1. 1 IDF Annual Members Meeting June 21, 2005 Handle / Proxy Distribution And Load Balancing

2. 2 IDF Annual Members Meeting June 21, 2005 Handle is (can be) a highly federated system providing fault tolerance and higher throughput capabilities. Distributing the Handle system is very easy. All Local Handle Servers (LHS) coordinate via the one Global Handle Server (GHS). The Handle system was built to to do this! Distributing the proxy server is not as easy due to the challenge of load balancing across resources distributed in different domains. Issues of concern: Log management Even load distribution Fault tolerance

3. 3 IDF Annual Members Meeting June 21, 2005 Before… CNRI Off Site Data-center IP Load Balancer Proxy 1 Proxy 2 GHS LHS Primary (Default) CNRI Office Proxy 3 (backup) LHS Secondary (Default) LHS Secondary (Default) same domain

4. 4 IDF Annual Members Meeting June 21, 2005 Now … CNRI Off Site Data-center IP Load Balancer Proxy 1 Proxy 3 GHS LHS Primary (CrossRef) CNRI Office Proxy (backup) LHS Secondary (Default) LHS Secondary (Default) doi.org CrossRef Data-center Proxy xref-1 LHS Secondary (Crossref) Proxy 4 LHS Secondary (CrossRef) LHS Primary (Default)

5. 5 IDF Annual Members Meeting June 21, 2005 How does this work? A DNS sub-domain is created and serviced by four name servers dx.doi.org => nameD servers running on each proxy machine Each nameD server returns a different address, their own! Theory: if you can get to the nameD server you can get to that proxy When your computer goes to lookup where dx.doi.org is available, one of four addresses will be returned. Your computer will remember this address for a very short time and have to go back to DNS and ask again where dx.doi.org lives.

6. 6 IDF Annual Members Meeting June 21, 2005 March April May hdl:201/proxy1 : 2,338,904 2,312,693 2,689,267 hdl:201/proxy3 : 2,337,433 1,997,166 2,580,751 hdl:201/proxy4 : 2,342,089 2,289,693 2,711,311 hdl:201/xref-proxy1 : 796,471 1,465,786 1,385,282 CNRI automatically collects log information using KnowBots. CrossRefs proxy machine allows CNRI to enter and run a agent that collects the data and sends it back to CNRI for compilation and distribution. Logs …