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 vzctl.git
  43 pve-manager.git
  44 pve-kernel-2.6.32.git
  45 fence-agents-pve.git
  46
  47 Most source can be installed with 'make dinstall' command.
  48
  49 4.  Reboot the system.
  50 5.  Learn to use the quilt patch scripts.
  51 6.  Happy coding.
  52
  53 There is an experimental package containing the API documentation
  54 as ExtJS application:
  55
  56 pve2-api-doc.git
  57
  58 You can view the source code at:
  59
  60 https://git.proxmox.com
  61
  62
  63 REST vs. SOAP
  64 =============
  65
  66 We decided to change our SOAP API (1.X) and use a REST like API. The
  67 concept is described in [1] (Resource Oriented Architecture
  68 (ROA)). The main advantage is that we are able to remove a lot of code
  69 (the whole SOAP stack) to reduce software complexity.
  70
  71 We also moved away from server side content generation. Instead we use
  72 the ExtJS Rich Internet Application Framework
  73 (http://www.sencha.com).
  74
  75 That framework, like any other AJAX toolkit, can talk directly to the
  76 REST API using JSON. So we were able to remove the server side
  77 template toolkit completely.
  78
  79 JSON and JSON Schema
  80 ====================
  81
  82 We use JSON as data format, because it is simple and parse-able by any
  83 web browser.
  84
  85 Additionally, we use JSON Schema [2] to formally describe our API. So
  86 we can automatically generate the whole API Documentation, and we can
  87 verify all parameters and return values.
  88
  89 An great side effect was that we are able to use JSON Schema to
  90 produce command line argument parsers automatically. In fact, the REST
  91 API and the command line tools use the same code.
  92
  93 Object linkage is done using the JSON Hyper Schema (links property).
  94
  95 A small utility called 'pvesh' exposes the whole REST API on the command
  96 line.
  97
  98 So here is a summary of the advantage:
  99
 100    - easy, human readable data format (native web browser format)
 101    - automatic parameter verification (we can also verify return values)
 102    - automatic generation of API documentation
 103    - easy way to create command line tools (using same API).
 104
 105 API Implementation (PVE::RESTHandler)
 106 =====================================
 107
 108 All classes exposing methods on the API use PVE::RESTHandler as base class.
 109
 110   use base qw(PVE::RESTHandler);
 111
 112 To expose methods, one needs to call register_method():
 113
 114   __PACKAGE__->register_method ($schema);
 115
 116 Where $schema is a PVE method schema as described in
 117 PVE::JSONSchema. It includes a description of parameters and return
 118 values, and a reference to the actual code
 119
 120 __PACKAGE__->register_method ({
 121     name => 'echo',
 122     path => 'echo',
 123     method => 'GET',
 124     description => "simple return value of parameter 'text'",
 125     parameters => {
 126         additionalProperties => 0,
 127         properties => {
 128             text => {
 129                  type => 'string',
 130             }
 131         },
 132     },
 133     returns => {
 134         type => 'string',
 135     },
 136     code => sub {
 137         my ($conn, $resp, $param) = @_;
 138
 139         return $param->{text};
 140     }
 141 });
 142
 143 The 'name' property is only used if you want to call the method
 144 directly from Perl. You can do that using:
 145
 146   print __PACKAGE__->echo({ text => "a test" });
 147
 148 We use Perl's AUTOLOAD feature to implement this. Note: You need to
 149 pass parameters a HASH reference.
 150
 151 There is a special helper method called cli_handler(). This is used by
 152 the CLIHandler Class for command line tools, where you want to pass
 153 arguments as array of strings. This uses Getopt::Long to parse parameters.
 154
 155 There is a second way to map names to methods - using the 'path'
 156 property.  And you can register subclasses. That way you can set up a
 157 filesystem like hierarchy to access methods.
 158
 159 Here is an example:
 160 ----------------------------
 161 package C1;
 162
 163 __PACKAGE__->register_method ({
 164     subclass => "C2",
 165     path => 'sub2',
 166 });
 167
 168
 169 __PACKAGE__->register_method ({
 170     name => 'list1',
 171     path => 'index',
 172     method => 'GET',
 173     ...
 174 });
 175
 176 package C2;
 177
 178 __PACKAGE__->register_method ({
 179     name => 'list2',
 180     path => 'index',
 181     method => 'GET',
 182     ...
 183 });
 184 -------------------------------
 185
 186 The utily method find_handler (in PVE::RESTHandler) can be use to do
 187 'path' related method lookups.
 188
 189 C1->find_handler('GET', "/index")      => C1::list1
 190 C1->find_handler('GET', "/sub2/index") => C2::list2
 191
 192 The HTTP server use the URL (a path) to find the corresponding method.
 193
 194
 195 References
 196 ==========
 197 [1] RESTful Web Services
 198 Web services for the real world
 199
 200 By
 201     Leonard Richardson, Sam Ruby
 202 Publisher:
 203     O'Reilly Media
 204 Released:
 205     May 2007
 206
 207 [2] JSON Schema links: http://json-schema.org/