http, ftp, ssl-tunneling, icp v2.
• Configuration opportunities: several types of acl (unfortunately, such abundance of acl observed in squid I haven't produced yet). For eg.:
  
  

 group localusers { 
 networks 192.168/16 127/8;
 badports [0:79],110,138,139,513,[6000:6010]; 
 bandwidth 8k; 
     icp { 
     allow dstdomain * ; 
    } 
     http { 
    allow dstdomain * ; 
    } 
   } 
     group otherworld { 
      networks 0/0; 
      icp { 
      deny dstdomain * ; 
   } 
     http { 
       deny dstdomain * ; 
   } 
  }