Wishlist for Velocity (CPT4?)

I went to Rob’s presentation on Velocity tonight, it’s a great presentation and a lot of information shared with audience.

I prepare a wishlist for Velocity (CPT4 or next beta release) and hope the Velocity team can take my wishlist into consideration.

1. A new method: bool DataCache.ContainsRegion(string region).
   • This method checks if the region exists in the named cache or not.
   • See my previous post for details.
2. Update the method DataCache.GetObjectsByAnyTag(List<DataCacheTag> tags, string region) so the keys of returned cache items are unique.
   • Make sure the cache key is not contained in the keys, then add the item into the collection.
   • See my previous post for example.
3. Make sure the default region name is not arbitratry.
   • DataCache.GetCacheItem Method – Gets a DataCacheItem object to retrieve all information associated with your cached object in the cluster.
   • DataCache.GetCacheItem (String) -> Gets a DataCacheItem object to retrieve all information associated with your cached object in the cluster.
   • DataCache.GetCacheItem (String, String) -> Gets a DataCacheItem object to retrieve all information associated with your cached object in the cluster. For objects stored in regions.
   • When using the DataCache.GetCacheItem (String) method (without region specified), the return object’s property -RegionName – is kind of arbitrary.
4. A new commad for administrators to create region in PowerShell.
   • New-CacheRegion [-CacheName] <CacheName> [-RegionName] <RegionName>
   • Example 1:
     • New-CacheRegion -CacheName Products -RegionName MyRegion -> this creates a region “MyRegion” in the named cache “Products”.
   • Example 2:
     • New-CacheRegion -RegionName MyRegion -> this creates a region “MyRegion” in the default cache “default”

Velocity (CTP3) – DataCache.GetObjectsByAnyTag Method

I was writing some code to experiment the Tag search in Velocity CTP3 and I found there is some small bug in one of the get objects by tag methods – DataCache.GetObjectsByAnyTag.

The definition of the method of DataCache.GetObjectsByAnyTag is:

Gets an enumerable list of all cached objects in the specified region that have any of the same tags in common.

For example I have 3 cache items:

Item 1: key = “111″, content = “aaa”, tag = “a”

Item 2: key = “222″, content = “bbb”, tag = “b”

Item 3: key = “333″, content = “ccc”, tag = “a,b,c”

Here are some scenarios:

(1) If I search with Tag “a” via DataCache.GetObjectsByAnyTag(<a>, “my_region”), I get:

Item 1: key = “111″, content = “aaa”, tag = “a”

Item 3: key = “333″, content = “ccc”, tag = “a,b,c”

(2) If I search with Tag “b” via DataCache.GetObjectsByAnyTag(<b>, “my_region”), I get:

Item 2: key = “222″, content = “bbb”, tag = “b”

(3) But if I search with Tags “a,b” via DataCache.GetObjectsByAnyTag(<a, b>, “my_region”), I get:

Item 1: key = “111″, content = “aaa”, tag = “a”

Item 3: key = “333″, content = “ccc”, tag = “a,b,c”

Item 3: key = “333″, content = “ccc”, tag = “a,b,c”

Item 2: key = “222″, content = “bbb”, tag = “b”

Here are some scenarios:

(1) If I search with Tag “a” via DataCache.GetObjectsByAnyTag(<a>, “my_region”), I get:

Item 1: key = “111″, content = “aaa”, tag = “a”

Item 3: key = “333″, content = “ccc”, tag = “a,b,c”

(2) If I search with Tag “b” via DataCache.GetObjectsByAnyTag(<b>, “my_region”), I get:

Item 2: key = “222″, content = “bbb”, tag = “b”

Item 3: key = “333″, content = “ccc”, tag = “a,b,c”

(3) But if I search with Tags “a,b” via DataCache.GetObjectsByAnyTag(<a, b>, “my_region”), I get:

Item 1: key = “111″, content = “aaa”, tag = “a”

Item 2: key = “222″, content = “bbb”, tag = “b”

Item 3: key = “333″, content = “ccc”, tag = “a,b,c”

Item 3: key = “333″, content = “ccc”, tag = “a,b,c”

In scenario (3), the item 3 has been added twice because its tags are “a,b,c” and I search by <a,b> (Any Tag).

I believe this method - DataCache.GetObjectsByAnyTag - should check if the cache key is contained in the collection, if not, then add it to the collection – unless the velocity team want the developers do the checking of duplicated key in the caller program.

I will list my code and some screenshots.

The first file is CacheWorker.cs:

using System;

using Microsoft.Data.Caching;

namespace VelocityTest

{

public class CacheWorker

{

public const string DEFAULT_CACHE_REGION = “Default_Cache_Region”;

private static object _synclock = new object();

private static CacheWorker _cacheWorker = null;

private static DataCacheFactory _cacheFactory = null;

private static DataCache _defaultCache = null;

private static DataCache _eventCache = null;

private CacheWorker()

{

}

public static CacheWorker Instance

{

get

{

lock (_synclock)

{

try

{

if (_cacheWorker == null)

{

_cacheWorker = new CacheWorker();

// we use configuration file

_cacheFactory = new DataCacheFactory();

// default cache

_defaultCache = _cacheFactory.GetDefaultCache();

_defaultCache.RemoveRegion(DEFAULT_CACHE_REGION);

_defaultCache.CreateRegion(DEFAULT_CACHE_REGION, true);

// names cache

_eventCache = _cacheFactory.GetCache(“Event2″);

}

return _cacheWorker;

}

catch (DataCacheException ex)

{

return null;

}

}

}

}

public DataCacheFactory CacheFactory

{

get { return _cacheFactory; }

}

public DataCache DefaultCache

{

get { return _defaultCache; }

}

public DataCache EventCache

{

get { return _eventCache; }

}

public DataCacheItemVersion AddCache(string key, object value, TimeSpan? timeout)

{

DataCacheItemVersion version = null;

if (timeout.HasValue)

{

version = _defaultCache.Put(key, value, timeout.Value);

}

else

{

version = _defaultCache.Put(key, value);

}

return version;

}

}

}

The second file is Default3.aspx page:

<%@ Page Language=”C#” AutoEventWireup=”true” CodeBehind=”Default3.aspx.cs” Inherits=”VelocityTest.Default3″ %>

<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.0 Transitional//EN” “http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd”>

<html xmlns=”http://www.w3.org/1999/xhtml” >

<head runat=”server”>

<title>Velocity – Tag Example</title>

</head>

<body>

<form id=”form1″ runat=”server”>

<p>

<h3>Velocity – Tag Example</h3>

<table border=”0″ cellpadding=”2″>

<tr>

<td><b>Cache Key</b></td>

<td>

<asp:TextBox ID=”txtCacheKey” runat=”server” />

<asp:RequiredFieldValidator ID=”vadCacheKey” runat=”server” ControlToValidate=”txtCacheKey” ErrorMessage=”* required” Display=”Dynamic” />

</td>

</tr>

<tr>

<td><b>Cache Content</b></td>

<td>

<asp:TextBox ID=”txtCacheContent” runat=”server” />

<asp:RequiredFieldValidator ID=”vadCacheContent” runat=”server” ControlToValidate=”txtCacheContent” ErrorMessage=”* required” Display=”Dynamic” />

</td>

</tr>

<tr>

<td><b>Cache Tags</b></td>

<td><asp:TextBox ID=”txtCacheTag” runat=”server” />(Tags are seperated by comma)</td>

</tr>

<tr>

<td>&nbsp;</td>

<td>

<asp:Button ID=”btnCancel” runat=”server” Text=”Cancel” CausesValidation=”false” />

<asp:Button ID=”btnSave” runat=”server” Text=”Save” />

</td>

</tr>

</table>

</p>

<hr />

<p>

<table border=”0″ cellpadding=”2″>

<tr>

<td><b>Search Method:</b></td>

<td>

<asp:RadioButtonList ID=”radSearchMethodList” runat=”server” RepeatDirection=”Horizontal”>

<asp:ListItem Text=”No Tag” Value=”NoTag” />

<asp:ListItem Text=”All Tags” Value=”AllTags” />

<asp:ListItem Text=”Any Tag” Value=”AnyTag” />

<asp:ListItem Text=”One Tag” Value=”OneTag” />

</asp:RadioButtonList>

</td>

</tr>

<tr>

<td><b>Search Tags:</b></td>

<td><asp:TextBox ID=”txtSearchTag” runat=”server” />(Tags are seperated by comma)</td>

</tr>

<tr>

<td>&nbsp;</td>

<td>

<asp:Button ID=”btnClearSearch” runat=”server” Text=”Clear” CausesValidation=”false” />

<asp:Button ID=”btnSearch” runat=”server” Text=”Search” CausesValidation=”false” />

</td>

</tr>

</table>

</p>

<hr />

<p>

<asp:GridView ID=”gvCache” runat=”server”

AutoGenerateColumns=”false”

EmptyDataText=”No cache data”>

<Columns>

<asp:TemplateField HeaderText=”Key” ShowHeader=”true”>

<ItemTemplate>

<asp:Label ID=”lblCacheKey” runat=”server” />

</ItemTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText=”Content” ShowHeader=”true”>

<ItemTemplate>

<asp:Label ID=”lblCacheContent” runat=”server” />

</ItemTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText=”Tags” ShowHeader=”true”>

<ItemTemplate>

<asp:Label ID=”lblCacheTag” runat=”server” />

</ItemTemplate>

</asp:TemplateField>

</Columns>

</asp:GridView>

</p>

</form>

</body>

</html>

The third file is Default3.aspx.cs code-behind:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Web;

using System.Web.UI;

using System.Web.UI.WebControls;

using System.Text;

using Microsoft.Data.Caching;

namespace VelocityTest

{

[Serializable]

public class MyCacheItem

{

public string Key { get; set; }

public string Content { get; set; }

public List<DataCacheTag> Tags { get; set; }

public MyCacheItem(string key, string conent)

{

Key = key;

Content = conent;

Tags = new List<DataCacheTag>();

}

public MyCacheItem(string key, string conent, string[] tags)

{

Key = key;

Content = conent;

Tags = new List<DataCacheTag>();

foreach (string tag in tags)

{

Tags.Add(new DataCacheTag(tag));

}

}

public string[] GetTags()

{

string[] tags = null;

if (Tags != null && Tags.Count > 0)

{

tags = new string[Tags.Count];

int i = 0;

foreach (DataCacheTag tag in Tags)

{

tags[i++] = tag.ToString();

}

}

return tags;

}

}

public enum TagSearchMethod

{

NoTag,

AllTags,

AnyTag,

OneTag

}

public partial class Default3 : System.Web.UI.Page

{

protected const string DEFAULT_DELIMITER = “,”;

protected DataCacheFactory _factory = CacheWorker.Instance.CacheFactory;

protected DataCache _cache = CacheWorker.Instance.DefaultCache;

protected void Page_Load(object sender, EventArgs e)

{

btnSave.Click += new EventHandler(btnSave_Click);

btnCancel.Click += new EventHandler(btnCancel_Click);

btnClearSearch.Click += new EventHandler(btnClearSearch_Click);

btnSearch.Click += new EventHandler(btnSearch_Click);

gvCache.RowDataBound += new GridViewRowEventHandler(gvCache_RowDataBound);

gvCache.DataSource = GetCacheDataSource(TagSearchMethod.NoTag, null);

gvCache.DataBind();

}

protected List<MyCacheItem> GetCacheDataSource(TagSearchMethod method, List<DataCacheTag> tags)

{

List<MyCacheItem> items = new List<MyCacheItem>();

IEnumerable<KeyValuePair<string, Object>> cachePairs = null;

if (method == TagSearchMethod.NoTag)

{

cachePairs = _cache.GetObjectsInRegion(CacheWorker.DEFAULT_CACHE_REGION);

}

else if (method == TagSearchMethod.AllTags)

{

cachePairs = _cache.GetObjectsByAllTags(tags, CacheWorker.DEFAULT_CACHE_REGION);

}

else if (method == TagSearchMethod.AnyTag)

{

cachePairs = _cache.GetObjectsByAnyTag(tags, CacheWorker.DEFAULT_CACHE_REGION);

}

else if (method == TagSearchMethod.OneTag)

{

cachePairs = _cache.GetObjectsByTag(tags[0], CacheWorker.DEFAULT_CACHE_REGION);

}

if (cachePairs != null)

{

foreach (KeyValuePair<string, object> item in cachePairs)

{

items.Add((MyCacheItem)item.Value);

}

}

return items;

}

protected void gvCache_RowDataBound(object sender, GridViewRowEventArgs e)

{

if (e.Row.RowType == DataControlRowType.DataRow)

{

MyCacheItem data = e.Row.DataItem as MyCacheItem;

if (data != null)

{

Label lblCacheKey = e.Row.FindControl(“lblCacheKey”) as Label;

if (lblCacheKey != null)

{

lblCacheKey.Text = data.Key;

}

Label lblCacheContent = e.Row.FindControl(“lblCacheContent”) as Label;

if (lblCacheContent != null)

{

lblCacheContent.Text = data.Content;

}

Label lblCacheTag = e.Row.FindControl(“lblCacheTag”) as Label;

if (lblCacheTag != null)

{

if (data.Tags != null)

{

lblCacheTag.Text = String.Join(“,”, data.GetTags());

}

else

{

lblCacheTag.Text = “&nbsp;”;

}

}

}

}

}

protected void btnSearch_Click(object sender, EventArgs e)

{

if (radSearchMethodList.SelectedItem != null)

{

TagSearchMethod method = (TagSearchMethod)Enum.Parse(typeof(TagSearchMethod), radSearchMethodList.SelectedValue);

List<DataCacheTag> tags = GetTags(txtSearchTag.Text.Trim());

gvCache.DataSource = GetCacheDataSource(method, tags);

}

else

{

gvCache.DataSource = GetCacheDataSource(TagSearchMethod.NoTag, null);

}

gvCache.DataBind();

}

protected void btnClearSearch_Click(object sender, EventArgs e)

{

Response.Redirect(Request.RawUrl);

}

protected void btnCancel_Click(object sender, EventArgs e)

{

Response.Redirect(Request.RawUrl);

}

protected void btnSave_Click(object sender, EventArgs e)

{

if (!String.IsNullOrEmpty(txtCacheKey.Text.Trim()) &&

!String.IsNullOrEmpty(txtCacheContent.Text.Trim()))

{

MyCacheItem item = null;

string[] tags = null;

if (!String.IsNullOrEmpty(txtCacheTag.Text.Trim()))

{

tags = (string[])txtCacheTag.Text.Trim().Split(DEFAULT_DELIMITER.ToCharArray());

}

if (tags != null && tags.Length > 0)

{

item = new MyCacheItem(txtCacheKey.Text.Trim(), txtCacheContent.Text.Trim(), tags);

}

else

{

item = new MyCacheItem(txtCacheKey.Text.Trim(), txtCacheContent.Text.Trim());

}

_cache.Put(item.Key, item, item.Tags, CacheWorker.DEFAULT_CACHE_REGION);

}

gvCache.DataSource = GetCacheDataSource(TagSearchMethod.NoTag, null);

gvCache.DataBind();

}

protected List<DataCacheTag> GetTags(string tagString)

{

List<DataCacheTag> tags = new List<DataCacheTag>();

string[] items = tagString.Split(DEFAULT_DELIMITER.ToCharArray());

foreach (string item in items)

{

tags.Add(new DataCacheTag(item));

}

return tags;

}

}

}

The following are screenshots.

This screenshot has nothing is cache.

This screenshot has 3 cache items.

This screenshot is search by AllTags <a>.

This screenshot is search by AllTags <a, b>.

This screenshot is search by AnyTag <a>.

This screenshot is search by AnyTag <b>.

This screenshot is search by Tag <a, b> – there are 4 cache items!

Velocity (CTP3) – How do I know if a cache region is created?

In Velocity (CTP3) we can create, remove, and clean a cache region programmatically by calling the following methods:

• DataCache.CreateRegion
• DataCache.RemoveRegion
• DataCache.ClearRegion

But there is no method to indicate if a cache region is created or not; so if I create a region which has been created already, an exception is thrown with the error code DataCacheErrorCode.RegionAlreadyExsits.

So far the walkaround is remove the cache region before creating it:

_defaultCache.RemoveRegion(DEFAULT_CACHE_REGION);

_defaultCache.CreateRegion(DEFAULT_CACHE_REGION, true);

But this is not a good approach; so I hope the Velocity team will add the feature in the next release to check if a cache region is created.

Use Velocity (CTP3) as Session State Provider

The blog shows how to configure web.config to use Velocity as session state provider, but it only works for CTP2.

I did some experiment and found out the following configuration in web.config will work in Velocity CTP3:

<sessionState mode=“Custom“ customProvider=“SessionStoreProvider“>

<providers>

<add name=“SessionStoreProvider“ type=“Microsoft.Data.Caching.DataCacheSessionStoreProvider, ClientLibrary“ />

</providers>

</sessionState>

Notification callback in Velocity CTP3

This is an example of how to make the Notification callback work in Velocity CTP3.

Here is my web.config – the cache is a routing client:

<?xml version=“1.0“?>

<configuration>

<configSections>

<!– required to read the <dataCacheClient> element –>

<section name=“dataCacheClient“

type=“Microsoft.Data.Caching.DataCacheClientSection,CacheBaseLibrary“

allowLocation=“true“

allowDefinition=“Everywhere“/>

<!– required to read the <fabric> element, when present –>

<section name=“fabric“

type=“System.Data.Fabric.Common.ConfigFile,FabricCommon“

allowLocation=“true“

allowDefinition=“Everywhere“/>

<!– routing client–>

<dataCacheClient deployment=“routing“>

<clientNotification pollInterval=“300“ />

<!– cache host(s) –>

<hosts>

<host

name=“VIRTUALB-UJT42H“

cachePort=“22233“

cacheHostName=“DistributedCacheService“/>

</hosts>

</dataCacheClient>

</configuration>

Here is the cache cluster configuration via the command Export-CacheClusterConfig:

<?xml version=“1.0“ encoding=“utf-8“?>

<configuration>

<configSections>

<section name=“dataCache“ type=“Microsoft.Data.Caching.DataCacheSection, CacheBaseLibrary, Version=1.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91“ />

</configSections>

<dataCache cluster=“Velocity_Cluster_1“ size=“Small“>

<caches>

<cache type=“partitioned“ consistency=“strong“ name=“default“>

<policy>

<eviction type=“lru“ />

<expiration defaultTTL=“10“ isExpirable=“true“ />

<serverNotification isEnabled=“true“ />

</policy>

</cache>

<cache type=“partitioned“ consistency=“strong“ name=“default_2“>

<policy>

<eviction type=“lru“ />

<expiration defaultTTL=“10“ isExpirable=“true“ />

<serverNotification isEnabled=“true“ />

</policy>

</cache>

</caches>

<hosts>

<host clusterPort=“22234“ hostId=“1825498580“ size=“1024“ quorumHost=“true“

name=“VIRTUALB-UJT42H“ cacheHostName=“DistributedCacheService“

cachePort=“22233“ />

</hosts>

<advancedProperties>

<partitionStoreConnectionSettings providerName=“System.Data.SqlClient“

connectionString=“Data Source=VIRTUALB-UJT42H\SQLEXPRESS;Initial Catalog=Velocity_Shared_1;User Id=Not_sa;Password=ForYourEyesOnly;“

leadHostManagement=“false“ />

</advancedProperties>

</dataCache>

</configuration>

Here is the code of CacheWorker.cs (kind of helper class with singleton pattern):

using System;

using Microsoft.Data.Caching;

namespace VelocityTest

{

public class CacheWorker

{

private static object _synclock = new object();

private static CacheWorker _cacheWorker = null;

private static DataCacheFactory _cacheFactory = null;

private static DataCache _defaultCache = null;

private CacheWorker()

{

}

public static CacheWorker Instance

{

get

{

lock (_synclock)

{

try

{

if (_cacheWorker == null)

{

_cacheWorker = new CacheWorker();

// we use configuration file

_cacheFactory = new DataCacheFactory();

// default cache

_defaultCache = _cacheFactory.GetDefaultCache();

}

return _cacheWorker;

}

catch (DataCacheException ex)

{

return null;

}

}

}

}

public DataCacheFactory CacheFactory

{

get { return _cacheFactory; }

}

public DataCache DefaultCache

{

get { return _defaultCache; }

}

}

}

Here is the partial code-behind of the test page:

public partial class _Default : System.Web.UI.Page

{

public const string CACHE_KEY = “{8768036E-2B99-4563-8BA5-C2D07B5B6023}”;

protected static DataCacheFactory _factory = CacheWorker.Instance.CacheFactory;

protected static DataCache _cache = CacheWorker.Instance.DefaultCache;

protected void Page_Load(object sender, EventArgs e)

{

if (!Page.IsPostBack)

{

DataCacheOperation filter = DataCacheOperation.AddItem | DataCacheOperation.RemoveItem | DataCacheOperation.ReplaceItem | DataCacheOperation.ClearRegion | DataCacheOperation.CreateRegion | DataCacheOperation.RemoveRegion;

DataCacheNotificationDescriptor dn = _cache.AddCacheLevelCallback(filter, OnCacheNotificationReceived);

SetCache(MyPerson, true);

ShowCache(GetCache());

}

btnUpdate.Click += new EventHandler(btnUpdate_Click);

btnRefresh.Click += new EventHandler(btnRefresh_Click);

btnRemove.Click += new EventHandler(btnRemove_Click);

btnGet.Click += new EventHandler(btnGet_Click);

btnAnotherPage.Click += new EventHandler(btnAnotherPage_Click);

}

// other code is here….

public void OnCacheNotificationReceived(string cacheName, string regionName, string key, DataCacheItemVersion version, DataCacheOperation cacheOperation, DataCacheNotificationDescriptor nd)

{

StringBuilder sb = new StringBuilder();

sb.Append(“cacheName: “ + cacheName + Environment.NewLine);

sb.Append(“regionName: “ + regionName + Environment.NewLine);

sb.Append(“key: “ + key + Environment.NewLine);

sb.Append(“cacheOperation: “ + cacheOperation.ToString() + Environment.NewLine);

txtMessageBox.Text = sb.ToString();

}

}

Basically the configuration has the Notification enabled and set the client as routing client. The callback is fired when ever there is a change in cache item or region.