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