• 搜狐网站诚聘Java、PHP和C++工程师
• 北京: 千橡集团暨校内网诚聘软件研发工程师

void doIt() {
Object o = new Object();
o = null;
}

public static void main() {
  A a = new A();
  a.doSomthing();
}
class A() {
  doSomething() {
    B b = new B();
    b.doSomething();
  }
}
class B() {
  doSomehing() {
    C c = new C();
    c.doSomething;
  }
}

• 搜狐网站诚聘Java、PHP和C++工程师
• 北京: 千橡集团暨校内网诚聘软件研发工程师

• 搜狐网站诚聘Java、PHP和C++工程师
• 北京: 千橡集团暨校内网诚聘软件研发工程师

Network Working Group                                        D. Waitzman
Request for Comments: 1149                                       BBN STC
                                                            1 April 1990

   A Standard for the Transmission of IP Datagrams on Avian Carriers

Status of this Memo

   This memo describes an experimental method for the encapsulation of
   IP datagrams in avian carriers.  This specification is primarily
   useful in Metropolitan Area Networks.  This is an experimental, not
   recommended standard.  Distribution of this memo is unlimited.

Overview and Rational

   Avian carriers can provide high delay, low throughput, and low
   altitude service.  The connection topology is limited to a single
   point-to-point path for each carrier, used with standard carriers,
   but many carriers can be used without significant interference with
   each other, outside of early spring.  This is because of the 3D ether
   space available to the carriers, in contrast to the 1D ether used by
   IEEE802.3.  The carriers have an intrinsic collision avoidance
   system, which increases availability.  Unlike some network
   technologies, such as packet radio, communication is not limited to
   line-of-sight distance.  Connection oriented service is available in
   some cities, usually based upon a central hub topology.

Frame Format

   The IP datagram is printed, on a small scroll of paper, in
   hexadecimal, with each octet separated by whitestuff and blackstuff.
   The scroll of paper is wrapped around one leg of the avian carrier.
   A band of duct tape is used to secure the datagram's edges.  The
   bandwidth is limited to the leg length.  The MTU is variable, and
   paradoxically, generally increases with increased carrier age.  A
   typical MTU is 256 milligrams.  Some datagram padding may be needed.

   Upon receipt, the duct tape is removed and the paper copy of the
   datagram is optically scanned into a electronically transmittable
   form.

Discussion

   Multiple types of service can be provided with a prioritized pecking
   order.  An additional property is built-in worm detection and
   eradication.  Because IP only guarantees best effort delivery, loss
   of a carrier can be tolerated.  With time, the carriers are self-

   regenerating.  While broadcasting is not specified, storms can cause
   data loss.  There is persistent delivery retry, until the carrier
   drops.  Audit trails are automatically generated, and can often be
   found on logs and cable trays.

Security Considerations

   Security is not generally a problem in normal operation, but special
   measures must be taken (such as data encryption) when avian carriers
   are used in a tactical environment.

Author's Address

   David Waitzman
   BBN Systems and Technologies Corporation
   BBN Labs Division
   10 Moulton Street
   Cambridge, MA 02238

   Phone: (617) 873-4323

   EMail: dwaitzman@BBN.COM

• 北京: 千橡集团暨校内网诚聘软件研发工程师
• 搜狐网站诚聘Java、PHP和C++工程师