README.dev

   1 ====================================
   2 Setup PVE v2 Development Environment
   3 ====================================
   4
   5 1.  Install Debian 'squeeze'
   6 2.  Install prerequisites for development environment:
   7
   8 apt-get -y install build-essential git-core debhelper autotools-dev \
   9 doxygen check pkg-config libnss3-dev groff quilt dpatch libxml2-dev \
  10 libncurses5-dev libslang2-dev libldap2-dev xsltproc python-pexpect \
  11 python-pycurl libdbus-1-dev openipmi sg3-utils libnet-snmp-perl \
  12 libnet-telnet-perl snmp python-openssl libxml2-utils automake autoconf \
  13 libsqlite3-dev sqlite3 libfuse-dev libglib2.0-dev librrd-dev \
  14 librrds-perl rrdcached lintian libdevel-cycle-perl libjson-perl \
  15 liblinux-inotify2-perl libio-stringy-perl unzip fuse-utils \
  16 libcrypt-openssl-random-perl libcrypt-openssl-rsa-perl \
  17 libauthen-pam-perl libterm-readline-gnu-perl libssl-dev open-iscsi \
  18 libapache2-mod-perl2 libfilesys-df-perl libfile-readbackwards-perl \
  19 libpci-dev texi2html libgnutls-dev libsdl1.2-dev bridge-utils \
  20 libvncserver0 rpm2cpio  apache2-mpm-prefork libintl-perl \
  21 libapache2-request-perl libnet-dns-perl vlan libio-socket-ssl-perl \
  22 libfile-sync-perl ifenslave-2.6 libnet-ldap-perl console-data
  23
  24 3.  Download and install the following git modules in order from top to bottom:
  25
  26 # git clone git://git.proxmox.com/git/<PACKAGE.git>
  27
  28 You currently need the following packages:
  29
  30 libqb.git
  31 corosync-pve.git
  32 openais-pve.git
  33 pve-common.git
  34 pve-cluster.git
  35 redhat-cluster-pve.git
  36 lvm.git
  37 pve-access-control.git
  38 pve-storage.git
  39 pve-qemu-kvm.git
  40 qemu-server.git
  41 vncterm.git
  42 pve-manager.git
  43 pve-kernel-2.6.32.git
  44 fence-agents-pve.git
  45
  46 Most source can be installed with 'make dinstall' command.
  47
  48 4.  Reboot the system.
  49 5.  Learn to use the quilt patch scripts.
  50 6.  Happy coding.
  51
  52 There is an experimental package containing the API documentation
  53 as ExtJS application:
  54
  55 pve2-api-doc.git
  56
  57 You can view the source code at:
  58
  59 https://git.proxmox.com
  60
  61
  62 REST vs. SOAP
  63 =============
  64
  65 We decided to change our SOAP API (1.X) and use a REST like API. The
  66 concept is described in [1] (Resource Oriented Architecture
  67 (ROA)). The main advantage is that we are able to remove a lot of code
  68 (the whole SOAP stack) to reduce software complexity.
  69
  70 We also moved away from server side content generation. Instead we use
  71 the ExtJS Rich Internet Application Framework
  72 (http://www.sencha.com).
  73
  74 That framework, like any other AJAX toolkit, can talk directly to the
  75 REST API using JSON. So we were able to remove the server side
  76 template toolkit completely.
  77
  78 JSON and JSON Schema
  79 ====================
  80
  81 We use JSON as data format, because it is simple and parse-able by any
  82 web browser.
  83
  84 Additionally, we use JSON Schema [2] to formally describe our API. So
  85 we can automatically generate the whole API Documentation, and we can
  86 verify all parameters and return values.
  87
  88 An great side effect was that we are able to use JSON Schema to
  89 produce command line argument parsers automatically. In fact, the REST
  90 API and the command line tools use the same code.
  91
  92 Object linkage is done using the JSON Hyper Schema (links property).
  93
  94 A small utility called 'pvesh' exposes the whole REST API on the command
  95 line.
  96
  97 So here is a summary of the advantage:
  98
  99    - easy, human readable data format (native web browser format)
 100    - automatic parameter verification (we can also verify return values)
 101    - automatic generation of API documentation
 102    - easy way to create command line tools (using same API).
 103
 104 API Implementation (PVE::RESTHandler)
 105 =====================================
 106
 107 All classes exposing methods on the API use PVE::RESTHandler as base class.
 108
 109   use base qw(PVE::RESTHandler);
 110
 111 To expose methods, one needs to call register_method():
 112
 113   __PACKAGE__->register_method ($schema);
 114
 115 Where $schema is a PVE method schema as described in
 116 PVE::JSONSchema. It includes a description of parameters and return
 117 values, and a reference to the actual code
 118
 119 __PACKAGE__->register_method ({
 120     name => 'echo',
 121     path => 'echo',
 122     method => 'GET',
 123     description => "simple return value of parameter 'text'",
 124     parameters => {
 125         additionalProperties => 0,
 126         properties => {
 127             text => {
 128                  type => 'string',
 129             }
 130         },
 131     },
 132     returns => {
 133         type => 'string',
 134     },
 135     code => sub {
 136         my ($conn, $resp, $param) = @_;
 137
 138         return $param->{text};
 139     }
 140 });
 141
 142 The 'name' property is only used if you want to call the method
 143 directly from Perl. You can do that using:
 144
 145   print __PACKAGE__->echo({ text => "a test" });
 146
 147 We use Perl's AUTOLOAD feature to implement this. Note: You need to
 148 pass parameters a HASH reference.
 149
 150 There is a special helper method called cli_handler(). This is used by
 151 the CLIHandler Class for command line tools, where you want to pass
 152 arguments as array of strings. This uses Getopt::Long to parse parameters.
 153
 154 There is a second way to map names to methods - using the 'path'
 155 property.  And you can register subclasses. That way you can set up a
 156 filesystem like hierarchy to access methods.
 157
 158 Here is an example:
 159 ----------------------------
 160 package C1;
 161
 162 __PACKAGE__->register_method ({
 163     subclass => "C2",
 164     path => 'sub2',
 165 });
 166
 167
 168 __PACKAGE__->register_method ({
 169     name => 'list1',
 170     path => 'index',
 171     method => 'GET',
 172     ...
 173 });
 174
 175 package C2;
 176
 177 __PACKAGE__->register_method ({
 178     name => 'list2',
 179     path => 'index',
 180     method => 'GET',
 181     ...
 182 });
 183 -------------------------------
 184
 185 The utily method find_handler (in PVE::RESTHandler) can be use to do
 186 'path' related method lookups.
 187
 188 C1->find_handler('GET', "/index")      => C1::list1
 189 C1->find_handler('GET', "/sub2/index") => C2::list2
 190
 191 The HTTP server use the URL (a path) to find the corresponding method.
 192
 193
 194 References
 195 ==========
 196 [1] RESTful Web Services
 197 Web services for the real world
 198
 199 By
 200     Leonard Richardson, Sam Ruby
 201 Publisher:
 202     O'Reilly Media
 203 Released:
 204     May 2007
 205
 206 [2] JSON Schema links: http://json-schema.org/