CDRS is a native Cassandra driver written in Rust. The motivation to write it in Rust is a lack of native one. Existing ones are bindings to C clients.
CDRS is under active development at the moment, so API may not be stable.
As well CDRS provides tools for mapping results into Rust structures It supports 4-th version of Cassandra protocol.
[x] RESULT (Schema_change)
To use password authenticator, just include the one implemented in
cdrs::authenticators.
rust
use cdrs::client::CDRS;
use cdrs::authenticators::PasswordAuthenticator;
use cdrs::transport::Transport;
After that you can create a new instance of CDRS and establish new connection:
```rust let authenticator = PasswordAuthenticator::new("user", "pass"); let addr = "127.0.0.1:9042"; let tcp_transport = Transport::new(addr).unwrap();
// pass authenticator and transport into CDRS' constructor let client = CDRS::new(tcp_transport, authenticator); use cdrs::compression; // start session without compression let mut session = try!(client.start(compression::None)); ```
If Server does not require authorization authenticator won't be used, but is still
required for the constructor (most probably it will be refactored in future).
To be able to create SSL-encrypted connection CDRS should be used with
ssl feature enabled. Apart of CDRS itself openssl must also be imported.
```toml [dependencies] openssl = "0.9.6"
[dependencies.cdrs] version = "*" features = ["ssl"] ```
rust
use cdrs::client::CDRS;
use cdrs::authenticators::PasswordAuthenticator;
use cdrs::transport_ssl::Transport;
use openssl::ssl::{SslConnectorBuilder, SslMethod};
use std::path::Path;
After that you can create a new instance of CDRS and establish new connection:
```rust let authenticator = PasswordAuthenticator::new("user", "pass"); let addr = "127.0.0.1:9042";
// here needs to be a path of your SSL certificate let path = Path::new("./node0.cer.pem"); let mut sslconnectorbuilder = SslConnectorBuilder::new(SslMethod::tls()).unwrap(); sslconnectorbuilder.buildermut().setcafile(path).unwrap(); let connector = sslconnector_builder.build();
let ssl_transport = Transport::new(addr, &connector).unwrap();
// pass authenticator and SSL transport into CDRS' constructor let client = CDRS::new(ssl_transport, authenticator); ```
There is an option to create r2d2 connection pool of CDRS connections both plain and SSL-encrypted:
```rust use cdrs::connection_manager::ConnectionManager;
let config = r2d2::Config::builder() .pool_size(15) .build(); let transport = Transport::new(ADDR).unwrap(); let authenticator = PasswordAuthenticator::new(USER, PASS); let manager = ConnectionManager::new(transport, authenticator, Compression::None);
let pool = r2d2::Pool::new(config, manager).unwrap();
for _ in 0..20 { let pool = pool.clone(); thread::spawn(move || { let conn = pool.get().unwrap(); // use the connection // it will be returned to the pool when it falls out of scope. }); }
```
There is a related example.
Before session established an application may want to know which options are
supported by a server (for instance to figure out which compression to use).
That's why CDRS instance has a method get_options which could be called
before session get started. Options are presented as HashMap<String, Vec<String>>.
rust
let options = try!(client.get_options());
This should be called before session started to let you know which compression
to choose and because session object borrows CDRS instance.
Two types of compression are supported - snappy and lz4. To use compression just start connection with desired type:
rust
// session without compression
let mut session_res = client.start(compression::None);
// session lz4 compression
let mut session_res = client.start(compression::Lz4);
// v with snappy compression
let mut session_res = client.start(compression::Snappy);
Query execution is provided in scope of Session. So to start executing queries you need to start Session first.
```rust
let usequerystring = String::from("USE mynamespace;"); let withtracing = false; let with_warnings = false;
match session.prepare(usequerystring, withtracing, withwarnings) { Ok(setkeyspace) => { // usekeyspace is a result frame of type SetKeyspace }, Err(err) => log!(err) } ```
Creating new table could be performed via session.query. In case of success
method return Schema Change frame that contains Change Type, Target and options
that contain namespace and a name of created table.
```rust use std::default::Default; use cdrs::client::{Query, QueryBuilder}; use cdrs::consistency::Consistency;
let mut selectquery: Query = QueryBuilder::new("CREATE TABLE keyspace.emp ( empID int, deptID int, firstname varchar, lastname varchar, PRIMARY KEY (empID, deptID) );") .consistency(Consistency::One) .finalize(); let withtracing = false; let with_warnings = false;
let tablecreated = session.query(selectquery, withtracing, withwarnings).is_ok();
```
As a response to select query CDRS returns a result frame of type Rows with data items (columns) encoded in Cassandra's way.
```rust use std::default::Default; use cdrs::client::Query; use cdrs::consistency::Consistency;
let mut selectquery: Query = QueryBuilder::new(usequery.clone()).finalize(); let withtracing = false; let withwarnings = false;
match session.query(selectquery, withtracing, withwarnings) { Ok(res) => println!("Result frame: {:?},\nparsed body: {:?}", res, res.getbody());, Err(err) => log!(err) } ```
Once CDRS got response to SELECT query you can map rows encapsulated within
Result frame into Rust values or into List, Map or UDT helper structures
which provide a way to convert wrapped values into plain ones.
As an example let's consider a case when application gets a collection of messages of following format:
```rust
struct Message { pub author: String, pub text: String }
```
To get a collection of messages Vec<Message> let's convert a result of query
into collection of rows Vec<cdrs::types::row::Row> and then convert each column
into appropriate Rust type:
```rust use cdrs::error::{Result as CResult};
let resbody = parsed.getbody();
let rows = resbody.intorows().unwrap();
let messages: Vec
```
There is no difference between Cassandra's List and Sets in terms of Rust.
They could be represented as Vec<T>. To convert a frame into a structure
that contains a collection of elements do as follows:
```rust
struct Author {
pub name: String,
pub messages: Vec
//...
use cdrs::error::{Result as CResult};
let resbody = parsed.getbody();
let rows = resbody.intorows().unwrap();
let messages: Vec
```
The MIT License (MIT)
Copyright (c) 2016 Alex Pikalov
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