==================================== Setup PVE v2 Development Environment ==================================== 1. Install Debian 'squeeze' 2. Install prerequisites for development environment: apt-get -y install build-essential git-core debhelper autotools-dev \ doxygen check pkg-config libnss3-dev groff quilt dpatch libxml2-dev \ libncurses5-dev libslang2-dev libldap2-dev xsltproc python-pexpect \ python-pycurl libdbus-1-dev openipmi sg3-utils libnet-snmp-perl \ libnet-telnet-perl snmp python-openssl libxml2-utils automake autoconf \ libsqlite3-dev sqlite3 libfuse-dev libglib2.0-dev librrd-dev \ librrds-perl rrdcached lintian libdevel-cycle-perl libjson-perl \ liblinux-inotify2-perl libio-stringy-perl unzip fuse-utils \ libcrypt-openssl-random-perl libcrypt-openssl-rsa-perl \ libauthen-pam-perl libterm-readline-gnu-perl libssl-dev open-iscsi \ libapache2-mod-perl2 libfilesys-df-perl libfile-readbackwards-perl \ libpci-dev texi2html libgnutls-dev libsdl1.2-dev bridge-utils \ libvncserver0 rpm2cpio apache2-mpm-prefork libintl-perl \ libapache2-request-perl libnet-dns-perl vlan libio-socket-ssl-perl \ libfile-sync-perl ifenslave-2.6 libnet-ldap-perl console-data \ libtool dietlibc-dev liblocale-po-perl 3. Download and install the following git modules in order from top to bottom: # git clone git://git.proxmox.com/git/ You currently need the following packages: libqb.git corosync-pve.git openais-pve.git pve-common.git pve-cluster.git redhat-cluster-pve.git lvm.git pve-access-control.git pve-storage.git pve-qemu-kvm.git qemu-server.git vncterm.git vzctl.git pve-manager.git pve-kernel-2.6.32.git fence-agents-pve.git Most source can be installed with 'make dinstall' command. 4. Reboot the system. 5. Learn to use the quilt patch scripts. 6. Happy coding. There is an experimental package containing the API documentation as ExtJS application: pve2-api-doc.git You can view the source code at: https://git.proxmox.com REST vs. SOAP ============= We decided to change our SOAP API (1.X) and use a REST like API. The concept is described in [1] (Resource Oriented Architecture (ROA)). The main advantage is that we are able to remove a lot of code (the whole SOAP stack) to reduce software complexity. We also moved away from server side content generation. Instead we use the ExtJS Rich Internet Application Framework (http://www.sencha.com). That framework, like any other AJAX toolkit, can talk directly to the REST API using JSON. So we were able to remove the server side template toolkit completely. JSON and JSON Schema ==================== We use JSON as data format, because it is simple and parse-able by any web browser. Additionally, we use JSON Schema [2] to formally describe our API. So we can automatically generate the whole API Documentation, and we can verify all parameters and return values. An great side effect was that we are able to use JSON Schema to produce command line argument parsers automatically. In fact, the REST API and the command line tools use the same code. Object linkage is done using the JSON Hyper Schema (links property). A small utility called 'pvesh' exposes the whole REST API on the command line. So here is a summary of the advantage: - easy, human readable data format (native web browser format) - automatic parameter verification (we can also verify return values) - automatic generation of API documentation - easy way to create command line tools (using same API). API Implementation (PVE::RESTHandler) ===================================== All classes exposing methods on the API use PVE::RESTHandler as base class. use base qw(PVE::RESTHandler); To expose methods, one needs to call register_method(): __PACKAGE__->register_method ($schema); Where $schema is a PVE method schema as described in PVE::JSONSchema. It includes a description of parameters and return values, and a reference to the actual code __PACKAGE__->register_method ({ name => 'echo', path => 'echo', method => 'GET', description => "simple return value of parameter 'text'", parameters => { additionalProperties => 0, properties => { text => { type => 'string', } }, }, returns => { type => 'string', }, code => sub { my ($conn, $resp, $param) = @_; return $param->{text}; } }); The 'name' property is only used if you want to call the method directly from Perl. You can do that using: print __PACKAGE__->echo({ text => "a test" }); We use Perl's AUTOLOAD feature to implement this. Note: You need to pass parameters a HASH reference. There is a special helper method called cli_handler(). This is used by the CLIHandler Class for command line tools, where you want to pass arguments as array of strings. This uses Getopt::Long to parse parameters. There is a second way to map names to methods - using the 'path' property. And you can register subclasses. That way you can set up a filesystem like hierarchy to access methods. Here is an example: ---------------------------- package C1; __PACKAGE__->register_method ({ subclass => "C2", path => 'sub2', }); __PACKAGE__->register_method ({ name => 'list1', path => 'index', method => 'GET', ... }); package C2; __PACKAGE__->register_method ({ name => 'list2', path => 'index', method => 'GET', ... }); ------------------------------- The utily method find_handler (in PVE::RESTHandler) can be use to do 'path' related method lookups. C1->find_handler('GET', "/index") => C1::list1 C1->find_handler('GET', "/sub2/index") => C2::list2 The HTTP server use the URL (a path) to find the corresponding method. References ========== [1] RESTful Web Services Web services for the real world By Leonard Richardson, Sam Ruby Publisher: O'Reilly Media Released: May 2007 [2] JSON Schema links: http://json-schema.org/