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 libtool dietlibc-dev liblocale-po-perl
  24
  25 3.  Download and install the following git modules in order from top to bottom:
  26
  27 # git clone git://git.proxmox.com/git/<PACKAGE.git>
  28
  29 You currently need the following packages:
  30
  31 libqb.git
  32 corosync-pve.git
  33 openais-pve.git
  34 pve-common.git
  35 pve-cluster.git
  36 redhat-cluster-pve.git
  37 lvm.git
  38 pve-access-control.git
  39 pve-storage.git
  40 pve-qemu-kvm.git
  41 qemu-server.git
  42 vncterm.git
  43 vzctl.git
  44 pve-manager.git
  45 pve-kernel-2.6.32.git
  46 fence-agents-pve.git
  47
  48 Most source can be installed with 'make dinstall' command.
  49
  50 4.  Reboot the system.
  51 5.  Learn to use the quilt patch scripts.
  52 6.  Happy coding.
  53
  54 There is an experimental package containing the API documentation
  55 as ExtJS application:
  56
  57 pve2-api-doc.git
  58
  59 You can view the source code at:
  60
  61 https://git.proxmox.com
  62
  63
  64 REST vs. SOAP
  65 =============
  66
  67 We decided to change our SOAP API (1.X) and use a REST like API. The
  68 concept is described in [1] (Resource Oriented Architecture
  69 (ROA)). The main advantage is that we are able to remove a lot of code
  70 (the whole SOAP stack) to reduce software complexity.
  71
  72 We also moved away from server side content generation. Instead we use
  73 the ExtJS Rich Internet Application Framework
  74 (http://www.sencha.com).
  75
  76 That framework, like any other AJAX toolkit, can talk directly to the
  77 REST API using JSON. So we were able to remove the server side
  78 template toolkit completely.
  79
  80 JSON and JSON Schema
  81 ====================
  82
  83 We use JSON as data format, because it is simple and parse-able by any
  84 web browser.
  85
  86 Additionally, we use JSON Schema [2] to formally describe our API. So
  87 we can automatically generate the whole API Documentation, and we can
  88 verify all parameters and return values.
  89
  90 An great side effect was that we are able to use JSON Schema to
  91 produce command line argument parsers automatically. In fact, the REST
  92 API and the command line tools use the same code.
  93
  94 Object linkage is done using the JSON Hyper Schema (links property).
  95
  96 A small utility called 'pvesh' exposes the whole REST API on the command
  97 line.
  98
  99 So here is a summary of the advantage:
 100
 101    - easy, human readable data format (native web browser format)
 102    - automatic parameter verification (we can also verify return values)
 103    - automatic generation of API documentation
 104    - easy way to create command line tools (using same API).
 105
 106 API Implementation (PVE::RESTHandler)
 107 =====================================
 108
 109 All classes exposing methods on the API use PVE::RESTHandler as base class.
 110
 111   use base qw(PVE::RESTHandler);
 112
 113 To expose methods, one needs to call register_method():
 114
 115   __PACKAGE__->register_method ($schema);
 116
 117 Where $schema is a PVE method schema as described in
 118 PVE::JSONSchema. It includes a description of parameters and return
 119 values, and a reference to the actual code
 120
 121 __PACKAGE__->register_method ({
 122     name => 'echo',
 123     path => 'echo',
 124     method => 'GET',
 125     description => "simple return value of parameter 'text'",
 126     parameters => {
 127         additionalProperties => 0,
 128         properties => {
 129             text => {
 130                  type => 'string',
 131             }
 132         },
 133     },
 134     returns => {
 135         type => 'string',
 136     },
 137     code => sub {
 138         my ($conn, $resp, $param) = @_;
 139
 140         return $param->{text};
 141     }
 142 });
 143
 144 The 'name' property is only used if you want to call the method
 145 directly from Perl. You can do that using:
 146
 147   print __PACKAGE__->echo({ text => "a test" });
 148
 149 We use Perl's AUTOLOAD feature to implement this. Note: You need to
 150 pass parameters a HASH reference.
 151
 152 There is a special helper method called cli_handler(). This is used by
 153 the CLIHandler Class for command line tools, where you want to pass
 154 arguments as array of strings. This uses Getopt::Long to parse parameters.
 155
 156 There is a second way to map names to methods - using the 'path'
 157 property.  And you can register subclasses. That way you can set up a
 158 filesystem like hierarchy to access methods.
 159
 160 Here is an example:
 161 ----------------------------
 162 package C1;
 163
 164 __PACKAGE__->register_method ({
 165     subclass => "C2",
 166     path => 'sub2',
 167 });
 168
 169
 170 __PACKAGE__->register_method ({
 171     name => 'list1',
 172     path => 'index',
 173     method => 'GET',
 174     ...
 175 });
 176
 177 package C2;
 178
 179 __PACKAGE__->register_method ({
 180     name => 'list2',
 181     path => 'index',
 182     method => 'GET',
 183     ...
 184 });
 185 -------------------------------
 186
 187 The utily method find_handler (in PVE::RESTHandler) can be use to do
 188 'path' related method lookups.
 189
 190 C1->find_handler('GET', "/index")      => C1::list1
 191 C1->find_handler('GET', "/sub2/index") => C2::list2
 192
 193 The HTTP server use the URL (a path) to find the corresponding method.
 194
 195
 196 References
 197 ==========
 198 [1] RESTful Web Services
 199 Web services for the real world
 200
 201 By
 202     Leonard Richardson, Sam Ruby
 203 Publisher:
 204     O'Reilly Media
 205 Released:
 206     May 2007
 207
 208 [2] JSON Schema links: http://json-schema.org/