Locus, V, Mach: Difference between revisions
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Debate about the pros and cons of RPC. Topic: RPCs are the right foundation for the distributed applications (on today's Internet). | Debate about the pros and cons of RPC. Topic: RPCs are the right foundation for the distributed applications (on today's Internet). | ||
== | ===Pros=== | ||
# Easy to use | # Easy to use | ||
#* makes remove procedure calls look like local calls | #* makes remove procedure calls look like local calls | ||
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# RPC can be abstracted from the protocol design | # RPC can be abstracted from the protocol design | ||
# (Counter to fourth con) Use threads for interactivity. Manage complexity by doing things pairwise. | # (Counter to fourth con) Use threads for interactivity. Manage complexity by doing things pairwise. | ||
# | |||
== | ===Cons=== | ||
# Language/implementation specific | # Language/implementation specific | ||
# (Counter to third pro) Not easy to debug. example: NullPointerException thrown on server, containing line of erroneous code running on the server. | # (Counter to third pro) Not easy to debug. example: NullPointerException thrown on server, containing line of erroneous code running on the server. | ||
# Counter to fifth pro) But there is more overhead - slower | # Counter to fifth pro) But there is more overhead - slower | ||
# Synchronous - wrong model for large, distributed applications, and also bad for users | # Synchronous - wrong model for large, distributed applications, and also bad for users | ||
# Limited scalability - hard to do well | |||
# Limited control of communication details | |||
# Authentication is opaque | |||
# Larger attack surface area | |||
==Questions to be discussed== | ==Questions to be discussed== | ||
Revision as of 20:37, 16 January 2008
Readings
David R. Cheriton, "The V Distributed System."
Bruce Walker et al., "The LOCUS Distributed Operating System."
These two papers describe V and LOCUS, two early distributed operating systems.
This paper describes some key ideas behind Mach, a seminal microkernel-based operating system. The design of Mach informs later work in distributed operating systems. For more background on Mach, I suggest reading Wikipedia's article on Mach.
Debate
Debate about the pros and cons of RPC. Topic: RPCs are the right foundation for the distributed applications (on today's Internet).
Pros
- Easy to use
- makes remove procedure calls look like local calls
- local is easy
- therefore remove is easy with RPC - good!
- (Counter to first con) Use standards, problem goes away
- Easy to debug
- Avoids complexity of protocol design
- RPC can be abstracted from the protocol design
- (Counter to fourth con) Use threads for interactivity. Manage complexity by doing things pairwise.
Cons
- Language/implementation specific
- (Counter to third pro) Not easy to debug. example: NullPointerException thrown on server, containing line of erroneous code running on the server.
- Counter to fifth pro) But there is more overhead - slower
- Synchronous - wrong model for large, distributed applications, and also bad for users
- Limited scalability - hard to do well
- Limited control of communication details
- Authentication is opaque
- Larger attack surface area
Questions to be discussed
- What did the (technical) world look like when this distributed OS was designed & implemented?
- What are the key design features of the OS? What are the key compromises?
- To what extent is their system a "distributed operating system"?
- What is the basic argument for their design choices? What evidence do they cite in their favor?
- To what extent do you "believe" their design choices were right? Why?
- To what extent does their design work in the context of the modern Internet? Discuss wins and limitations.
- What concepts from the paper have been adopted by today's systems? What concepts should be adopted? What should be ignored?