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 subversion 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 svn modules in order from top to bottom:
  25
  26 svn://devel.proxmox.com/var/svn/pve/
  27
  28 libqb/trunk
  29 corosync/trunk
  30 openais/trunk
  31 pve-common/trunk
  32 pve-cluster/trunk
  33 redhat-cluster/trunk
  34 pve-access-control/trunk
  35 pve-storage/pve2
  36 pve-qemu-kvm/pve2
  37 qemu-server/pve2
  38 vncterm/pve2
  39 pve-manager/pve2
  40 pve-kernel-2.6.32-rh/pve2
  41
  42 Most source can be installed with 'make dinstall' command.
  43
  44 4.  Reboot the system.
  45 5.  Learn to use the quilt patch scripts.
  46 6.  Happy coding.
  47
  48 There is an experimental package containing the API documentation
  49 as ExtJS application:
  50
  51 pve2-api-doc/trunk
  52
  53
  54 REST vs. SOAP
  55 =============
  56
  57 We decided to change our SOAP API (1.X) and use a REST like API. The
  58 concept is described in [1] (Resource Oriented Architecture
  59 (ROA)). The main advantage is that we are able to remove a lot of code
  60 (the whole SOAP stack) to reduce software complexity.
  61
  62 We also moved away from server side content generation. Instead we use
  63 the ExtJS Rich Internet Application Framework
  64 (http://www.sencha.com).
  65
  66 That framework, like any other AJAX toolkit, can talk directly to the
  67 REST API using JSON. So we were able to remove the server side
  68 template toolkit completely.
  69
  70 JSON and JSON Schema
  71 ====================
  72
  73 We use JSON as data format, because it is simple and parse-able by any
  74 web browser.
  75
  76 Additionally, we use JSON Schema [2] to formally describe our API. So
  77 we can automatically generate the whole API Documentation, and we can
  78 verify all parameters and return values.
  79
  80 An great side effect was that we are able to use JSON Schema to
  81 produce command line argument parsers automatically. In fact, the REST
  82 API and the command line tools use the same code.
  83
  84 Object linkage is done using the JSON Hyper Schema (links property).
  85
  86 A small utility called 'pvesh' exposes the whole REST API on the command
  87 line.
  88
  89 So here is a summary of the advantage:
  90
  91    - easy, human readable data format (native web browser format)
  92    - automatic parameter verification (we can also verify return values)
  93    - automatic generation of API documentation
  94    - easy way to create command line tools (using same API).
  95
  96 API Implementation (PVE::RESTHandler)
  97 =====================================
  98
  99 All classes exposing methods on the API use PVE::RESTHandler as base class.
 100
 101   use base qw(PVE::RESTHandler);
 102
 103 To expose methods, one needs to call register_method():
 104
 105   __PACKAGE__->register_method ($schema);
 106
 107 Where $schema is a PVE method schema as described in
 108 PVE::JSONSchema. It includes a description of parameters and return
 109 values, and a reference to the actual code
 110
 111 __PACKAGE__->register_method ({
 112     name => 'echo',
 113     path => 'echo',
 114     method => 'GET',
 115     description => "simple return value of parameter 'text'",
 116     parameters => {
 117         additionalProperties => 0,
 118         properties => {
 119             text => {
 120                  type => 'string',
 121             }
 122         },
 123     },
 124     returns => {
 125         type => 'string',
 126     },
 127     code => sub {
 128         my ($conn, $resp, $param) = @_;
 129
 130         return $param->{text};
 131     }
 132 });
 133
 134 The 'name' property is only used if you want to call the method
 135 directly from Perl. You can do that using:
 136
 137   print __PACKAGE__->echo({ text => "a test" });
 138
 139 We use Perl's AUTOLOAD feature to implement this. Note: You need to
 140 pass parameters a HASH reference.
 141
 142 There is a special helper method called cli_handler(). This is used by
 143 the CLIHandler Class for command line tools, where you want to pass
 144 arguments as array of strings. This uses Getopt::Long to parse parameters.
 145
 146 There is a second way to map names to methods - using the 'path'
 147 property.  And you can register subclasses. That way you can set up a
 148 filesystem like hierarchy to access methods.
 149
 150 Here is an example:
 151 ----------------------------
 152 package C1;
 153
 154 __PACKAGE__->register_method ({
 155     subclass => "C2",
 156     path => 'sub2',
 157 });
 158
 159
 160 __PACKAGE__->register_method ({
 161     name => 'list1',
 162     path => 'index',
 163     method => 'GET',
 164     ...
 165 });
 166
 167 package C2;
 168
 169 __PACKAGE__->register_method ({
 170     name => 'list2',
 171     path => 'index',
 172     method => 'GET',
 173     ...
 174 });
 175 -------------------------------
 176
 177 The utily method find_handler (in PVE::RESTHandler) can be use to do
 178 'path' related method lookups.
 179
 180 C1->find_handler('GET', "/index")      => C1::list1
 181 C1->find_handler('GET', "/sub2/index") => C2::list2
 182
 183 The HTTP server use the URL (a path) to find the corresponding method.
 184
 185
 186 References
 187 ==========
 188 [1] RESTful Web Services
 189 Web services for the real world
 190
 191 By
 192     Leonard Richardson, Sam Ruby
 193 Publisher:
 194     O'Reilly Media
 195 Released:
 196     May 2007
 197
 198 [2] JSON Schema links: http://json-schema.org/