Simple Example

Hike at Mt Rainier

In this example, we will use VDMS to store all the photos and metadata taken during a hiking day at Mount Rainier, WA.

We will use the Python Client module to connect to VDMS and send queries.

Let's start by connectin to VDMS.

import vdms
import json

db = vdms.vdms()
db.connect("localhost") # Will connecto to localhost on port 55555

Now, let's add some metadata about the place of the hiking.

props = {}
props["place"] = "Mt Rainier"
props["id"] = 4543
props["type"] = "Volcano"

addEntity = {}
addEntity["properties"] = props
addEntity["class"] = "Hike"

Finally, lets create a query and send it to VDMS.

query = {}
query["AddEntity"] = addEntity

all_queries = []
all_queries.append(query)

print "Query Sent: "
print(all_queries)

response, res_arr = db.query(all_queries)

This will print:

    Query Sent:
    [
        {
            "AddEntity": {
                "properties": {
                    "type": "Volcano",
                    "place": "Mt Rainier",
                    "id": 4543
                },
                "class": "Hike"
            }
        }
    ]

Now, lets print the response we get from VDMS

response = json.loads(response)

print "VDMS Response:"
vdms.aux_print_json(response)

This will print:

    VDMS Response:
    [
        {
            "AddEntity": {
                "status": 0
            }
        }
    ]

Alright! This means that the server added that entity successfully. Now lets add two people and connect them to this hike. For this, we will use the FindEntity command (to get a reference to the "Hike" entity we added), and the link block inside the AddEntity (for adding a "Person") to define the connection.

# As an example, we build the FindEntity command directly
query = {
          "FindEntity" : {
             "class": "Hike",
             "_ref": 3,
             "constraints": {
                 "id": ["==", 4543]
             }
          }
       }

all_queries = []
all_queries.append(query)

props = {}
props["name"]     = "Tom"
props["lastname"] = "Lluhs"
props["id"]       = 453

link = {}
link["ref"] = 3

addEntity = {}
addEntity["properties"] = props
addEntity["class"] = "Person"
addEntity["link"] = link

query = {}
query["AddEntity"] = addEntity

all_queries.append(query)

props = {}
props["name"]     = "Sophia"
props["lastname"] = "Ferdinand"
props["id"]       = 454

link = {}
link["ref"] = 3

addEntity = {}
addEntity["properties"] = props
addEntity["class"] = "Person"
addEntity["link"] = link

query = {}
query["AddEntity"] = addEntity

all_queries.append(query)

print "Query Sent:"
print(all_queries)

response, res_arr = db.query(all_queries)

The query sent will be:

    Query Sent:
    [
        {
            "FindEntity": {
                "_ref": 3,
                "class": "Hike",
                "constraints": {
                    "id": [ "==", 4543 ]
                }
            }
        },
        {
            "AddEntity": {
                "link": {
                    "ref": 3
                },
                "properties": {
                    "lastname": "Tom",
                    "name": "Lluhs",
                    "id": 0
                },
                "class": "Person"
            }
        },
        {
            "AddEntity": {
                "link": {
                    "ref": 3
                },
                "properties": {
                    "lastname": "Ferdinand",
                    "name": "Isof",
                    "id": 2
                },
                "class": "Person"
            }
        }
    ]

Note that nothing prevent us from inserting the "Hike" entity together with the "Person" entities all together in a single transaction. We use separate transactions just for demonstration purposes.

Now let's print the response we get from VDMS

response = json.loads(response)

print "VDMS Response:"
vdms.aux_print_json(response)

    VDMS Response:
    [
        {
            "FindEntity": {
                "status": 0
            }
        },
        {
            "AddEntity": {
                "status": 0
            }
        },
        {
            "AddEntity": {
                "status": 0
            }
        }
    ]