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Determine Dependencies of Services in Network

This example shows how to analyze dependencies among services in a network using the MATLAB® interface to Neo4j®. Assume that you have graph data that is stored on a Neo4j® database which represents a network. This database has seven nodes and seven relationships. Each node has only one unique property key name with values Service1 through Service7. Each relationship has type DEPENDS_ON.

To find the number of services each service depends on, use the MATLAB® interface to Neo4j® and the digraph object. For details about the MATLAB® interface to Neo4j®, see Graph Database Workflow for Neo4j Database Interfaces.

The local machine hosts the Neo4j® database with port number 7474, user name neo4j, and password matlab. For a visual representation of the data in the database, see this figure.

Connect to Neo4j® Database

Create a Neo4j® connection object neo4jconn using the URL http://localhost:7474/db/data, user name neo4j, and password matlab.

url = 'http://localhost:7474/db/data';
username = 'neo4j';
password = 'matlab';

neo4jconn = neo4j(url,username,password);

Check the Message property of the Neo4j® connection object neo4jconn. The blank Message property indicates a successful connection.

neo4jconn.Message
ans =

     []

Retrieve Entire Graph

Retrieves all relationships of type DEPENDS_ON and all nodes associated with each relationship.

network_graphdata = searchGraph(neo4jconn,{'DEPENDS_ON'})
network_graphdata = struct with fields:
        Nodes: [7×3 table]
    Relations: [7×5 table]

Convert Graph Data to Directed Graph

Using the table network_graphdata.Nodes, access the name property for each node that appears in the NodeData variable of the table.

Assign the table network_graphdata.Nodes to nodestable.

nodestable = network_graphdata.Nodes
nodestable=7×3 table
         NodeLabels      NodeData                  NodeObject             
         __________    ____________    ___________________________________

    6    'Service'     [1×1 struct]    [1x1 database.neo4j.http.Neo4jNode]
    0    'Service'     [1×1 struct]    [1x1 database.neo4j.http.Neo4jNode]
    4    'Service'     [1×1 struct]    [1x1 database.neo4j.http.Neo4jNode]
    2    'Service'     [1×1 struct]    [1x1 database.neo4j.http.Neo4jNode]
    3    'Service'     [1×1 struct]    [1x1 database.neo4j.http.Neo4jNode]
    5    'Service'     [1×1 struct]    [1x1 database.neo4j.http.Neo4jNode]
    1    'Service'     [1×1 struct]    [1x1 database.neo4j.http.Neo4jNode]

Assign the row names for each row to rownames.

rownames = nodestable.Properties.RowNames
rownames = 7×1 cell array
    {'6'}
    {'0'}
    {'4'}
    {'2'}
    {'3'}
    {'5'}
    {'1'}

Access the NodeData variable from nodestable for each row. nodedata contains an array of structures.

nodedata = [nodestable.NodeData{rownames}]
nodedata = 1×7 struct array with fields:
    name

To retrieve the name field from each structure, index into the array. nodenames is a cell array of character vectors that contains node names.

nodenames = {nodedata(:).name}
nodenames = 1×7 cell array
    {'Service7'}    {'Service6'}    {'Service1'}    {'Service3'}    {'Service2'}    {'Service4'}    {'Service5'}

Create the digraph object network_graph using the neo4jStruct2Digraph function and the graph network_graphdata.

network_graph = neo4jStruct2Digraph(network_graphdata,'NodeNames',nodenames)
network_graph = 
  digraph with properties:

    Edges: [7×3 table]
    Nodes: [7×3 table]

To see a visual representation of the graph, create a figure that displays the graph network_graph.

plot(network_graph,'EdgeLabel',network_graph.Edges.RelationType)

Find Dependency Count of Each Service

Find the number of services that each service depends on in the graph network_graph. Determine the dependency count for each node by iterating through the nodes in the graph using a for loop. To determine the dependency count, use the nearest function.

Create the table dependency_count that stores the count of the dependent services for each service. Sort the rows in the table by dependency count in descending order.

dependency_count = table;

for i = 1:height(network_graph.Nodes)
    nodeid = network_graph.Nodes.Name(i);
    nearest_node = nearest(network_graph,nodeid,Inf,'Direction','outgoing');
    nearest_length = length(nearest_node);
    dependency_count = [dependency_count; ...
        table(nodeid,nearest_length, ...
        'VariableNames',{'Node','Dependency_count'})];
end

dependency_count = sortrows(dependency_count,-2)
dependency_count=7×2 table
       Node       Dependency_count
    __________    ________________

    'Service6'           5        
    'Service7'           3        
    'Service4'           2        
    'Service5'           2        
    'Service3'           1        
    'Service2'           1        
    'Service1'           0        

Find All Dependencies for Specific Service

Find all the services that the service Service6 depends on in the graph network_graph using the nearest function.

disp('Service6 depends on the following services:');
Service6 depends on the following services:
nearest(network_graph,'Service6',Inf,'Direction','outgoing')
ans = 5×1 cell array
    {'Service4'}
    {'Service5'}
    {'Service3'}
    {'Service2'}
    {'Service1'}

Close Database Connection

close(neo4jconn)

See Also

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