README.dev

   1 ====================================
   2 Setup PVE v2 Development Environment
   3 ====================================
   4
   5 1.  Install Debian 'wheezy'
   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 libstring-shellquote-perl \
  24 libio-multiplex-perl liblockfile-simple-perl
  25
  26 3.  Download and install the following git modules in order from top to bottom:
  27
  28 # git clone git://git.proxmox.com/git/<PACKAGE.git>
  29
  30 You currently need the following packages:
  31
  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 vzquota.git
  44 vzctl.git
  45 fence-agents-pve.git
  46 resource-agents-pve.git
  47 pve-manager.git
  48 pve-kernel-2.6.32.git
  49 libiscsi.git
  50 gfs2-utils.git
  51 ksm-control-daemon.git
  52
  53 Most packages can be installed with 'make dinstall' command.
  54
  55 4.  Reboot the system.
  56 5.  Learn to use the quilt patch scripts.
  57 6.  Happy coding.
  58
  59 There is an experimental package containing the API documentation
  60 as ExtJS application:
  61
  62 pve2-api-doc.git
  63
  64 You can view the source code at:
  65
  66 https://git.proxmox.com
  67
  68
  69 REST vs. SOAP
  70 =============
  71
  72 We decided to change our SOAP API (1.X) and use a REST like API. The
  73 concept is described in [1] (Resource Oriented Architecture
  74 (ROA)). The main advantage is that we are able to remove a lot of code
  75 (the whole SOAP stack) to reduce software complexity.
  76
  77 We also moved away from server side content generation. Instead we use
  78 the ExtJS Rich Internet Application Framework
  79 (http://www.sencha.com).
  80
  81 That framework, like any other AJAX toolkit, can talk directly to the
  82 REST API using JSON. So we were able to remove the server side
  83 template toolkit completely.
  84
  85 JSON and JSON Schema
  86 ====================
  87
  88 We use JSON as data format, because it is simple and parse-able by any
  89 web browser.
  90
  91 Additionally, we use JSON Schema [2] to formally describe our API. So
  92 we can automatically generate the whole API Documentation, and we can
  93 verify all parameters and return values.
  94
  95 A great side effect was that we are able to use JSON Schema to
  96 produce command line argument parsers automatically. In fact, the REST
  97 API and the command line tools use the same code.
  98
  99 Object linkage is done using the JSON Hyper Schema (links property).
 100
 101 A small utility called 'pvesh' exposes the whole REST API on the command
 102 line.
 103
 104 So here is a summary of the advantage:
 105
 106    - easy, human readable data format (native web browser format)
 107    - automatic parameter verification (we can also verify return values)
 108    - automatic generation of API documentation
 109    - easy way to create command line tools (using same API).
 110
 111 API Implementation (PVE::RESTHandler)
 112 =====================================
 113
 114 All classes exposing methods on the API use PVE::RESTHandler as base class.
 115
 116   use base qw(PVE::RESTHandler);
 117
 118 To expose methods, one needs to call register_method():
 119
 120   __PACKAGE__->register_method ($schema);
 121
 122 Where $schema is a PVE method schema as described in
 123 PVE::JSONSchema. It includes a description of parameters and return
 124 values, and a reference to the actual code
 125
 126 __PACKAGE__->register_method ({
 127     name => 'echo',
 128     path => 'echo',
 129     method => 'GET',
 130     description => "simple return value of parameter 'text'",
 131     parameters => {
 132         additionalProperties => 0,
 133         properties => {
 134             text => {
 135                  type => 'string',
 136             }
 137         },
 138     },
 139     returns => {
 140         type => 'string',
 141     },
 142     code => sub {
 143         my ($conn, $resp, $param) = @_;
 144
 145         return $param->{text};
 146     }
 147 });
 148
 149 The 'name' property is only used if you want to call the method
 150 directly from Perl. You can do that using:
 151
 152   print __PACKAGE__->echo({ text => "a test" });
 153
 154 We use Perl's AUTOLOAD feature to implement this. Note: You need to
 155 pass parameters a HASH reference.
 156
 157 There is a special helper method called cli_handler(). This is used by
 158 the CLIHandler Class for command line tools, where you want to pass
 159 arguments as array of strings. This uses Getopt::Long to parse parameters.
 160
 161 There is a second way to map names to methods - using the 'path'
 162 property.  And you can register subclasses. That way you can set up a
 163 filesystem like hierarchy to access methods.
 164
 165 Here is an example:
 166 ----------------------------
 167 package C1;
 168
 169 __PACKAGE__->register_method ({
 170     subclass => "C2",
 171     path => 'sub2',
 172 });
 173
 174
 175 __PACKAGE__->register_method ({
 176     name => 'list1',
 177     path => 'index',
 178     method => 'GET',
 179     ...
 180 });
 181
 182 package C2;
 183
 184 __PACKAGE__->register_method ({
 185     name => 'list2',
 186     path => 'index',
 187     method => 'GET',
 188     ...
 189 });
 190 -------------------------------
 191
 192 The utily method find_handler (in PVE::RESTHandler) can be use to do
 193 'path' related method lookups.
 194
 195 C1->find_handler('GET', "/index")      => C1::list1
 196 C1->find_handler('GET', "/sub2/index") => C2::list2
 197
 198 The HTTP server use the URL (a path) to find the corresponding method.
 199
 200
 201 References
 202 ==========
 203 [1] RESTful Web Services
 204 Web services for the real world
 205
 206 By
 207     Leonard Richardson, Sam Ruby
 208 Publisher:
 209     O'Reilly Media
 210 Released:
 211     May 2007
 212
 213 [2] JSON Schema links: http://json-schema.org/