/ 
REST-Neo4p-0.4003
River stage one • 1 direct dependent • 1 total dependent
/ REST::Neo4p::Agent

NAME

REST::Neo4p::Agent - HTTP client interacting with Neo4j

SYNOPSIS

$agent = REST::Neo4p::Agent->new();
$agent->server_url('http://127.0.0.1:7474');
unless ($agent->connect) {
 print STDERR "Didn't find the server\n";
}

See examples under "METHODS" below.

DESCRIPTION

The agent's job is to encapsulate and connect to the REST service URLs of a running Neo4j server. It also stores the discovered URLs for various actions and provides those URLs as getters from the agent object. The getter names are the keys in the JSON objects returned by the server. See the Neo4j docs for more details.

API and HTTP errors are distinguished and thrown by Exception::Class subclasses. See REST::Neo4p::Exceptions.

A REST::Neo4p::Agent instance is created as a subclass of a choice of HTTP user agents:

REST::Neo4p::Agent responses are always HTTP::Response objects.

REST::Neo4p::Agent will retry requests that fail with REST::Neo4p::CommException. The default number of retries is 3; the default wait time between retries is 5 sec. These can be adjusted by setting the package variables

$REST::Neo4p::Agent::RQ_RETRIES
$REST::Neo4p::Agent::RETRY_WAIT

to the desired values.

According to the Neo4j recommendation, the agent requests streamed responses by default; i.e.,

X-Stream: true

is a default header for requests. The server responds to requests with chunked content, which is handled correctly by any of the underlying user agents.

REST::Neo4p::Query and REST::Neo4p::Batch take advantage of streamed responsed by retrieving and returning JSON objects incrementally and (with the Mojo::UserAgent backend) in a non-blocking way. New Neo4j server versions may break the incremental parsing. If this happens, make a ticket. In the meantime, you should be able to keep things going (albeit more slowly) by turning off streaming at the agent:

REST::Neo4p->agent->no_stream;

Streaming responses can be requested again by issuing

REST::Neo4p->agent->stream

For batch API features, see "Batch Mode".

METHODS

new()
$agent = REST::Neo4p::Agent->new();
$agent = REST::Neo4p::Agent->new( agent_module => 'HTTP::Thin');
$agent = REST::Neo4p::Agent->new("http://127.0.0.1:7474");

Returns a new agent. The agent_module parameter may be set to

LWP::UserAgent (default)
Mojo::UserAgent
HTTP::Thin

to select the underlying user agent class. Additional arguments are passed to the user agent constructor.

server_url()
$agent->server_url("http://127.0.0.1:7474");

Sets the server address and port.

data()
$neo4j_data_url = $agent->data();

Returns the base of the Neo4j server API.

admin()
$neo4j_admin_url = $agent->admin();

Returns the Neo4j server admin url.

node()
reference_node()
node_index()
relationship_index()
extensions_info()
relationship_types()
batch()
cypher()
$relationship_type_url = $agent->relationship_types;

These methods get the REST URL for the named API actions. Other named actions may also be available for a given server; these are auto-loaded from self-discovery responses provided by Neo4j. Use available_actions() to identify them.

You will probably prefer using the "get_{action}()", "put_{action}()", "post_{action}()", and "delete_{action}()" methods to make requests directly.

neo4j_version()
$version = $agent->neo4j_version;
($major, $minor, $patch, $milestone) = $agent->neo4j_version;

Returns the version string/components of the connected Neo4j server.

available_actions()
@actions = $agent->available_actions();

Returns all discovered actions.

location()
$agent->post_node(); # create new node
$new_node_url = $agent->location;

Returns the value of the "location" key in the response JSON.

get_{action}()
$decoded_response = $agent->get_data(@url_components,\%rest_params)
$types_array_ref = $agent->get_relationship_types();

Makes a GET request to the REST endpoint mapped to {action}. Arguments are additional URL components (without slashes). If the final argument is a hashref, it will be sent as key-value form parameters.

put_{action}()
# add a property to an existing node
$agent->put_node([13, 'properties'], { name => 'Herman' });

Makes a PUT request to the REST endpoint mapped to {action}. The first argument, if present, must be an array reference of additional URL components. The second argument, if present, is a hashref that will be sent in the request as (encoded) JSON content. The third argument, if present, is a hashref containing additional request headers.

post_{action}()
# create a new node with given properties
$agent->post_node({ name => 'Wanda' });
# do a cypher query and save content to file
$agent->post_cypher([], { query => 'MATCH (n) RETURN n', params=>{}},
                    { ':content_file' => $my_file_name });

Makes a POST request to the REST endpoint mapped to {action}. The first argument, if present, must be an array reference of additional URL components. The second argument, if present, is a hashref that will be sent in the request as (encoded) JSON content. The third argument, if present, is a hashref containing additional request headers.

delete_{action}()
$agent->delete_node(13);
$agent->delete_node_index('myindex');

Makes a DELETE request to the REST endpoint mapped to {action}. Arguments are additional URL components (without slashes). If the final argument is a hashref, it will be sent in the request as (encoded) JSON content.

decoded_content()
$decoded_json = $agent->decoded_content;

Returns the response content of the last agent request, as decoded by JSON. It is generally a reference, but can be a scalar if a bareword was returned by the server.

raw_response()
$resp = $agent->raw_response

Returns the HTTP::Response object returned by the last request made by the backend user agent.

no_stream()
$agent->no_stream;

Removes X-Stream: true from the default headers.

stream()
$agent->stream;

Adds X-Stream: true to the default headers.

Batch Mode

Neo4j version 4.0+: Batch mode is a Neo4j REST API feature that bit the big one along with that API. The Neo4j::Driver agent will complain if you use these methods.

When the agent is in batch mode, the usual request calls are not executed immediately, but added to a queue. The "execute_batch()" method sends the queued calls in the format required by the Neo4p REST API (using the post_batch method outside of batch mode). "execute_batch()" returns the decoded json server response in the return format specified by the Neo4p REST batch API.

batch_mode()
print ($agent->batch_mode ? "I am " : "I am not ")." in batch mode\n";
$agent->batch_mode(1);

Set/get current agent mode.

batch_length()
if ($agent->batch_length() > $JOB_LIMIT) {
  print "Queue getting long; better execute\n"
}

Returns current queue length. Throws REST::Neo4p::LocalException if agent not in batch mode.

execute_batch()
$tmpfh = $agent->execute_batch();
$tmpfh = $agent->execute_batch(50);

while (<$tmpfn>) {
  # handle responses
}

Processes the queued calls and returns the decoded json response from server in a temporary file. Returns with undef if batch length is zero. Throws REST::Neo4p::LocalException if not in batch mode.

Second form takes an integer argument; this will submit the next [integer] jobs and return the server response in the tempfile. The batch length is updated.

The filehandle returned is a File::Temp object. The file will be unlinked when the object is destroyed.

execute_batch_chunk()
while (my $tmpf = $agent->execute_batch_chunk ) {
 # handle response
}

Convenience form of execute_batch($REST::Neo4p::JOB_CHUNK). $REST::Neo4p::JOB_CHUNK has default value of 1024.

AUTHOR

Mark A. Jensen
CPAN ID: MAJENSEN
majensen -at- cpan -dot- org

LICENSE

Copyright (c) 2012-2022 Mark A. Jensen. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.