A youtube videoclip titled "Roy T. Fielding: Understanding the REST Style"
------------------------------------------------
These are my notes on "Roy T. Fielding: Understanding the REST Style" youtube videoclip:
No technical information.
"It's really an accessible piece of work. It is not full of equations. There is one equation. The equation is there just to have an equation, by the way."
Historically, the difference between scripting languages and real programming languages has been seen as presence or absence of a compilation step. However, from time to time we have seen interpreters for languages that were originally meant to be compiled, and we have also seen compilers for languages that were originally meant to be interpreted. Furthermore, some scripting engines today internally compile to bytecode, while many compiled languages do the same, and in both cases bytecode can be executed either by first translating it to machine code or by directly interpreting it, thus further blurring the distinction. So, compiled vs. interpreted does not seem to be the real differentiating factor between scripting languages and real programming languages. Nonetheless, we can usually tell a scripting language when we see one. So, what is it that we see?
My notes on Devoxx 2016 Belgium - Microservices Evolution: How to break your monolithic database by Edson Yanaga (I attended this conference)
Reduce maintenance window
Achieve zero downtime deployments
"Code is easy, state is hard"
Changes in a database schema from one version to another are called database migrations
Tools: Flyweight Liquibase
Migrations require back and forward compatibility
Baby steps = Smallest Possible Batch Size
Too many rows = Long Locks
Shard your updates (not updating the entire table in one go)
Renaming a column
ALTER TABLE customers RENAME COLUMN wrong TO correct; becomes:
ALTER TABLE customers ADD COLUMN correct VARCHAR(20); UPDATE customers SET correct = wrong WHERE id < 100; UPDATE customers SET correct = wrong WHERE id >= 100 AND id < 200; ... (later)ALTER TABLE customers DELETE COLUMN wrong;
Adding a column ADD COLUMN, setting NULL/DEFAULT value/computed value Next release: Use Column
Renaming / Changeing Type / Format of a Column: Next version: ADD COLUMN, Copy data using small shards Next release: Code reads from old column and writes to both Next release: Code reads from new column and writes to both Next release: Code reads and writes from new column Next release: Delete old column
Deleting a column
Next version: Stop using the column but keep updating the column Next version: Delete the column
For migrating from a monolithic application with a monolithic database to many microservices with own database each:
Using Event Sourcing
tool: debezium.io You tell it which tables you want to monitor, and from then on it monitors them and generates an event for each DDL/DML statement you issue. The event is propagated to as many event consumers as you want. So, microservices can receive these events and update their own databases.
"HTTP and REST are incredibly slow"
My notes on Devoxx US 2017, Knowledge is Power: Getting out of trouble by understanding Git by Steve Smith
"If that doesn't fix it, git.txt contains the phone number of a friend of mine who understands git. Just wait through a few minutes of 'It's really pretty simple, just think of branches as...' and eventually you'll learn the commands that will fix everything."
My notes on GOTO 2015 - Progress Toward an Engineering Discipline of Software - Mary Shaw
Notes
17:28 past the bridges and into software engineering
Software Engineering is all design. Production used to be printing the CDs, and nowadays it is hitting the "deploy" button.
"scaling the costs to the consequences" -- the point is not to minimize the cost, the point is to scale it to the consequences. Risks must be taken, and if the potential gains are huge, then the risks can be correspondingly large.
My notes on GOTO 2014 - REST: I don't Think it Means What You Think it Does - Stefan Tilkov
"People decide they want to build something in a RESTful fashion, so they spend all their time arguing about where the slashes go".
"It is the first litmus test for your REST API whether you depend on specific characters in your URIs for things to work."
(From the client's point of view.)
"Version numbers in URIs just suck. Everybody does it which doesn't make it any less sucky. It is a stupid idea. Don't do that."
"The version number is in the URI because the URI is the API". <-- ? I would assume the URI is NOT the API.
Versioning: "Version your documentation documents. Wait what? --Yes, no versioning".
Postel's law "TCP implementations should follow a general principle of robustness: Be conservative in what you do, be liberal in what you accept from others." http://tools.ietf.org/html/rfc761
Client rules Don't depend on URI structure Support unknown links Ignore unknown content
Server rules Don't break URI structure unnecessarily Evolve via additional resources Support older formats
