- What do Etcd, Consul, and Zookeeper do?
- Service Registration:
- Host, port number, and sometimes authentication credentials, protocols, versions numbers, and/or environment details.
- Service Discovery:
- Ability for client application to query the central registry to learn of service location.
- Consistent and durable general-purpose K/V store across distributed system.
- Some solutions support this better than others.
- Based on Paxos or some derivative (i.e. Raft) algorithm to quickly converge to a consistent state.
- Service Registration:
- Centralized locking can be based on this K/V store.
One of my colleagues shared an article on writing (good) Git commit messages today: How to Write a Git Commit Message. This excellent article explains why good Git commit messages are important, and explains what constitutes a good commit message. I wholeheartedly agree with what @cbeams writes in his article. (Have you read it yet? If not, go read it now. I'll wait.) It's sensible stuff. So I decided to start following the
Spurred by recent events (https://news.ycombinator.com/item?id=8244700), this is a quick set of jotted-down thoughts about the state of "Semantic" Versioning, and why we should be fighting the good fight against it.
For a long time in the history of software, version numbers indicated the relative progress and change in a given piece of software. A major release (1.x.x) was major, a minor release (x.1.x) was minor, and a patch release was just a small patch. You could evaluate a given piece of software by name + version, and get a feeling for how far away version 2.0.1 was from version 2.8.0.
But Semantic Versioning (henceforth, SemVer), as specified at http://semver.org/, changes this to prioritize a mechanistic understanding of a codebase over a human one. Any "breaking" change to the software must be accompanied with a new major version number. It's alright for robots, but bad for us.
SemVer tries to compress a huge amount of information — the nature of the change, the percentage of users that wil
<?php | |
if (!function_exists('interface_exists')) { | |
die('PHP version too old'); | |
} | |
$throwables = listThrowableClasses(); | |
$throwablesPerParent = splitInParents($throwables); | |
printTree($throwablesPerParent); | |
if (count($throwablesPerParent) !== 0) { | |
die('ERROR!!!'); |
[T]he difference between a bad programmer and a | |
good one is whether he considers his code or his | |
data structures more important. Bad programmers | |
worry about the code. Good programmers worry about | |
data structures and their relationships. | |
-- Linus Torvalds | |
~~~ | |
Clarity and brevity sometimes are at odds. | |
When they are, I choose clarity. | |
-- Jacob Kaplan-Moss |
<?php | |
// 第一种方法 | |
function UUIDS() | |
{ | |
if (function_exists('com_create_guid')) | |
{ | |
$uuid = com_create_guid(); | |
return substr($uuid, 1, -1); | |
} |